diff --git a/plugins/ics-viewer/ical.es5.min.cjs b/plugins/ics-viewer/ical.es5.min.cjs
deleted file mode 100644
index f94cf9767..000000000
--- a/plugins/ics-viewer/ical.es5.min.cjs
+++ /dev/null
@@ -1,5 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/.
- * Portions Copyright (C) Philipp Kewisch */
-!function(t,e){"object"==typeof exports&&"undefined"!=typeof module?module.exports=e():"function"==typeof define&&define.amd?define(e):(t="undefined"!=typeof globalThis?globalThis:t||self).ICAL=e()}(this,(function(){"use strict";function t(t,e,n){if("function"==typeof t?t===e:t.has(e))return arguments.length<3?e:n;throw new TypeError("Private element is not present on this object")}function e(t,e,r){return e=h(e),function(t,e){if(e&&("object"==typeof e||"function"==typeof e))return e;if(void 0!==e)throw new TypeError("Derived constructors may only return object or undefined");return function(t){if(void 0===t)throw new ReferenceError("this hasn't been initialised - super() hasn't been called");return t}(t)}(t,n()?Reflect.construct(e,r||[],h(t).constructor):e.apply(t,r))}function n(){try{var t=!Boolean.prototype.valueOf.call(Reflect.construct(Boolean,[],(function(){})))}catch(t){}return(n=function(){return!!t})()}function r(t){var e=function(t,e){if("object"!=typeof t||!t)return t;var 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t.day=1,t.month=1,t.isDate=!0,t.hour=0,t.minute=0,t.second=0,t}},{key:"endOfYear",value:function(){var t=this.clone();return t.day=31,t.month=12,t.isDate=!0,t.hour=0,t.minute=0,t.second=0,t}},{key:"startDoyWeek",value:function(t){var n=t||e.SUNDAY,r=this.dayOfWeek()-n;return r<0&&(r+=7),this.dayOfYear()-r}},{key:"getDominicalLetter",value:function(){return e.getDominicalLetter(this.year)}},{key:"nthWeekDay",value:function(t,n){var r,i=e.daysInMonth(this.month,this.year),a=n,s=0,o=this.clone();if(a>=0){o.day=1,0!=a&&a--,s=o.day;var u=t-o.dayOfWeek();u<0&&(u+=7),s+=u,s-=t,r=t}else{o.day=i,a++,(r=o.dayOfWeek()-t)<0&&(r+=7),r=i-r}return s+(r+=7*a)}},{key:"isNthWeekDay",value:function(t,e){var n=this.dayOfWeek();return 0===e&&n===t||this.nthWeekDay(t,e)===this.day}},{key:"weekNumber",value:function(t){var n,r=(this.year<<12)+(this.month<<8)+(this.day<<3)+t;if(r in e._wnCache)return e._wnCache[r];var i=this.clone();i.isDate=!0;var a=this.year;12==i.month&&i.day>25?(n=e.weekOneStarts(a+1,t),i.compare(n)<0?n=e.weekOneStarts(a,t):a++):(n=e.weekOneStarts(a,t),i.compare(n)<0&&(n=e.weekOneStarts(--a,t)));var s=H(i.subtractDate(n).toSeconds()/86400/7)+1;return e._wnCache[r]=s,s}},{key:"addDuration",value:function(t){var e=t.isNegative?-1:1,n=this.second,r=this.minute,i=this.hour,a=this.day;n+=e*t.seconds,r+=e*t.minutes,i+=e*t.hours,a+=e*t.days,a+=7*e*t.weeks,this.second=n,this.minute=r,this.hour=i,this.day=a,this._cachedUnixTime=null}},{key:"subtractDate",value:function(t){var e=this.toUnixTime()+this.utcOffset(),n=t.toUnixTime()+t.utcOffset();return T.fromSeconds(e-n)}},{key:"subtractDateTz",value:function(t){var e=this.toUnixTime(),n=t.toUnixTime();return T.fromSeconds(e-n)}},{key:"compare",value:function(t){var e=this.toUnixTime(),n=t.toUnixTime();return e>n?1:n>e?-1:0}},{key:"compareDateOnlyTz",value:function(t,n){var r=this.convertToZone(n),i=t.convertToZone(n),a=0;return 0!=(a=e._cmp_attr(r,i,"year"))||0!=(a=e._cmp_attr(r,i,"month"))||(a=e._cmp_attr(r,i,"day")),a}},{key:"convertToZone",value:function(t){var e=this.clone(),n=this.zone.tzid==t.tzid;return this.isDate||n||C.convert_time(e,this.zone,t),e.zone=t,e}},{key:"utcOffset",value:function(){return this.zone==C.localTimezone||this.zone==C.utcTimezone?0:this.zone.utcOffset(this)}},{key:"toICALString",value:function(){var t=this.toString();return t.length>10?Ct.icalendar.value["date-time"].toICAL(t):Ct.icalendar.value.date.toICAL(t)}},{key:"toString",value:function(){var t=this.year+"-"+R(this.month)+"-"+R(this.day);return this.isDate||(t+="T"+R(this.hour)+":"+R(this.minute)+":"+R(this.second),this.zone===C.utcTimezone&&(t+="Z")),t}},{key:"toJSDate",value:function(){return this.zone==C.localTimezone?this.isDate?new Date(this.year,this.month-1,this.day):new Date(this.year,this.month-1,this.day,this.hour,this.minute,this.second,0):new Date(1e3*this.toUnixTime())}},{key:"_normalize",value:function(){return this._time.isDate&&(this._time.hour=0,this._time.minute=0,this._time.second=0),this.adjust(0,0,0,0),this}},{key:"adjust",value:function(t,n,r,i,a){var s,o,u,l,h,c,f,d=0,y=0,m=a||this._time;if(m.isDate||(u=m.second+i,m.second=u%60,s=H(u/60),m.second<0&&(m.second+=60,s--),l=m.minute+r+s,m.minute=l%60,o=H(l/60),m.minute<0&&(m.minute+=60,o--),h=m.hour+n+o,m.hour=h%24,d=H(h/24),m.hour<0&&(m.hour+=24,d--)),m.month>12?y=H((m.month-1)/12):m.month<1&&(y=H(m.month/12)-1),m.year+=y,m.month-=12*y,(c=m.day+t+d)>0)for(;!(c<=(f=e.daysInMonth(m.month,m.year)));)m.month++,m.month>12&&(m.year++,m.month=1),c-=f;else for(;c<=0;)1==m.month?(m.year--,m.month=12):m.month--,c+=e.daysInMonth(m.month,m.year);return m.day=c,this._cachedUnixTime=null,this}},{key:"fromUnixTime",value:function(t){this.zone=C.utcTimezone;var e=new 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t=this.toSeconds(),e=this.factor;t<-43200;)t+=97200;for(;t>50400;)t-=97200;this.fromSeconds(t),0==t&&(this.factor=e)}},{key:"toICALString",value:function(){return Ct.icalendar.value["utc-offset"].toICAL(this.toString())}},{key:"toString",value:function(){return(1==this.factor?"+":"-")+R(this.hours)+":"+R(this.minutes)}}],[{key:"fromString",value:function(e){var n={};return n.factor="+"===e[0]?1:-1,n.hours=L(e.slice(1,3)),n.minutes=L(e.slice(4,6)),new t(n)}},{key:"fromSeconds",value:function(e){var n=new t;return n.fromSeconds(e),n}}])}(),q=function(t){function n(t,r,i){var s;return a(this,n),u(s=e(this,n,[t,r]),"icalclass","vcardtime"),u(s,"icaltype","date-and-or-time"),s.icaltype=i||"date-and-or-time",s}return l(n,t),o(n,[{key:"clone",value:function(){return new n(this._time,this.zone,this.icaltype)}},{key:"_normalize",value:function(){return this}},{key:"utcOffset",value:function(){return this.zone instanceof K?this.zone.toSeconds():k.prototype.utcOffset.apply(this,arguments)}},{key:"toICALString",value:function(){return Ct.vcard.value[this.icaltype].toICAL(this.toString())}},{key:"toString",value:function(){var t,e=this.year,n=this.month,r=this.day,i=this.hour,a=this.minute,s=this.second,o=null!==n,u=null!==r,l=null!==i,h=null!==a,c=null!==s,f=(null!==e?R(e)+(o||u?"-":""):o||u?"--":"")+(o?R(n):"")+(u?"-"+R(r):""),d=(l?R(i):"-")+(l&&h?":":"")+(h?R(a):"")+(l||h?"":"-")+(h&&c?":":"")+(c?R(s):"");if(this.zone===C.utcTimezone)t="Z";else if(this.zone instanceof K)t=this.zone.toString();else if(this.zone===C.localTimezone)t="";else if(this.zone instanceof C){t=K.fromSeconds(this.zone.utcOffset(this)).toString()}else t="";switch(this.icaltype){case"time":return d+t;case"date-and-or-time":case"date-time":return f+("--"==d?"":"T"+d+t);case"date":return f}return null}}],[{key:"fromDateAndOrTimeString",value:function(t,e){function r(t,e,n){return t?L(t.slice(e,e+n)):null}var i=t.split("T"),a=i[0],s=i[1],o=s?Ct.vcard.value.time._splitZone(s):[],u=o[0],l=o[1],h=a?a.length:0,c=l?l.length:0,f=a&&"-"==a[0]&&"-"==a[1],d=l&&"-"==l[0];return new n({year:f?null:r(a,0,4),month:!f||4!=h&&7!=h?7==h||10==h?r(a,5,2):null:r(a,2,2),day:5==h?r(a,3,2):7==h&&f?r(a,5,2):10==h?r(a,8,2):null,hour:d?null:r(l,0,2),minute:d&&3==c?r(l,1,2):c>4?r(l,d?1:3,2):null,second:4==c?r(l,2,2):6==c?r(l,4,2):8==c?r(l,6,2):null},u="Z"==u?C.utcTimezone:u&&":"==u[3]?K.fromString(u):null,e)}}])}(k),J=function(){function t(e){a(this,t),u(this,"completed",!1),u(this,"rule",null),u(this,"dtstart",null),u(this,"last",null),u(this,"occurrence_number",0),u(this,"by_indices",null),u(this,"initialized",!1),u(this,"by_data",null),u(this,"days",null),u(this,"days_index",0),this.fromData(e)}return o(t,[{key:"fromData",value:function(t){if(this.rule=z(t.rule,tt),!this.rule)throw new Error("iterator requires a (ICAL.Recur) rule");if(this.dtstart=z(t.dtstart,k),!this.dtstart)throw new Error("iterator requires a (ICAL.Time) dtstart");t.by_data?this.by_data=t.by_data:this.by_data=j(this.rule.parts,!0),t.occurrence_number&&(this.occurrence_number=t.occurrence_number),this.days=t.days||[],t.last&&(this.last=z(t.last,k)),this.by_indices=t.by_indices,this.by_indices||(this.by_indices={BYSECOND:0,BYMINUTE:0,BYHOUR:0,BYDAY:0,BYMONTH:0,BYWEEKNO:0,BYMONTHDAY:0}),this.initialized=t.initialized||!1,this.initialized||this.init()}},{key:"init",value:function(){this.initialized=!0,this.last=this.dtstart.clone();var t=this.by_data;if("BYDAY"in t&&this.sort_byday_rules(t.BYDAY),"BYYEARDAY"in t&&("BYMONTH"in t||"BYWEEKNO"in t||"BYMONTHDAY"in t||"BYDAY"in t))throw new Error("Invalid BYYEARDAY rule");if("BYWEEKNO"in t&&"BYMONTHDAY"in t)throw new Error("BYWEEKNO does not fit to BYMONTHDAY");if("MONTHLY"==this.rule.freq&&("BYYEARDAY"in t||"BYWEEKNO"in t))throw new Error("For MONTHLY recurrences neither BYYEARDAY nor BYWEEKNO may appear");if("WEEKLY"==this.rule.freq&&("BYYEARDAY"in t||"BYMONTHDAY"in t))throw new Error("For WEEKLY recurrences neither BYMONTHDAY nor BYYEARDAY may appear");if("YEARLY"!=this.rule.freq&&"BYYEARDAY"in t)throw new Error("BYYEARDAY may only appear in YEARLY rules");this.last.second=this.setup_defaults("BYSECOND","SECONDLY",this.dtstart.second),this.last.minute=this.setup_defaults("BYMINUTE","MINUTELY",this.dtstart.minute),this.last.hour=this.setup_defaults("BYHOUR","HOURLY",this.dtstart.hour);var e=this.last.day=this.setup_defaults("BYMONTHDAY","DAILY",this.dtstart.day);if(this.last.month=this.setup_defaults("BYMONTH","MONTHLY",this.dtstart.month),"WEEKLY"==this.rule.freq)if("BYDAY"in t){var n=d(this.ruleDayOfWeek(t.BYDAY[0],this.rule.wkst),2)[1],r=n-this.last.dayOfWeek(this.rule.wkst);(this.last.dayOfWeek(this.rule.wkst)<n&&r>=0||r<0)&&(this.last.day+=r)}else{var i=tt.numericDayToIcalDay(this.dtstart.dayOfWeek());t.BYDAY=[i]}if("YEARLY"==this.rule.freq){for(;this.expand_year_days(this.last.year),!(this.days.length>0);)this.increment_year(this.rule.interval);this._nextByYearDay()}if("MONTHLY"==this.rule.freq&&this.has_by_data("BYDAY")){var a,s=null,o=this.last.clone(),u=k.daysInMonth(this.last.month,this.last.year),l=p(this.by_data.BYDAY);try{for(l.s();!(a=l.n()).done;){var h=a.value;this.last=o.clone();var c=d(this.ruleDayOfWeek(h),2),f=c[0],y=c[1],m=this.last.nthWeekDay(y,f);if(f>=6||f<=-6)throw new Error("Malformed values in BYDAY part");if(m>u||m<=0){if(s&&s.month==o.month)continue;for(;m>u||m<=0;)this.increment_month(),u=k.daysInMonth(this.last.month,this.last.year),m=this.last.nthWeekDay(y,f)}this.last.day=m,(!s||this.last.compare(s)<0)&&(s=this.last.clone())}}catch(t){l.e(t)}finally{l.f()}if(this.last=s.clone(),this.has_by_data("BYMONTHDAY")&&this._byDayAndMonthDay(!0),this.last.day>u||0==this.last.day)throw new Error("Malformed values in BYDAY part")}else if(this.has_by_data("BYMONTHDAY")){this.last.day=1;var v=k.daysInMonth(this.last.month,this.last.year);if(e<0)this.last.day=v+e+1;else if(this.by_data.BYMONTHDAY[0]>v){if(!this.next_month()&&!this.next_month()&&!this.next_month())throw new Error("No possible occurrences")}else this.last.day=e}}},{key:"next",value:function(){var t,e=this.last?this.last.clone():null;if(this.rule.count&&this.occurrence_number>=this.rule.count||this.rule.until&&this.last.compare(this.rule.until)>0)return this.completed=!0,null;if(0==this.occurrence_number&&this.last.compare(this.dtstart)>=0)return this.occurrence_number++,this.last;do{switch(t=1,this.rule.freq){case"SECONDLY":this.next_second();break;case"MINUTELY":this.next_minute();break;case"HOURLY":this.next_hour();break;case"DAILY":this.next_day();break;case"WEEKLY":this.next_week();break;case"MONTHLY":t=this.next_month();break;case"YEARLY":this.next_year();break;default:return null}}while(!this.check_contracting_rules()||this.last.compare(this.dtstart)<0||!t);if(0==this.last.compare(e))throw new Error("Same occurrence found twice, protecting you from death by recursion");return this.rule.until&&this.last.compare(this.rule.until)>0?(this.completed=!0,null):(this.occurrence_number++,this.last)}},{key:"next_second",value:function(){return this.next_generic("BYSECOND","SECONDLY","second","minute")}},{key:"increment_second",value:function(t){return this.increment_generic(t,"second",60,"minute")}},{key:"next_minute",value:function(){return this.next_generic("BYMINUTE","MINUTELY","minute","hour","next_second")}},{key:"increment_minute",value:function(t){return this.increment_generic(t,"minute",60,"hour")}},{key:"next_hour",value:function(){return this.next_generic("BYHOUR","HOURLY","hour","monthday","next_minute")}},{key:"increment_hour",value:function(t){this.increment_generic(t,"hour",24,"monthday")}},{key:"next_day",value:function(){var t="DAILY"==this.rule.freq;return 0==this.next_hour()||(t?this.increment_monthday(this.rule.interval):this.increment_monthday(1)),0}},{key:"next_week",value:function(){var t=0;if(0==this.next_weekday_by_week())return t;if(this.has_by_data("BYWEEKNO")){this.by_indices.BYWEEKNO++,this.by_indices.BYWEEKNO==this.by_data.BYWEEKNO.length&&(this.by_indices.BYWEEKNO=0,t=1),this.last.month=1,this.last.day=1;var e=this.by_data.BYWEEKNO[this.by_indices.BYWEEKNO];this.last.day+=7*e,t&&this.increment_year(1)}else this.increment_monthday(7*this.rule.interval);return t}},{key:"normalizeByMonthDayRules",value:function(t,e,n){for(var r,i=k.daysInMonth(e,t),a=[],s=0,o=n.length;s<o;s++)if(r=n[s],!(Math.abs(r)>i)){if(r<0)r=i+(r+1);else if(0===r)continue;-1===a.indexOf(r)&&a.push(r)}return a.sort((function(t,e){return t-e}))}},{key:"_byDayAndMonthDay",value:function(t){var e,n,r,i,a=this.by_data.BYDAY,s=0,o=a.length,u=0,l=this,h=this.last.day;function c(){for(i=k.daysInMonth(l.last.month,l.last.year),e=l.normalizeByMonthDayRules(l.last.year,l.last.month,l.by_data.BYMONTHDAY),r=e.length;e[s]<=h&&(!t||e[s]!=h)&&s<r-1;)s++}function f(){h=0,l.increment_month(),s=0,c()}c(),t&&(h-=1);for(var d=48;!u&&d;)if(d--,(n=h+1)>i)f();else{var y=e[s++];if(y>=n){h=y;for(var m=0;m<o;m++){var p=this.ruleDayOfWeek(a[m]),v=p[0],_=p[1];if(this.last.day=h,this.last.isNthWeekDay(_,v)){u=1;break}}u||s!==r||f()}else f()}if(d<=0)throw new Error("Malformed values in BYDAY combined with BYMONTHDAY parts");return u}},{key:"next_month",value:function(){var t=1;if(0==this.next_hour())return t;if(this.has_by_data("BYDAY")&&this.has_by_data("BYMONTHDAY"))t=this._byDayAndMonthDay();else if(this.has_by_data("BYDAY")){var e,n=k.daysInMonth(this.last.month,this.last.year),r=0,i=0;if(this.has_by_data("BYSETPOS")){for(var a=this.last.day,s=1;s<=n;s++)this.last.day=s,this.is_day_in_byday(this.last)&&(i++,s<=a&&r++);this.last.day=a}for(t=0,e=this.last.day+1;e<=n;e++)if(this.last.day=e,this.is_day_in_byday(this.last)&&(!this.has_by_data("BYSETPOS")||this.check_set_position(++r)||this.check_set_position(r-i-1))){t=1;break}e>n&&(this.last.day=1,this.increment_month(),this.is_day_in_byday(this.last)?this.has_by_data("BYSETPOS")&&!this.check_set_position(1)||(t=1):t=0)}else if(this.has_by_data("BYMONTHDAY")){this.by_indices.BYMONTHDAY++,this.by_indices.BYMONTHDAY>=this.by_data.BYMONTHDAY.length&&(this.by_indices.BYMONTHDAY=0,this.increment_month());var o=k.daysInMonth(this.last.month,this.last.year),u=this.by_data.BYMONTHDAY[this.by_indices.BYMONTHDAY];u<0&&(u=o+u+1),u>o?(this.last.day=1,t=this.is_day_in_byday(this.last)):this.last.day=u}else{this.increment_month();var l=k.daysInMonth(this.last.month,this.last.year);this.by_data.BYMONTHDAY[0]>l?t=0:this.last.day=this.by_data.BYMONTHDAY[0]}return t}},{key:"next_weekday_by_week",value:function(){var t=0;if(0==this.next_hour())return t;if(!this.has_by_data("BYDAY"))return 1;for(;;){var e=new k;this.by_indices.BYDAY++,this.by_indices.BYDAY==Object.keys(this.by_data.BYDAY).length&&(this.by_indices.BYDAY=0,t=1);var n=this.by_data.BYDAY[this.by_indices.BYDAY],r=this.ruleDayOfWeek(n)[1];(r-=this.rule.wkst)<0&&(r+=7),e.year=this.last.year,e.month=this.last.month,e.day=this.last.day;var i=e.startDoyWeek(this.rule.wkst);if(!(r+i<1)||t){var a=k.fromDayOfYear(i+r,this.last.year);return this.last.year=a.year,this.last.month=a.month,this.last.day=a.day,t}}}},{key:"next_year",value:function(){if(0==this.next_hour())return 0;if(++this.days_index==this.days.length){this.days_index=0;do{this.increment_year(this.rule.interval),this.expand_year_days(this.last.year)}while(0==this.days.length)}return this._nextByYearDay(),1}},{key:"_nextByYearDay",value:function(){var t=this.days[this.days_index],e=this.last.year;t<1&&(t+=1,e+=1);var n=k.fromDayOfYear(t,e);this.last.day=n.day,this.last.month=n.month}},{key:"ruleDayOfWeek",value:function(t,e){var n=t.match(/([+-]?[0-9])?(MO|TU|WE|TH|FR|SA|SU)/);return n?[parseInt(n[1]||0,10),t=tt.icalDayToNumericDay(n[2],e)]:[0,0]}},{key:"next_generic",value:function(t,e,n,r,i){var a=t in this.by_data,s=this.rule.freq==e,o=0;if(i&&0==this[i]())return o;if(a){this.by_indices[t]++;var u=this.by_data[t];this.by_indices[t]==u.length&&(this.by_indices[t]=0,o=1),this.last[n]=u[this.by_indices[t]]}else s&&this["increment_"+n](this.rule.interval);return a&&o&&s&&this["increment_"+r](1),o}},{key:"increment_monthday",value:function(t){for(var e=0;e<t;e++){var n=k.daysInMonth(this.last.month,this.last.year);this.last.day++,this.last.day>n&&(this.last.day-=n,this.increment_month())}}},{key:"increment_month",value:function(){if(this.last.day=1,this.has_by_data("BYMONTH"))this.by_indices.BYMONTH++,this.by_indices.BYMONTH==this.by_data.BYMONTH.length&&(this.by_indices.BYMONTH=0,this.increment_year(1)),this.last.month=this.by_data.BYMONTH[this.by_indices.BYMONTH];else{"MONTHLY"==this.rule.freq?this.last.month+=this.rule.interval:this.last.month++,this.last.month--;var t=H(this.last.month/12);this.last.month%=12,this.last.month++,0!=t&&this.increment_year(t)}}},{key:"increment_year",value:function(t){this.last.year+=t}},{key:"increment_generic",value:function(t,e,n,r){this.last[e]+=t;var i=H(this.last[e]/n);this.last[e]%=n,0!=i&&this["increment_"+r](i)}},{key:"has_by_data",value:function(t){return t in this.rule.parts}},{key:"expand_year_days",value:function(t){var e=new k;this.days=[];for(var n={},r=0,i=["BYDAY","BYWEEKNO","BYMONTHDAY","BYMONTH","BYYEARDAY"];r<i.length;r++){var a=i[r];a in this.rule.parts&&(n[a]=this.rule.parts[a])}if("BYMONTH"in n&&"BYWEEKNO"in n){var s=1,o={};e.year=t,e.isDate=!0;for(var u=0;u<this.by_data.BYMONTH.length;u++){var l=this.by_data.BYMONTH[u];e.month=l,e.day=1;var h=e.weekNumber(this.rule.wkst);e.day=k.daysInMonth(l,t);var c=e.weekNumber(this.rule.wkst);for(u=h;u<c;u++)o[u]=1}for(var f=0;f<this.by_data.BYWEEKNO.length&&s;f++){this.by_data.BYWEEKNO[f]<52?s&=o[f]:s=0}s?delete n.BYMONTH:delete n.BYWEEKNO}var d=Object.keys(n).length;if(0==d){var y=this.dtstart.clone();y.year=this.last.year,this.days.push(y.dayOfYear())}else if(1==d&&"BYMONTH"in n){var m,v=p(this.by_data.BYMONTH);try{for(v.s();!(m=v.n()).done;){var _=m.value,g=this.dtstart.clone();g.year=t,g.month=_,g.isDate=!0,this.days.push(g.dayOfYear())}}catch(t){v.e(t)}finally{v.f()}}else if(1==d&&"BYMONTHDAY"in n){var D,T=p(this.by_data.BYMONTHDAY);try{for(T.s();!(D=T.n()).done;){var Y=D.value,b=this.dtstart.clone();if(Y<0)Y=Y+k.daysInMonth(b.month,t)+1;b.day=Y,b.year=t,b.isDate=!0,this.days.push(b.dayOfYear())}}catch(t){T.e(t)}finally{T.f()}}else if(2==d&&"BYMONTHDAY"in n&&"BYMONTH"in n){var O,A=p(this.by_data.BYMONTH);try{for(A.s();!(O=A.n()).done;){var S,w=O.value,E=k.daysInMonth(w,t),C=p(this.by_data.BYMONTHDAY);try{for(C.s();!(S=C.n()).done;){var x=S.value;x<0&&(x=x+E+1),e.day=x,e.month=w,e.year=t,e.isDate=!0,this.days.push(e.dayOfYear())}}catch(t){C.e(t)}finally{C.f()}}}catch(t){A.e(t)}finally{A.f()}}else if(1==d&&"BYWEEKNO"in n);else if(2==d&&"BYWEEKNO"in n&&"BYMONTHDAY"in n);else if(1==d&&"BYDAY"in n)this.days=this.days.concat(this.expand_by_day(t));else if(2==d&&"BYDAY"in n&&"BYMONTH"in n){var N,I=p(this.by_data.BYMONTH);try{for(I.s();!(N=I.n()).done;){var B=N.value,M=k.daysInMonth(B,t);e.year=t,e.month=B,e.day=1,e.isDate=!0;var L=e.dayOfWeek(),z=e.dayOfYear()-1;e.day=M;var P=e.dayOfWeek();if(this.has_by_data("BYSETPOS")){for(var U=[],j=1;j<=M;j++)e.day=j,this.is_day_in_byday(e)&&U.push(j);for(var V=0;V<U.length;V++)(this.check_set_position(V+1)||this.check_set_position(V-U.length))&&this.days.push(z+U[V])}else{var R,H=p(this.by_data.BYDAY);try{for(H.s();!(R=H.n()).done;){var W=R.value,F=this.ruleDayOfWeek(W),K=F[0],q=F[1],J=void 0,Z=(q+7-L)%7+1,G=M-(P+7-q)%7;if(0==K)for(var X=Z;X<=M;X+=7)this.days.push(z+X);else K>0?(J=Z+7*(K-1))<=M&&this.days.push(z+J):(J=G+7*(K+1))>0&&this.days.push(z+J)}}catch(t){H.e(t)}finally{H.f()}}}}catch(t){I.e(t)}finally{I.f()}this.days.sort((function(t,e){return t-e}))}else if(2==d&&"BYDAY"in n&&"BYMONTHDAY"in n){var Q,$=p(this.expand_by_day(t));try{for($.s();!(Q=$.n()).done;){var tt=Q.value,et=k.fromDayOfYear(tt,t);this.by_data.BYMONTHDAY.indexOf(et.day)>=0&&this.days.push(tt)}}catch(t){$.e(t)}finally{$.f()}}else if(3==d&&"BYDAY"in n&&"BYMONTHDAY"in n&&"BYMONTH"in n){var nt,rt=p(this.expand_by_day(t));try{for(rt.s();!(nt=rt.n()).done;){var it=nt.value,at=k.fromDayOfYear(it,t);this.by_data.BYMONTH.indexOf(at.month)>=0&&this.by_data.BYMONTHDAY.indexOf(at.day)>=0&&this.days.push(it)}}catch(t){rt.e(t)}finally{rt.f()}}else if(2==d&&"BYDAY"in n&&"BYWEEKNO"in n){var st,ot=p(this.expand_by_day(t));try{for(ot.s();!(st=ot.n()).done;){var ut=st.value,lt=k.fromDayOfYear(ut,t).weekNumber(this.rule.wkst);this.by_data.BYWEEKNO.indexOf(lt)&&this.days.push(ut)}}catch(t){ot.e(t)}finally{ot.f()}}else 3==d&&"BYDAY"in n&&"BYWEEKNO"in n&&"BYMONTHDAY"in n||(this.days=1==d&&"BYYEARDAY"in n?this.days.concat(this.by_data.BYYEARDAY):[]);return 0}},{key:"expand_by_day",value:function(t){var e=[],n=this.last.clone();n.year=t,n.month=1,n.day=1,n.isDate=!0;var r=n.dayOfWeek();n.month=12,n.day=31,n.isDate=!0;var i,a=n.dayOfWeek(),s=n.dayOfYear(),o=p(this.by_data.BYDAY);try{for(o.s();!(i=o.n()).done;){var u=i.value,l=this.ruleDayOfWeek(u),h=l[0],c=l[1];if(0==h)for(var f=(c+7-r)%7+1;f<=s;f+=7)e.push(f);else if(h>0){var d=void 0;d=c>=r?c-r+1:c-r+8,e.push(d+7*(h-1))}else{var y=void 0;h=-h,y=c<=a?s-a+c:s-a+c-7,e.push(y-7*(h-1))}}}catch(t){o.e(t)}finally{o.f()}return e}},{key:"is_day_in_byday",value:function(t){if(this.by_data.BYDAY){var e,n=p(this.by_data.BYDAY);try{for(n.s();!(e=n.n()).done;){var r=e.value,i=this.ruleDayOfWeek(r),a=i[0],s=i[1],o=t.dayOfWeek();if(0==a&&s==o||t.nthWeekDay(s,a)==t.day)return 1}}catch(t){n.e(t)}finally{n.f()}}return 0}},{key:"check_set_position",value:function(t){return!!this.has_by_data("BYSETPOS")&&-1!==this.by_data.BYSETPOS.indexOf(t)}},{key:"sort_byday_rules",value:function(t){for(var e=0;e<t.length;e++)for(var n=0;n<e;n++){if(this.ruleDayOfWeek(t[n],this.rule.wkst)[1]>this.ruleDayOfWeek(t[e],this.rule.wkst)[1]){var r=t[e];t[e]=t[n],t[n]=r}}}},{key:"check_contract_restriction",value:function(e,n){var r=t._indexMap[e],i=t._expandMap[this.rule.freq][r],a=!1;if(e in this.by_data&&i==t.CONTRACT){var s,o=p(this.by_data[e]);try{for(o.s();!(s=o.n()).done;){if(s.value==n){a=!0;break}}}catch(t){o.e(t)}finally{o.f()}}else a=!0;return a}},{key:"check_contracting_rules",value:function(){var t=this.last.dayOfWeek(),e=this.last.weekNumber(this.rule.wkst),n=this.last.dayOfYear();return this.check_contract_restriction("BYSECOND",this.last.second)&&this.check_contract_restriction("BYMINUTE",this.last.minute)&&this.check_contract_restriction("BYHOUR",this.last.hour)&&this.check_contract_restriction("BYDAY",tt.numericDayToIcalDay(t))&&this.check_contract_restriction("BYWEEKNO",e)&&this.check_contract_restriction("BYMONTHDAY",this.last.day)&&this.check_contract_restriction("BYMONTH",this.last.month)&&this.check_contract_restriction("BYYEARDAY",n)}},{key:"setup_defaults",value:function(e,n,r){var i=t._indexMap[e];return t._expandMap[this.rule.freq][i]!=t.CONTRACT&&(e in this.by_data||(this.by_data[e]=[r]),this.rule.freq!=n)?this.by_data[e][0]:r}},{key:"toJSON",value:function(){var t=Object.create(null);return t.initialized=this.initialized,t.rule=this.rule.toJSON(),t.dtstart=this.dtstart.toJSON(),t.by_data=this.by_data,t.days=this.days,t.last=this.last.toJSON(),t.by_indices=this.by_indices,t.occurrence_number=this.occurrence_number,t}}])}();u(J,"_indexMap",{BYSECOND:0,BYMINUTE:1,BYHOUR:2,BYDAY:3,BYMONTHDAY:4,BYYEARDAY:5,BYWEEKNO:6,BYMONTH:7,BYSETPOS:8}),u(J,"_expandMap",{SECONDLY:[1,1,1,1,1,1,1,1],MINUTELY:[2,1,1,1,1,1,1,1],HOURLY:[2,2,1,1,1,1,1,1],DAILY:[2,2,2,1,1,1,1,1],WEEKLY:[2,2,2,2,3,3,1,1],MONTHLY:[2,2,2,2,2,3,3,1],YEARLY:[2,2,2,2,2,2,2,2]}),u(J,"UNKNOWN",0),u(J,"CONTRACT",1),u(J,"EXPAND",2),u(J,"ILLEGAL",3);var Z=/^(SU|MO|TU|WE|TH|FR|SA)$/,G=/^([+-])?(5[0-3]|[1-4][0-9]|[1-9])?(SU|MO|TU|WE|TH|FR|SA)$/,X={SU:k.SUNDAY,MO:k.MONDAY,TU:k.TUESDAY,WE:k.WEDNESDAY,TH:k.THURSDAY,FR:k.FRIDAY,SA:k.SATURDAY},Q=Object.fromEntries(Object.entries(X).map((function(t){return t.reverse()}))),$=["SECONDLY","MINUTELY","HOURLY","DAILY","WEEKLY","MONTHLY","YEARLY"],tt=function(){function t(e){a(this,t),u(this,"parts",null),u(this,"interval",1),u(this,"wkst",k.MONDAY),u(this,"until",null),u(this,"count",null),u(this,"freq",null),u(this,"icalclass","icalrecur"),u(this,"icaltype","recur"),this.wrappedJSObject=this,this.parts={},e&&"object"===i(e)&&this.fromData(e)}return o(t,[{key:"iterator",value:function(t){return new J({rule:this,dtstart:t})}},{key:"clone",value:function(){return new t(this.toJSON())}},{key:"isFinite",value:function(){return!(!this.count&&!this.until)}},{key:"isByCount",value:function(){return!(!this.count||this.until)}},{key:"addComponent",value:function(t,e){var n=t.toUpperCase();n in this.parts?this.parts[n].push(e):this.parts[n]=[e]}},{key:"setComponent",value:function(t,e){this.parts[t.toUpperCase()]=e.slice()}},{key:"getComponent",value:function(t){var e=t.toUpperCase();return e in this.parts?this.parts[e].slice():[]}},{key:"getNextOccurrence",value:function(t,e){var n,r=this.iterator(t);do{n=r.next()}while(n&&n.compare(e)<=0);return n&&e.zone&&(n.zone=e.zone),n}},{key:"fromData",value:function(e){for(var n in e){var r=n.toUpperCase();r in rt?Array.isArray(e[n])?this.parts[r]=e[n]:this.parts[r]=[e[n]]:this[n]=e[n]}this.interval&&"number"!=typeof this.interval&&nt.INTERVAL(this.interval,this),this.wkst&&"number"!=typeof this.wkst&&(this.wkst=t.icalDayToNumericDay(this.wkst)),!this.until||this.until instanceof k||(this.until=k.fromString(this.until))}},{key:"toJSON",value:function(){var e=Object.create(null);e.freq=this.freq,this.count&&(e.count=this.count),this.interval>1&&(e.interval=this.interval);for(var n=0,r=Object.entries(this.parts);n<r.length;n++){var i=d(r[n],2),a=i[0],s=i[1];Array.isArray(s)&&1==s.length?e[a.toLowerCase()]=s[0]:e[a.toLowerCase()]=j(s)}return this.until&&(e.until=this.until.toString()),"wkst"in this&&this.wkst!==k.DEFAULT_WEEK_START&&(e.wkst=t.numericDayToIcalDay(this.wkst)),e}},{key:"toString",value:function(){var e="FREQ="+this.freq;this.count&&(e+=";COUNT="+this.count),this.interval>1&&(e+=";INTERVAL="+this.interval);for(var n=0,r=Object.entries(this.parts);n<r.length;n++){var i=d(r[n],2);e+=";"+i[0]+"="+i[1]}return this.until&&(e+=";UNTIL="+this.until.toICALString()),"wkst"in this&&this.wkst!==k.DEFAULT_WEEK_START&&(e+=";WKST="+t.numericDayToIcalDay(this.wkst)),e}}],[{key:"fromString",value:function(e){return new t(this._stringToData(e,!1))}},{key:"fromData",value:function(e){return new t(e)}},{key:"_stringToData",value:function(t,e){for(var n=Object.create(null),r=t.split(";"),i=r.length,a=0;a<i;a++){var s=r[a].split("="),o=s[0].toUpperCase(),u=s[0].toLowerCase(),l=e?u:o,h=s[1];if(o in rt){for(var c=h.split(","),f=0,d=c.length;f<d;f++)c[f]=rt[o](c[f]);n[l]=1==c.length?c[0]:c}else o in nt?nt[o](h,n,e):n[u]=h}return n}},{key:"icalDayToNumericDay",value:function(t,e){var n=e||k.SUNDAY;return(X[t]-n+7)%7+1}},{key:"numericDayToIcalDay",value:function(t,e){var n=t+(e||k.SUNDAY)-k.SUNDAY;return n>7&&(n-=7),Q[n]}}])}();function et(t,e,n,r){var i=r;if("+"===r[0]&&(i=r.slice(1)),i=L(i),void 0!==e&&r<e)throw new Error(t+': invalid value "'+r+'" must be > '+e);if(void 0!==n&&r>n)throw new Error(t+': invalid value "'+r+'" must be < '+e);return i}var nt={FREQ:function(t,e,n){if(-1===$.indexOf(t))throw new Error('invalid frequency "'+t+'" expected: "'+$.join(", ")+'"');e.freq=t},COUNT:function(t,e,n){e.count=L(t)},INTERVAL:function(t,e,n){e.interval=L(t),e.interval<1&&(e.interval=1)},UNTIL:function(t,e,n){t.length>10?e.until=Ct.icalendar.value["date-time"].fromICAL(t):e.until=Ct.icalendar.value.date.fromICAL(t),n||(e.until=k.fromString(e.until))},WKST:function(t,e,n){if(!Z.test(t))throw new Error('invalid WKST value "'+t+'"');e.wkst=tt.icalDayToNumericDay(t)}},rt={BYSECOND:et.bind(void 0,"BYSECOND",0,60),BYMINUTE:et.bind(void 0,"BYMINUTE",0,59),BYHOUR:et.bind(void 0,"BYHOUR",0,23),BYDAY:function(t){if(G.test(t))return t;throw new Error('invalid BYDAY value "'+t+'"')},BYMONTHDAY:et.bind(void 0,"BYMONTHDAY",-31,31),BYYEARDAY:et.bind(void 0,"BYYEARDAY",-366,366),BYWEEKNO:et.bind(void 0,"BYWEEKNO",-53,53),BYMONTH:et.bind(void 0,"BYMONTH",1,12),BYSETPOS:et.bind(void 0,"BYSETPOS",-366,366)},it=function(){function t(e){if(a(this,t),u(this,"start",null),u(this,"end",null),u(this,"duration",null),u(this,"icalclass","icalperiod"),u(this,"icaltype","period"),this.wrappedJSObject=this,e&&"start"in e){if(e.start&&!(e.start instanceof k))throw new TypeError(".start must be an instance of ICAL.Time");this.start=e.start}if(e&&e.end&&e.duration)throw new Error("cannot accept both end and duration");if(e&&"end"in e){if(e.end&&!(e.end instanceof k))throw new TypeError(".end must be an instance of ICAL.Time");this.end=e.end}if(e&&"duration"in e){if(e.duration&&!(e.duration instanceof T))throw new TypeError(".duration must be an instance of ICAL.Duration");this.duration=e.duration}}return o(t,[{key:"clone",value:function(){return t.fromData({start:this.start?this.start.clone():null,end:this.end?this.end.clone():null,duration:this.duration?this.duration.clone():null})}},{key:"getDuration",value:function(){return this.duration?this.duration:this.end.subtractDate(this.start)}},{key:"getEnd",value:function(){if(this.end)return this.end;var t=this.start.clone();return t.addDuration(this.duration),t}},{key:"toString",value:function(){return this.start+"/"+(this.end||this.duration)}},{key:"toJSON",value:function(){return[this.start.toString(),(this.end||this.duration).toString()]}},{key:"toICALString",value:function(){return this.start.toICALString()+"/"+(this.end||this.duration).toICALString()}}],[{key:"fromString",value:function(e,n){var r=e.split("/");if(2!==r.length)throw new Error('Invalid string value: "'+e+'" must contain a "/" char.');var i={start:k.fromDateTimeString(r[0],n)},a=r[1];return T.isValueString(a)?i.duration=T.fromString(a):i.end=k.fromDateTimeString(a,n),new t(i)}},{key:"fromData",value:function(e){return new t(e)}},{key:"fromJSON",value:function(e,n,r){function i(t,e){return r?k.fromString(t,e):k.fromDateTimeString(t,e)}return T.isValueString(e[1])?t.fromData({start:i(e[0],n),duration:T.fromString(e[1])}):t.fromData({start:i(e[0],n),end:i(e[1],n)})}}])}(),at=/\\\\|\\,|\\[Nn]/g,st=/\\|,|\n/g;function ot(t,e){return{matches:/.*/,fromICAL:function(e,n){return function(t,e,n){if(-1===t.indexOf("\\"))return t;n&&(e=new RegExp(e.source+"|\\\\"+n,e.flags));return t.replace(e,_t)}(e,t,n)},toICAL:function(t,n){var r=e;return n&&(r=new RegExp(r.source+"|"+n,r.flags)),t.replace(r,(function(t){switch(t){case"\\":return"\\\\";case";":return"\\;";case",":return"\\,";case"\n":return"\\n";default:return t}}))}}}var ut={defaultType:"text"},lt={defaultType:"text",multiValue:","},ht={defaultType:"text",structuredValue:";"},ct={defaultType:"integer"},ft={defaultType:"date-time",allowedTypes:["date-time","date"]},dt={defaultType:"date-time"},yt={defaultType:"uri"},mt={defaultType:"utc-offset"},pt={defaultType:"recur"},vt={defaultType:"date-and-or-time",allowedTypes:["date-time","date","text"]};function _t(t){switch(t){case"\\\\":return"\\";case"\\;":return";";case"\\,":return",";case"\\n":case"\\N":return"\n";default:return t}}var gt={categories:lt,url:yt,version:ut,uid:ut},Dt={boolean:{values:["TRUE","FALSE"],fromICAL:function(t){return"TRUE"===t},toICAL:function(t){return t?"TRUE":"FALSE"}},float:{matches:/^[+-]?\d+\.\d+$/,fromICAL:function(t){var e=parseFloat(t);return M(e)?0:e},toICAL:function(t){return String(t)}},integer:{fromICAL:function(t){var e=parseInt(t);return M(e)?0:e},toICAL:function(t){return String(t)}},"utc-offset":{toICAL:function(t){return t.length<7?t.slice(0,3)+t.slice(4,6):t.slice(0,3)+t.slice(4,6)+t.slice(7,9)},fromICAL:function(t){return t.length<6?t.slice(0,3)+":"+t.slice(3,5):t.slice(0,3)+":"+t.slice(3,5)+":"+t.slice(5,7)},decorate:function(t){return K.fromString(t)},undecorate:function(t){return t.toString()}}},Tt=W(Dt,{text:ot(/\\\\|\\;|\\,|\\[Nn]/g,/\\|;|,|\n/g),uri:{},binary:{decorate:function(t){return _.fromString(t)},undecorate:function(t){return t.toString()}},"cal-address":{},date:{decorate:function(t,e){return Ct.strict?k.fromDateString(t,e):k.fromString(t,e)},undecorate:function(t){return t.toString()},fromICAL:function(t){return!Ct.strict&&t.length>=15?Tt["date-time"].fromICAL(t):t.slice(0,4)+"-"+t.slice(4,6)+"-"+t.slice(6,8)},toICAL:function(t){var e=t.length;return 10==e?t.slice(0,4)+t.slice(5,7)+t.slice(8,10):e>=19?Tt["date-time"].toICAL(t):t}},"date-time":{fromICAL:function(t){if(Ct.strict||8!=t.length){var e=t.slice(0,4)+"-"+t.slice(4,6)+"-"+t.slice(6,8)+"T"+t.slice(9,11)+":"+t.slice(11,13)+":"+t.slice(13,15);return t[15]&&"Z"===t[15]&&(e+="Z"),e}return Tt.date.fromICAL(t)},toICAL:function(t){var e=t.length;if(10!=e||Ct.strict){if(e>=19){var n=t.slice(0,4)+t.slice(5,7)+t.slice(8,13)+t.slice(14,16)+t.slice(17,19);return t[19]&&"Z"===t[19]&&(n+="Z"),n}return t}return Tt.date.toICAL(t)},decorate:function(t,e){return Ct.strict?k.fromDateTimeString(t,e):k.fromString(t,e)},undecorate:function(t){return t.toString()}},duration:{decorate:function(t){return T.fromString(t)},undecorate:function(t){return t.toString()}},period:{fromICAL:function(t){var e=t.split("/");return e[0]=Tt["date-time"].fromICAL(e[0]),T.isValueString(e[1])||(e[1]=Tt["date-time"].fromICAL(e[1])),e},toICAL:function(t){return t=t.slice(),Ct.strict||10!=t[0].length?t[0]=Tt["date-time"].toICAL(t[0]):t[0]=Tt.date.toICAL(t[0]),T.isValueString(t[1])||(Ct.strict||10!=t[1].length?t[1]=Tt["date-time"].toICAL(t[1]):t[1]=Tt.date.toICAL(t[1])),t.join("/")},decorate:function(t,e){return it.fromJSON(t,e,!Ct.strict)},undecorate:function(t){return t.toJSON()}},recur:{fromICAL:function(t){return tt._stringToData(t,!0)},toICAL:function(t){for(var e="",n=0,r=Object.entries(t);n<r.length;n++){var i=d(r[n],2),a=i[0],s=i[1];"until"==a?s=s.length>10?Tt["date-time"].toICAL(s):Tt.date.toICAL(s):"wkst"==a?"number"==typeof s&&(s=tt.numericDayToIcalDay(s)):Array.isArray(s)&&(s=s.join(",")),e+=a.toUpperCase()+"="+s+";"}return e.slice(0,Math.max(0,e.length-1))},decorate:function(t){return tt.fromData(t)},undecorate:function(t){return t.toJSON()}},time:{fromICAL:function(t){if(t.length<6)return t;var e=t.slice(0,2)+":"+t.slice(2,4)+":"+t.slice(4,6);return"Z"===t[6]&&(e+="Z"),e},toICAL:function(t){if(t.length<8)return t;var e=t.slice(0,2)+t.slice(3,5)+t.slice(6,8);return"Z"===t[8]&&(e+="Z"),e}}}),Yt=W(gt,{action:ut,attach:{defaultType:"uri"},attendee:{defaultType:"cal-address"},calscale:ut,class:ut,comment:ut,completed:dt,contact:ut,created:dt,description:ut,dtend:ft,dtstamp:dt,dtstart:ft,due:ft,duration:{defaultType:"duration"},exdate:{defaultType:"date-time",allowedTypes:["date-time","date"],multiValue:","},exrule:pt,freebusy:{defaultType:"period",multiValue:","},geo:{defaultType:"float",structuredValue:";"},"last-modified":dt,location:ut,method:ut,organizer:{defaultType:"cal-address"},"percent-complete":ct,priority:ct,prodid:ut,"related-to":ut,repeat:ct,rdate:{defaultType:"date-time",allowedTypes:["date-time","date","period"],multiValue:",",detectType:function(t){return-1!==t.indexOf("/")?"period":-1===t.indexOf("T")?"date":"date-time"}},"recurrence-id":ft,resources:lt,"request-status":ht,rrule:pt,sequence:ct,status:ut,summary:ut,transp:ut,trigger:{defaultType:"duration",allowedTypes:["duration","date-time"]},tzoffsetfrom:mt,tzoffsetto:mt,tzurl:yt,tzid:ut,tzname:ut}),kt=W(Dt,{text:ot(at,st),uri:ot(at,st),date:{decorate:function(t){return q.fromDateAndOrTimeString(t,"date")},undecorate:function(t){return t.toString()},fromICAL:function(t){return 8==t.length?Tt.date.fromICAL(t):"-"==t[0]&&6==t.length?t.slice(0,4)+"-"+t.slice(4):t},toICAL:function(t){return 10==t.length?Tt.date.toICAL(t):"-"==t[0]&&7==t.length?t.slice(0,4)+t.slice(5):t}},time:{decorate:function(t){return q.fromDateAndOrTimeString("T"+t,"time")},undecorate:function(t){return t.toString()},fromICAL:function(t){var e=kt.time._splitZone(t,!0),n=e[0],r=e[1];return 6==r.length?r=r.slice(0,2)+":"+r.slice(2,4)+":"+r.slice(4,6):4==r.length&&"-"!=r[0]?r=r.slice(0,2)+":"+r.slice(2,4):5==r.length&&(r=r.slice(0,3)+":"+r.slice(3,5)),5!=n.length||"-"!=n[0]&&"+"!=n[0]||(n=n.slice(0,3)+":"+n.slice(3)),r+n},toICAL:function(t){var e=kt.time._splitZone(t),n=e[0],r=e[1];return 8==r.length?r=r.slice(0,2)+r.slice(3,5)+r.slice(6,8):5==r.length&&"-"!=r[0]?r=r.slice(0,2)+r.slice(3,5):6==r.length&&(r=r.slice(0,3)+r.slice(4,6)),6!=n.length||"-"!=n[0]&&"+"!=n[0]||(n=n.slice(0,3)+n.slice(4)),r+n},_splitZone:function(t,e){var n,r,i=t.length-1,a=t.length-(e?5:6),s=t[a];return"Z"==t[i]?(n=t[i],r=t.slice(0,Math.max(0,i))):t.length>6&&("-"==s||"+"==s)?(n=t.slice(a),r=t.slice(0,Math.max(0,a))):(n="",r=t),[n,r]}},"date-time":{decorate:function(t){return q.fromDateAndOrTimeString(t,"date-time")},undecorate:function(t){return t.toString()},fromICAL:function(t){return kt["date-and-or-time"].fromICAL(t)},toICAL:function(t){return kt["date-and-or-time"].toICAL(t)}},"date-and-or-time":{decorate:function(t){return q.fromDateAndOrTimeString(t,"date-and-or-time")},undecorate:function(t){return t.toString()},fromICAL:function(t){var e=t.split("T");return(e[0]?kt.date.fromICAL(e[0]):"")+(e[1]?"T"+kt.time.fromICAL(e[1]):"")},toICAL:function(t){var e=t.split("T");return kt.date.toICAL(e[0])+(e[1]?"T"+kt.time.toICAL(e[1]):"")}},timestamp:Tt["date-time"],"language-tag":{matches:/^[a-zA-Z0-9-]+$/},"phone-number":{fromICAL:function(t){return Array.from(t).filter((function(t){return"\\"===t?void 0:t})).join("")},toICAL:function(t){return Array.from(t).map((function(t){return","===t||";"===t?"\\"+t:t})).join("")}}}),bt=W(gt,{adr:{defaultType:"text",structuredValue:";",multiValue:","},anniversary:vt,bday:vt,caladruri:yt,caluri:yt,clientpidmap:ht,email:ut,fburl:yt,fn:ut,gender:ht,geo:yt,impp:yt,key:yt,kind:ut,lang:{defaultType:"language-tag"},logo:yt,member:yt,n:{defaultType:"text",structuredValue:";",multiValue:","},nickname:lt,note:ut,org:{defaultType:"text",structuredValue:";"},photo:yt,related:yt,rev:{defaultType:"timestamp"},role:ut,sound:yt,source:yt,tel:{defaultType:"uri",allowedTypes:["uri","text"]},title:ut,tz:{defaultType:"text",allowedTypes:["text","utc-offset","uri"]},xml:ut}),Ot=W(Dt,{binary:Tt.binary,date:kt.date,"date-time":kt["date-time"],"phone-number":kt["phone-number"],uri:Tt.uri,text:Tt.text,time:Tt.time,vcard:Tt.text,"utc-offset":{toICAL:function(t){return t.slice(0,7)},fromICAL:function(t){return t.slice(0,7)},decorate:function(t){return K.fromString(t)},undecorate:function(t){return t.toString()}}}),At=W(gt,{fn:ut,n:{defaultType:"text",structuredValue:";",multiValue:","},nickname:lt,photo:{defaultType:"binary",allowedTypes:["binary","uri"]},bday:{defaultType:"date-time",allowedTypes:["date-time","date"],detectType:function(t){return-1===t.indexOf("T")?"date":"date-time"}},adr:{defaultType:"text",structuredValue:";",multiValue:","},label:ut,tel:{defaultType:"phone-number"},email:ut,mailer:ut,tz:{defaultType:"utc-offset",allowedTypes:["utc-offset","text"]},geo:{defaultType:"float",structuredValue:";"},title:ut,role:ut,logo:{defaultType:"binary",allowedTypes:["binary","uri"]},agent:{defaultType:"vcard",allowedTypes:["vcard","text","uri"]},org:ht,note:lt,prodid:ut,rev:{defaultType:"date-time",allowedTypes:["date-time","date"],detectType:function(t){return-1===t.indexOf("T")?"date":"date-time"}},"sort-string":ut,sound:{defaultType:"binary",allowedTypes:["binary","uri"]},class:ut,key:{defaultType:"binary",allowedTypes:["binary","text"]}}),St={value:Tt,param:{cutype:{values:["INDIVIDUAL","GROUP","RESOURCE","ROOM","UNKNOWN"],allowXName:!0,allowIanaToken:!0},"delegated-from":{valueType:"cal-address",multiValue:",",multiValueSeparateDQuote:!0},"delegated-to":{valueType:"cal-address",multiValue:",",multiValueSeparateDQuote:!0},encoding:{values:["8BIT","BASE64"]},fbtype:{values:["FREE","BUSY","BUSY-UNAVAILABLE","BUSY-TENTATIVE"],allowXName:!0,allowIanaToken:!0},member:{valueType:"cal-address",multiValue:",",multiValueSeparateDQuote:!0},partstat:{values:["NEEDS-ACTION","ACCEPTED","DECLINED","TENTATIVE","DELEGATED","COMPLETED","IN-PROCESS"],allowXName:!0,allowIanaToken:!0},range:{values:["THISANDFUTURE"]},related:{values:["START","END"]},reltype:{values:["PARENT","CHILD","SIBLING"],allowXName:!0,allowIanaToken:!0},role:{values:["REQ-PARTICIPANT","CHAIR","OPT-PARTICIPANT","NON-PARTICIPANT"],allowXName:!0,allowIanaToken:!0},rsvp:{values:["TRUE","FALSE"]},"sent-by":{valueType:"cal-address"},tzid:{matches:/^\//},value:{values:["binary","boolean","cal-address","date","date-time","duration","float","integer","period","recur","text","time","uri","utc-offset"],allowXName:!0,allowIanaToken:!0}},property:Yt,propertyGroups:!1},wt={value:kt,param:{type:{valueType:"text",multiValue:","},value:{values:["text","uri","date","time","date-time","date-and-or-time","timestamp","boolean","integer","float","utc-offset","language-tag"],allowXName:!0,allowIanaToken:!0}},property:bt,propertyGroups:!0},Et={value:Ot,param:{type:{valueType:"text",multiValue:","},value:{values:["text","uri","date","date-time","phone-number","time","boolean","integer","float","utc-offset","vcard","binary"],allowXName:!0,allowIanaToken:!0}},property:At,propertyGroups:!0},Ct={strict:!0,defaultSet:St,defaultType:"unknown",components:{vcard:wt,vcard3:Et,vevent:St,vtodo:St,vjournal:St,valarm:St,vtimezone:St,daylight:St,standard:St},icalendar:St,vcard:wt,vcard3:Et,getDesignSet:function(t){return t&&t in Ct.components?Ct.components[t]:Ct.defaultSet}},xt="\r\n",Nt="unknown",It={'"':"^'","\n":"^n","^":"^^"};function Bt(t){"string"==typeof t[0]&&(t=[t]);for(var e=0,n=t.length,r="";e<n;e++)r+=Bt.component(t[e])+xt;return r}Bt.component=function(t,e){var n=t[0].toUpperCase(),r="BEGIN:"+n+xt,i=t[1],a=0,s=i.length,o=t[0];for("vcard"===o&&t[1].length>0&&("version"!==t[1][0][0]||"4.0"!==t[1][0][3])&&(o="vcard3"),e=e||Ct.getDesignSet(o);a<s;a++)r+=Bt.property(i[a],e)+xt;for(var u=t[2]||[],l=0,h=u.length;l<h;l++)r+=Bt.component(u[l],e)+xt;return r+="END:"+n},Bt.property=function(t,e,n){var r=t[0].toUpperCase(),i=t[0],a=t[1];e||(e=Ct.defaultSet);var s,o=a.group;s=e.propertyGroups&&o?o.toUpperCase()+"."+r:r;for(var u=function(){var t=d(h[l],2),n=t[0],r=t[1];if(e.propertyGroups&&"group"==n)return 1;var i=e.param[n],a=i&&i.multiValue;a&&Array.isArray(r)?(r=r.map((function(t){return t=Bt._rfc6868Unescape(t),t=Bt.paramPropertyValue(t,i.multiValueSeparateDQuote)})),r=Bt.multiValue(r,a,"unknown",null,e)):(r=Bt._rfc6868Unescape(r),r=Bt.paramPropertyValue(r)),s+=";"+n.toUpperCase()+"="+r},l=0,h=Object.entries(a);l<h.length;l++)u();if(3===t.length)return s+":";var c,f=t[2],y=!1,m=!1,p=!1;return i in e.property?("multiValue"in(c=e.property[i])&&(y=c.multiValue),"structuredValue"in c&&Array.isArray(t[3])&&(m=c.structuredValue),"defaultType"in c?f===c.defaultType&&(p=!0):f===Nt&&(p=!0)):f===Nt&&(p=!0),p||(s+=";VALUE="+f.toUpperCase()),s+=":",s+=y&&m?Bt.multiValue(t[3],m,f,y,e,m):y?Bt.multiValue(t.slice(3),y,f,null,e,!1):m?Bt.multiValue(t[3],m,f,null,e,m):Bt.value(t[3],f,e,!1),n?s:V(s)},Bt.paramPropertyValue=function(t,e){return e||-1!==P(t,",")||-1!==P(t,":")||-1!==P(t,";")?'"'+t+'"':t},Bt.multiValue=function(t,e,n,r,i,a){for(var s="",o=t.length,u=0;u<o;u++)r&&Array.isArray(t[u])?s+=Bt.multiValue(t[u],r,n,null,i,a):s+=Bt.value(t[u],n,i,a),u!==o-1&&(s+=e);return s},Bt.value=function(t,e,n,r){return e in n.value&&"toICAL"in n.value[e]?n.value[e].toICAL(t,r):t},Bt._rfc6868Unescape=function(t){return t.replace(/[\n^"]/g,(function(t){return It[t]}))};var Mt=function(){function t(e,n){a(this,t),this._parent=n||null,"string"==typeof e?(this.jCal=[e,{},Ct.defaultType],this.jCal[2]=this.getDefaultType()):this.jCal=e,this._updateType()}return o(t,[{key:"type",get:function(){return this.jCal[2]}},{key:"name",get:function(){return this.jCal[0]}},{key:"parent",get:function(){return this._parent},set:function(t){var e=!this._parent||t&&t._designSet!=this._parent._designSet;this._parent=t,this.type==Ct.defaultType&&e&&(this.jCal[2]=this.getDefaultType(),this._updateType())}},{key:"_designSet",get:function(){return this.parent?this.parent._designSet:Ct.defaultSet}},{key:"_updateType",value:function(){var t=this._designSet;this.type in t.value&&("decorate"in t.value[this.type]?this.isDecorated=!0:this.isDecorated=!1,this.name in t.property&&(this.isMultiValue="multiValue"in t.property[this.name],this.isStructuredValue="structuredValue"in t.property[this.name]))}},{key:"_hydrateValue",value:function(t){return this._values&&this._values[t]?this._values[t]:this.jCal.length<=3+t?null:this.isDecorated?(this._values||(this._values=[]),this._values[t]=this._decorate(this.jCal[3+t])):this.jCal[3+t]}},{key:"_decorate",value:function(t){return this._designSet.value[this.type].decorate(t,this)}},{key:"_undecorate",value:function(t){return this._designSet.value[this.type].undecorate(t,this)}},{key:"_setDecoratedValue",value:function(t,e){this._values||(this._values=[]),"object"===i(t)&&"icaltype"in t?(this.jCal[3+e]=this._undecorate(t),this._values[e]=t):(this.jCal[3+e]=t,this._values[e]=this._decorate(t))}},{key:"getParameter",value:function(t){return t in this.jCal[1]?this.jCal[1][t]:void 0}},{key:"getFirstParameter",value:function(t){var e=this.getParameter(t);return Array.isArray(e)?e[0]:e}},{key:"setParameter",value:function(t,e){var n=t.toLowerCase();"string"==typeof e&&n in this._designSet.param&&"multiValue"in this._designSet.param[n]&&(e=[e]),this.jCal[1][t]=e}},{key:"removeParameter",value:function(t){delete this.jCal[1][t]}},{key:"getDefaultType",value:function(){var t=this.jCal[0],e=this._designSet;if(t in e.property){var n=e.property[t];if("defaultType"in n)return n.defaultType}return Ct.defaultType}},{key:"resetType",value:function(t){this.removeAllValues(),this.jCal[2]=t,this._updateType()}},{key:"getFirstValue",value:function(){return this._hydrateValue(0)}},{key:"getValues",value:function(){var t=this.jCal.length-3;if(t<1)return[];for(var e=0,n=[];e<t;e++)n[e]=this._hydrateValue(e);return n}},{key:"removeAllValues",value:function(){this._values&&(this._values.length=0),this.jCal.length=3}},{key:"setValues",value:function(t){if(!this.isMultiValue)throw new Error(this.name+": does not not support mulitValue.\noverride isMultiValue");var e=t.length,n=0;if(this.removeAllValues(),e>0&&"object"===i(t[0])&&"icaltype"in t[0]&&this.resetType(t[0].icaltype),this.isDecorated)for(;n<e;n++)this._setDecoratedValue(t[n],n);else for(;n<e;n++)this.jCal[3+n]=t[n]}},{key:"setValue",value:function(t){this.removeAllValues(),"object"===i(t)&&"icaltype"in t&&this.resetType(t.icaltype),this.isDecorated?this._setDecoratedValue(t,0):this.jCal[3]=t}},{key:"toJSON",value:function(){return this.jCal}},{key:"toICALString",value:function(){return Bt.property(this.jCal,this._designSet,!0)}}],[{key:"fromString",value:function(e,n){return new t(S.property(e,n))}}])}(),Lt=function(){function t(e,n){a(this,t),u(this,"_hydratedPropertyCount",0),u(this,"_hydratedComponentCount",0),u(this,"_timezoneCache",null),"string"==typeof e&&(e=[e,[],[]]),this.jCal=e,this.parent=n||null,this.parent||"vcalendar"!==this.name||(this._timezoneCache=new Map)}return o(t,[{key:"name",get:function(){return this.jCal[0]}},{key:"_designSet",get:function(){return this.parent&&this.parent._designSet||Ct.getDesignSet(this.name)}},{key:"_hydrateComponent",value:function(e){if(this._components||(this._components=[],this._hydratedComponentCount=0),this._components[e])return this._components[e];var n=new t(this.jCal[2][e],this);return this._hydratedComponentCount++,this._components[e]=n}},{key:"_hydrateProperty",value:function(t){if(this._properties||(this._properties=[],this._hydratedPropertyCount=0),this._properties[t])return this._properties[t];var e=new Mt(this.jCal[1][t],this);return this._hydratedPropertyCount++,this._properties[t]=e}},{key:"getFirstSubcomponent",value:function(t){if(t)for(var e=0,n=this.jCal[2],r=n.length;e<r;e++){if(n[e][0]===t)return this._hydrateComponent(e)}else if(this.jCal[2].length)return this._hydrateComponent(0);return null}},{key:"getAllSubcomponents",value:function(t){var e=this.jCal[2].length,n=0;if(t){for(var r=this.jCal[2],i=[];n<e;n++)t===r[n][0]&&i.push(this._hydrateComponent(n));return i}if(!this._components||this._hydratedComponentCount!==e)for(;n<e;n++)this._hydrateComponent(n);return this._components||[]}},{key:"hasProperty",value:function(t){for(var e=this.jCal[1],n=e.length,r=0;r<n;r++)if(e[r][0]===t)return!0;return!1}},{key:"getFirstProperty",value:function(t){if(t)for(var e=0,n=this.jCal[1],r=n.length;e<r;e++){if(n[e][0]===t)return this._hydrateProperty(e)}else if(this.jCal[1].length)return this._hydrateProperty(0);return null}},{key:"getFirstPropertyValue",value:function(t){var e=this.getFirstProperty(t);return e?e.getFirstValue():null}},{key:"getAllProperties",value:function(t){var e=this.jCal[1].length,n=0;if(t){for(var r=this.jCal[1],i=[];n<e;n++)t===r[n][0]&&i.push(this._hydrateProperty(n));return i}if(!this._properties||this._hydratedPropertyCount!==e)for(;n<e;n++)this._hydrateProperty(n);return this._properties||[]}},{key:"_removeObjectByIndex",value:function(t,e,n){if((e=e||[])[n]){var r=e[n];"parent"in r&&(r.parent=null)}e.splice(n,1),this.jCal[t].splice(n,1)}},{key:"_removeObject",value:function(t,e,n){var r=0,i=this.jCal[t],a=i.length,s=this[e];if("string"==typeof n){for(;r<a;r++)if(i[r][0]===n)return this._removeObjectByIndex(t,s,r),!0}else if(s)for(;r<a;r++)if(s[r]&&s[r]===n)return this._removeObjectByIndex(t,s,r),!0;return!1}},{key:"_removeAllObjects",value:function(t,e,n){for(var r=this[e],i=this.jCal[t],a=i.length-1;a>=0;a--)n&&i[a][0]!==n||this._removeObjectByIndex(t,r,a)}},{key:"addSubcomponent",value:function(t){this._components||(this._components=[],this._hydratedComponentCount=0),t.parent&&t.parent.removeSubcomponent(t);var e=this.jCal[2].push(t.jCal);return this._components[e-1]=t,this._hydratedComponentCount++,t.parent=this,t}},{key:"removeSubcomponent",value:function(t){var e=this._removeObject(2,"_components",t);return e&&this._hydratedComponentCount--,e}},{key:"removeAllSubcomponents",value:function(t){var e=this._removeAllObjects(2,"_components",t);return this._hydratedComponentCount=0,e}},{key:"addProperty",value:function(t){if(!(t instanceof Mt))throw new TypeError("must be instance of ICAL.Property");this._properties||(this._properties=[],this._hydratedPropertyCount=0),t.parent&&t.parent.removeProperty(t);var e=this.jCal[1].push(t.jCal);return this._properties[e-1]=t,this._hydratedPropertyCount++,t.parent=this,t}},{key:"addPropertyWithValue",value:function(t,e){var n=new Mt(t);return n.setValue(e),this.addProperty(n),n}},{key:"updatePropertyWithValue",value:function(t,e){var n=this.getFirstProperty(t);return n?n.setValue(e):n=this.addPropertyWithValue(t,e),n}},{key:"removeProperty",value:function(t){var e=this._removeObject(1,"_properties",t);return e&&this._hydratedPropertyCount--,e}},{key:"removeAllProperties",value:function(t){var e=this._removeAllObjects(1,"_properties",t);return this._hydratedPropertyCount=0,e}},{key:"toJSON",value:function(){return this.jCal}},{key:"toString",value:function(){return Bt.component(this.jCal,this._designSet)}},{key:"getTimeZoneByID",value:function(t){if(this.parent)return this.parent.getTimeZoneByID(t);if(!this._timezoneCache)return null;if(this._timezoneCache.has(t))return this._timezoneCache.get(t);var e,n=p(this.getAllSubcomponents("vtimezone"));try{for(n.s();!(e=n.n()).done;){var r=e.value;if(r.getFirstProperty("tzid").getFirstValue()===t){var i=new C({component:r,tzid:t});return this._timezoneCache.set(t,i),i}}}catch(t){n.e(t)}finally{n.f()}return null}}],[{key:"fromString",value:function(e){return new t(S.component(e))}}])}(),zt=function(){return o((function t(e){a(this,t),u(this,"complete",!1),u(this,"ruleIterators",null),u(this,"ruleDates",null),u(this,"exDates",null),u(this,"ruleDateInc",0),u(this,"exDateInc",0),u(this,"exDate",null),u(this,"ruleDate",null),u(this,"dtstart",null),u(this,"last",null),this.ruleDates=[],this.exDates=[],this.fromData(e)}),[{key:"fromData",value:function(t){var e=z(t.dtstart,k);if(!e)throw new Error(".dtstart (ICAL.Time) must be given");if(this.dtstart=e,t.component)this._init(t.component);else{if(this.last=z(t.last,k)||e.clone(),!t.ruleIterators)throw new Error(".ruleIterators or .component must be given");this.ruleIterators=t.ruleIterators.map((function(t){return z(t,J)})),this.ruleDateInc=t.ruleDateInc,this.exDateInc=t.exDateInc,t.ruleDates&&(this.ruleDates=t.ruleDates.map((function(t){return z(t,k)})),this.ruleDate=this.ruleDates[this.ruleDateInc]),t.exDates&&(this.exDates=t.exDates.map((function(t){return z(t,k)})),this.exDate=this.exDates[this.exDateInc]),void 0!==t.complete&&(this.complete=t.complete)}}},{key:"next",value:function(){for(var t,e,n,r=0;;){if(r++>500)throw new Error("max tries have occurred, rule may be impossible to fulfill.");if(e=this.ruleDate,t=this._nextRecurrenceIter(this.last),!e&&!t){this.complete=!0;break}if((!e||t&&e.compare(t.last)>0)&&(e=t.last.clone(),t.next()),this.ruleDate===e&&this._nextRuleDay(),this.last=e,!this.exDate||((n=this.exDate.compare(this.last))<0&&this._nextExDay(),0!==n))return this.last;this._nextExDay()}}},{key:"toJSON",value:function(){function t(t){return t.toJSON()}var e=Object.create(null);return e.ruleIterators=this.ruleIterators.map(t),this.ruleDates&&(e.ruleDates=this.ruleDates.map(t)),this.exDates&&(e.exDates=this.exDates.map(t)),e.ruleDateInc=this.ruleDateInc,e.exDateInc=this.exDateInc,e.last=this.last.toJSON(),e.dtstart=this.dtstart.toJSON(),e.complete=this.complete,e}},{key:"_extractDates",value:function(t,e){for(var n=[],r=t.getAllProperties(e),i=0,a=r.length;i<a;i++){var s,o=p(r[i].getValues());try{for(o.s();!(s=o.n()).done;){var u=s.value,l=U(n,u,(function(t,e){return t.compare(e)}));n.splice(l,0,u)}}catch(t){o.e(t)}finally{o.f()}}return n}},{key:"_init",value:function(t){if(this.ruleIterators=[],this.last=this.dtstart.clone(),!t.hasProperty("rdate")&&!t.hasProperty("rrule")&&!t.hasProperty("recurrence-id"))return this.ruleDate=this.last.clone(),void(this.complete=!0);if(t.hasProperty("rdate")&&(this.ruleDates=this._extractDates(t,"rdate"),this.ruleDates[0]&&this.ruleDates[0].compare(this.dtstart)<0?(this.ruleDateInc=0,this.last=this.ruleDates[0].clone()):this.ruleDateInc=U(this.ruleDates,this.last,(function(t,e){return t.compare(e)})),this.ruleDate=this.ruleDates[this.ruleDateInc]),t.hasProperty("rrule"))for(var e,n=t.getAllProperties("rrule"),r=0,i=n.length;r<i;r++)e=n[r].getFirstValue().iterator(this.dtstart),this.ruleIterators.push(e),e.next();t.hasProperty("exdate")&&(this.exDates=this._extractDates(t,"exdate"),this.exDateInc=U(this.exDates,this.last,(function(t,e){return t.compare(e)})),this.exDate=this.exDates[this.exDateInc])}},{key:"_nextExDay",value:function(){this.exDate=this.exDates[++this.exDateInc]}},{key:"_nextRuleDay",value:function(){this.ruleDate=this.ruleDates[++this.ruleDateInc]}},{key:"_nextRecurrenceIter",value:function(){var t=this.ruleIterators;if(0===t.length)return null;for(var e,n,r,i=t.length,a=0;a<i;a++)n=(e=t[a]).last,e.completed?(i--,0!==a&&a--,t.splice(a,1)):(!r||r.last.compare(n)>0)&&(r=e);return r}}])}(),Pt=function(){function t(e,n){a(this,t),u(this,"exceptions",null),u(this,"strictExceptions",!1),e instanceof Lt||(n=e,e=null),this.component=e||new Lt("vevent"),this._rangeExceptionCache=Object.create(null),this.exceptions=Object.create(null),this.rangeExceptions=[],n&&n.strictExceptions&&(this.strictExceptions=n.strictExceptions),n&&n.exceptions?n.exceptions.forEach(this.relateException,this):this.component.parent&&!this.isRecurrenceException()&&this.component.parent.getAllSubcomponents("vevent").forEach((function(t){t.hasProperty("recurrence-id")&&this.relateException(t)}),this)}return o(t,[{key:"relateException",value:function(e){if(this.isRecurrenceException())throw new Error("cannot relate exception to exceptions");if(e instanceof Lt&&(e=new t(e)),this.strictExceptions&&e.uid!==this.uid)throw new Error("attempted to relate unrelated exception");var n=e.recurrenceId.toString();if(this.exceptions[n]=e,e.modifiesFuture()){var r=[e.recurrenceId.toUnixTime(),n],i=U(this.rangeExceptions,r,Ut);this.rangeExceptions.splice(i,0,r)}}},{key:"modifiesFuture",value:function(){return!!this.component.hasProperty("recurrence-id")&&this.component.getFirstProperty("recurrence-id").getParameter("range")===t.THISANDFUTURE}},{key:"findRangeException",value:function(t){if(!this.rangeExceptions.length)return null;var e=t.toUnixTime(),n=U(this.rangeExceptions,[e],Ut);if((n-=1)<0)return null;var r=this.rangeExceptions[n];return e<r[0]?null:r[1]}},{key:"getOccurrenceDetails",value:function(t){var e,n=t.toString(),r=t.convertToZone(C.utcTimezone).toString(),i={recurrenceId:t};if(n in this.exceptions)e=i.item=this.exceptions[n],i.startDate=e.startDate,i.endDate=e.endDate,i.item=e;else if(r in this.exceptions)e=this.exceptions[r],i.startDate=e.startDate,i.endDate=e.endDate,i.item=e;else{var a,s=this.findRangeException(t);if(s){var o=this.exceptions[s];i.item=o;var u=this._rangeExceptionCache[s];if(!u){var l=o.recurrenceId.clone(),h=o.startDate.clone();l.zone=h.zone,u=h.subtractDate(l),this._rangeExceptionCache[s]=u}var c=t.clone();c.zone=o.startDate.zone,c.addDuration(u),(a=c.clone()).addDuration(o.duration),i.startDate=c,i.endDate=a}else(a=t.clone()).addDuration(this.duration),i.endDate=a,i.startDate=t,i.item=this}return i}},{key:"iterator",value:function(t){return new zt({component:this.component,dtstart:t||this.startDate})}},{key:"isRecurring",value:function(){var t=this.component;return t.hasProperty("rrule")||t.hasProperty("rdate")}},{key:"isRecurrenceException",value:function(){return this.component.hasProperty("recurrence-id")}},{key:"getRecurrenceTypes",value:function(){for(var t=this.component.getAllProperties("rrule"),e=0,n=t.length,r=Object.create(null);e<n;e++){r[t[e].getFirstValue().freq]=!0}return r}},{key:"uid",get:function(){return this._firstProp("uid")},set:function(t){this._setProp("uid",t)}},{key:"startDate",get:function(){return this._firstProp("dtstart")},set:function(t){this._setTime("dtstart",t)}},{key:"endDate",get:function(){var t=this._firstProp("dtend");if(!t){var e=this._firstProp("duration");t=this.startDate.clone(),e?t.addDuration(e):t.isDate&&(t.day+=1)}return t},set:function(t){this.component.hasProperty("duration")&&this.component.removeProperty("duration"),this._setTime("dtend",t)}},{key:"duration",get:function(){var t=this._firstProp("duration");return t||this.endDate.subtractDateTz(this.startDate)},set:function(t){this.component.hasProperty("dtend")&&this.component.removeProperty("dtend"),this._setProp("duration",t)}},{key:"location",get:function(){return this._firstProp("location")},set:function(t){this._setProp("location",t)}},{key:"attendees",get:function(){return this.component.getAllProperties("attendee")}},{key:"summary",get:function(){return this._firstProp("summary")},set:function(t){this._setProp("summary",t)}},{key:"description",get:function(){return this._firstProp("description")},set:function(t){this._setProp("description",t)}},{key:"color",get:function(){return this._firstProp("color")},set:function(t){this._setProp("color",t)}},{key:"organizer",get:function(){return this._firstProp("organizer")},set:function(t){this._setProp("organizer",t)}},{key:"sequence",get:function(){return this._firstProp("sequence")},set:function(t){this._setProp("sequence",t)}},{key:"recurrenceId",get:function(){return this._firstProp("recurrence-id")},set:function(t){this._setTime("recurrence-id",t)}},{key:"_setTime",value:function(t,e){var n=this.component.getFirstProperty(t);n||(n=new Mt(t),this.component.addProperty(n)),e.zone===C.localTimezone||e.zone===C.utcTimezone?n.removeParameter("tzid"):n.setParameter("tzid",e.zone.tzid),n.setValue(e)}},{key:"_setProp",value:function(t,e){this.component.updatePropertyWithValue(t,e)}},{key:"_firstProp",value:function(t){return this.component.getFirstPropertyValue(t)}},{key:"toString",value:function(){return this.component.toString()}}])}();function Ut(t,e){return t[0]>e[0]?1:e[0]>t[0]?-1:0}u(Pt,"THISANDFUTURE","THISANDFUTURE");var jt=function(){return o((function t(e){a(this,t),u(this,"parseEvent",!0),u(this,"parseTimezone",!0),u(this,"oncomplete",(function(){})),u(this,"onerror",(function(t){})),u(this,"ontimezone",(function(t){})),u(this,"onevent",(function(t){})),void 0===e&&(e={});for(var n=0,r=Object.entries(e);n<r.length;n++){var i=d(r[n],2),s=i[0],o=i[1];this[s]=o}}),[{key:"process",value:function(t){"string"==typeof t&&(t=S(t)),t instanceof Lt||(t=new Lt(t));for(var e,n=t.getAllSubcomponents(),r=0,i=n.length;r<i;r++)switch((e=n[r]).name){case"vtimezone":if(this.parseTimezone){var a=e.getFirstPropertyValue("tzid");a&&this.ontimezone(new C({tzid:a,component:e}))}break;case"vevent":this.parseEvent&&this.onevent(new Pt(e));break;default:continue}this.oncomplete()}}])}(),Vt={foldLength:75,debug:!1,newLineChar:"\r\n",Binary:_,Component:Lt,ComponentParser:jt,Duration:T,Event:Pt,Period:it,Property:Mt,Recur:tt,RecurExpansion:zt,RecurIterator:J,Time:k,Timezone:C,TimezoneService:B,UtcOffset:K,VCardTime:q,parse:S,stringify:Bt,design:Ct,helpers:F};return Vt}));
diff --git a/plugins/ics-viewer/ical.js b/plugins/ics-viewer/ical.js
new file mode 100644
index 000000000..97ec65305
--- /dev/null
+++ b/plugins/ics-viewer/ical.js
@@ -0,0 +1,9526 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ * Portions Copyright (C) Philipp Kewisch */
+
+ICAL = (() => {
+
+/**
+ * Represents the BINARY value type, which contains extra methods for encoding and decoding.
+ *
+ * @memberof ICAL
+ */
+class Binary {
+  /**
+   * Creates a binary value from the given string.
+   *
+   * @param {String} aString        The binary value string
+   * @return {Binary}               The binary value instance
+   */
+  static fromString(aString) {
+    return new Binary(aString);
+  }
+
+  /**
+   * Creates a new ICAL.Binary instance
+   *
+   * @param {String} aValue     The binary data for this value
+   */
+  constructor(aValue) {
+    this.value = aValue;
+  }
+
+  /**
+   * The type name, to be used in the jCal object.
+   * @default "binary"
+   * @constant
+   */
+  icaltype = "binary";
+
+  /**
+   * Base64 decode the current value
+   *
+   * @return {String}         The base64-decoded value
+   */
+  decodeValue() {
+    return this._b64_decode(this.value);
+  }
+
+  /**
+   * Encodes the passed parameter with base64 and sets the internal
+   * value to the result.
+   *
+   * @param {String} aValue      The raw binary value to encode
+   */
+  setEncodedValue(aValue) {
+    this.value = this._b64_encode(aValue);
+  }
+
+  _b64_encode(data) {
+    // http://kevin.vanzonneveld.net
+    // +   original by: Tyler Akins (http://rumkin.com)
+    // +   improved by: Bayron Guevara
+    // +   improved by: Thunder.m
+    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
+    // +   bugfixed by: Pellentesque Malesuada
+    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
+    // +   improved by: Rafał Kukawski (http://kukawski.pl)
+    // *     example 1: base64_encode('Kevin van Zonneveld');
+    // *     returns 1: 'S2V2aW4gdmFuIFpvbm5ldmVsZA=='
+    // mozilla has this native
+    // - but breaks in 2.0.0.12!
+    //if (typeof this.window['atob'] == 'function') {
+    //    return atob(data);
+    //}
+    let b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" +
+              "abcdefghijklmnopqrstuvwxyz0123456789+/=";
+    let o1, o2, o3, h1, h2, h3, h4, bits, i = 0,
+      ac = 0,
+      enc = "",
+      tmp_arr = [];
+
+    if (!data) {
+      return data;
+    }
+
+    do { // pack three octets into four hexets
+      o1 = data.charCodeAt(i++);
+      o2 = data.charCodeAt(i++);
+      o3 = data.charCodeAt(i++);
+
+      bits = o1 << 16 | o2 << 8 | o3;
+
+      h1 = bits >> 18 & 0x3f;
+      h2 = bits >> 12 & 0x3f;
+      h3 = bits >> 6 & 0x3f;
+      h4 = bits & 0x3f;
+
+      // use hexets to index into b64, and append result to encoded string
+      tmp_arr[ac++] = b64.charAt(h1) + b64.charAt(h2) + b64.charAt(h3) + b64.charAt(h4);
+    } while (i < data.length);
+
+    enc = tmp_arr.join('');
+
+    let r = data.length % 3;
+
+    return (r ? enc.slice(0, r - 3) : enc) + '==='.slice(r || 3);
+
+  }
+
+  _b64_decode(data) {
+    // http://kevin.vanzonneveld.net
+    // +   original by: Tyler Akins (http://rumkin.com)
+    // +   improved by: Thunder.m
+    // +      input by: Aman Gupta
+    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
+    // +   bugfixed by: Onno Marsman
+    // +   bugfixed by: Pellentesque Malesuada
+    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
+    // +      input by: Brett Zamir (http://brett-zamir.me)
+    // +   bugfixed by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
+    // *     example 1: base64_decode('S2V2aW4gdmFuIFpvbm5ldmVsZA==');
+    // *     returns 1: 'Kevin van Zonneveld'
+    // mozilla has this native
+    // - but breaks in 2.0.0.12!
+    //if (typeof this.window['btoa'] == 'function') {
+    //    return btoa(data);
+    //}
+    let b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" +
+              "abcdefghijklmnopqrstuvwxyz0123456789+/=";
+    let o1, o2, o3, h1, h2, h3, h4, bits, i = 0,
+      ac = 0,
+      dec = "",
+      tmp_arr = [];
+
+    if (!data) {
+      return data;
+    }
+
+    data += '';
+
+    do { // unpack four hexets into three octets using index points in b64
+      h1 = b64.indexOf(data.charAt(i++));
+      h2 = b64.indexOf(data.charAt(i++));
+      h3 = b64.indexOf(data.charAt(i++));
+      h4 = b64.indexOf(data.charAt(i++));
+
+      bits = h1 << 18 | h2 << 12 | h3 << 6 | h4;
+
+      o1 = bits >> 16 & 0xff;
+      o2 = bits >> 8 & 0xff;
+      o3 = bits & 0xff;
+
+      if (h3 == 64) {
+        tmp_arr[ac++] = String.fromCharCode(o1);
+      } else if (h4 == 64) {
+        tmp_arr[ac++] = String.fromCharCode(o1, o2);
+      } else {
+        tmp_arr[ac++] = String.fromCharCode(o1, o2, o3);
+      }
+    } while (i < data.length);
+
+    dec = tmp_arr.join('');
+
+    return dec;
+  }
+
+  /**
+   * The string representation of this value
+   * @return {String}
+   */
+  toString() {
+    return this.value;
+  }
+}
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ * Portions Copyright (C) Philipp Kewisch */
+
+const DURATION_LETTERS = /([PDWHMTS]{1,1})/;
+const DATA_PROPS_TO_COPY = ["weeks", "days", "hours", "minutes", "seconds", "isNegative"];
+
+/**
+ * This class represents the "duration" value type, with various calculation
+ * and manipulation methods.
+ *
+ * @memberof ICAL
+ */
+class Duration {
+  /**
+   * Returns a new ICAL.Duration instance from the passed seconds value.
+   *
+   * @param {Number} aSeconds       The seconds to create the instance from
+   * @return {Duration}             The newly created duration instance
+   */
+  static fromSeconds(aSeconds) {
+    return (new Duration()).fromSeconds(aSeconds);
+  }
+
+  /**
+   * Checks if the given string is an iCalendar duration value.
+   *
+   * @param {String} value      The raw ical value
+   * @return {Boolean}          True, if the given value is of the
+   *                              duration ical type
+   */
+  static isValueString(string) {
+    return (string[0] === 'P' || string[1] === 'P');
+  }
+
+  /**
+   * Creates a new {@link ICAL.Duration} instance from the passed string.
+   *
+   * @param {String} aStr       The string to parse
+   * @return {Duration}         The created duration instance
+   */
+  static fromString(aStr) {
+    let pos = 0;
+    let dict = Object.create(null);
+    let chunks = 0;
+
+    while ((pos = aStr.search(DURATION_LETTERS)) !== -1) {
+      let type = aStr[pos];
+      let numeric = aStr.slice(0, Math.max(0, pos));
+      aStr = aStr.slice(pos + 1);
+
+      chunks += parseDurationChunk(type, numeric, dict);
+    }
+
+    if (chunks < 2) {
+      // There must be at least a chunk with "P" and some unit chunk
+      throw new Error(
+        'invalid duration value: Not enough duration components in "' + aStr + '"'
+      );
+    }
+
+    return new Duration(dict);
+  }
+
+  /**
+   * Creates a new ICAL.Duration instance from the given data object.
+   *
+   * @param {Object} aData                An object with members of the duration
+   * @param {Number=} aData.weeks         Duration in weeks
+   * @param {Number=} aData.days          Duration in days
+   * @param {Number=} aData.hours         Duration in hours
+   * @param {Number=} aData.minutes       Duration in minutes
+   * @param {Number=} aData.seconds       Duration in seconds
+   * @param {Boolean=} aData.isNegative   If true, the duration is negative
+   * @return {Duration}                   The createad duration instance
+   */
+  static fromData(aData) {
+    return new Duration(aData);
+  }
+
+  /**
+   * Creates a new ICAL.Duration instance.
+   *
+   * @param {Object} data                 An object with members of the duration
+   * @param {Number=} data.weeks          Duration in weeks
+   * @param {Number=} data.days           Duration in days
+   * @param {Number=} data.hours          Duration in hours
+   * @param {Number=} data.minutes        Duration in minutes
+   * @param {Number=} data.seconds        Duration in seconds
+   * @param {Boolean=} data.isNegative    If true, the duration is negative
+   */
+  constructor(data) {
+    this.wrappedJSObject = this;
+    this.fromData(data);
+  }
+
+  /**
+   * The weeks in this duration
+   * @type {Number}
+   * @default 0
+   */
+  weeks = 0;
+
+  /**
+   * The days in this duration
+   * @type {Number}
+   * @default 0
+   */
+  days = 0;
+
+  /**
+   * The days in this duration
+   * @type {Number}
+   * @default 0
+   */
+  hours = 0;
+
+  /**
+   * The minutes in this duration
+   * @type {Number}
+   * @default 0
+   */
+  minutes = 0;
+
+  /**
+   * The seconds in this duration
+   * @type {Number}
+   * @default 0
+   */
+  seconds = 0;
+
+  /**
+   * The seconds in this duration
+   * @type {Boolean}
+   * @default false
+   */
+  isNegative = false;
+
+  /**
+   * The class identifier.
+   * @constant
+   * @type {String}
+   * @default "icalduration"
+   */
+  icalclass = "icalduration";
+
+  /**
+   * The type name, to be used in the jCal object.
+   * @constant
+   * @type {String}
+   * @default "duration"
+   */
+  icaltype = "duration";
+
+  /**
+   * Returns a clone of the duration object.
+   *
+   * @return {Duration}      The cloned object
+   */
+  clone() {
+    return Duration.fromData(this);
+  }
+
+  /**
+   * The duration value expressed as a number of seconds.
+   *
+   * @return {Number}             The duration value in seconds
+   */
+  toSeconds() {
+    let seconds = this.seconds + 60 * this.minutes + 3600 * this.hours +
+                  86400 * this.days + 7 * 86400 * this.weeks;
+    return (this.isNegative ? -seconds : seconds);
+  }
+
+  /**
+   * Reads the passed seconds value into this duration object. Afterwards,
+   * members like {@link ICAL.Duration#days days} and {@link ICAL.Duration#weeks weeks} will be set up
+   * accordingly.
+   *
+   * @param {Number} aSeconds     The duration value in seconds
+   * @return {Duration}           Returns this instance
+   */
+  fromSeconds(aSeconds) {
+    let secs = Math.abs(aSeconds);
+
+    this.isNegative = (aSeconds < 0);
+    this.days = trunc(secs / 86400);
+
+    // If we have a flat number of weeks, use them.
+    if (this.days % 7 == 0) {
+      this.weeks = this.days / 7;
+      this.days = 0;
+    } else {
+      this.weeks = 0;
+    }
+
+    secs -= (this.days + 7 * this.weeks) * 86400;
+
+    this.hours = trunc(secs / 3600);
+    secs -= this.hours * 3600;
+
+    this.minutes = trunc(secs / 60);
+    secs -= this.minutes * 60;
+
+    this.seconds = secs;
+    return this;
+  }
+
+  /**
+   * Sets up the current instance using members from the passed data object.
+   *
+   * @param {Object} aData                An object with members of the duration
+   * @param {Number=} aData.weeks         Duration in weeks
+   * @param {Number=} aData.days          Duration in days
+   * @param {Number=} aData.hours         Duration in hours
+   * @param {Number=} aData.minutes       Duration in minutes
+   * @param {Number=} aData.seconds       Duration in seconds
+   * @param {Boolean=} aData.isNegative   If true, the duration is negative
+   */
+  fromData(aData) {
+    for (let prop of DATA_PROPS_TO_COPY) {
+      if (aData && prop in aData) {
+        this[prop] = aData[prop];
+      } else {
+        this[prop] = 0;
+      }
+    }
+  }
+
+  /**
+   * Resets the duration instance to the default values, i.e. PT0S
+   */
+  reset() {
+    this.isNegative = false;
+    this.weeks = 0;
+    this.days = 0;
+    this.hours = 0;
+    this.minutes = 0;
+    this.seconds = 0;
+  }
+
+  /**
+   * Compares the duration instance with another one.
+   *
+   * @param {Duration} aOther             The instance to compare with
+   * @return {Number}                     -1, 0 or 1 for less/equal/greater
+   */
+  compare(aOther) {
+    let thisSeconds = this.toSeconds();
+    let otherSeconds = aOther.toSeconds();
+    return (thisSeconds > otherSeconds) - (thisSeconds < otherSeconds);
+  }
+
+  /**
+   * Normalizes the duration instance. For example, a duration with a value
+   * of 61 seconds will be normalized to 1 minute and 1 second.
+   */
+  normalize() {
+    this.fromSeconds(this.toSeconds());
+  }
+
+  /**
+   * The string representation of this duration.
+   * @return {String}
+   */
+  toString() {
+    if (this.toSeconds() == 0) {
+      return "PT0S";
+    } else {
+      let str = "";
+      if (this.isNegative) str += "-";
+      str += "P";
+      if (this.weeks) str += this.weeks + "W";
+      if (this.days) str += this.days + "D";
+
+      if (this.hours || this.minutes || this.seconds) {
+        str += "T";
+        if (this.hours) str += this.hours + "H";
+        if (this.minutes) str += this.minutes + "M";
+        if (this.seconds) str += this.seconds + "S";
+      }
+      return str;
+    }
+  }
+
+  /**
+   * The iCalendar string representation of this duration.
+   * @return {String}
+   */
+  toICALString() {
+    return this.toString();
+  }
+}
+
+/**
+ * Internal helper function to handle a chunk of a duration.
+ *
+ * @private
+ * @param {String} letter type of duration chunk
+ * @param {String} number numeric value or -/+
+ * @param {Object} dict target to assign values to
+ */
+function parseDurationChunk(letter, number, object) {
+  let type;
+  switch (letter) {
+    case 'P':
+      if (number && number === '-') {
+        object.isNegative = true;
+      } else {
+        object.isNegative = false;
+      }
+      // period
+      break;
+    case 'D':
+      type = 'days';
+      break;
+    case 'W':
+      type = 'weeks';
+      break;
+    case 'H':
+      type = 'hours';
+      break;
+    case 'M':
+      type = 'minutes';
+      break;
+    case 'S':
+      type = 'seconds';
+      break;
+    default:
+      // Not a valid chunk
+      return 0;
+  }
+
+  if (type) {
+    if (!number && number !== 0) {
+      throw new Error(
+        'invalid duration value: Missing number before "' + letter + '"'
+      );
+    }
+    let num = parseInt(number, 10);
+    if (isStrictlyNaN(num)) {
+      throw new Error(
+        'invalid duration value: Invalid number "' + number + '" before "' + letter + '"'
+      );
+    }
+    object[type] = num;
+  }
+
+  return 1;
+}
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ * Portions Copyright (C) Philipp Kewisch */
+
+/**
+ * This lets typescript resolve our custom types in the
+ * generated d.ts files (jsdoc typedefs are converted to typescript types).
+ * Ignore prevents the typedefs from being documented more than once.
+ *
+ * @ignore
+ * @typedef {import("./types.js").weekDay} weekDay
+ * Imports the 'weekDay' type from the "types.js" module
+ */
+
+/**
+ * @classdesc
+ * iCalendar Time representation (similar to JS Date object).  Fully
+ * independent of system (OS) timezone / time.  Unlike JS Date, the month
+ * January is 1, not zero.
+ *
+ * @example
+ * var time = new ICAL.Time({
+ *   year: 2012,
+ *   month: 10,
+ *   day: 11
+ *   minute: 0,
+ *   second: 0,
+ *   isDate: false
+ * });
+ *
+ *
+ * @memberof ICAL
+*/
+class Time {
+  static _dowCache = {};
+  static _wnCache = {};
+
+  /**
+   * Returns the days in the given month
+   *
+   * @param {Number} month      The month to check
+   * @param {Number} year       The year to check
+   * @return {Number}           The number of days in the month
+   */
+  static daysInMonth(month, year) {
+    let _daysInMonth = [0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
+    let days = 30;
+
+    if (month < 1 || month > 12) return days;
+
+    days = _daysInMonth[month];
+
+    if (month == 2) {
+      days += Time.isLeapYear(year);
+    }
+
+    return days;
+  }
+
+  /**
+   * Checks if the year is a leap year
+   *
+   * @param {Number} year       The year to check
+   * @return {Boolean}          True, if the year is a leap year
+   */
+  static isLeapYear(year) {
+    if (year <= 1752) {
+      return ((year % 4) == 0);
+    } else {
+      return (((year % 4 == 0) && (year % 100 != 0)) || (year % 400 == 0));
+    }
+  }
+
+  /**
+   * Create a new ICAL.Time from the day of year and year. The date is returned
+   * in floating timezone.
+   *
+   * @param {Number} aDayOfYear     The day of year
+   * @param {Number} aYear          The year to create the instance in
+   * @return {Time}                 The created instance with the calculated date
+   */
+  static fromDayOfYear(aDayOfYear, aYear) {
+    let year = aYear;
+    let doy = aDayOfYear;
+    let tt = new Time();
+    tt.auto_normalize = false;
+    let is_leap = (Time.isLeapYear(year) ? 1 : 0);
+
+    if (doy < 1) {
+      year--;
+      is_leap = (Time.isLeapYear(year) ? 1 : 0);
+      doy += Time.daysInYearPassedMonth[is_leap][12];
+      return Time.fromDayOfYear(doy, year);
+    } else if (doy > Time.daysInYearPassedMonth[is_leap][12]) {
+      is_leap = (Time.isLeapYear(year) ? 1 : 0);
+      doy -= Time.daysInYearPassedMonth[is_leap][12];
+      year++;
+      return Time.fromDayOfYear(doy, year);
+    }
+
+    tt.year = year;
+    tt.isDate = true;
+
+    for (let month = 11; month >= 0; month--) {
+      if (doy > Time.daysInYearPassedMonth[is_leap][month]) {
+        tt.month = month + 1;
+        tt.day = doy - Time.daysInYearPassedMonth[is_leap][month];
+        break;
+      }
+    }
+
+    tt.auto_normalize = true;
+    return tt;
+  }
+
+  /**
+   * Returns a new ICAL.Time instance from a date string, e.g 2015-01-02.
+   *
+   * @deprecated                Use {@link ICAL.Time.fromDateString} instead
+   * @param {String} str        The string to create from
+   * @return {Time}             The date/time instance
+   */
+  static fromStringv2(str) {
+    return new Time({
+      year: parseInt(str.slice(0, 4), 10),
+      month: parseInt(str.slice(5, 7), 10),
+      day: parseInt(str.slice(8, 10), 10),
+      isDate: true
+    });
+  }
+
+  /**
+   * Returns a new ICAL.Time instance from a date string, e.g 2015-01-02.
+   *
+   * @param {String} aValue     The string to create from
+   * @return {Time}             The date/time instance
+   */
+  static fromDateString(aValue) {
+    // Dates should have no timezone.
+    // Google likes to sometimes specify Z on dates
+    // we specifically ignore that to avoid issues.
+
+    // YYYY-MM-DD
+    // 2012-10-10
+    return new Time({
+      year: strictParseInt(aValue.slice(0, 4)),
+      month: strictParseInt(aValue.slice(5, 7)),
+      day: strictParseInt(aValue.slice(8, 10)),
+      isDate: true
+    });
+  }
+
+  /**
+   * Returns a new ICAL.Time instance from a date-time string, e.g
+   * 2015-01-02T03:04:05. If a property is specified, the timezone is set up
+   * from the property's TZID parameter.
+   *
+   * @param {String} aValue         The string to create from
+   * @param {Property=} prop        The property the date belongs to
+   * @return {Time}                 The date/time instance
+   */
+  static fromDateTimeString(aValue, prop) {
+    if (aValue.length < 19) {
+      throw new Error(
+        'invalid date-time value: "' + aValue + '"'
+      );
+    }
+
+    let zone;
+    let zoneId;
+
+    if (aValue[19] && aValue[19] === 'Z') {
+      zone = Timezone.utcTimezone;
+    } else if (prop) {
+      zoneId = prop.getParameter('tzid');
+
+      if (prop.parent) {
+        if (prop.parent.name === 'standard' || prop.parent.name === 'daylight') {
+          // Per RFC 5545 3.8.2.4 and 3.8.2.2, start/end date-times within
+          // these components MUST be specified in local time.
+          zone = Timezone.localTimezone;
+        } else if (zoneId) {
+          // If the desired time zone is defined within the component tree,
+          // fetch its definition and prefer that.
+          zone = prop.parent.getTimeZoneByID(zoneId);
+        }
+      }
+    }
+
+    const timeData = {
+      year: strictParseInt(aValue.slice(0, 4)),
+      month: strictParseInt(aValue.slice(5, 7)),
+      day: strictParseInt(aValue.slice(8, 10)),
+      hour: strictParseInt(aValue.slice(11, 13)),
+      minute: strictParseInt(aValue.slice(14, 16)),
+      second: strictParseInt(aValue.slice(17, 19)),
+    };
+
+    // Although RFC 5545 requires that all TZIDs used within a file have a
+    // corresponding time zone definition, we may not be parsing the full file
+    // or we may be dealing with a non-compliant file; in either case, we can
+    // check our own time zone service for the TZID in a last-ditch effort.
+    if (zoneId && !zone) {
+      timeData.timezone = zoneId;
+    }
+
+    // 2012-10-10T10:10:10(Z)?
+    return new Time(timeData, zone);
+  }
+
+  /**
+   * Returns a new ICAL.Time instance from a date or date-time string,
+   *
+   * @param {String} aValue         The string to create from
+   * @param {Property=} prop        The property the date belongs to
+   * @return {Time}                 The date/time instance
+   */
+  static fromString(aValue, aProperty) {
+    if (aValue.length > 10) {
+      return Time.fromDateTimeString(aValue, aProperty);
+    } else {
+      return Time.fromDateString(aValue);
+    }
+  }
+
+  /**
+   * Creates a new ICAL.Time instance from the given Javascript Date.
+   *
+   * @param {?Date} aDate             The Javascript Date to read, or null to reset
+   * @param {Boolean} [useUTC=false]  If true, the UTC values of the date will be used
+   */
+  static fromJSDate(aDate, useUTC) {
+    let tt = new Time();
+    return tt.fromJSDate(aDate, useUTC);
+  }
+
+  /**
+   * Creates a new ICAL.Time instance from the the passed data object.
+   *
+   * @param {Object} aData            Time initialization
+   * @param {Number=} aData.year      The year for this date
+   * @param {Number=} aData.month     The month for this date
+   * @param {Number=} aData.day       The day for this date
+   * @param {Number=} aData.hour      The hour for this date
+   * @param {Number=} aData.minute    The minute for this date
+   * @param {Number=} aData.second    The second for this date
+   * @param {Boolean=} aData.isDate   If true, the instance represents a date
+   *                                    (as opposed to a date-time)
+   * @param {Timezone=} aZone         Timezone this position occurs in
+   */
+  static fromData = function fromData(aData, aZone) {
+    let t = new Time();
+    return t.fromData(aData, aZone);
+  };
+
+  /**
+   * Creates a new ICAL.Time instance from the current moment.
+   * The instance is “floating” - has no timezone relation.
+   * To create an instance considering the time zone, call
+   * ICAL.Time.fromJSDate(new Date(), true)
+   * @return {Time}
+   */
+  static now() {
+    return Time.fromJSDate(new Date(), false);
+  }
+
+  /**
+   * Returns the date on which ISO week number 1 starts.
+   *
+   * @see Time#weekNumber
+   * @param {Number} aYear                  The year to search in
+   * @param {weekDay=} aWeekStart           The week start weekday, used for calculation.
+   * @return {Time}                         The date on which week number 1 starts
+   */
+  static weekOneStarts(aYear, aWeekStart) {
+    let t = Time.fromData({
+      year: aYear,
+      month: 1,
+      day: 1,
+      isDate: true
+    });
+
+    let dow = t.dayOfWeek();
+    let wkst = aWeekStart || Time.DEFAULT_WEEK_START;
+    if (dow > Time.THURSDAY) {
+      t.day += 7;
+    }
+    if (wkst > Time.THURSDAY) {
+      t.day -= 7;
+    }
+
+    t.day -= dow - wkst;
+
+    return t;
+  }
+
+  /**
+   * Get the dominical letter for the given year. Letters range from A - G for
+   * common years, and AG to GF for leap years.
+   *
+   * @param {Number} yr           The year to retrieve the letter for
+   * @return {String}             The dominical letter.
+   */
+  static getDominicalLetter(yr) {
+    let LTRS = "GFEDCBA";
+    let dom = (yr + (yr / 4 | 0) + (yr / 400 | 0) - (yr / 100 | 0) - 1) % 7;
+    let isLeap = Time.isLeapYear(yr);
+    if (isLeap) {
+      return LTRS[(dom + 6) % 7] + LTRS[dom];
+    } else {
+      return LTRS[dom];
+    }
+  }
+
+  static #epochTime = null;
+  /**
+   * January 1st, 1970 as an ICAL.Time.
+   * @type {Time}
+   * @constant
+   * @instance
+   */
+  static get epochTime() {
+    if (!this.#epochTime) {
+      this.#epochTime = Time.fromData({
+        year: 1970,
+        month: 1,
+        day: 1,
+        hour: 0,
+        minute: 0,
+        second: 0,
+        isDate: false,
+        timezone: "Z"
+      });
+    }
+    return this.#epochTime;
+  }
+
+  static _cmp_attr(a, b, attr) {
+    if (a[attr] > b[attr]) return 1;
+    if (a[attr] < b[attr]) return -1;
+    return 0;
+  }
+
+  /**
+   * The days that have passed in the year after a given month. The array has
+   * two members, one being an array of passed days for non-leap years, the
+   * other analog for leap years.
+   * @example
+   * var isLeapYear = ICAL.Time.isLeapYear(year);
+   * var passedDays = ICAL.Time.daysInYearPassedMonth[isLeapYear][month];
+   * @type {Array.<Array.<Number>>}
+   */
+  static daysInYearPassedMonth = [
+    [0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365],
+    [0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366]
+  ];
+
+  static SUNDAY = 1;
+  static MONDAY = 2;
+  static TUESDAY = 3;
+  static WEDNESDAY = 4;
+  static THURSDAY = 5;
+  static FRIDAY = 6;
+  static SATURDAY = 7;
+
+  /**
+   * The default weekday for the WKST part.
+   * @constant
+   * @default ICAL.Time.MONDAY
+   */
+  static DEFAULT_WEEK_START = 2; // MONDAY
+
+  /**
+   * Creates a new ICAL.Time instance.
+   *
+   * @param {Object} data           Time initialization
+   * @param {Number=} data.year     The year for this date
+   * @param {Number=} data.month    The month for this date
+   * @param {Number=} data.day      The day for this date
+   * @param {Number=} data.hour     The hour for this date
+   * @param {Number=} data.minute   The minute for this date
+   * @param {Number=} data.second   The second for this date
+   * @param {Boolean=} data.isDate  If true, the instance represents a date (as
+   *                                  opposed to a date-time)
+   * @param {Timezone} zone         timezone this position occurs in
+   */
+  constructor(data, zone) {
+    this.wrappedJSObject = this;
+    let time = this._time = Object.create(null);
+
+    /* time defaults */
+    time.year = 0;
+    time.month = 1;
+    time.day = 1;
+    time.hour = 0;
+    time.minute = 0;
+    time.second = 0;
+    time.isDate = false;
+
+    this.fromData(data, zone);
+  }
+
+  /**
+   * The class identifier.
+   * @constant
+   * @type {String}
+   * @default "icaltime"
+   */
+  icalclass = "icaltime";
+  _cachedUnixTime = null;
+
+  /**
+   * The type name, to be used in the jCal object. This value may change and
+   * is strictly defined by the {@link ICAL.Time#isDate isDate} member.
+   * @type {String}
+   * @default "date-time"
+   */
+  get icaltype() {
+    return this.isDate ? 'date' : 'date-time';
+  }
+
+  /**
+   * The timezone for this time.
+   * @type {Timezone}
+   */
+  zone = null;
+
+  /**
+   * Internal uses to indicate that a change has been made and the next read
+   * operation must attempt to normalize the value (for example changing the
+   * day to 33).
+   *
+   * @type {Boolean}
+   * @private
+   */
+  _pendingNormalization = false;
+
+  /**
+   * Returns a clone of the time object.
+   *
+   * @return {Time}              The cloned object
+   */
+  clone() {
+    return new Time(this._time, this.zone);
+  }
+
+  /**
+   * Reset the time instance to epoch time
+   */
+  reset() {
+    this.fromData(Time.epochTime);
+    this.zone = Timezone.utcTimezone;
+  }
+
+  /**
+   * Reset the time instance to the given date/time values.
+   *
+   * @param {Number} year             The year to set
+   * @param {Number} month            The month to set
+   * @param {Number} day              The day to set
+   * @param {Number} hour             The hour to set
+   * @param {Number} minute           The minute to set
+   * @param {Number} second           The second to set
+   * @param {Timezone} timezone       The timezone to set
+   */
+  resetTo(year, month, day, hour, minute, second, timezone) {
+    this.fromData({
+      year: year,
+      month: month,
+      day: day,
+      hour: hour,
+      minute: minute,
+      second: second,
+      zone: timezone
+    });
+  }
+
+  /**
+   * Set up the current instance from the Javascript date value.
+   *
+   * @param {?Date} aDate             The Javascript Date to read, or null to reset
+   * @param {Boolean} [useUTC=false]  If true, the UTC values of the date will be used
+   */
+  fromJSDate(aDate, useUTC) {
+    if (!aDate) {
+      this.reset();
+    } else {
+      if (useUTC) {
+        this.zone = Timezone.utcTimezone;
+        this.year = aDate.getUTCFullYear();
+        this.month = aDate.getUTCMonth() + 1;
+        this.day = aDate.getUTCDate();
+        this.hour = aDate.getUTCHours();
+        this.minute = aDate.getUTCMinutes();
+        this.second = aDate.getUTCSeconds();
+      } else {
+        this.zone = Timezone.localTimezone;
+        this.year = aDate.getFullYear();
+        this.month = aDate.getMonth() + 1;
+        this.day = aDate.getDate();
+        this.hour = aDate.getHours();
+        this.minute = aDate.getMinutes();
+        this.second = aDate.getSeconds();
+      }
+    }
+    this._cachedUnixTime = null;
+    return this;
+  }
+
+  /**
+   * Sets up the current instance using members from the passed data object.
+   *
+   * @param {Object} aData            Time initialization
+   * @param {Number=} aData.year      The year for this date
+   * @param {Number=} aData.month     The month for this date
+   * @param {Number=} aData.day       The day for this date
+   * @param {Number=} aData.hour      The hour for this date
+   * @param {Number=} aData.minute    The minute for this date
+   * @param {Number=} aData.second    The second for this date
+   * @param {Boolean=} aData.isDate   If true, the instance represents a date
+   *                                    (as opposed to a date-time)
+   * @param {Timezone=} aZone         Timezone this position occurs in
+   */
+  fromData(aData, aZone) {
+    if (aData) {
+      for (let [key, value] of Object.entries(aData)) {
+          // ical type cannot be set
+          if (key === 'icaltype') continue;
+        this[key] = value;
+      }
+    }
+
+    if (aZone) {
+      this.zone = aZone;
+    }
+
+    if (aData && !("isDate" in aData)) {
+      this.isDate = !("hour" in aData);
+    } else if (aData && ("isDate" in aData)) {
+      this.isDate = aData.isDate;
+    }
+
+    if (aData && "timezone" in aData) {
+      let zone = TimezoneService.get(
+        aData.timezone
+      );
+
+      this.zone = zone || Timezone.localTimezone;
+    }
+
+    if (aData && "zone" in aData) {
+      this.zone = aData.zone;
+    }
+
+    if (!this.zone) {
+      this.zone = Timezone.localTimezone;
+    }
+
+    this._cachedUnixTime = null;
+    return this;
+  }
+
+  /**
+   * Calculate the day of week.
+   * @param {weekDay=} aWeekStart
+   *        The week start weekday, defaults to SUNDAY
+   * @return {weekDay}
+   */
+  dayOfWeek(aWeekStart) {
+    let firstDow = aWeekStart || Time.SUNDAY;
+    let dowCacheKey = (this.year << 12) + (this.month << 8) + (this.day << 3) + firstDow;
+    if (dowCacheKey in Time._dowCache) {
+      return Time._dowCache[dowCacheKey];
+    }
+
+    // Using Zeller's algorithm
+    let q = this.day;
+    let m = this.month + (this.month < 3 ? 12 : 0);
+    let Y = this.year - (this.month < 3 ? 1 : 0);
+
+    let h = (q + Y + trunc(((m + 1) * 26) / 10) + trunc(Y / 4));
+    { // eslint-disable-line no-constant-condition
+      h += trunc(Y / 100) * 6 + trunc(Y / 400);
+    }
+
+    // Normalize to 1 = wkst
+    h = ((h + 7 - firstDow) % 7) + 1;
+    Time._dowCache[dowCacheKey] = h;
+    return h;
+  }
+
+  /**
+   * Calculate the day of year.
+   * @return {Number}
+   */
+  dayOfYear() {
+    let is_leap = (Time.isLeapYear(this.year) ? 1 : 0);
+    let diypm = Time.daysInYearPassedMonth;
+    return diypm[is_leap][this.month - 1] + this.day;
+  }
+
+  /**
+   * Returns a copy of the current date/time, rewound to the start of the
+   * week. The resulting ICAL.Time instance is of icaltype date, even if this
+   * is a date-time.
+   *
+   * @param {weekDay=} aWeekStart
+   *        The week start weekday, defaults to SUNDAY
+   * @return {Time}      The start of the week (cloned)
+   */
+  startOfWeek(aWeekStart) {
+    let firstDow = aWeekStart || Time.SUNDAY;
+    let result = this.clone();
+    result.day -= ((this.dayOfWeek() + 7 - firstDow) % 7);
+    result.isDate = true;
+    result.hour = 0;
+    result.minute = 0;
+    result.second = 0;
+    return result;
+  }
+
+  /**
+   * Returns a copy of the current date/time, shifted to the end of the week.
+   * The resulting ICAL.Time instance is of icaltype date, even if this is a
+   * date-time.
+   *
+   * @param {weekDay=} aWeekStart
+   *        The week start weekday, defaults to SUNDAY
+   * @return {Time}      The end of the week (cloned)
+   */
+  endOfWeek(aWeekStart) {
+    let firstDow = aWeekStart || Time.SUNDAY;
+    let result = this.clone();
+    result.day += (7 - this.dayOfWeek() + firstDow - Time.SUNDAY) % 7;
+    result.isDate = true;
+    result.hour = 0;
+    result.minute = 0;
+    result.second = 0;
+    return result;
+  }
+
+  /**
+   * Returns a copy of the current date/time, rewound to the start of the
+   * month. The resulting ICAL.Time instance is of icaltype date, even if
+   * this is a date-time.
+   *
+   * @return {Time}      The start of the month (cloned)
+   */
+  startOfMonth() {
+    let result = this.clone();
+    result.day = 1;
+    result.isDate = true;
+    result.hour = 0;
+    result.minute = 0;
+    result.second = 0;
+    return result;
+  }
+
+  /**
+   * Returns a copy of the current date/time, shifted to the end of the
+   * month.  The resulting ICAL.Time instance is of icaltype date, even if
+   * this is a date-time.
+   *
+   * @return {Time}      The end of the month (cloned)
+   */
+  endOfMonth() {
+    let result = this.clone();
+    result.day = Time.daysInMonth(result.month, result.year);
+    result.isDate = true;
+    result.hour = 0;
+    result.minute = 0;
+    result.second = 0;
+    return result;
+  }
+
+  /**
+   * Returns a copy of the current date/time, rewound to the start of the
+   * year. The resulting ICAL.Time instance is of icaltype date, even if
+   * this is a date-time.
+   *
+   * @return {Time}      The start of the year (cloned)
+   */
+  startOfYear() {
+    let result = this.clone();
+    result.day = 1;
+    result.month = 1;
+    result.isDate = true;
+    result.hour = 0;
+    result.minute = 0;
+    result.second = 0;
+    return result;
+  }
+
+  /**
+   * Returns a copy of the current date/time, shifted to the end of the
+   * year.  The resulting ICAL.Time instance is of icaltype date, even if
+   * this is a date-time.
+   *
+   * @return {Time}      The end of the year (cloned)
+   */
+  endOfYear() {
+    let result = this.clone();
+    result.day = 31;
+    result.month = 12;
+    result.isDate = true;
+    result.hour = 0;
+    result.minute = 0;
+    result.second = 0;
+    return result;
+  }
+
+  /**
+   * First calculates the start of the week, then returns the day of year for
+   * this date. If the day falls into the previous year, the day is zero or negative.
+   *
+   * @param {weekDay=} aFirstDayOfWeek
+   *        The week start weekday, defaults to SUNDAY
+   * @return {Number}     The calculated day of year
+   */
+  startDoyWeek(aFirstDayOfWeek) {
+    let firstDow = aFirstDayOfWeek || Time.SUNDAY;
+    let delta = this.dayOfWeek() - firstDow;
+    if (delta < 0) delta += 7;
+    return this.dayOfYear() - delta;
+  }
+
+  /**
+   * Get the dominical letter for the current year. Letters range from A - G
+   * for common years, and AG to GF for leap years.
+   *
+   * @param {Number} yr           The year to retrieve the letter for
+   * @return {String}             The dominical letter.
+   */
+  getDominicalLetter() {
+    return Time.getDominicalLetter(this.year);
+  }
+
+  /**
+   * Finds the nthWeekDay relative to the current month (not day).  The
+   * returned value is a day relative the month that this month belongs to so
+   * 1 would indicate the first of the month and 40 would indicate a day in
+   * the following month.
+   *
+   * @param {Number} aDayOfWeek   Day of the week see the day name constants
+   * @param {Number} aPos         Nth occurrence of a given week day values
+   *        of 1 and 0 both indicate the first weekday of that type. aPos may
+   *        be either positive or negative
+   *
+   * @return {Number} numeric value indicating a day relative
+   *                   to the current month of this time object
+   */
+  nthWeekDay(aDayOfWeek, aPos) {
+    let daysInMonth = Time.daysInMonth(this.month, this.year);
+    let weekday;
+    let pos = aPos;
+
+    let start = 0;
+
+    let otherDay = this.clone();
+
+    if (pos >= 0) {
+      otherDay.day = 1;
+
+      // because 0 means no position has been given
+      // 1 and 0 indicate the same day.
+      if (pos != 0) {
+        // remove the extra numeric value
+        pos--;
+      }
+
+      // set current start offset to current day.
+      start = otherDay.day;
+
+      // find the current day of week
+      let startDow = otherDay.dayOfWeek();
+
+      // calculate the difference between current
+      // day of the week and desired day of the week
+      let offset = aDayOfWeek - startDow;
+
+
+      // if the offset goes into the past
+      // week we add 7 so it goes into the next
+      // week. We only want to go forward in time here.
+      if (offset < 0)
+        // this is really important otherwise we would
+        // end up with dates from in the past.
+        offset += 7;
+
+      // add offset to start so start is the same
+      // day of the week as the desired day of week.
+      start += offset;
+
+      // because we are going to add (and multiply)
+      // the numeric value of the day we subtract it
+      // from the start position so not to add it twice.
+      start -= aDayOfWeek;
+
+      // set week day
+      weekday = aDayOfWeek;
+    } else {
+
+      // then we set it to the last day in the current month
+      otherDay.day = daysInMonth;
+
+      // find the ends weekday
+      let endDow = otherDay.dayOfWeek();
+
+      pos++;
+
+      weekday = (endDow - aDayOfWeek);
+
+      if (weekday < 0) {
+        weekday += 7;
+      }
+
+      weekday = daysInMonth - weekday;
+    }
+
+    weekday += pos * 7;
+
+    return start + weekday;
+  }
+
+  /**
+   * Checks if current time is the nth weekday, relative to the current
+   * month.  Will always return false when rule resolves outside of current
+   * month.
+   *
+   * @param {weekDay} aDayOfWeek                 Day of week to check
+   * @param {Number} aPos                        Relative position
+   * @return {Boolean}                           True, if it is the nth weekday
+   */
+  isNthWeekDay(aDayOfWeek, aPos) {
+    let dow = this.dayOfWeek();
+
+    if (aPos === 0 && dow === aDayOfWeek) {
+      return true;
+    }
+
+    // get pos
+    let day = this.nthWeekDay(aDayOfWeek, aPos);
+
+    if (day === this.day) {
+      return true;
+    }
+
+    return false;
+  }
+
+  /**
+   * Calculates the ISO 8601 week number. The first week of a year is the
+   * week that contains the first Thursday. The year can have 53 weeks, if
+   * January 1st is a Friday.
+   *
+   * Note there are regions where the first week of the year is the one that
+   * starts on January 1st, which may offset the week number. Also, if a
+   * different week start is specified, this will also affect the week
+   * number.
+   *
+   * @see Time.weekOneStarts
+   * @param {weekDay} aWeekStart                  The weekday the week starts with
+   * @return {Number}                             The ISO week number
+   */
+  weekNumber(aWeekStart) {
+    let wnCacheKey = (this.year << 12) + (this.month << 8) + (this.day << 3) + aWeekStart;
+    if (wnCacheKey in Time._wnCache) {
+      return Time._wnCache[wnCacheKey];
+    }
+    // This function courtesty of Julian Bucknall, published under the MIT license
+    // http://www.boyet.com/articles/publishedarticles/calculatingtheisoweeknumb.html
+    // plus some fixes to be able to use different week starts.
+    let week1;
+
+    let dt = this.clone();
+    dt.isDate = true;
+    let isoyear = this.year;
+
+    if (dt.month == 12 && dt.day > 25) {
+      week1 = Time.weekOneStarts(isoyear + 1, aWeekStart);
+      if (dt.compare(week1) < 0) {
+        week1 = Time.weekOneStarts(isoyear, aWeekStart);
+      } else {
+        isoyear++;
+      }
+    } else {
+      week1 = Time.weekOneStarts(isoyear, aWeekStart);
+      if (dt.compare(week1) < 0) {
+        week1 = Time.weekOneStarts(--isoyear, aWeekStart);
+      }
+    }
+
+    let daysBetween = (dt.subtractDate(week1).toSeconds() / 86400);
+    let answer = trunc(daysBetween / 7) + 1;
+    Time._wnCache[wnCacheKey] = answer;
+    return answer;
+  }
+
+  /**
+   * Adds the duration to the current time. The instance is modified in
+   * place.
+   *
+   * @param {Duration} aDuration         The duration to add
+   */
+  addDuration(aDuration) {
+    let mult = (aDuration.isNegative ? -1 : 1);
+
+    // because of the duration optimizations it is much
+    // more efficient to grab all the values up front
+    // then set them directly (which will avoid a normalization call).
+    // So we don't actually normalize until we need it.
+    let second = this.second;
+    let minute = this.minute;
+    let hour = this.hour;
+    let day = this.day;
+
+    second += mult * aDuration.seconds;
+    minute += mult * aDuration.minutes;
+    hour += mult * aDuration.hours;
+    day += mult * aDuration.days;
+    day += mult * 7 * aDuration.weeks;
+
+    this.second = second;
+    this.minute = minute;
+    this.hour = hour;
+    this.day = day;
+
+    this._cachedUnixTime = null;
+  }
+
+  /**
+   * Subtract the date details (_excluding_ timezone).  Useful for finding
+   * the relative difference between two time objects excluding their
+   * timezone differences.
+   *
+   * @param {Time} aDate     The date to subtract
+   * @return {Duration}      The difference as a duration
+   */
+  subtractDate(aDate) {
+    let unixTime = this.toUnixTime() + this.utcOffset();
+    let other = aDate.toUnixTime() + aDate.utcOffset();
+    return Duration.fromSeconds(unixTime - other);
+  }
+
+  /**
+   * Subtract the date details, taking timezones into account.
+   *
+   * @param {Time} aDate  The date to subtract
+   * @return {Duration}   The difference in duration
+   */
+  subtractDateTz(aDate) {
+    let unixTime = this.toUnixTime();
+    let other = aDate.toUnixTime();
+    return Duration.fromSeconds(unixTime - other);
+  }
+
+  /**
+   * Compares the ICAL.Time instance with another one.
+   *
+   * @param {Duration} aOther        The instance to compare with
+   * @return {Number}                     -1, 0 or 1 for less/equal/greater
+   */
+  compare(other) {
+    let a = this.toUnixTime();
+    let b = other.toUnixTime();
+
+    if (a > b) return 1;
+    if (b > a) return -1;
+    return 0;
+  }
+
+  /**
+   * Compares only the date part of this instance with another one.
+   *
+   * @param {Duration} other              The instance to compare with
+   * @param {Timezone} tz                 The timezone to compare in
+   * @return {Number}                     -1, 0 or 1 for less/equal/greater
+   */
+  compareDateOnlyTz(other, tz) {
+    let a = this.convertToZone(tz);
+    let b = other.convertToZone(tz);
+    let rc = 0;
+
+    if ((rc = Time._cmp_attr(a, b, "year")) != 0) return rc;
+    if ((rc = Time._cmp_attr(a, b, "month")) != 0) return rc;
+    if ((rc = Time._cmp_attr(a, b, "day")) != 0) return rc;
+
+    return rc;
+  }
+
+  /**
+   * Convert the instance into another timezone. The returned ICAL.Time
+   * instance is always a copy.
+   *
+   * @param {Timezone} zone      The zone to convert to
+   * @return {Time}              The copy, converted to the zone
+   */
+  convertToZone(zone) {
+    let copy = this.clone();
+    let zone_equals = (this.zone.tzid == zone.tzid);
+
+    if (!this.isDate && !zone_equals) {
+      Timezone.convert_time(copy, this.zone, zone);
+    }
+
+    copy.zone = zone;
+    return copy;
+  }
+
+  /**
+   * Calculates the UTC offset of the current date/time in the timezone it is
+   * in.
+   *
+   * @return {Number}     UTC offset in seconds
+   */
+  utcOffset() {
+    if (this.zone == Timezone.localTimezone ||
+        this.zone == Timezone.utcTimezone) {
+      return 0;
+    } else {
+      return this.zone.utcOffset(this);
+    }
+  }
+
+  /**
+   * Returns an RFC 5545 compliant ical representation of this object.
+   *
+   * @return {String} ical date/date-time
+   */
+  toICALString() {
+    let string = this.toString();
+
+    if (string.length > 10) {
+      return design$1.icalendar.value['date-time'].toICAL(string);
+    } else {
+      return design$1.icalendar.value.date.toICAL(string);
+    }
+  }
+
+  /**
+   * The string representation of this date/time, in jCal form
+   * (including : and - separators).
+   * @return {String}
+   */
+  toString() {
+    let result = this.year + '-' +
+                 pad2(this.month) + '-' +
+                 pad2(this.day);
+
+    if (!this.isDate) {
+        result += 'T' + pad2(this.hour) + ':' +
+                  pad2(this.minute) + ':' +
+                  pad2(this.second);
+
+      if (this.zone === Timezone.utcTimezone) {
+        result += 'Z';
+      }
+    }
+
+    return result;
+  }
+
+  /**
+   * Converts the current instance to a Javascript date
+   * @return {Date}
+   */
+  toJSDate() {
+    if (this.zone == Timezone.localTimezone) {
+      if (this.isDate) {
+        return new Date(this.year, this.month - 1, this.day);
+      } else {
+        return new Date(this.year, this.month - 1, this.day,
+                        this.hour, this.minute, this.second, 0);
+      }
+    } else {
+      return new Date(this.toUnixTime() * 1000);
+    }
+  }
+
+  _normalize() {
+    if (this._time.isDate) {
+      this._time.hour = 0;
+      this._time.minute = 0;
+      this._time.second = 0;
+    }
+    this.adjust(0, 0, 0, 0);
+
+    return this;
+  }
+
+  /**
+   * Adjust the date/time by the given offset
+   *
+   * @param {Number} aExtraDays       The extra amount of days
+   * @param {Number} aExtraHours      The extra amount of hours
+   * @param {Number} aExtraMinutes    The extra amount of minutes
+   * @param {Number} aExtraSeconds    The extra amount of seconds
+   * @param {Number=} aTime           The time to adjust, defaults to the
+   *                                    current instance.
+   */
+  adjust(aExtraDays, aExtraHours, aExtraMinutes, aExtraSeconds, aTime) {
+
+    let minutesOverflow, hoursOverflow,
+        daysOverflow = 0, yearsOverflow = 0;
+
+    let second, minute, hour, day;
+    let daysInMonth;
+
+    let time = aTime || this._time;
+
+    if (!time.isDate) {
+      second = time.second + aExtraSeconds;
+      time.second = second % 60;
+      minutesOverflow = trunc(second / 60);
+      if (time.second < 0) {
+        time.second += 60;
+        minutesOverflow--;
+      }
+
+      minute = time.minute + aExtraMinutes + minutesOverflow;
+      time.minute = minute % 60;
+      hoursOverflow = trunc(minute / 60);
+      if (time.minute < 0) {
+        time.minute += 60;
+        hoursOverflow--;
+      }
+
+      hour = time.hour + aExtraHours + hoursOverflow;
+
+      time.hour = hour % 24;
+      daysOverflow = trunc(hour / 24);
+      if (time.hour < 0) {
+        time.hour += 24;
+        daysOverflow--;
+      }
+    }
+
+
+    // Adjust month and year first, because we need to know what month the day
+    // is in before adjusting it.
+    if (time.month > 12) {
+      yearsOverflow = trunc((time.month - 1) / 12);
+    } else if (time.month < 1) {
+      yearsOverflow = trunc(time.month / 12) - 1;
+    }
+
+    time.year += yearsOverflow;
+    time.month -= 12 * yearsOverflow;
+
+    // Now take care of the days (and adjust month if needed)
+    day = time.day + aExtraDays + daysOverflow;
+
+    if (day > 0) {
+      for (;;) {
+        daysInMonth = Time.daysInMonth(time.month, time.year);
+        if (day <= daysInMonth) {
+          break;
+        }
+
+        time.month++;
+        if (time.month > 12) {
+          time.year++;
+          time.month = 1;
+        }
+
+        day -= daysInMonth;
+      }
+    } else {
+      while (day <= 0) {
+        if (time.month == 1) {
+          time.year--;
+          time.month = 12;
+        } else {
+          time.month--;
+        }
+
+        day += Time.daysInMonth(time.month, time.year);
+      }
+    }
+
+    time.day = day;
+
+    this._cachedUnixTime = null;
+    return this;
+  }
+
+  /**
+   * Sets up the current instance from unix time, the number of seconds since
+   * January 1st, 1970.
+   *
+   * @param {Number} seconds      The seconds to set up with
+   */
+  fromUnixTime(seconds) {
+    this.zone = Timezone.utcTimezone;
+    // We could use `fromJSDate` here, but this is about twice as fast.
+    // We could also clone `epochTime` and use `adjust` for a more
+    // ical.js-centric approach, but this is about 100 times as fast.
+    let date = new Date(seconds * 1000);
+    this.year = date.getUTCFullYear();
+    this.month = date.getUTCMonth() + 1;
+    this.day = date.getUTCDate();
+    if (this._time.isDate) {
+      this.hour = 0;
+      this.minute = 0;
+      this.second = 0;
+    } else {
+      this.hour = date.getUTCHours();
+      this.minute = date.getUTCMinutes();
+      this.second = date.getUTCSeconds();
+    }
+
+    this._cachedUnixTime = null;
+  }
+
+  /**
+   * Converts the current instance to seconds since January 1st 1970.
+   *
+   * @return {Number}         Seconds since 1970
+   */
+  toUnixTime() {
+    if (this._cachedUnixTime !== null) {
+      return this._cachedUnixTime;
+    }
+    let offset = this.utcOffset();
+
+    // we use the offset trick to ensure
+    // that we are getting the actual UTC time
+    let ms = Date.UTC(
+      this.year,
+      this.month - 1,
+      this.day,
+      this.hour,
+      this.minute,
+      this.second - offset
+    );
+
+    // seconds
+    this._cachedUnixTime = ms / 1000;
+    return this._cachedUnixTime;
+  }
+
+  /**
+   * Converts time to into Object which can be serialized then re-created
+   * using the constructor.
+   *
+   * @example
+   * // toJSON will automatically be called
+   * var json = JSON.stringify(mytime);
+   *
+   * var deserialized = JSON.parse(json);
+   *
+   * var time = new ICAL.Time(deserialized);
+   *
+   * @return {Object}
+   */
+  toJSON() {
+    let copy = [
+      'year',
+      'month',
+      'day',
+      'hour',
+      'minute',
+      'second',
+      'isDate'
+    ];
+
+    let result = Object.create(null);
+
+    let i = 0;
+    let len = copy.length;
+    let prop;
+
+    for (; i < len; i++) {
+      prop = copy[i];
+      result[prop] = this[prop];
+    }
+
+    if (this.zone) {
+      result.timezone = this.zone.tzid;
+    }
+
+    return result;
+  }
+}
+
+(function setupNormalizeAttributes() {
+  // This needs to run before any instances are created!
+  function defineAttr(attr) {
+    Object.defineProperty(Time.prototype, attr, {
+      get: function getTimeAttr() {
+        if (this._pendingNormalization) {
+          this._normalize();
+          this._pendingNormalization = false;
+        }
+
+        return this._time[attr];
+      },
+      set: function setTimeAttr(val) {
+        // Check if isDate will be set and if was not set to normalize date.
+        // This avoids losing days when seconds, minutes and hours are zeroed
+        // what normalize will do when time is a date.
+        if (attr === "isDate" && val && !this._time.isDate) {
+          this.adjust(0, 0, 0, 0);
+        }
+        this._cachedUnixTime = null;
+        this._pendingNormalization = true;
+        this._time[attr] = val;
+      }
+    });
+
+  }
+
+    defineAttr("year");
+    defineAttr("month");
+    defineAttr("day");
+    defineAttr("hour");
+    defineAttr("minute");
+    defineAttr("second");
+    defineAttr("isDate");
+})();
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ * Portions Copyright (C) Philipp Kewisch */
+
+/**
+ * This lets typescript resolve our custom types in the
+ * generated d.ts files (jsdoc typedefs are converted to typescript types).
+ * Ignore prevents the typedefs from being documented more than once.
+ *
+ * @ignore
+ * @typedef {import("./types.js").parserState} parserState
+ * Imports the 'parserState' type from the "types.js" module
+ * @typedef {import("./types.js").designSet} designSet
+ * Imports the 'designSet' type from the "types.js" module
+ */
+
+const CHAR = /[^ \t]/;
+const VALUE_DELIMITER = ':';
+const PARAM_DELIMITER = ';';
+const PARAM_NAME_DELIMITER = '=';
+const DEFAULT_VALUE_TYPE$1 = 'unknown';
+const DEFAULT_PARAM_TYPE = 'text';
+const RFC6868_REPLACE_MAP$1 = { "^'": '"', "^n": "\n", "^^": "^" };
+
+/**
+ * Parses iCalendar or vCard data into a raw jCal object. Consult
+ * documentation on the {@tutorial layers|layers of parsing} for more
+ * details.
+ *
+ * @function ICAL.parse
+ * @memberof ICAL
+ * @variation function
+ * @todo Fix the API to be more clear on the return type
+ * @param {String} input      The string data to parse
+ * @return {Object|Object[]}  A single jCal object, or an array thereof
+ */
+function parse(input) {
+  let state = {};
+  let root = state.component = [];
+
+  state.stack = [root];
+
+  parse._eachLine(input, function(err, line) {
+    parse._handleContentLine(line, state);
+  });
+
+
+  // when there are still items on the stack
+  // throw a fatal error, a component was not closed
+  // correctly in that case.
+  if (state.stack.length > 1) {
+    throw new ParserError(
+      'invalid ical body. component began but did not end'
+    );
+  }
+
+  state = null;
+
+  return (root.length == 1 ? root[0] : root);
+}
+
+/**
+ * Parse an iCalendar property value into the jCal for a single property
+ *
+ * @function ICAL.parse.property
+ * @param {String} str
+ *   The iCalendar property string to parse
+ * @param {designSet=} designSet
+ *   The design data to use for this property
+ * @return {Object}
+ *   The jCal Object containing the property
+ */
+parse.property = function(str, designSet) {
+  let state = {
+    component: [[], []],
+    designSet: designSet || design$1.defaultSet
+  };
+  parse._handleContentLine(str, state);
+  return state.component[1][0];
+};
+
+/**
+ * Convenience method to parse a component. You can use ICAL.parse() directly
+ * instead.
+ *
+ * @function ICAL.parse.component
+ * @see ICAL.parse(function)
+ * @param {String} str    The iCalendar component string to parse
+ * @return {Object}       The jCal Object containing the component
+ */
+parse.component = function(str) {
+  return parse(str);
+};
+
+
+/**
+ * An error that occurred during parsing.
+ *
+ * @param {String} message        The error message
+ * @memberof ICAL.parse
+ * @extends {Error}
+ */
+class ParserError extends Error {
+  name = this.constructor.name;
+}
+
+// classes & constants
+parse.ParserError = ParserError;
+
+
+/**
+ * Handles a single line of iCalendar/vCard, updating the state.
+ *
+ * @private
+ * @function ICAL.parse._handleContentLine
+ * @param {String} line          The content line to process
+ * @param {parserState} state    The current state of the line parsing
+ */
+parse._handleContentLine = function(line, state) {
+  // break up the parts of the line
+  let valuePos = line.indexOf(VALUE_DELIMITER);
+  let paramPos = line.indexOf(PARAM_DELIMITER);
+
+  let lastParamIndex;
+  let lastValuePos;
+
+  // name of property or begin/end
+  let name;
+  let value;
+  // params is only overridden if paramPos !== -1.
+  // we can't do params = params || {} later on
+  // because it sacrifices ops.
+  let params = {};
+
+  /**
+   * Different property cases
+   *
+   *
+   * 1. RRULE:FREQ=foo
+   *    // FREQ= is not a param but the value
+   *
+   * 2. ATTENDEE;ROLE=REQ-PARTICIPANT;
+   *    // ROLE= is a param because : has not happened yet
+   */
+    // when the parameter delimiter is after the
+    // value delimiter then it is not a parameter.
+
+  if ((paramPos !== -1 && valuePos !== -1)) {
+    // when the parameter delimiter is after the
+    // value delimiter then it is not a parameter.
+    if (paramPos > valuePos) {
+      paramPos = -1;
+    }
+  }
+
+  let parsedParams;
+  if (paramPos !== -1) {
+    name = line.slice(0, Math.max(0, paramPos)).toLowerCase();
+    parsedParams = parse._parseParameters(line.slice(Math.max(0, paramPos)), 0, state.designSet);
+    if (parsedParams[2] == -1) {
+      throw new ParserError("Invalid parameters in '" + line + "'");
+    }
+    params = parsedParams[0];
+    lastParamIndex = parsedParams[1].length + parsedParams[2] + paramPos;
+    if ((lastValuePos =
+      line.slice(Math.max(0, lastParamIndex)).indexOf(VALUE_DELIMITER)) !== -1) {
+      value = line.slice(Math.max(0, lastParamIndex + lastValuePos + 1));
+    } else {
+      throw new ParserError("Missing parameter value in '" + line + "'");
+    }
+  } else if (valuePos !== -1) {
+    // without parmeters (BEGIN:VCAENDAR, CLASS:PUBLIC)
+    name = line.slice(0, Math.max(0, valuePos)).toLowerCase();
+    value = line.slice(Math.max(0, valuePos + 1));
+
+    if (name === 'begin') {
+      let newComponent = [value.toLowerCase(), [], []];
+      if (state.stack.length === 1) {
+        state.component.push(newComponent);
+      } else {
+        state.component[2].push(newComponent);
+      }
+      state.stack.push(state.component);
+      state.component = newComponent;
+      if (!state.designSet) {
+        state.designSet = design$1.getDesignSet(state.component[0]);
+      }
+      return;
+    } else if (name === 'end') {
+      state.component = state.stack.pop();
+      return;
+    }
+    // If it is not begin/end, then this is a property with an empty value,
+    // which should be considered valid.
+  } else {
+    /**
+     * Invalid line.
+     * The rational to throw an error is we will
+     * never be certain that the rest of the file
+     * is sane and it is unlikely that we can serialize
+     * the result correctly either.
+     */
+    throw new ParserError(
+      'invalid line (no token ";" or ":") "' + line + '"'
+    );
+  }
+
+  let valueType;
+  let multiValue = false;
+  let structuredValue = false;
+  let propertyDetails;
+  let splitName;
+  let ungroupedName;
+
+  // fetch the ungrouped part of the name
+  if (state.designSet.propertyGroups && name.indexOf('.') !== -1) {
+    splitName = name.split('.');
+    params.group = splitName[0];
+    ungroupedName = splitName[1];
+  } else {
+    ungroupedName = name;
+  }
+
+  if (ungroupedName in state.designSet.property) {
+    propertyDetails = state.designSet.property[ungroupedName];
+
+    if ('multiValue' in propertyDetails) {
+      multiValue = propertyDetails.multiValue;
+    }
+
+    if ('structuredValue' in propertyDetails) {
+      structuredValue = propertyDetails.structuredValue;
+    }
+
+    if (value && 'detectType' in propertyDetails) {
+      valueType = propertyDetails.detectType(value);
+    }
+  }
+
+  // attempt to determine value
+  if (!valueType) {
+    if (!('value' in params)) {
+      if (propertyDetails) {
+        valueType = propertyDetails.defaultType;
+      } else {
+        valueType = DEFAULT_VALUE_TYPE$1;
+      }
+    } else {
+      // possible to avoid this?
+      valueType = params.value.toLowerCase();
+    }
+  }
+
+  delete params.value;
+
+  /**
+   * Note on `var result` juggling:
+   *
+   * I observed that building the array in pieces has adverse
+   * effects on performance, so where possible we inline the creation.
+   * It is a little ugly but resulted in ~2000 additional ops/sec.
+   */
+
+  let result;
+  if (multiValue && structuredValue) {
+    value = parse._parseMultiValue(value, structuredValue, valueType, [], multiValue, state.designSet, structuredValue);
+    result = [ungroupedName, params, valueType, value];
+  } else if (multiValue) {
+    result = [ungroupedName, params, valueType];
+    parse._parseMultiValue(value, multiValue, valueType, result, null, state.designSet, false);
+  } else if (structuredValue) {
+    value = parse._parseMultiValue(value, structuredValue, valueType, [], null, state.designSet, structuredValue);
+    result = [ungroupedName, params, valueType, value];
+  } else {
+    value = parse._parseValue(value, valueType, state.designSet, false);
+    result = [ungroupedName, params, valueType, value];
+  }
+  // rfc6350 requires that in vCard 4.0 the first component is the VERSION
+  // component with as value 4.0, note that 3.0 does not have this requirement.
+  if (state.component[0] === 'vcard' && state.component[1].length === 0 &&
+          !(name === 'version' && value === '4.0')) {
+    state.designSet = design$1.getDesignSet("vcard3");
+  }
+  state.component[1].push(result);
+};
+
+/**
+ * Parse a value from the raw value into the jCard/jCal value.
+ *
+ * @private
+ * @function ICAL.parse._parseValue
+ * @param {String} value          Original value
+ * @param {String} type           Type of value
+ * @param {Object} designSet      The design data to use for this value
+ * @return {Object} varies on type
+ */
+parse._parseValue = function(value, type, designSet, structuredValue) {
+  if (type in designSet.value && 'fromICAL' in designSet.value[type]) {
+    return designSet.value[type].fromICAL(value, structuredValue);
+  }
+  return value;
+};
+
+/**
+ * Parse parameters from a string to object.
+ *
+ * @function ICAL.parse._parseParameters
+ * @private
+ * @param {String} line           A single unfolded line
+ * @param {Number} start         Position to start looking for properties
+ * @param {Object} designSet      The design data to use for this property
+ * @return {Object} key/value pairs
+ */
+parse._parseParameters = function(line, start, designSet) {
+  let lastParam = start;
+  let pos = 0;
+  let delim = PARAM_NAME_DELIMITER;
+  let result = {};
+  let name, lcname;
+  let value, valuePos = -1;
+  let type, multiValue, mvdelim;
+
+  // find the next '=' sign
+  // use lastParam and pos to find name
+  // check if " is used if so get value from "->"
+  // then increment pos to find next ;
+
+  while ((pos !== false) &&
+         (pos = line.indexOf(delim, pos + 1)) !== -1) {
+
+    name = line.slice(lastParam + 1, pos);
+    if (name.length == 0) {
+      throw new ParserError("Empty parameter name in '" + line + "'");
+    }
+    lcname = name.toLowerCase();
+    mvdelim = false;
+    multiValue = false;
+
+    if (lcname in designSet.param && designSet.param[lcname].valueType) {
+      type = designSet.param[lcname].valueType;
+    } else {
+      type = DEFAULT_PARAM_TYPE;
+    }
+
+    if (lcname in designSet.param) {
+      multiValue = designSet.param[lcname].multiValue;
+      if (designSet.param[lcname].multiValueSeparateDQuote) {
+        mvdelim = parse._rfc6868Escape('"' + multiValue + '"');
+      }
+    }
+
+    let nextChar = line[pos + 1];
+    if (nextChar === '"') {
+      valuePos = pos + 2;
+      pos = line.indexOf('"', valuePos);
+      if (multiValue && pos != -1) {
+          let extendedValue = true;
+          while (extendedValue) {
+            if (line[pos + 1] == multiValue && line[pos + 2] == '"') {
+              pos = line.indexOf('"', pos + 3);
+            } else {
+              extendedValue = false;
+            }
+          }
+        }
+      if (pos === -1) {
+        throw new ParserError(
+          'invalid line (no matching double quote) "' + line + '"'
+        );
+      }
+      value = line.slice(valuePos, pos);
+      lastParam = line.indexOf(PARAM_DELIMITER, pos);
+      let propValuePos = line.indexOf(VALUE_DELIMITER, pos);
+      // if either no next parameter or delimeter in property value, let's stop here
+      if (lastParam === -1 || (propValuePos !== -1 && lastParam > propValuePos)) {
+        pos = false;
+      }
+    } else {
+      valuePos = pos + 1;
+
+      // move to next ";"
+      let nextPos = line.indexOf(PARAM_DELIMITER, valuePos);
+      let propValuePos = line.indexOf(VALUE_DELIMITER, valuePos);
+      if (propValuePos !== -1 && nextPos > propValuePos) {
+        // this is a delimiter in the property value, let's stop here
+        nextPos = propValuePos;
+        pos = false;
+      } else if (nextPos === -1) {
+        // no ";"
+        if (propValuePos === -1) {
+          nextPos = line.length;
+        } else {
+          nextPos = propValuePos;
+        }
+        pos = false;
+      } else {
+        lastParam = nextPos;
+        pos = nextPos;
+      }
+
+      value = line.slice(valuePos, nextPos);
+    }
+
+    const length_before = value.length;
+    value = parse._rfc6868Escape(value);
+    valuePos += length_before - value.length;
+    if (multiValue) {
+      let delimiter = mvdelim || multiValue;
+      value = parse._parseMultiValue(value, delimiter, type, [], null, designSet);
+    } else {
+      value = parse._parseValue(value, type, designSet);
+    }
+
+    if (multiValue && (lcname in result)) {
+      if (Array.isArray(result[lcname])) {
+        result[lcname].push(value);
+      } else {
+        result[lcname] = [
+          result[lcname],
+          value
+        ];
+      }
+    } else {
+      result[lcname] = value;
+    }
+  }
+  return [result, value, valuePos];
+};
+
+/**
+ * Internal helper for rfc6868. Exposing this on ICAL.parse so that
+ * hackers can disable the rfc6868 parsing if the really need to.
+ *
+ * @function ICAL.parse._rfc6868Escape
+ * @param {String} val        The value to escape
+ * @return {String}           The escaped value
+ */
+parse._rfc6868Escape = function(val) {
+  return val.replace(/\^['n^]/g, function(x) {
+    return RFC6868_REPLACE_MAP$1[x];
+  });
+};
+
+/**
+ * Parse a multi value string. This function is used either for parsing
+ * actual multi-value property's values, or for handling parameter values. It
+ * can be used for both multi-value properties and structured value properties.
+ *
+ * @private
+ * @function ICAL.parse._parseMultiValue
+ * @param {String} buffer           The buffer containing the full value
+ * @param {String} delim            The multi-value delimiter
+ * @param {String} type             The value type to be parsed
+ * @param {Array.<?>} result        The array to append results to, varies on value type
+ * @param {String} innerMulti       The inner delimiter to split each value with
+ * @param {designSet} designSet     The design data for this value
+ * @return {?|Array.<?>}            Either an array of results, or the first result
+ */
+parse._parseMultiValue = function(buffer, delim, type, result, innerMulti, designSet, structuredValue) {
+  let pos = 0;
+  let lastPos = 0;
+  let value;
+  if (delim.length === 0) {
+    return buffer;
+  }
+
+  // split each piece
+  while ((pos = unescapedIndexOf(buffer, delim, lastPos)) !== -1) {
+    value = buffer.slice(lastPos, pos);
+    if (innerMulti) {
+      value = parse._parseMultiValue(value, innerMulti, type, [], null, designSet, structuredValue);
+    } else {
+      value = parse._parseValue(value, type, designSet, structuredValue);
+    }
+    result.push(value);
+    lastPos = pos + delim.length;
+  }
+
+  // on the last piece take the rest of string
+  value = buffer.slice(lastPos);
+  if (innerMulti) {
+    value = parse._parseMultiValue(value, innerMulti, type, [], null, designSet, structuredValue);
+  } else {
+    value = parse._parseValue(value, type, designSet, structuredValue);
+  }
+  result.push(value);
+
+  return result.length == 1 ? result[0] : result;
+};
+
+/**
+ * Process a complete buffer of iCalendar/vCard data line by line, correctly
+ * unfolding content. Each line will be processed with the given callback
+ *
+ * @private
+ * @function ICAL.parse._eachLine
+ * @param {String} buffer                         The buffer to process
+ * @param {function(?String, String)} callback    The callback for each line
+ */
+parse._eachLine = function(buffer, callback) {
+  let len = buffer.length;
+  let lastPos = buffer.search(CHAR);
+  let pos = lastPos;
+  let line;
+  let firstChar;
+
+  let newlineOffset;
+
+  do {
+    pos = buffer.indexOf('\n', lastPos) + 1;
+
+    if (pos > 1 && buffer[pos - 2] === '\r') {
+      newlineOffset = 2;
+    } else {
+      newlineOffset = 1;
+    }
+
+    if (pos === 0) {
+      pos = len;
+      newlineOffset = 0;
+    }
+
+    firstChar = buffer[lastPos];
+
+    if (firstChar === ' ' || firstChar === '\t') {
+      // add to line
+      line += buffer.slice(lastPos + 1, pos - newlineOffset);
+    } else {
+      if (line)
+        callback(null, line);
+      // push line
+      line = buffer.slice(lastPos, pos - newlineOffset);
+    }
+
+    lastPos = pos;
+  } while (pos !== len);
+
+  // extra ending line
+  line = line.trim();
+
+  if (line.length)
+    callback(null, line);
+};
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ * Portions Copyright (C) Philipp Kewisch */
+
+const OPTIONS = ["tzid", "location", "tznames", "latitude", "longitude"];
+
+/**
+ * Timezone representation.
+ *
+ * @example
+ * var vcalendar;
+ * var timezoneComp = vcalendar.getFirstSubcomponent('vtimezone');
+ * var tzid = timezoneComp.getFirstPropertyValue('tzid');
+ *
+ * var timezone = new ICAL.Timezone({
+ *   component: timezoneComp,
+ *   tzid
+ * });
+ *
+ * @memberof ICAL
+ */
+class Timezone {
+  static _compare_change_fn(a, b) {
+    if (a.year < b.year) return -1;
+    else if (a.year > b.year) return 1;
+
+    if (a.month < b.month) return -1;
+    else if (a.month > b.month) return 1;
+
+    if (a.day < b.day) return -1;
+    else if (a.day > b.day) return 1;
+
+    if (a.hour < b.hour) return -1;
+    else if (a.hour > b.hour) return 1;
+
+    if (a.minute < b.minute) return -1;
+    else if (a.minute > b.minute) return 1;
+
+    if (a.second < b.second) return -1;
+    else if (a.second > b.second) return 1;
+
+    return 0;
+  }
+
+  /**
+   * Convert the date/time from one zone to the next.
+   *
+   * @param {Time} tt                  The time to convert
+   * @param {Timezone} from_zone       The source zone to convert from
+   * @param {Timezone} to_zone         The target zone to convert to
+   * @return {Time}                    The converted date/time object
+   */
+  static convert_time(tt, from_zone, to_zone) {
+    if (tt.isDate ||
+        from_zone.tzid == to_zone.tzid ||
+        from_zone == Timezone.localTimezone ||
+        to_zone == Timezone.localTimezone) {
+      tt.zone = to_zone;
+      return tt;
+    }
+
+    let utcOffset = from_zone.utcOffset(tt);
+    tt.adjust(0, 0, 0, - utcOffset);
+
+    utcOffset = to_zone.utcOffset(tt);
+    tt.adjust(0, 0, 0, utcOffset);
+
+    return null;
+  }
+
+  /**
+   * Creates a new ICAL.Timezone instance from the passed data object.
+   *
+   * @param {Component|Object} aData options for class
+   * @param {String|Component} aData.component
+   *        If aData is a simple object, then this member can be set to either a
+   *        string containing the component data, or an already parsed
+   *        ICAL.Component
+   * @param {String} aData.tzid      The timezone identifier
+   * @param {String} aData.location  The timezone locationw
+   * @param {String} aData.tznames   An alternative string representation of the
+   *                                  timezone
+   * @param {Number} aData.latitude  The latitude of the timezone
+   * @param {Number} aData.longitude The longitude of the timezone
+   */
+  static fromData(aData) {
+    let tt = new Timezone();
+    return tt.fromData(aData);
+  }
+
+  /**
+   * The instance describing the UTC timezone
+   * @type {Timezone}
+   * @constant
+   * @instance
+   */
+  static #utcTimezone = null;
+  static get utcTimezone() {
+    if (!this.#utcTimezone) {
+      this.#utcTimezone = Timezone.fromData({
+        tzid: "UTC"
+      });
+    }
+    return this.#utcTimezone;
+  }
+
+  /**
+   * The instance describing the local timezone
+   * @type {Timezone}
+   * @constant
+   * @instance
+   */
+  static #localTimezone = null;
+  static get localTimezone() {
+    if (!this.#localTimezone) {
+      this.#localTimezone = Timezone.fromData({
+        tzid: "floating"
+      });
+    }
+    return this.#localTimezone;
+  }
+
+  /**
+   * Adjust a timezone change object.
+   * @private
+   * @param {Object} change     The timezone change object
+   * @param {Number} days       The extra amount of days
+   * @param {Number} hours      The extra amount of hours
+   * @param {Number} minutes    The extra amount of minutes
+   * @param {Number} seconds    The extra amount of seconds
+   */
+  static adjust_change(change, days, hours, minutes, seconds) {
+    return Time.prototype.adjust.call(
+      change,
+      days,
+      hours,
+      minutes,
+      seconds,
+      change
+    );
+  }
+
+  static _minimumExpansionYear = -1;
+  static EXTRA_COVERAGE = 5;
+
+  /**
+   * Creates a new ICAL.Timezone instance, by passing in a tzid and component.
+   *
+   * @param {Component|Object} data options for class
+   * @param {String|Component} data.component
+   *        If data is a simple object, then this member can be set to either a
+   *        string containing the component data, or an already parsed
+   *        ICAL.Component
+   * @param {String} data.tzid      The timezone identifier
+   * @param {String} data.location  The timezone locationw
+   * @param {String} data.tznames   An alternative string representation of the
+   *                                  timezone
+   * @param {Number} data.latitude  The latitude of the timezone
+   * @param {Number} data.longitude The longitude of the timezone
+   */
+  constructor(data) {
+    this.wrappedJSObject = this;
+    this.fromData(data);
+  }
+
+
+  /**
+   * Timezone identifier
+   * @type {String}
+   */
+  tzid = "";
+
+  /**
+   * Timezone location
+   * @type {String}
+   */
+  location = "";
+
+  /**
+   * Alternative timezone name, for the string representation
+   * @type {String}
+   */
+  tznames = "";
+
+  /**
+   * The primary latitude for the timezone.
+   * @type {Number}
+   */
+  latitude = 0.0;
+
+  /**
+   * The primary longitude for the timezone.
+   * @type {Number}
+   */
+  longitude = 0.0;
+
+  /**
+   * The vtimezone component for this timezone.
+   * @type {Component}
+   */
+  component = null;
+
+  /**
+   * The year this timezone has been expanded to. All timezone transition
+   * dates until this year are known and can be used for calculation
+   *
+   * @private
+   * @type {Number}
+   */
+  expandedUntilYear = 0;
+
+  /**
+   * The class identifier.
+   * @constant
+   * @type {String}
+   * @default "icaltimezone"
+   */
+  icalclass = "icaltimezone";
+
+  /**
+   * Sets up the current instance using members from the passed data object.
+   *
+   * @param {Component|Object} aData options for class
+   * @param {String|Component} aData.component
+   *        If aData is a simple object, then this member can be set to either a
+   *        string containing the component data, or an already parsed
+   *        ICAL.Component
+   * @param {String} aData.tzid      The timezone identifier
+   * @param {String} aData.location  The timezone locationw
+   * @param {String} aData.tznames   An alternative string representation of the
+   *                                  timezone
+   * @param {Number} aData.latitude  The latitude of the timezone
+   * @param {Number} aData.longitude The longitude of the timezone
+   */
+  fromData(aData) {
+    this.expandedUntilYear = 0;
+    this.changes = [];
+
+    if (aData instanceof Component) {
+      // Either a component is passed directly
+      this.component = aData;
+    } else {
+      // Otherwise the component may be in the data object
+      if (aData && "component" in aData) {
+        if (typeof aData.component == "string") {
+          // If a string was passed, parse it as a component
+          let jCal = parse(aData.component);
+          this.component = new Component(jCal);
+        } else if (aData.component instanceof Component) {
+          // If it was a component already, then just set it
+          this.component = aData.component;
+        } else {
+          // Otherwise just null out the component
+          this.component = null;
+        }
+      }
+
+      // Copy remaining passed properties
+      for (let prop of OPTIONS) {
+        if (aData && prop in aData) {
+          this[prop] = aData[prop];
+        }
+      }
+    }
+
+    // If we have a component but no TZID, attempt to get it from the
+    // component's properties.
+    if (this.component instanceof Component && !this.tzid) {
+      this.tzid = this.component.getFirstPropertyValue('tzid');
+    }
+
+    return this;
+  }
+
+  /**
+   * Finds the utcOffset the given time would occur in this timezone.
+   *
+   * @param {Time} tt         The time to check for
+   * @return {Number}         utc offset in seconds
+   */
+  utcOffset(tt) {
+    if (this == Timezone.utcTimezone || this == Timezone.localTimezone) {
+      return 0;
+    }
+
+    this._ensureCoverage(tt.year);
+
+    if (!this.changes.length) {
+      return 0;
+    }
+
+    let tt_change = {
+      year: tt.year,
+      month: tt.month,
+      day: tt.day,
+      hour: tt.hour,
+      minute: tt.minute,
+      second: tt.second
+    };
+
+    let change_num = this._findNearbyChange(tt_change);
+    let change_num_to_use = -1;
+    let step = 1;
+
+    // TODO: replace with bin search?
+    for (;;) {
+      let change = clone(this.changes[change_num], true);
+      if (change.utcOffset < change.prevUtcOffset) {
+        Timezone.adjust_change(change, 0, 0, 0, change.utcOffset);
+      } else {
+        Timezone.adjust_change(change, 0, 0, 0,
+                                        change.prevUtcOffset);
+      }
+
+      let cmp = Timezone._compare_change_fn(tt_change, change);
+
+      if (cmp >= 0) {
+        change_num_to_use = change_num;
+      } else {
+        step = -1;
+      }
+
+      if (step == -1 && change_num_to_use != -1) {
+        break;
+      }
+
+      change_num += step;
+
+      if (change_num < 0) {
+        return 0;
+      }
+
+      if (change_num >= this.changes.length) {
+        break;
+      }
+    }
+
+    let zone_change = this.changes[change_num_to_use];
+    let utcOffset_change = zone_change.utcOffset - zone_change.prevUtcOffset;
+
+    if (utcOffset_change < 0 && change_num_to_use > 0) {
+      let tmp_change = clone(zone_change, true);
+      Timezone.adjust_change(tmp_change, 0, 0, 0, tmp_change.prevUtcOffset);
+
+      if (Timezone._compare_change_fn(tt_change, tmp_change) < 0) {
+        let prev_zone_change = this.changes[change_num_to_use - 1];
+
+        let want_daylight = false; // TODO
+
+        if (zone_change.is_daylight != want_daylight &&
+            prev_zone_change.is_daylight == want_daylight) {
+          zone_change = prev_zone_change;
+        }
+      }
+    }
+
+    // TODO return is_daylight?
+    return zone_change.utcOffset;
+  }
+
+  _findNearbyChange(change) {
+    // find the closest match
+    let idx = binsearchInsert(
+      this.changes,
+      change,
+      Timezone._compare_change_fn
+    );
+
+    if (idx >= this.changes.length) {
+      return this.changes.length - 1;
+    }
+
+    return idx;
+  }
+
+  _ensureCoverage(aYear) {
+    if (Timezone._minimumExpansionYear == -1) {
+      let today = Time.now();
+      Timezone._minimumExpansionYear = today.year;
+    }
+
+    let changesEndYear = aYear;
+    if (changesEndYear < Timezone._minimumExpansionYear) {
+      changesEndYear = Timezone._minimumExpansionYear;
+    }
+
+    changesEndYear += Timezone.EXTRA_COVERAGE;
+
+    if (!this.changes.length || this.expandedUntilYear < aYear) {
+      let subcomps = this.component.getAllSubcomponents();
+      let compLen = subcomps.length;
+      let compIdx = 0;
+
+      for (; compIdx < compLen; compIdx++) {
+        this._expandComponent(
+          subcomps[compIdx], changesEndYear, this.changes
+        );
+      }
+
+      this.changes.sort(Timezone._compare_change_fn);
+      this.expandedUntilYear = changesEndYear;
+    }
+  }
+
+  _expandComponent(aComponent, aYear, changes) {
+    if (!aComponent.hasProperty("dtstart") ||
+        !aComponent.hasProperty("tzoffsetto") ||
+        !aComponent.hasProperty("tzoffsetfrom")) {
+      return null;
+    }
+
+    let dtstart = aComponent.getFirstProperty("dtstart").getFirstValue();
+    let change;
+
+    function convert_tzoffset(offset) {
+      return offset.factor * (offset.hours * 3600 + offset.minutes * 60);
+    }
+
+    function init_changes() {
+      let changebase = {};
+      changebase.is_daylight = (aComponent.name == "daylight");
+      changebase.utcOffset = convert_tzoffset(
+        aComponent.getFirstProperty("tzoffsetto").getFirstValue()
+      );
+
+      changebase.prevUtcOffset = convert_tzoffset(
+        aComponent.getFirstProperty("tzoffsetfrom").getFirstValue()
+      );
+
+      return changebase;
+    }
+
+    if (!aComponent.hasProperty("rrule") && !aComponent.hasProperty("rdate")) {
+      change = init_changes();
+      change.year = dtstart.year;
+      change.month = dtstart.month;
+      change.day = dtstart.day;
+      change.hour = dtstart.hour;
+      change.minute = dtstart.minute;
+      change.second = dtstart.second;
+
+      Timezone.adjust_change(change, 0, 0, 0, -change.prevUtcOffset);
+      changes.push(change);
+    } else {
+      let props = aComponent.getAllProperties("rdate");
+      for (let rdate of props) {
+        let time = rdate.getFirstValue();
+        change = init_changes();
+
+        change.year = time.year;
+        change.month = time.month;
+        change.day = time.day;
+
+        if (time.isDate) {
+          change.hour = dtstart.hour;
+          change.minute = dtstart.minute;
+          change.second = dtstart.second;
+
+          if (dtstart.zone != Timezone.utcTimezone) {
+            Timezone.adjust_change(change, 0, 0, 0, -change.prevUtcOffset);
+          }
+        } else {
+          change.hour = time.hour;
+          change.minute = time.minute;
+          change.second = time.second;
+
+          if (time.zone != Timezone.utcTimezone) {
+            Timezone.adjust_change(change, 0, 0, 0, -change.prevUtcOffset);
+          }
+        }
+
+        changes.push(change);
+      }
+
+      let rrule = aComponent.getFirstProperty("rrule");
+
+      if (rrule) {
+        rrule = rrule.getFirstValue();
+        change = init_changes();
+
+        if (rrule.until && rrule.until.zone == Timezone.utcTimezone) {
+          rrule.until.adjust(0, 0, 0, change.prevUtcOffset);
+          rrule.until.zone = Timezone.localTimezone;
+        }
+
+        let iterator = rrule.iterator(dtstart);
+
+        let occ;
+        while ((occ = iterator.next())) {
+          change = init_changes();
+          if (occ.year > aYear || !occ) {
+            break;
+          }
+
+          change.year = occ.year;
+          change.month = occ.month;
+          change.day = occ.day;
+          change.hour = occ.hour;
+          change.minute = occ.minute;
+          change.second = occ.second;
+          change.isDate = occ.isDate;
+
+          Timezone.adjust_change(change, 0, 0, 0, -change.prevUtcOffset);
+          changes.push(change);
+        }
+      }
+    }
+
+    return changes;
+  }
+
+  /**
+   * The string representation of this timezone.
+   * @return {String}
+   */
+  toString() {
+    return (this.tznames ? this.tznames : this.tzid);
+  }
+}
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ * Portions Copyright (C) Philipp Kewisch */
+
+let zones = null;
+
+/**
+ * @classdesc
+ * Singleton class to contain timezones.  Right now it is all manual registry in
+ * the future we may use this class to download timezone information or handle
+ * loading pre-expanded timezones.
+ *
+ * @exports module:ICAL.TimezoneService
+ * @memberof ICAL
+ */
+const TimezoneService = {
+  get count() {
+    if (zones === null) {
+      return 0;
+    }
+
+    return Object.keys(zones).length;
+  },
+
+  reset: function() {
+    zones = Object.create(null);
+    let utc = Timezone.utcTimezone;
+
+    zones.Z = utc;
+    zones.UTC = utc;
+    zones.GMT = utc;
+  },
+  _hard_reset: function() {
+    zones = null;
+  },
+
+  /**
+   * Checks if timezone id has been registered.
+   *
+   * @param {String} tzid     Timezone identifier (e.g. America/Los_Angeles)
+   * @return {Boolean}        False, when not present
+   */
+  has: function(tzid) {
+    if (zones === null) {
+      return false;
+    }
+
+    return !!zones[tzid];
+  },
+
+  /**
+   * Returns a timezone by its tzid if present.
+   *
+   * @param {String} tzid               Timezone identifier (e.g. America/Los_Angeles)
+   * @return {Timezone | undefined}     The timezone, or undefined if not found
+   */
+  get: function(tzid) {
+    if (zones === null) {
+      this.reset();
+    }
+
+    return zones[tzid];
+  },
+
+  /**
+   * Registers a timezone object or component.
+   *
+   * @param {Component|Timezone} timezone
+   *        The initialized zone or vtimezone.
+   *
+   * @param {String=} name
+   *        The name of the timezone. Defaults to the component's TZID if not
+   *        passed.
+   */
+  register: function(timezone, name) {
+    if (zones === null) {
+      this.reset();
+    }
+
+    // This avoids a breaking change by the change of argument order
+    // TODO remove in v3
+    if (typeof timezone === "string" && name instanceof Timezone) {
+      [timezone, name] = [name, timezone];
+    }
+
+    if (!name) {
+      if (timezone instanceof Timezone) {
+        name = timezone.tzid;
+      } else {
+        if (timezone.name === 'vtimezone') {
+          timezone = new Timezone(timezone);
+          name = timezone.tzid;
+        }
+      }
+    }
+
+    if (!name) {
+      throw new TypeError("Neither a timezone nor a name was passed");
+    }
+
+    if (timezone instanceof Timezone) {
+      zones[name] = timezone;
+    } else {
+      throw new TypeError('timezone must be ICAL.Timezone or ICAL.Component');
+    }
+  },
+
+  /**
+   * Removes a timezone by its tzid from the list.
+   *
+   * @param {String} tzid     Timezone identifier (e.g. America/Los_Angeles)
+   * @return {?Timezone}      The removed timezone, or null if not registered
+   */
+  remove: function(tzid) {
+    if (zones === null) {
+      return null;
+    }
+
+    return (delete zones[tzid]);
+  }
+};
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ * Portions Copyright (C) Philipp Kewisch */
+
+/**
+ * Helper functions used in various places within ical.js
+ * @module ICAL.helpers
+ */
+
+/**
+ * Compiles a list of all referenced TZIDs in all subcomponents and
+ * removes any extra VTIMEZONE subcomponents. In addition, if any TZIDs
+ * are referenced by a component, but a VTIMEZONE does not exist,
+ * an attempt will be made to generate a VTIMEZONE using ICAL.TimezoneService.
+ *
+ * @param {Component} vcal     The top-level VCALENDAR component.
+ * @return {Component}         The ICAL.Component that was passed in.
+ */
+function updateTimezones(vcal) {
+  let allsubs, properties, vtimezones, reqTzid, i;
+
+  if (!vcal || vcal.name !== "vcalendar") {
+    //not a top-level vcalendar component
+    return vcal;
+  }
+
+  //Store vtimezone subcomponents in an object reference by tzid.
+  //Store properties from everything else in another array
+  allsubs = vcal.getAllSubcomponents();
+  properties = [];
+  vtimezones = {};
+  for (i = 0; i < allsubs.length; i++) {
+    if (allsubs[i].name === "vtimezone") {
+      let tzid = allsubs[i].getFirstProperty("tzid").getFirstValue();
+      vtimezones[tzid] = allsubs[i];
+    } else {
+      properties = properties.concat(allsubs[i].getAllProperties());
+    }
+  }
+
+  //create an object with one entry for each required tz
+  reqTzid = {};
+  for (i = 0; i < properties.length; i++) {
+    let tzid = properties[i].getParameter("tzid");
+    if (tzid) {
+      reqTzid[tzid] = true;
+    }
+  }
+
+  //delete any vtimezones that are not on the reqTzid list.
+  for (let [tzid, comp] of Object.entries(vtimezones)) {
+    if (!reqTzid[tzid]) {
+      vcal.removeSubcomponent(comp);
+    }
+  }
+
+  //create any missing, but registered timezones
+  for (let tzid of Object.keys(reqTzid)) {
+    if (!vtimezones[tzid] && TimezoneService.has(tzid)) {
+      vcal.addSubcomponent(TimezoneService.get(tzid).component);
+    }
+  }
+
+  return vcal;
+}
+
+/**
+ * Checks if the given type is of the number type and also NaN.
+ *
+ * @param {Number} number     The number to check
+ * @return {Boolean}          True, if the number is strictly NaN
+ */
+function isStrictlyNaN(number) {
+  return typeof(number) === 'number' && isNaN(number);
+}
+
+/**
+ * Parses a string value that is expected to be an integer, when the valid is
+ * not an integer throws a decoration error.
+ *
+ * @param {String} string     Raw string input
+ * @return {Number}           Parsed integer
+ */
+function strictParseInt(string) {
+  let result = parseInt(string, 10);
+
+  if (isStrictlyNaN(result)) {
+    throw new Error(
+      'Could not extract integer from "' + string + '"'
+    );
+  }
+
+  return result;
+}
+
+/**
+ * Creates or returns a class instance of a given type with the initialization
+ * data if the data is not already an instance of the given type.
+ *
+ * @example
+ * var time = new ICAL.Time(...);
+ * var result = ICAL.helpers.formatClassType(time, ICAL.Time);
+ *
+ * (result instanceof ICAL.Time)
+ * // => true
+ *
+ * result = ICAL.helpers.formatClassType({}, ICAL.Time);
+ * (result isntanceof ICAL.Time)
+ * // => true
+ *
+ *
+ * @param {Object} data       object initialization data
+ * @param {Object} type       object type (like ICAL.Time)
+ * @return {?}                An instance of the found type.
+ */
+function formatClassType(data, type) {
+  if (typeof(data) === 'undefined') {
+    return undefined;
+  }
+
+  if (data instanceof type) {
+    return data;
+  }
+  return new type(data);
+}
+
+/**
+ * Identical to indexOf but will only match values when they are not preceded
+ * by a backslash character.
+ *
+ * @param {String} buffer         String to search
+ * @param {String} search         Value to look for
+ * @param {Number} pos            Start position
+ * @return {Number}               The position, or -1 if not found
+ */
+function unescapedIndexOf(buffer, search, pos) {
+  while ((pos = buffer.indexOf(search, pos)) !== -1) {
+    if (pos > 0 && buffer[pos - 1] === '\\') {
+      pos += 1;
+    } else {
+      return pos;
+    }
+  }
+  return -1;
+}
+
+/**
+ * Find the index for insertion using binary search.
+ *
+ * @param {Array} list            The list to search
+ * @param {?} seekVal             The value to insert
+ * @param {function(?,?)} cmpfunc The comparison func, that can
+ *                                  compare two seekVals
+ * @return {Number}               The insert position
+ */
+function binsearchInsert(list, seekVal, cmpfunc) {
+  if (!list.length)
+    return 0;
+
+  let low = 0, high = list.length - 1,
+      mid, cmpval;
+
+  while (low <= high) {
+    mid = low + Math.floor((high - low) / 2);
+    cmpval = cmpfunc(seekVal, list[mid]);
+
+    if (cmpval < 0)
+      high = mid - 1;
+    else if (cmpval > 0)
+      low = mid + 1;
+    else
+      break;
+  }
+
+  if (cmpval < 0)
+    return mid; // insertion is displacing, so use mid outright.
+  else if (cmpval > 0)
+    return mid + 1;
+  else
+    return mid;
+}
+
+/**
+ * Clone the passed object or primitive. By default a shallow clone will be
+ * executed.
+ *
+ * @param {*} aSrc            The thing to clone
+ * @param {Boolean=} aDeep    If true, a deep clone will be performed
+ * @return {*}                The copy of the thing
+ */
+function clone(aSrc, aDeep) {
+  if (!aSrc || typeof aSrc != "object") {
+    return aSrc;
+  } else if (aSrc instanceof Date) {
+    return new Date(aSrc.getTime());
+  } else if ("clone" in aSrc) {
+    return aSrc.clone();
+  } else if (Array.isArray(aSrc)) {
+    let arr = [];
+    for (let i = 0; i < aSrc.length; i++) {
+      arr.push(aDeep ? clone(aSrc[i], true) : aSrc[i]);
+    }
+    return arr;
+  } else {
+    let obj = {};
+    for (let [name, value] of Object.entries(aSrc)) {
+      if (aDeep) {
+        obj[name] = clone(value, true);
+      } else {
+        obj[name] = value;
+      }
+    }
+    return obj;
+  }
+}
+
+/**
+ * Performs iCalendar line folding. A line ending character is inserted and
+ * the next line begins with a whitespace.
+ *
+ * @example
+ * SUMMARY:This line will be fold
+ *  ed right in the middle of a word.
+ *
+ * @param {String} aLine      The line to fold
+ * @return {String}           The folded line
+ */
+function foldline(aLine) {
+  let result = "";
+  let line = aLine || "", pos = 0, line_length = 0;
+  //pos counts position in line for the UTF-16 presentation
+  //line_length counts the bytes for the UTF-8 presentation
+  while (line.length) {
+    let cp = line.codePointAt(pos);
+    if (cp < 128) ++line_length;
+    else if (cp < 2048) line_length += 2;//needs 2 UTF-8 bytes
+    else if (cp < 65536) line_length += 3;
+    else line_length += 4; //cp is less than 1114112
+    if (line_length < ICALmodule.foldLength + 1)
+      pos += cp > 65535 ? 2 : 1;
+    else {
+      result += ICALmodule.newLineChar + " " + line.slice(0, Math.max(0, pos));
+      line = line.slice(Math.max(0, pos));
+      pos = line_length = 0;
+    }
+  }
+  return result.slice(ICALmodule.newLineChar.length + 1);
+}
+
+/**
+ * Pads the given string or number with zeros so it will have at least two
+ * characters.
+ *
+ * @param {String|Number} data    The string or number to pad
+ * @return {String}               The number padded as a string
+ */
+function pad2(data) {
+  if (typeof(data) !== 'string') {
+    // handle fractions.
+    if (typeof(data) === 'number') {
+      data = parseInt(data);
+    }
+    data = String(data);
+  }
+
+  let len = data.length;
+
+  switch (len) {
+    case 0:
+      return '00';
+    case 1:
+      return '0' + data;
+    default:
+      return data;
+  }
+}
+
+/**
+ * Truncates the given number, correctly handling negative numbers.
+ *
+ * @param {Number} number     The number to truncate
+ * @return {Number}           The truncated number
+ */
+function trunc(number) {
+  return (number < 0 ? Math.ceil(number) : Math.floor(number));
+}
+
+/**
+ * Poor-man's cross-browser object extension. Doesn't support all the
+ * features, but enough for our usage. Note that the target's properties are
+ * not overwritten with the source properties.
+ *
+ * @example
+ * var child = ICAL.helpers.extend(parent, {
+ *   "bar": 123
+ * });
+ *
+ * @param {Object} source     The object to extend
+ * @param {Object} target     The object to extend with
+ * @return {Object}           Returns the target.
+ */
+function extend(source, target) {
+  for (let key in source) {
+    let descr = Object.getOwnPropertyDescriptor(source, key);
+    if (descr && !Object.getOwnPropertyDescriptor(target, key)) {
+      Object.defineProperty(target, key, descr);
+    }
+  }
+  return target;
+}
+
+var helpers = /*#__PURE__*/Object.freeze({
+  __proto__: null,
+  updateTimezones: updateTimezones,
+  isStrictlyNaN: isStrictlyNaN,
+  strictParseInt: strictParseInt,
+  formatClassType: formatClassType,
+  unescapedIndexOf: unescapedIndexOf,
+  binsearchInsert: binsearchInsert,
+  clone: clone,
+  foldline: foldline,
+  pad2: pad2,
+  trunc: trunc,
+  extend: extend
+});
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ * Portions Copyright (C) Philipp Kewisch */
+
+/**
+ * This class represents the "utc-offset" value type, with various calculation and manipulation
+ * methods.
+ *
+ * @memberof ICAL
+ */
+class UtcOffset {
+  /**
+   * Creates a new {@link ICAL.UtcOffset} instance from the passed string.
+   *
+   * @param {String} aString    The string to parse
+   * @return {Duration}         The created utc-offset instance
+   */
+  static fromString(aString) {
+    // -05:00
+    let options = {};
+    //TODO: support seconds per rfc5545 ?
+    options.factor = (aString[0] === '+') ? 1 : -1;
+    options.hours = strictParseInt(aString.slice(1, 3));
+    options.minutes = strictParseInt(aString.slice(4, 6));
+
+    return new UtcOffset(options);
+  }
+
+  /**
+   * Creates a new {@link ICAL.UtcOffset} instance from the passed seconds
+   * value.
+   *
+   * @param {Number} aSeconds       The number of seconds to convert
+   */
+  static fromSeconds(aSeconds) {
+    let instance = new UtcOffset();
+    instance.fromSeconds(aSeconds);
+    return instance;
+  }
+
+  /**
+   * Creates a new ICAL.UtcOffset instance.
+   *
+   * @param {Object} aData          An object with members of the utc offset
+   * @param {Number=} aData.hours   The hours for the utc offset
+   * @param {Number=} aData.minutes The minutes in the utc offset
+   * @param {Number=} aData.factor  The factor for the utc-offset, either -1 or 1
+   */
+  constructor(aData) {
+    this.fromData(aData);
+  }
+
+  /**
+   * The hours in the utc-offset
+   * @type {Number}
+   */
+  hours = 0;
+
+  /**
+   * The minutes in the utc-offset
+   * @type {Number}
+   */
+  minutes = 0;
+
+  /**
+   * The sign of the utc offset, 1 for positive offset, -1 for negative
+   * offsets.
+   * @type {Number}
+   */
+  factor = 1;
+
+  /**
+   * The type name, to be used in the jCal object.
+   * @constant
+   * @type {String}
+   * @default "utc-offset"
+   */
+  icaltype = "utc-offset";
+
+  /**
+   * Returns a clone of the utc offset object.
+   *
+   * @return {UtcOffset}     The cloned object
+   */
+  clone() {
+    return UtcOffset.fromSeconds(this.toSeconds());
+  }
+
+  /**
+   * Sets up the current instance using members from the passed data object.
+   *
+   * @param {Object} aData          An object with members of the utc offset
+   * @param {Number=} aData.hours   The hours for the utc offset
+   * @param {Number=} aData.minutes The minutes in the utc offset
+   * @param {Number=} aData.factor  The factor for the utc-offset, either -1 or 1
+   */
+  fromData(aData) {
+    if (aData) {
+      for (let [key, value] of Object.entries(aData)) {
+        this[key] = value;
+      }
+    }
+    this._normalize();
+  }
+
+  /**
+   * Sets up the current instance from the given seconds value. The seconds
+   * value is truncated to the minute. Offsets are wrapped when the world
+   * ends, the hour after UTC+14:00 is UTC-12:00.
+   *
+   * @param {Number} aSeconds         The seconds to convert into an offset
+   */
+  fromSeconds(aSeconds) {
+    let secs = Math.abs(aSeconds);
+
+    this.factor = aSeconds < 0 ? -1 : 1;
+    this.hours = trunc(secs / 3600);
+
+    secs -= (this.hours * 3600);
+    this.minutes = trunc(secs / 60);
+    return this;
+  }
+
+  /**
+   * Convert the current offset to a value in seconds
+   *
+   * @return {Number}                 The offset in seconds
+   */
+  toSeconds() {
+    return this.factor * (60 * this.minutes + 3600 * this.hours);
+  }
+
+  /**
+   * Compare this utc offset with another one.
+   *
+   * @param {UtcOffset} other             The other offset to compare with
+   * @return {Number}                     -1, 0 or 1 for less/equal/greater
+   */
+  compare(other) {
+    let a = this.toSeconds();
+    let b = other.toSeconds();
+    return (a > b) - (b > a);
+  }
+
+  _normalize() {
+    // Range: 97200 seconds (with 1 hour inbetween)
+    let secs = this.toSeconds();
+    let factor = this.factor;
+    while (secs < -43200) { // = UTC-12:00
+      secs += 97200;
+    }
+    while (secs > 50400) { // = UTC+14:00
+      secs -= 97200;
+    }
+
+    this.fromSeconds(secs);
+
+    // Avoid changing the factor when on zero seconds
+    if (secs == 0) {
+      this.factor = factor;
+    }
+  }
+
+  /**
+   * The iCalendar string representation of this utc-offset.
+   * @return {String}
+   */
+  toICALString() {
+    return design$1.icalendar.value['utc-offset'].toICAL(this.toString());
+  }
+
+  /**
+   * The string representation of this utc-offset.
+   * @return {String}
+   */
+  toString() {
+    return (this.factor == 1 ? "+" : "-") + pad2(this.hours) + ':' + pad2(this.minutes);
+  }
+}
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ * Portions Copyright (C) Philipp Kewisch */
+
+/**
+ * Describes a vCard time, which has slight differences to the ICAL.Time.
+ * Properties can be null if not specified, for example for dates with
+ * reduced accuracy or truncation.
+ *
+ * Note that currently not all methods are correctly re-implemented for
+ * VCardTime. For example, comparison will have undefined results when some
+ * members are null.
+ *
+ * Also, normalization is not yet implemented for this class!
+ *
+ * @memberof ICAL
+ * @extends {ICAL.Time}
+ */
+class VCardTime extends Time {
+  /**
+   * Returns a new ICAL.VCardTime instance from a date and/or time string.
+   *
+   * @param {String} aValue     The string to create from
+   * @param {String} aIcalType  The type for this instance, e.g. date-and-or-time
+   * @return {VCardTime}        The date/time instance
+   */
+  static fromDateAndOrTimeString(aValue, aIcalType) {
+    function part(v, s, e) {
+      return v ? strictParseInt(v.slice(s, s + e)) : null;
+    }
+    let parts = aValue.split('T');
+    let dt = parts[0], tmz = parts[1];
+    let splitzone = tmz ? design$1.vcard.value.time._splitZone(tmz) : [];
+    let zone = splitzone[0], tm = splitzone[1];
+
+    let dtlen = dt ? dt.length : 0;
+    let tmlen = tm ? tm.length : 0;
+
+    let hasDashDate = dt && dt[0] == '-' && dt[1] == '-';
+    let hasDashTime = tm && tm[0] == '-';
+
+    let o = {
+      year: hasDashDate ? null : part(dt, 0, 4),
+      month: hasDashDate && (dtlen == 4 || dtlen == 7) ? part(dt, 2, 2) : dtlen == 7 ? part(dt, 5, 2) : dtlen == 10 ? part(dt, 5, 2) : null,
+      day: dtlen == 5 ? part(dt, 3, 2) : dtlen == 7 && hasDashDate ? part(dt, 5, 2) : dtlen == 10 ? part(dt, 8, 2) : null,
+
+      hour: hasDashTime ? null : part(tm, 0, 2),
+      minute: hasDashTime && tmlen == 3 ? part(tm, 1, 2) : tmlen > 4 ? hasDashTime ? part(tm, 1, 2) : part(tm, 3, 2) : null,
+      second: tmlen == 4 ? part(tm, 2, 2) : tmlen == 6 ? part(tm, 4, 2) : tmlen == 8 ? part(tm, 6, 2) : null
+    };
+
+    if (zone == 'Z') {
+      zone = Timezone.utcTimezone;
+    } else if (zone && zone[3] == ':') {
+      zone = UtcOffset.fromString(zone);
+    } else {
+      zone = null;
+    }
+
+    return new VCardTime(o, zone, aIcalType);
+  }
+
+
+  /**
+   * Creates a new ICAL.VCardTime instance.
+   *
+   * @param {Object} data                           The data for the time instance
+   * @param {Number=} data.year                     The year for this date
+   * @param {Number=} data.month                    The month for this date
+   * @param {Number=} data.day                      The day for this date
+   * @param {Number=} data.hour                     The hour for this date
+   * @param {Number=} data.minute                   The minute for this date
+   * @param {Number=} data.second                   The second for this date
+   * @param {Timezone|UtcOffset} zone               The timezone to use
+   * @param {String} icaltype                       The type for this date/time object
+   */
+  constructor(data, zone, icaltype) {
+    super(data, zone);
+    this.icaltype = icaltype || "date-and-or-time";
+  }
+
+  /**
+   * The class identifier.
+   * @constant
+   * @type {String}
+   * @default "vcardtime"
+   */
+  icalclass = "vcardtime";
+
+  /**
+   * The type name, to be used in the jCal object.
+   * @type {String}
+   * @default "date-and-or-time"
+   */
+  icaltype = "date-and-or-time";
+
+  /**
+   * Returns a clone of the vcard date/time object.
+   *
+   * @return {VCardTime}     The cloned object
+   */
+  clone() {
+    return new VCardTime(this._time, this.zone, this.icaltype);
+  }
+
+  _normalize() {
+    return this;
+  }
+
+  /**
+   * @inheritdoc
+   */
+  utcOffset() {
+    if (this.zone instanceof UtcOffset) {
+      return this.zone.toSeconds();
+    } else {
+      return Time.prototype.utcOffset.apply(this, arguments);
+    }
+  }
+
+  /**
+   * Returns an RFC 6350 compliant representation of this object.
+   *
+   * @return {String}         vcard date/time string
+   */
+  toICALString() {
+    return design$1.vcard.value[this.icaltype].toICAL(this.toString());
+  }
+
+  /**
+   * The string representation of this date/time, in jCard form
+   * (including : and - separators).
+   * @return {String}
+   */
+  toString() {
+    let y = this.year, m = this.month, d = this.day;
+    let h = this.hour, mm = this.minute, s = this.second;
+
+    let hasYear = y !== null, hasMonth = m !== null, hasDay = d !== null;
+    let hasHour = h !== null, hasMinute = mm !== null, hasSecond = s !== null;
+
+    let datepart = (hasYear ? pad2(y) + (hasMonth || hasDay ? '-' : '') : (hasMonth || hasDay ? '--' : '')) +
+                   (hasMonth ? pad2(m) : '') +
+                   (hasDay ? '-' + pad2(d) : '');
+    let timepart = (hasHour ? pad2(h) : '-') + (hasHour && hasMinute ? ':' : '') +
+                   (hasMinute ? pad2(mm) : '') + (!hasHour && !hasMinute ? '-' : '') +
+                   (hasMinute && hasSecond ? ':' : '') +
+                   (hasSecond ? pad2(s) : '');
+
+    let zone;
+    if (this.zone === Timezone.utcTimezone) {
+      zone = 'Z';
+    } else if (this.zone instanceof UtcOffset) {
+      zone = this.zone.toString();
+    } else if (this.zone === Timezone.localTimezone) {
+      zone = '';
+    } else if (this.zone instanceof Timezone) {
+      let offset = UtcOffset.fromSeconds(this.zone.utcOffset(this));
+      zone = offset.toString();
+    } else {
+      zone = '';
+    }
+
+    switch (this.icaltype) {
+      case "time":
+        return timepart + zone;
+      case "date-and-or-time":
+      case "date-time":
+        return datepart + (timepart == '--' ? '' : 'T' + timepart + zone);
+      case "date":
+        return datepart;
+    }
+    return null;
+  }
+}
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ * Portions Copyright (C) Philipp Kewisch */
+
+/**
+ * This lets typescript resolve our custom types in the
+ * generated d.ts files (jsdoc typedefs are converted to typescript types).
+ * Ignore prevents the typedefs from being documented more than once.
+ *
+ * @ignore
+ * @typedef {import("./types.js").weekDay} weekDay
+ * Imports the 'weekDay' type from the "types.js" module
+ */
+
+/**
+ * An iterator for a single recurrence rule. This class usually doesn't have to be instanciated
+ * directly, the convenience method {@link ICAL.Recur#iterator} can be used.
+ *
+ * @memberof ICAL
+ */
+class RecurIterator {
+  static _indexMap = {
+    "BYSECOND": 0,
+    "BYMINUTE": 1,
+    "BYHOUR": 2,
+    "BYDAY": 3,
+    "BYMONTHDAY": 4,
+    "BYYEARDAY": 5,
+    "BYWEEKNO": 6,
+    "BYMONTH": 7,
+    "BYSETPOS": 8
+  };
+
+  static _expandMap = {
+    "SECONDLY": [1, 1, 1, 1, 1, 1, 1, 1],
+    "MINUTELY": [2, 1, 1, 1, 1, 1, 1, 1],
+    "HOURLY": [2, 2, 1, 1, 1, 1, 1, 1],
+    "DAILY": [2, 2, 2, 1, 1, 1, 1, 1],
+    "WEEKLY": [2, 2, 2, 2, 3, 3, 1, 1],
+    "MONTHLY": [2, 2, 2, 2, 2, 3, 3, 1],
+    "YEARLY": [2, 2, 2, 2, 2, 2, 2, 2]
+  };
+
+  static UNKNOWN = 0;
+  static CONTRACT = 1;
+  static EXPAND = 2;
+  static ILLEGAL = 3;
+
+  /**
+   * Creates a new ICAL.RecurIterator instance. The options object may contain additional members
+   * when resuming iteration from a previous run.
+   *
+   * @param {Object} options                The iterator options
+   * @param {Recur} options.rule            The rule to iterate.
+   * @param {Time} options.dtstart          The start date of the event.
+   * @param {Boolean=} options.initialized  When true, assume that options are
+   *        from a previously constructed iterator. Initialization will not be
+   *        repeated.
+   */
+  constructor(options) {
+    this.fromData(options);
+  }
+
+  /**
+   * True when iteration is finished.
+   * @type {Boolean}
+   */
+  completed = false;
+
+  /**
+   * The rule that is being iterated
+   * @type {Recur}
+   */
+  rule = null;
+
+  /**
+   * The start date of the event being iterated.
+   * @type {Time}
+   */
+  dtstart = null;
+
+  /**
+   * The last occurrence that was returned from the
+   * {@link RecurIterator#next} method.
+   * @type {Time}
+   */
+  last = null;
+
+  /**
+   * The sequence number from the occurrence
+   * @type {Number}
+   */
+  occurrence_number = 0;
+
+  /**
+   * The indices used for the {@link ICAL.RecurIterator#by_data} object.
+   * @type {Object}
+   * @private
+   */
+  by_indices = null;
+
+  /**
+   * If true, the iterator has already been initialized
+   * @type {Boolean}
+   * @private
+   */
+  initialized = false;
+
+  /**
+   * The initializd by-data.
+   * @type {Object}
+   * @private
+   */
+  by_data = null;
+
+  /**
+   * The expanded yeardays
+   * @type {Array}
+   * @private
+   */
+  days = null;
+
+  /**
+   * The index in the {@link ICAL.RecurIterator#days} array.
+   * @type {Number}
+   * @private
+   */
+  days_index = 0;
+
+  /**
+   * Initialize the recurrence iterator from the passed data object. This
+   * method is usually not called directly, you can initialize the iterator
+   * through the constructor.
+   *
+   * @param {Object} options                The iterator options
+   * @param {Recur} options.rule            The rule to iterate.
+   * @param {Time} options.dtstart          The start date of the event.
+   * @param {Boolean=} options.initialized  When true, assume that options are
+   *        from a previously constructed iterator. Initialization will not be
+   *        repeated.
+   */
+  fromData(options) {
+    this.rule = formatClassType(options.rule, Recur);
+
+    if (!this.rule) {
+      throw new Error('iterator requires a (ICAL.Recur) rule');
+    }
+
+    this.dtstart = formatClassType(options.dtstart, Time);
+
+    if (!this.dtstart) {
+      throw new Error('iterator requires a (ICAL.Time) dtstart');
+    }
+
+    if (options.by_data) {
+      this.by_data = options.by_data;
+    } else {
+      this.by_data = clone(this.rule.parts, true);
+    }
+
+    if (options.occurrence_number)
+      this.occurrence_number = options.occurrence_number;
+
+    this.days = options.days || [];
+    if (options.last) {
+      this.last = formatClassType(options.last, Time);
+    }
+
+    this.by_indices = options.by_indices;
+
+    if (!this.by_indices) {
+      this.by_indices = {
+        "BYSECOND": 0,
+        "BYMINUTE": 0,
+        "BYHOUR": 0,
+        "BYDAY": 0,
+        "BYMONTH": 0,
+        "BYWEEKNO": 0,
+        "BYMONTHDAY": 0
+      };
+    }
+
+    this.initialized = options.initialized || false;
+
+    if (!this.initialized) {
+      try {
+        this.init();
+      } catch (e) {
+        if (e instanceof InvalidRecurrenceRuleError) {
+          // Init may error if there are no possible recurrence instances from
+          // the rule, but we don't want to bubble this error up. Instead, we
+          // create an empty iterator.
+          this.completed = true;
+        } else {
+          // Propagate other errors to consumers.
+          throw e;
+        }
+      }
+    }
+  }
+
+  /**
+   * Initialize the iterator
+   * @private
+   */
+  init() {
+    this.initialized = true;
+    this.last = this.dtstart.clone();
+    let parts = this.by_data;
+
+    if ("BYDAY" in parts) {
+      // libical does this earlier when the rule is loaded, but we postpone to
+      // now so we can preserve the original order.
+      this.sort_byday_rules(parts.BYDAY);
+    }
+
+    // If the BYYEARDAY appares, no other date rule part may appear
+    if ("BYYEARDAY" in parts) {
+      if ("BYMONTH" in parts || "BYWEEKNO" in parts ||
+          "BYMONTHDAY" in parts || "BYDAY" in parts) {
+        throw new Error("Invalid BYYEARDAY rule");
+      }
+    }
+
+    // BYWEEKNO and BYMONTHDAY rule parts may not both appear
+    if ("BYWEEKNO" in parts && "BYMONTHDAY" in parts) {
+      throw new Error("BYWEEKNO does not fit to BYMONTHDAY");
+    }
+
+    // For MONTHLY recurrences (FREQ=MONTHLY) neither BYYEARDAY nor
+    // BYWEEKNO may appear.
+    if (this.rule.freq == "MONTHLY" &&
+        ("BYYEARDAY" in parts || "BYWEEKNO" in parts)) {
+      throw new Error("For MONTHLY recurrences neither BYYEARDAY nor BYWEEKNO may appear");
+    }
+
+    // For WEEKLY recurrences (FREQ=WEEKLY) neither BYMONTHDAY nor
+    // BYYEARDAY may appear.
+    if (this.rule.freq == "WEEKLY" &&
+        ("BYYEARDAY" in parts || "BYMONTHDAY" in parts)) {
+      throw new Error("For WEEKLY recurrences neither BYMONTHDAY nor BYYEARDAY may appear");
+    }
+
+    // BYYEARDAY may only appear in YEARLY rules
+    if (this.rule.freq != "YEARLY" && "BYYEARDAY" in parts) {
+      throw new Error("BYYEARDAY may only appear in YEARLY rules");
+    }
+
+    this.last.second = this.setup_defaults("BYSECOND", "SECONDLY", this.dtstart.second);
+    this.last.minute = this.setup_defaults("BYMINUTE", "MINUTELY", this.dtstart.minute);
+    this.last.hour = this.setup_defaults("BYHOUR", "HOURLY", this.dtstart.hour);
+    this.last.day = this.setup_defaults("BYMONTHDAY", "DAILY", this.dtstart.day);
+    this.last.month = this.setup_defaults("BYMONTH", "MONTHLY", this.dtstart.month);
+
+    if (this.rule.freq == "WEEKLY") {
+      if ("BYDAY" in parts) {
+        let [, dow] = this.ruleDayOfWeek(parts.BYDAY[0], this.rule.wkst);
+        let wkdy = dow - this.last.dayOfWeek(this.rule.wkst);
+        if ((this.last.dayOfWeek(this.rule.wkst) < dow && wkdy >= 0) || wkdy < 0) {
+          // Initial time is after first day of BYDAY data
+          this.last.day += wkdy;
+        }
+      } else {
+        let dayName = Recur.numericDayToIcalDay(this.dtstart.dayOfWeek());
+        parts.BYDAY = [dayName];
+      }
+    }
+
+    if (this.rule.freq == "YEARLY") {
+      // Some yearly recurrence rules may be specific enough to not actually
+      // occur on a yearly basis, e.g. the 29th day of February or the fifth
+      // Monday of a given month. The standard isn't clear on the intended
+      // behavior in these cases, but `libical` at least will iterate until it
+      // finds a matching year.
+      // CAREFUL: Some rules may specify an occurrence that can never happen,
+      // e.g. the first Monday of April so long as it falls on the 15th
+      // through the 21st. Detecting these is non-trivial, so ensure that we
+      // stop iterating at some point.
+      const untilYear = this.rule.until ? this.rule.until.year : 20000;
+      while (this.last.year <= untilYear) {
+        this.expand_year_days(this.last.year);
+        if (this.days.length > 0) {
+          break;
+        }
+        this.increment_year(this.rule.interval);
+      }
+
+      if (this.days.length == 0) {
+        throw new InvalidRecurrenceRuleError();
+      }
+
+      this._nextByYearDay();
+    }
+
+    if (this.rule.freq == "MONTHLY") {
+      if (this.has_by_data("BYDAY")) {
+        let tempLast = null;
+        let initLast = this.last.clone();
+        let daysInMonth = Time.daysInMonth(this.last.month, this.last.year);
+
+        // Check every weekday in BYDAY with relative dow and pos.
+        for (let bydow of this.by_data.BYDAY) {
+          this.last = initLast.clone();
+          let [pos, dow] = this.ruleDayOfWeek(bydow);
+          let dayOfMonth = this.last.nthWeekDay(dow, pos);
+
+          // If |pos| >= 6, the byday is invalid for a monthly rule.
+          if (pos >= 6 || pos <= -6) {
+            throw new Error("Malformed values in BYDAY part");
+          }
+
+          // If a Byday with pos=+/-5 is not in the current month it
+          // must be searched in the next months.
+          if (dayOfMonth > daysInMonth || dayOfMonth <= 0) {
+            // Skip if we have already found a "last" in this month.
+            if (tempLast && tempLast.month == initLast.month) {
+              continue;
+            }
+            while (dayOfMonth > daysInMonth || dayOfMonth <= 0) {
+              this.increment_month();
+              daysInMonth = Time.daysInMonth(this.last.month, this.last.year);
+              dayOfMonth = this.last.nthWeekDay(dow, pos);
+            }
+          }
+
+          this.last.day = dayOfMonth;
+          if (!tempLast || this.last.compare(tempLast) < 0) {
+            tempLast = this.last.clone();
+          }
+        }
+        this.last = tempLast.clone();
+
+        //XXX: This feels like a hack, but we need to initialize
+        //     the BYMONTHDAY case correctly and byDayAndMonthDay handles
+        //     this case. It accepts a special flag which will avoid incrementing
+        //     the initial value without the flag days that match the start time
+        //     would be missed.
+        if (this.has_by_data('BYMONTHDAY')) {
+          this._byDayAndMonthDay(true);
+        }
+
+        if (this.last.day > daysInMonth || this.last.day == 0) {
+          throw new Error("Malformed values in BYDAY part");
+        }
+      } else if (this.has_by_data("BYMONTHDAY")) {
+        // Change the day value so that normalisation won't change the month.
+        this.last.day = 1;
+
+        // Get a sorted list of days in the starting month that match the rule.
+        let normalized = this.normalizeByMonthDayRules(
+          this.last.year,
+          this.last.month,
+          this.rule.parts.BYMONTHDAY
+        ).filter(d => d >= this.last.day);
+
+        if (normalized.length) {
+          // There's at least one valid day, use it.
+          this.last.day = normalized[0];
+          this.by_data.BYMONTHDAY = normalized;
+        } else {
+          // There's no occurrence in this month, find the next valid month.
+          // The longest possible sequence of skipped months is February-April-June,
+          // so we might need to call next_month up to three times.
+          if (!this.next_month() && !this.next_month() && !this.next_month()) {
+            throw new Error("No possible occurrences");
+          }
+        }
+      }
+    }
+  }
+
+  /**
+   * Retrieve the next occurrence from the iterator.
+   * @return {Time}
+   */
+  next(again = false) {
+    let before = (this.last ? this.last.clone() : null);
+
+    if ((this.rule.count && this.occurrence_number >= this.rule.count) ||
+        (this.rule.until && this.last.compare(this.rule.until) > 0)) {
+      this.completed = true;
+    }
+
+    if (this.completed) {
+      return null;
+    }
+
+    if (this.occurrence_number == 0 && this.last.compare(this.dtstart) >= 0) {
+      // First of all, give the instance that was initialized
+      this.occurrence_number++;
+      return this.last;
+    }
+
+    let valid;
+    do {
+      valid = 1;
+
+      switch (this.rule.freq) {
+      case "SECONDLY":
+        this.next_second();
+        break;
+      case "MINUTELY":
+        this.next_minute();
+        break;
+      case "HOURLY":
+        this.next_hour();
+        break;
+      case "DAILY":
+        this.next_day();
+        break;
+      case "WEEKLY":
+        this.next_week();
+        break;
+      case "MONTHLY":
+        valid = this.next_month();
+        break;
+      case "YEARLY":
+        this.next_year();
+        break;
+
+      default:
+        return null;
+      }
+    } while (!this.check_contracting_rules() ||
+             this.last.compare(this.dtstart) < 0 ||
+             !valid);
+
+    if (this.last.compare(before) == 0) {
+      if (again) {
+        throw new Error("Same occurrence found twice, protecting you from death by recursion");
+      }
+      this.next(true);
+    }
+
+    if (this.rule.until && this.last.compare(this.rule.until) > 0) {
+      this.completed = true;
+      return null;
+    } else {
+      this.occurrence_number++;
+      return this.last;
+    }
+  }
+
+  next_second() {
+    return this.next_generic("BYSECOND", "SECONDLY", "second", "minute");
+  }
+
+  increment_second(inc) {
+    return this.increment_generic(inc, "second", 60, "minute");
+  }
+
+  next_minute() {
+    return this.next_generic("BYMINUTE", "MINUTELY",
+                             "minute", "hour", "next_second");
+  }
+
+  increment_minute(inc) {
+    return this.increment_generic(inc, "minute", 60, "hour");
+  }
+
+  next_hour() {
+    return this.next_generic("BYHOUR", "HOURLY", "hour",
+                             "monthday", "next_minute");
+  }
+
+  increment_hour(inc) {
+    this.increment_generic(inc, "hour", 24, "monthday");
+  }
+
+  next_day() {
+    let this_freq = (this.rule.freq == "DAILY");
+
+    if (this.next_hour() == 0) {
+      return 0;
+    }
+
+    if (this_freq) {
+      this.increment_monthday(this.rule.interval);
+    } else {
+      this.increment_monthday(1);
+    }
+
+    return 0;
+  }
+
+  next_week() {
+    let end_of_data = 0;
+
+    if (this.next_weekday_by_week() == 0) {
+      return end_of_data;
+    }
+
+    if (this.has_by_data("BYWEEKNO")) {
+      this.by_indices.BYWEEKNO++;
+
+      if (this.by_indices.BYWEEKNO == this.by_data.BYWEEKNO.length) {
+        this.by_indices.BYWEEKNO = 0;
+        end_of_data = 1;
+      }
+
+      // HACK should be first month of the year
+      this.last.month = 1;
+      this.last.day = 1;
+
+      let week_no = this.by_data.BYWEEKNO[this.by_indices.BYWEEKNO];
+
+      this.last.day += 7 * week_no;
+
+      if (end_of_data) {
+        this.increment_year(1);
+      }
+    } else {
+      // Jump to the next week
+      this.increment_monthday(7 * this.rule.interval);
+    }
+
+    return end_of_data;
+  }
+
+  /**
+   * Normalize each by day rule for a given year/month.
+   * Takes into account ordering and negative rules
+   *
+   * @private
+   * @param {Number} year         Current year.
+   * @param {Number} month        Current month.
+   * @param {Array}  rules        Array of rules.
+   *
+   * @return {Array} sorted and normalized rules.
+   *                 Negative rules will be expanded to their
+   *                 correct positive values for easier processing.
+   */
+  normalizeByMonthDayRules(year, month, rules) {
+    let daysInMonth = Time.daysInMonth(month, year);
+
+    // XXX: This is probably bad for performance to allocate
+    //      a new array for each month we scan, if possible
+    //      we should try to optimize this...
+    let newRules = [];
+
+    let ruleIdx = 0;
+    let len = rules.length;
+    let rule;
+
+    for (; ruleIdx < len; ruleIdx++) {
+      rule = parseInt(rules[ruleIdx], 10);
+      if (isNaN(rule)) {
+        throw new Error('Invalid BYMONTHDAY value');
+      }
+
+      // if this rule falls outside of given
+      // month discard it.
+      if (Math.abs(rule) > daysInMonth) {
+        continue;
+      }
+
+      // negative case
+      if (rule < 0) {
+        // we add (not subtract it is a negative number)
+        // one from the rule because 1 === last day of month
+        rule = daysInMonth + (rule + 1);
+      } else if (rule === 0) {
+        // skip zero: it is invalid.
+        continue;
+      }
+
+      // only add unique items...
+      if (newRules.indexOf(rule) === -1) {
+        newRules.push(rule);
+      }
+
+    }
+
+    // unique and sort
+    return newRules.sort(function(a, b) { return a - b; });
+  }
+
+  /**
+   * NOTES:
+   * We are given a list of dates in the month (BYMONTHDAY) (23, etc..)
+   * Also we are given a list of days (BYDAY) (MO, 2SU, etc..) when
+   * both conditions match a given date (this.last.day) iteration stops.
+   *
+   * @private
+   * @param {Boolean=} isInit     When given true will not increment the
+   *                                current day (this.last).
+   */
+  _byDayAndMonthDay(isInit) {
+    let byMonthDay; // setup in initMonth
+    let byDay = this.by_data.BYDAY;
+
+    let date;
+    let dateIdx = 0;
+    let dateLen; // setup in initMonth
+    let dayLen = byDay.length;
+
+    // we are not valid by default
+    let dataIsValid = 0;
+
+    let daysInMonth;
+    let self = this;
+    // we need a copy of this, because a DateTime gets normalized
+    // automatically if the day is out of range. At some points we
+    // set the last day to 0 to start counting.
+    let lastDay = this.last.day;
+
+    function initMonth() {
+      daysInMonth = Time.daysInMonth(
+        self.last.month, self.last.year
+      );
+
+      byMonthDay = self.normalizeByMonthDayRules(
+        self.last.year,
+        self.last.month,
+        self.by_data.BYMONTHDAY
+      );
+
+      dateLen = byMonthDay.length;
+
+      // For the case of more than one occurrence in one month
+      // we have to be sure to start searching after the last
+      // found date or at the last BYMONTHDAY, unless we are
+      // initializing the iterator because in this case we have
+      // to consider the last found date too.
+      while (byMonthDay[dateIdx] <= lastDay &&
+             !(isInit && byMonthDay[dateIdx] == lastDay) &&
+             dateIdx < dateLen - 1) {
+        dateIdx++;
+      }
+    }
+
+    function nextMonth() {
+      // since the day is incremented at the start
+      // of the loop below, we need to start at 0
+      lastDay = 0;
+      self.increment_month();
+      dateIdx = 0;
+      initMonth();
+    }
+
+    initMonth();
+
+    // should come after initMonth
+    if (isInit) {
+      lastDay -= 1;
+    }
+
+    // Use a counter to avoid an infinite loop with malformed rules.
+    // Stop checking after 4 years so we consider also a leap year.
+    let monthsCounter = 48;
+
+    while (!dataIsValid && monthsCounter) {
+      monthsCounter--;
+      // increment the current date. This is really
+      // important otherwise we may fall into the infinite
+      // loop trap. The initial date takes care of the case
+      // where the current date is the date we are looking
+      // for.
+      date = lastDay + 1;
+
+      if (date > daysInMonth) {
+        nextMonth();
+        continue;
+      }
+
+      // find next date
+      let next = byMonthDay[dateIdx++];
+
+      // this logic is dependent on the BYMONTHDAYS
+      // being in order (which is done by #normalizeByMonthDayRules)
+      if (next >= date) {
+        // if the next month day is in the future jump to it.
+        lastDay = next;
+      } else {
+        // in this case the 'next' monthday has past
+        // we must move to the month.
+        nextMonth();
+        continue;
+      }
+
+      // Now we can loop through the day rules to see
+      // if one matches the current month date.
+      for (let dayIdx = 0; dayIdx < dayLen; dayIdx++) {
+        let parts = this.ruleDayOfWeek(byDay[dayIdx]);
+        let pos = parts[0];
+        let dow = parts[1];
+
+        this.last.day = lastDay;
+        if (this.last.isNthWeekDay(dow, pos)) {
+          // when we find the valid one we can mark
+          // the conditions as met and break the loop.
+          // (Because we have this condition above
+          //  it will also break the parent loop).
+          dataIsValid = 1;
+          break;
+        }
+      }
+
+      // It is completely possible that the combination
+      // cannot be matched in the current month.
+      // When we reach the end of possible combinations
+      // in the current month we iterate to the next one.
+      // since dateIdx is incremented right after getting
+      // "next", we don't need dateLen -1 here.
+      if (!dataIsValid && dateIdx === dateLen) {
+        nextMonth();
+        continue;
+      }
+    }
+
+    if (monthsCounter <= 0) {
+      // Checked 4 years without finding a Byday that matches
+      // a Bymonthday. Maybe the rule is not correct.
+      throw new Error("Malformed values in BYDAY combined with BYMONTHDAY parts");
+    }
+
+
+    return dataIsValid;
+  }
+
+  next_month() {
+    let data_valid = 1;
+
+    if (this.next_hour() == 0) {
+      return data_valid;
+    }
+
+    if (this.has_by_data("BYDAY") && this.has_by_data("BYMONTHDAY")) {
+      data_valid = this._byDayAndMonthDay();
+    } else if (this.has_by_data("BYDAY")) {
+      let daysInMonth = Time.daysInMonth(this.last.month, this.last.year);
+      let setpos = 0;
+      let setpos_total = 0;
+
+      if (this.has_by_data("BYSETPOS")) {
+        let last_day = this.last.day;
+        for (let day = 1; day <= daysInMonth; day++) {
+          this.last.day = day;
+          if (this.is_day_in_byday(this.last)) {
+            setpos_total++;
+            if (day <= last_day) {
+              setpos++;
+            }
+          }
+        }
+        this.last.day = last_day;
+      }
+
+      data_valid = 0;
+      let day;
+      for (day = this.last.day + 1; day <= daysInMonth; day++) {
+        this.last.day = day;
+
+        if (this.is_day_in_byday(this.last)) {
+          if (!this.has_by_data("BYSETPOS") ||
+              this.check_set_position(++setpos) ||
+              this.check_set_position(setpos - setpos_total - 1)) {
+
+            data_valid = 1;
+            break;
+          }
+        }
+      }
+
+      if (day > daysInMonth) {
+        this.last.day = 1;
+        this.increment_month();
+
+        if (this.is_day_in_byday(this.last)) {
+          if (!this.has_by_data("BYSETPOS") || this.check_set_position(1)) {
+            data_valid = 1;
+          }
+        } else {
+          data_valid = 0;
+        }
+      }
+    } else if (this.has_by_data("BYMONTHDAY")) {
+      this.by_indices.BYMONTHDAY++;
+
+      if (this.by_indices.BYMONTHDAY >= this.by_data.BYMONTHDAY.length) {
+        this.by_indices.BYMONTHDAY = 0;
+        this.increment_month();
+        if (this.by_indices.BYMONTHDAY >= this.by_data.BYMONTHDAY.length) {
+          return 0;
+        }
+      }
+
+      let daysInMonth = Time.daysInMonth(this.last.month, this.last.year);
+      let day = this.by_data.BYMONTHDAY[this.by_indices.BYMONTHDAY];
+
+      if (day < 0) {
+        day = daysInMonth + day + 1;
+      }
+
+      if (day > daysInMonth) {
+        this.last.day = 1;
+        data_valid = this.is_day_in_byday(this.last);
+      } else {
+        this.last.day = day;
+      }
+    } else {
+      this.increment_month();
+      let daysInMonth = Time.daysInMonth(this.last.month, this.last.year);
+      if (this.by_data.BYMONTHDAY[0] > daysInMonth) {
+        data_valid = 0;
+      } else {
+        this.last.day = this.by_data.BYMONTHDAY[0];
+      }
+    }
+
+    return data_valid;
+  }
+
+  next_weekday_by_week() {
+    let end_of_data = 0;
+
+    if (this.next_hour() == 0) {
+      return end_of_data;
+    }
+
+    if (!this.has_by_data("BYDAY")) {
+      return 1;
+    }
+
+    for (;;) {
+      let tt = new Time();
+      this.by_indices.BYDAY++;
+
+      if (this.by_indices.BYDAY == Object.keys(this.by_data.BYDAY).length) {
+        this.by_indices.BYDAY = 0;
+        end_of_data = 1;
+      }
+
+      let coded_day = this.by_data.BYDAY[this.by_indices.BYDAY];
+      let parts = this.ruleDayOfWeek(coded_day);
+      let dow = parts[1];
+
+      dow -= this.rule.wkst;
+
+      if (dow < 0) {
+        dow += 7;
+      }
+
+      tt.year = this.last.year;
+      tt.month = this.last.month;
+      tt.day = this.last.day;
+
+      let startOfWeek = tt.startDoyWeek(this.rule.wkst);
+
+      if (dow + startOfWeek < 1) {
+        // The selected date is in the previous year
+        if (!end_of_data) {
+          continue;
+        }
+      }
+
+      let next = Time.fromDayOfYear(startOfWeek + dow, this.last.year);
+
+      /**
+       * The normalization horrors below are due to
+       * the fact that when the year/month/day changes
+       * it can effect the other operations that come after.
+       */
+      this.last.year = next.year;
+      this.last.month = next.month;
+      this.last.day = next.day;
+
+      return end_of_data;
+    }
+  }
+
+  next_year() {
+    if (this.next_hour() == 0) {
+      return 0;
+    }
+
+    if (++this.days_index == this.days.length) {
+      this.days_index = 0;
+      do {
+        this.increment_year(this.rule.interval);
+        if (this.has_by_data("BYMONTHDAY")) {
+          this.by_data.BYMONTHDAY = this.normalizeByMonthDayRules(
+            this.last.year,
+            this.last.month,
+            this.rule.parts.BYMONTHDAY
+          );
+        }
+        this.expand_year_days(this.last.year);
+      } while (this.days.length == 0);
+    }
+
+    this._nextByYearDay();
+
+    return 1;
+  }
+
+  _nextByYearDay() {
+    let doy = this.days[this.days_index];
+    let year = this.last.year;
+    if (doy < 1) {
+        // Time.fromDayOfYear(doy, year) indexes relative to the
+        // start of the given year. That is different from the
+        // semantics of BYYEARDAY where negative indexes are an
+        // offset from the end of the given year.
+        doy += 1;
+        year += 1;
+    }
+    let next = Time.fromDayOfYear(doy, year);
+    this.last.day = next.day;
+    this.last.month = next.month;
+  }
+
+  /**
+   * @param dow (eg: '1TU', '-1MO')
+   * @param {weekDay=} aWeekStart The week start weekday
+   * @return [pos, numericDow] (eg: [1, 3]) numericDow is relative to aWeekStart
+   */
+  ruleDayOfWeek(dow, aWeekStart) {
+    let matches = dow.match(/([+-]?[0-9])?(MO|TU|WE|TH|FR|SA|SU)/);
+    if (matches) {
+      let pos = parseInt(matches[1] || 0, 10);
+      dow = Recur.icalDayToNumericDay(matches[2], aWeekStart);
+      return [pos, dow];
+    } else {
+      return [0, 0];
+    }
+  }
+
+  next_generic(aRuleType, aInterval, aDateAttr, aFollowingAttr, aPreviousIncr) {
+    let has_by_rule = (aRuleType in this.by_data);
+    let this_freq = (this.rule.freq == aInterval);
+    let end_of_data = 0;
+
+    if (aPreviousIncr && this[aPreviousIncr]() == 0) {
+      return end_of_data;
+    }
+
+    if (has_by_rule) {
+      this.by_indices[aRuleType]++;
+      let dta = this.by_data[aRuleType];
+
+      if (this.by_indices[aRuleType] == dta.length) {
+        this.by_indices[aRuleType] = 0;
+        end_of_data = 1;
+      }
+      this.last[aDateAttr] = dta[this.by_indices[aRuleType]];
+    } else if (this_freq) {
+      this["increment_" + aDateAttr](this.rule.interval);
+    }
+
+    if (has_by_rule && end_of_data && this_freq) {
+      this["increment_" + aFollowingAttr](1);
+    }
+
+    return end_of_data;
+  }
+
+  increment_monthday(inc) {
+    for (let i = 0; i < inc; i++) {
+      let daysInMonth = Time.daysInMonth(this.last.month, this.last.year);
+      this.last.day++;
+
+      if (this.last.day > daysInMonth) {
+        this.last.day -= daysInMonth;
+        this.increment_month();
+      }
+    }
+  }
+
+  increment_month() {
+    this.last.day = 1;
+    if (this.has_by_data("BYMONTH")) {
+      this.by_indices.BYMONTH++;
+
+      if (this.by_indices.BYMONTH == this.by_data.BYMONTH.length) {
+        this.by_indices.BYMONTH = 0;
+        this.increment_year(1);
+      }
+
+      this.last.month = this.by_data.BYMONTH[this.by_indices.BYMONTH];
+    } else {
+      if (this.rule.freq == "MONTHLY") {
+        this.last.month += this.rule.interval;
+      } else {
+        this.last.month++;
+      }
+
+      this.last.month--;
+      let years = trunc(this.last.month / 12);
+      this.last.month %= 12;
+      this.last.month++;
+
+      if (years != 0) {
+        this.increment_year(years);
+      }
+    }
+
+    if (this.has_by_data("BYMONTHDAY")) {
+      this.by_data.BYMONTHDAY = this.normalizeByMonthDayRules(
+        this.last.year,
+        this.last.month,
+        this.rule.parts.BYMONTHDAY
+      );
+    }
+  }
+
+  increment_year(inc) {
+    // Don't jump into the next month if this.last is Feb 29.
+    this.last.day = 1;
+    this.last.year += inc;
+  }
+
+  increment_generic(inc, aDateAttr, aFactor, aNextIncrement) {
+    this.last[aDateAttr] += inc;
+    let nextunit = trunc(this.last[aDateAttr] / aFactor);
+    this.last[aDateAttr] %= aFactor;
+    if (nextunit != 0) {
+      this["increment_" + aNextIncrement](nextunit);
+    }
+  }
+
+  has_by_data(aRuleType) {
+    return (aRuleType in this.rule.parts);
+  }
+
+  expand_year_days(aYear) {
+    let t = new Time();
+    this.days = [];
+
+    // We need our own copy with a few keys set
+    let parts = {};
+    let rules = ["BYDAY", "BYWEEKNO", "BYMONTHDAY", "BYMONTH", "BYYEARDAY"];
+    for (let part of rules) {
+      if (part in this.rule.parts) {
+        parts[part] = this.rule.parts[part];
+      }
+    }
+
+    if ("BYMONTH" in parts && "BYWEEKNO" in parts) {
+      let valid = 1;
+      let validWeeks = {};
+      t.year = aYear;
+      t.isDate = true;
+
+      for (let monthIdx = 0; monthIdx < this.by_data.BYMONTH.length; monthIdx++) {
+        let month = this.by_data.BYMONTH[monthIdx];
+        t.month = month;
+        t.day = 1;
+        let first_week = t.weekNumber(this.rule.wkst);
+        t.day = Time.daysInMonth(month, aYear);
+        let last_week = t.weekNumber(this.rule.wkst);
+        for (monthIdx = first_week; monthIdx < last_week; monthIdx++) {
+          validWeeks[monthIdx] = 1;
+        }
+      }
+
+      for (let weekIdx = 0; weekIdx < this.by_data.BYWEEKNO.length && valid; weekIdx++) {
+        let weekno = this.by_data.BYWEEKNO[weekIdx];
+        if (weekno < 52) {
+          valid &= validWeeks[weekIdx];
+        } else {
+          valid = 0;
+        }
+      }
+
+      if (valid) {
+        delete parts.BYMONTH;
+      } else {
+        delete parts.BYWEEKNO;
+      }
+    }
+
+    let partCount = Object.keys(parts).length;
+
+    if (partCount == 0) {
+      let t1 = this.dtstart.clone();
+      t1.year = this.last.year;
+      this.days.push(t1.dayOfYear());
+    } else if (partCount == 1 && "BYMONTH" in parts) {
+      for (let month of this.by_data.BYMONTH) {
+        let t2 = this.dtstart.clone();
+        t2.year = aYear;
+        t2.month = month;
+        t2.isDate = true;
+        this.days.push(t2.dayOfYear());
+      }
+    } else if (partCount == 1 && "BYMONTHDAY" in parts) {
+      for (let monthday of this.by_data.BYMONTHDAY) {
+        let t3 = this.dtstart.clone();
+        if (monthday < 0) {
+          let daysInMonth = Time.daysInMonth(t3.month, aYear);
+          monthday = monthday + daysInMonth + 1;
+        }
+        t3.day = monthday;
+        t3.year = aYear;
+        t3.isDate = true;
+        this.days.push(t3.dayOfYear());
+      }
+    } else if (partCount == 2 &&
+               "BYMONTHDAY" in parts &&
+               "BYMONTH" in parts) {
+      for (let month of this.by_data.BYMONTH) {
+        let daysInMonth = Time.daysInMonth(month, aYear);
+        for (let monthday of this.by_data.BYMONTHDAY) {
+          if (monthday < 0) {
+            monthday = monthday + daysInMonth + 1;
+          }
+          t.day = monthday;
+          t.month = month;
+          t.year = aYear;
+          t.isDate = true;
+
+          this.days.push(t.dayOfYear());
+        }
+      }
+    } else if (partCount == 1 && "BYWEEKNO" in parts) ; else if (partCount == 2 &&
+               "BYWEEKNO" in parts &&
+               "BYMONTHDAY" in parts) ; else if (partCount == 1 && "BYDAY" in parts) {
+      this.days = this.days.concat(this.expand_by_day(aYear));
+    } else if (partCount == 2 && "BYDAY" in parts && "BYMONTH" in parts) {
+      for (let month of this.by_data.BYMONTH) {
+        let daysInMonth = Time.daysInMonth(month, aYear);
+
+        t.year = aYear;
+        t.month = month;
+        t.day = 1;
+        t.isDate = true;
+
+        let first_dow = t.dayOfWeek();
+        let doy_offset = t.dayOfYear() - 1;
+
+        t.day = daysInMonth;
+        let last_dow = t.dayOfWeek();
+
+        if (this.has_by_data("BYSETPOS")) {
+          let by_month_day = [];
+          for (let day = 1; day <= daysInMonth; day++) {
+            t.day = day;
+            if (this.is_day_in_byday(t)) {
+              by_month_day.push(day);
+            }
+          }
+
+          for (let spIndex = 0; spIndex < by_month_day.length; spIndex++) {
+            if (this.check_set_position(spIndex + 1) ||
+                this.check_set_position(spIndex - by_month_day.length)) {
+              this.days.push(doy_offset + by_month_day[spIndex]);
+            }
+          }
+        } else {
+          for (let coded_day of this.by_data.BYDAY) {
+            let bydayParts = this.ruleDayOfWeek(coded_day);
+            let pos = bydayParts[0];
+            let dow = bydayParts[1];
+            let month_day;
+
+            let first_matching_day = ((dow + 7 - first_dow) % 7) + 1;
+            let last_matching_day = daysInMonth - ((last_dow + 7 - dow) % 7);
+
+            if (pos == 0) {
+              for (let day = first_matching_day; day <= daysInMonth; day += 7) {
+                this.days.push(doy_offset + day);
+              }
+            } else if (pos > 0) {
+              month_day = first_matching_day + (pos - 1) * 7;
+
+              if (month_day <= daysInMonth) {
+                this.days.push(doy_offset + month_day);
+              }
+            } else {
+              month_day = last_matching_day + (pos + 1) * 7;
+
+              if (month_day > 0) {
+                this.days.push(doy_offset + month_day);
+              }
+            }
+          }
+        }
+      }
+      // Return dates in order of occurrence (1,2,3,...) instead
+      // of by groups of weekdays (1,8,15,...,2,9,16,...).
+      this.days.sort(function(a, b) { return a - b; }); // Comparator function allows to sort numbers.
+    } else if (partCount == 2 && "BYDAY" in parts && "BYMONTHDAY" in parts) {
+      let expandedDays = this.expand_by_day(aYear);
+
+      for (let day of expandedDays) {
+        let tt = Time.fromDayOfYear(day, aYear);
+        if (this.by_data.BYMONTHDAY.indexOf(tt.day) >= 0) {
+          this.days.push(day);
+        }
+      }
+    } else if (partCount == 3 &&
+               "BYDAY" in parts &&
+               "BYMONTHDAY" in parts &&
+               "BYMONTH" in parts) {
+      let expandedDays = this.expand_by_day(aYear);
+
+      for (let day of expandedDays) {
+        let tt = Time.fromDayOfYear(day, aYear);
+
+        if (this.by_data.BYMONTH.indexOf(tt.month) >= 0 &&
+            this.by_data.BYMONTHDAY.indexOf(tt.day) >= 0) {
+          this.days.push(day);
+        }
+      }
+    } else if (partCount == 2 && "BYDAY" in parts && "BYWEEKNO" in parts) {
+      let expandedDays = this.expand_by_day(aYear);
+
+      for (let day of expandedDays) {
+        let tt = Time.fromDayOfYear(day, aYear);
+        let weekno = tt.weekNumber(this.rule.wkst);
+
+        if (this.by_data.BYWEEKNO.indexOf(weekno)) {
+          this.days.push(day);
+        }
+      }
+    } else if (partCount == 3 &&
+               "BYDAY" in parts &&
+               "BYWEEKNO" in parts &&
+               "BYMONTHDAY" in parts) ; else if (partCount == 1 && "BYYEARDAY" in parts) {
+      this.days = this.days.concat(this.by_data.BYYEARDAY);
+    } else {
+      this.days = [];
+    }
+
+    let daysInYear = Time.isLeapYear(aYear) ? 366 : 365;
+    this.days.sort((a, b) => {
+      if (a < 0) a += daysInYear + 1;
+      if (b < 0) b += daysInYear + 1;
+      return a - b;
+    });
+
+    return 0;
+  }
+
+  expand_by_day(aYear) {
+
+    let days_list = [];
+    let tmp = this.last.clone();
+
+    tmp.year = aYear;
+    tmp.month = 1;
+    tmp.day = 1;
+    tmp.isDate = true;
+
+    let start_dow = tmp.dayOfWeek();
+
+    tmp.month = 12;
+    tmp.day = 31;
+    tmp.isDate = true;
+
+    let end_dow = tmp.dayOfWeek();
+    let end_year_day = tmp.dayOfYear();
+
+    for (let day of this.by_data.BYDAY) {
+      let parts = this.ruleDayOfWeek(day);
+      let pos = parts[0];
+      let dow = parts[1];
+
+      if (pos == 0) {
+        let tmp_start_doy = ((dow + 7 - start_dow) % 7) + 1;
+
+        for (let doy = tmp_start_doy; doy <= end_year_day; doy += 7) {
+          days_list.push(doy);
+        }
+
+      } else if (pos > 0) {
+        let first;
+        if (dow >= start_dow) {
+          first = dow - start_dow + 1;
+        } else {
+          first = dow - start_dow + 8;
+        }
+
+        days_list.push(first + (pos - 1) * 7);
+      } else {
+        let last;
+        pos = -pos;
+
+        if (dow <= end_dow) {
+          last = end_year_day - end_dow + dow;
+        } else {
+          last = end_year_day - end_dow + dow - 7;
+        }
+
+        days_list.push(last - (pos - 1) * 7);
+      }
+    }
+    return days_list;
+  }
+
+  is_day_in_byday(tt) {
+    if (this.by_data.BYDAY) {
+      for (let day of this.by_data.BYDAY) {
+        let parts = this.ruleDayOfWeek(day);
+        let pos = parts[0];
+        let dow = parts[1];
+        let this_dow = tt.dayOfWeek();
+
+        if ((pos == 0 && dow == this_dow) ||
+            (tt.nthWeekDay(dow, pos) == tt.day)) {
+          return 1;
+        }
+      }
+    }
+
+    return 0;
+  }
+
+  /**
+   * Checks if given value is in BYSETPOS.
+   *
+   * @private
+   * @param {Numeric} aPos position to check for.
+   * @return {Boolean} false unless BYSETPOS rules exist
+   *                   and the given value is present in rules.
+   */
+  check_set_position(aPos) {
+    if (this.has_by_data('BYSETPOS')) {
+      let idx = this.by_data.BYSETPOS.indexOf(aPos);
+      // negative numbers are not false-y
+      return idx !== -1;
+    }
+    return false;
+  }
+
+  sort_byday_rules(aRules) {
+    for (let i = 0; i < aRules.length; i++) {
+      for (let j = 0; j < i; j++) {
+        let one = this.ruleDayOfWeek(aRules[j], this.rule.wkst)[1];
+        let two = this.ruleDayOfWeek(aRules[i], this.rule.wkst)[1];
+
+        if (one > two) {
+          let tmp = aRules[i];
+          aRules[i] = aRules[j];
+          aRules[j] = tmp;
+        }
+      }
+    }
+  }
+
+  check_contract_restriction(aRuleType, v) {
+    let indexMapValue = RecurIterator._indexMap[aRuleType];
+    let ruleMapValue = RecurIterator._expandMap[this.rule.freq][indexMapValue];
+    let pass = false;
+
+    if (aRuleType in this.by_data &&
+        ruleMapValue == RecurIterator.CONTRACT) {
+
+      let ruleType = this.by_data[aRuleType];
+
+      for (let bydata of ruleType) {
+        if (bydata == v) {
+          pass = true;
+          break;
+        }
+      }
+    } else {
+      // Not a contracting byrule or has no data, test passes
+      pass = true;
+    }
+    return pass;
+  }
+
+  check_contracting_rules() {
+    let dow = this.last.dayOfWeek();
+    let weekNo = this.last.weekNumber(this.rule.wkst);
+    let doy = this.last.dayOfYear();
+
+    return (this.check_contract_restriction("BYSECOND", this.last.second) &&
+            this.check_contract_restriction("BYMINUTE", this.last.minute) &&
+            this.check_contract_restriction("BYHOUR", this.last.hour) &&
+            this.check_contract_restriction("BYDAY", Recur.numericDayToIcalDay(dow)) &&
+            this.check_contract_restriction("BYWEEKNO", weekNo) &&
+            this.check_contract_restriction("BYMONTHDAY", this.last.day) &&
+            this.check_contract_restriction("BYMONTH", this.last.month) &&
+            this.check_contract_restriction("BYYEARDAY", doy));
+  }
+
+  setup_defaults(aRuleType, req, deftime) {
+    let indexMapValue = RecurIterator._indexMap[aRuleType];
+    let ruleMapValue = RecurIterator._expandMap[this.rule.freq][indexMapValue];
+
+    if (ruleMapValue != RecurIterator.CONTRACT) {
+      if (!(aRuleType in this.by_data)) {
+        this.by_data[aRuleType] = [deftime];
+      }
+      if (this.rule.freq != req) {
+        return this.by_data[aRuleType][0];
+      }
+    }
+    return deftime;
+  }
+
+  /**
+   * Convert iterator into a serialize-able object.  Will preserve current
+   * iteration sequence to ensure the seamless continuation of the recurrence
+   * rule.
+   * @return {Object}
+   */
+  toJSON() {
+    let result = Object.create(null);
+
+    result.initialized = this.initialized;
+    result.rule = this.rule.toJSON();
+    result.dtstart = this.dtstart.toJSON();
+    result.by_data = this.by_data;
+    result.days = this.days;
+    result.last = this.last.toJSON();
+    result.by_indices = this.by_indices;
+    result.occurrence_number = this.occurrence_number;
+
+    return result;
+  }
+}
+
+/**
+ * An error indicating that a recurrence rule is invalid and produces no
+ * occurrences.
+ *
+ * @extends {Error}
+ * @class
+ */
+class InvalidRecurrenceRuleError extends Error {
+  constructor() {
+    super("Recurrence rule has no valid occurrences");
+  }
+}
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ * Portions Copyright (C) Philipp Kewisch */
+
+/**
+ * This lets typescript resolve our custom types in the
+ * generated d.ts files (jsdoc typedefs are converted to typescript types).
+ * Ignore prevents the typedefs from being documented more than once.
+ *
+ * @ignore
+ * @typedef {import("./types.js").weekDay} weekDay
+ * Imports the 'weekDay' type from the "types.js" module
+ * @typedef {import("./types.js").frequencyValues} frequencyValues
+ * Imports the 'frequencyValues' type from the "types.js" module
+ */
+
+const VALID_DAY_NAMES = /^(SU|MO|TU|WE|TH|FR|SA)$/;
+const VALID_BYDAY_PART = /^([+-])?(5[0-3]|[1-4][0-9]|[1-9])?(SU|MO|TU|WE|TH|FR|SA)$/;
+const DOW_MAP = {
+  SU: Time.SUNDAY,
+  MO: Time.MONDAY,
+  TU: Time.TUESDAY,
+  WE: Time.WEDNESDAY,
+  TH: Time.THURSDAY,
+  FR: Time.FRIDAY,
+  SA: Time.SATURDAY
+};
+
+const REVERSE_DOW_MAP = Object.fromEntries(Object.entries(DOW_MAP).map(entry => entry.reverse()));
+
+const ALLOWED_FREQ = ['SECONDLY', 'MINUTELY', 'HOURLY',
+                      'DAILY', 'WEEKLY', 'MONTHLY', 'YEARLY'];
+
+/**
+ * This class represents the "recur" value type, used for example by RRULE. It provides methods to
+ * calculate occurrences among others.
+ *
+ * @memberof ICAL
+ */
+class Recur {
+  /**
+   * Creates a new {@link ICAL.Recur} instance from the passed string.
+   *
+   * @param {String} string         The string to parse
+   * @return {Recur}                The created recurrence instance
+   */
+  static fromString(string) {
+    let data = this._stringToData(string, false);
+    return new Recur(data);
+  }
+
+  /**
+   * Creates a new {@link ICAL.Recur} instance using members from the passed
+   * data object.
+   *
+   * @param {Object} aData                              An object with members of the recurrence
+   * @param {frequencyValues=} aData.freq               The frequency value
+   * @param {Number=} aData.interval                    The INTERVAL value
+   * @param {weekDay=} aData.wkst                       The week start value
+   * @param {Time=} aData.until                         The end of the recurrence set
+   * @param {Number=} aData.count                       The number of occurrences
+   * @param {Array.<Number>=} aData.bysecond            The seconds for the BYSECOND part
+   * @param {Array.<Number>=} aData.byminute            The minutes for the BYMINUTE part
+   * @param {Array.<Number>=} aData.byhour              The hours for the BYHOUR part
+   * @param {Array.<String>=} aData.byday               The BYDAY values
+   * @param {Array.<Number>=} aData.bymonthday          The days for the BYMONTHDAY part
+   * @param {Array.<Number>=} aData.byyearday           The days for the BYYEARDAY part
+   * @param {Array.<Number>=} aData.byweekno            The weeks for the BYWEEKNO part
+   * @param {Array.<Number>=} aData.bymonth             The month for the BYMONTH part
+   * @param {Array.<Number>=} aData.bysetpos            The positionals for the BYSETPOS part
+   */
+  static fromData(aData) {
+    return new Recur(aData);
+  }
+
+  /**
+   * Converts a recurrence string to a data object, suitable for the fromData
+   * method.
+   *
+   * @private
+   * @param {String} string     The string to parse
+   * @param {Boolean} fmtIcal   If true, the string is considered to be an
+   *                              iCalendar string
+   * @return {Recur}            The recurrence instance
+   */
+  static _stringToData(string, fmtIcal) {
+    let dict = Object.create(null);
+
+    // split is slower in FF but fast enough.
+    // v8 however this is faster then manual split?
+    let values = string.split(';');
+    let len = values.length;
+
+    for (let i = 0; i < len; i++) {
+      let parts = values[i].split('=');
+      let ucname = parts[0].toUpperCase();
+      let lcname = parts[0].toLowerCase();
+      let name = (fmtIcal ? lcname : ucname);
+      let value = parts[1];
+
+      if (ucname in partDesign) {
+        let partArr = value.split(',');
+        let partSet = new Set();
+
+        for (let part of partArr) {
+          partSet.add(partDesign[ucname](part));
+        }
+        partArr = [...partSet];
+
+        dict[name] = (partArr.length == 1 ? partArr[0] : partArr);
+      } else if (ucname in optionDesign) {
+        optionDesign[ucname](value, dict, fmtIcal);
+      } else {
+        // Don't swallow unknown values. Just set them as they are.
+        dict[lcname] = value;
+      }
+    }
+
+    return dict;
+  }
+
+  /**
+   * Convert an ical representation of a day (SU, MO, etc..)
+   * into a numeric value of that day.
+   *
+   * @param {String} string     The iCalendar day name
+   * @param {weekDay=} aWeekStart
+   *        The week start weekday, defaults to SUNDAY
+   * @return {Number}           Numeric value of given day
+   */
+  static icalDayToNumericDay(string, aWeekStart) {
+    //XXX: this is here so we can deal
+    //     with possibly invalid string values.
+    let firstDow = aWeekStart || Time.SUNDAY;
+    return ((DOW_MAP[string] - firstDow + 7) % 7) + 1;
+  }
+
+  /**
+   * Convert a numeric day value into its ical representation (SU, MO, etc..)
+   *
+   * @param {Number} num        Numeric value of given day
+   * @param {weekDay=} aWeekStart
+   *        The week start weekday, defaults to SUNDAY
+   * @return {String}           The ICAL day value, e.g SU,MO,...
+   */
+  static numericDayToIcalDay(num, aWeekStart) {
+    //XXX: this is here so we can deal with possibly invalid number values.
+    //     Also, this allows consistent mapping between day numbers and day
+    //     names for external users.
+    let firstDow = aWeekStart || Time.SUNDAY;
+    let dow = (num + firstDow - Time.SUNDAY);
+    if (dow > 7) {
+      dow -= 7;
+    }
+    return REVERSE_DOW_MAP[dow];
+  }
+
+  /**
+   * Create a new instance of the Recur class.
+   *
+   * @param {Object} data                               An object with members of the recurrence
+   * @param {frequencyValues=} data.freq                The frequency value
+   * @param {Number=} data.interval                     The INTERVAL value
+   * @param {weekDay=} data.wkst                        The week start value
+   * @param {Time=} data.until                          The end of the recurrence set
+   * @param {Number=} data.count                        The number of occurrences
+   * @param {Array.<Number>=} data.bysecond             The seconds for the BYSECOND part
+   * @param {Array.<Number>=} data.byminute             The minutes for the BYMINUTE part
+   * @param {Array.<Number>=} data.byhour               The hours for the BYHOUR part
+   * @param {Array.<String>=} data.byday                The BYDAY values
+   * @param {Array.<Number>=} data.bymonthday           The days for the BYMONTHDAY part
+   * @param {Array.<Number>=} data.byyearday            The days for the BYYEARDAY part
+   * @param {Array.<Number>=} data.byweekno             The weeks for the BYWEEKNO part
+   * @param {Array.<Number>=} data.bymonth              The month for the BYMONTH part
+   * @param {Array.<Number>=} data.bysetpos             The positionals for the BYSETPOS part
+   */
+  constructor(data) {
+    this.wrappedJSObject = this;
+    this.parts = {};
+
+    if (data && typeof(data) === 'object') {
+      this.fromData(data);
+    }
+  }
+
+  /**
+   * An object holding the BY-parts of the recurrence rule
+   * @memberof ICAL.Recur
+   * @typedef {Object} byParts
+   * @property {Array.<Number>=} BYSECOND            The seconds for the BYSECOND part
+   * @property {Array.<Number>=} BYMINUTE            The minutes for the BYMINUTE part
+   * @property {Array.<Number>=} BYHOUR              The hours for the BYHOUR part
+   * @property {Array.<String>=} BYDAY               The BYDAY values
+   * @property {Array.<Number>=} BYMONTHDAY          The days for the BYMONTHDAY part
+   * @property {Array.<Number>=} BYYEARDAY           The days for the BYYEARDAY part
+   * @property {Array.<Number>=} BYWEEKNO            The weeks for the BYWEEKNO part
+   * @property {Array.<Number>=} BYMONTH             The month for the BYMONTH part
+   * @property {Array.<Number>=} BYSETPOS            The positionals for the BYSETPOS part
+   */
+
+  /**
+   * An object holding the BY-parts of the recurrence rule
+   * @type {byParts}
+   */
+  parts = null;
+
+  /**
+   * The interval value for the recurrence rule.
+   * @type {Number}
+   */
+  interval = 1;
+
+  /**
+   * The week start day
+   *
+   * @type {weekDay}
+   * @default ICAL.Time.MONDAY
+   */
+  wkst = Time.MONDAY;
+
+  /**
+   * The end of the recurrence
+   * @type {?Time}
+   */
+  until = null;
+
+  /**
+   * The maximum number of occurrences
+   * @type {?Number}
+   */
+  count = null;
+
+  /**
+   * The frequency value.
+   * @type {frequencyValues}
+   */
+  freq = null;
+
+  /**
+   * The class identifier.
+   * @constant
+   * @type {String}
+   * @default "icalrecur"
+   */
+  icalclass = "icalrecur";
+
+  /**
+   * The type name, to be used in the jCal object.
+   * @constant
+   * @type {String}
+   * @default "recur"
+   */
+  icaltype = "recur";
+
+  /**
+   * Create a new iterator for this recurrence rule. The passed start date
+   * must be the start date of the event, not the start of the range to
+   * search in.
+   *
+   * @example
+   * let recur = comp.getFirstPropertyValue('rrule');
+   * let dtstart = comp.getFirstPropertyValue('dtstart');
+   * let iter = recur.iterator(dtstart);
+   * for (let next = iter.next(); next; next = iter.next()) {
+   *   if (next.compare(rangeStart) < 0) {
+   *     continue;
+   *   }
+   *   console.log(next.toString());
+   * }
+   *
+   * @param {Time} aStart        The item's start date
+   * @return {RecurIterator}     The recurrence iterator
+   */
+  iterator(aStart) {
+    return new RecurIterator({
+      rule: this,
+      dtstart: aStart
+    });
+  }
+
+  /**
+   * Returns a clone of the recurrence object.
+   *
+   * @return {Recur}      The cloned object
+   */
+  clone() {
+    return new Recur(this.toJSON());
+  }
+
+  /**
+   * Checks if the current rule is finite, i.e. has a count or until part.
+   *
+   * @return {Boolean}        True, if the rule is finite
+   */
+  isFinite() {
+    return !!(this.count || this.until);
+  }
+
+  /**
+   * Checks if the current rule has a count part, and not limited by an until
+   * part.
+   *
+   * @return {Boolean}        True, if the rule is by count
+   */
+  isByCount() {
+    return !!(this.count && !this.until);
+  }
+
+  /**
+   * Adds a component (part) to the recurrence rule. This is not a component
+   * in the sense of {@link ICAL.Component}, but a part of the recurrence
+   * rule, i.e. BYMONTH.
+   *
+   * @param {String} aType            The name of the component part
+   * @param {Array|String} aValue     The component value
+   */
+  addComponent(aType, aValue) {
+    let ucname = aType.toUpperCase();
+    if (ucname in this.parts) {
+      this.parts[ucname].push(aValue);
+    } else {
+      this.parts[ucname] = [aValue];
+    }
+  }
+
+  /**
+   * Sets the component value for the given by-part.
+   *
+   * @param {String} aType        The component part name
+   * @param {Array} aValues       The component values
+   */
+  setComponent(aType, aValues) {
+    this.parts[aType.toUpperCase()] = aValues.slice();
+  }
+
+  /**
+   * Gets (a copy) of the requested component value.
+   *
+   * @param {String} aType        The component part name
+   * @return {Array}              The component part value
+   */
+  getComponent(aType) {
+    let ucname = aType.toUpperCase();
+    return (ucname in this.parts ? this.parts[ucname].slice() : []);
+  }
+
+  /**
+   * Retrieves the next occurrence after the given recurrence id. See the
+   * guide on {@tutorial terminology} for more details.
+   *
+   * NOTE: Currently, this method iterates all occurrences from the start
+   * date. It should not be called in a loop for performance reasons. If you
+   * would like to get more than one occurrence, you can iterate the
+   * occurrences manually, see the example on the
+   * {@link ICAL.Recur#iterator iterator} method.
+   *
+   * @param {Time} aStartTime        The start of the event series
+   * @param {Time} aRecurrenceId     The date of the last occurrence
+   * @return {Time}                  The next occurrence after
+   */
+  getNextOccurrence(aStartTime, aRecurrenceId) {
+    let iter = this.iterator(aStartTime);
+    let next;
+
+    do {
+      next = iter.next();
+    } while (next && next.compare(aRecurrenceId) <= 0);
+
+    if (next && aRecurrenceId.zone) {
+      next.zone = aRecurrenceId.zone;
+    }
+
+    return next;
+  }
+
+  /**
+   * Sets up the current instance using members from the passed data object.
+   *
+   * @param {Object} data                               An object with members of the recurrence
+   * @param {frequencyValues=} data.freq                The frequency value
+   * @param {Number=} data.interval                     The INTERVAL value
+   * @param {weekDay=} data.wkst                        The week start value
+   * @param {Time=} data.until                          The end of the recurrence set
+   * @param {Number=} data.count                        The number of occurrences
+   * @param {Array.<Number>=} data.bysecond             The seconds for the BYSECOND part
+   * @param {Array.<Number>=} data.byminute             The minutes for the BYMINUTE part
+   * @param {Array.<Number>=} data.byhour               The hours for the BYHOUR part
+   * @param {Array.<String>=} data.byday                The BYDAY values
+   * @param {Array.<Number>=} data.bymonthday           The days for the BYMONTHDAY part
+   * @param {Array.<Number>=} data.byyearday            The days for the BYYEARDAY part
+   * @param {Array.<Number>=} data.byweekno             The weeks for the BYWEEKNO part
+   * @param {Array.<Number>=} data.bymonth              The month for the BYMONTH part
+   * @param {Array.<Number>=} data.bysetpos             The positionals for the BYSETPOS part
+   */
+  fromData(data) {
+    for (let key in data) {
+      let uckey = key.toUpperCase();
+
+      if (uckey in partDesign) {
+        if (Array.isArray(data[key])) {
+          this.parts[uckey] = data[key];
+        } else {
+          this.parts[uckey] = [data[key]];
+        }
+      } else {
+        this[key] = data[key];
+      }
+    }
+
+    if (this.interval && typeof this.interval != "number") {
+      optionDesign.INTERVAL(this.interval, this);
+    }
+
+    if (this.wkst && typeof this.wkst != "number") {
+      this.wkst = Recur.icalDayToNumericDay(this.wkst);
+    }
+
+    if (this.until && !(this.until instanceof Time)) {
+      this.until = Time.fromString(this.until);
+    }
+  }
+
+  /**
+   * The jCal representation of this recurrence type.
+   * @return {Object}
+   */
+  toJSON() {
+    let res = Object.create(null);
+    res.freq = this.freq;
+
+    if (this.count) {
+      res.count = this.count;
+    }
+
+    if (this.interval > 1) {
+      res.interval = this.interval;
+    }
+
+    for (let [k, kparts] of Object.entries(this.parts)) {
+      if (Array.isArray(kparts) && kparts.length == 1) {
+        res[k.toLowerCase()] = kparts[0];
+      } else {
+        res[k.toLowerCase()] = clone(kparts);
+      }
+    }
+
+    if (this.until) {
+      res.until = this.until.toString();
+    }
+    if ('wkst' in this && this.wkst !== Time.DEFAULT_WEEK_START) {
+      res.wkst = Recur.numericDayToIcalDay(this.wkst);
+    }
+    return res;
+  }
+
+  /**
+   * The string representation of this recurrence rule.
+   * @return {String}
+   */
+  toString() {
+    // TODO retain order
+    let str = "FREQ=" + this.freq;
+    if (this.count) {
+      str += ";COUNT=" + this.count;
+    }
+    if (this.interval > 1) {
+      str += ";INTERVAL=" + this.interval;
+    }
+    for (let [k, v] of Object.entries(this.parts)) {
+      str += ";" + k + "=" + v;
+    }
+    if (this.until) {
+      str += ';UNTIL=' + this.until.toICALString();
+    }
+    if ('wkst' in this && this.wkst !== Time.DEFAULT_WEEK_START) {
+      str += ';WKST=' + Recur.numericDayToIcalDay(this.wkst);
+    }
+    return str;
+  }
+}
+
+function parseNumericValue(type, min, max, value) {
+  let result = value;
+
+  if (value[0] === '+') {
+    result = value.slice(1);
+  }
+
+  result = strictParseInt(result);
+
+  if (min !== undefined && value < min) {
+    throw new Error(
+      type + ': invalid value "' + value + '" must be > ' + min
+    );
+  }
+
+  if (max !== undefined && value > max) {
+    throw new Error(
+      type + ': invalid value "' + value + '" must be < ' + min
+    );
+  }
+
+  return result;
+}
+
+const optionDesign = {
+  FREQ: function(value, dict, fmtIcal) {
+    // yes this is actually equal or faster then regex.
+    // upside here is we can enumerate the valid values.
+    if (ALLOWED_FREQ.indexOf(value) !== -1) {
+      dict.freq = value;
+    } else {
+      throw new Error(
+        'invalid frequency "' + value + '" expected: "' +
+        ALLOWED_FREQ.join(', ') + '"'
+      );
+    }
+  },
+
+  COUNT: function(value, dict, fmtIcal) {
+    dict.count = strictParseInt(value);
+  },
+
+  INTERVAL: function(value, dict, fmtIcal) {
+    dict.interval = strictParseInt(value);
+    if (dict.interval < 1) {
+      // 0 or negative values are not allowed, some engines seem to generate
+      // it though. Assume 1 instead.
+      dict.interval = 1;
+    }
+  },
+
+  UNTIL: function(value, dict, fmtIcal) {
+    if (value.length > 10) {
+      dict.until = design$1.icalendar.value['date-time'].fromICAL(value);
+    } else {
+      dict.until = design$1.icalendar.value.date.fromICAL(value);
+    }
+    if (!fmtIcal) {
+      dict.until = Time.fromString(dict.until);
+    }
+  },
+
+  WKST: function(value, dict, fmtIcal) {
+    if (VALID_DAY_NAMES.test(value)) {
+      dict.wkst = Recur.icalDayToNumericDay(value);
+    } else {
+      throw new Error('invalid WKST value "' + value + '"');
+    }
+  }
+};
+
+const partDesign = {
+  BYSECOND: parseNumericValue.bind(undefined, 'BYSECOND', 0, 60),
+  BYMINUTE: parseNumericValue.bind(undefined, 'BYMINUTE', 0, 59),
+  BYHOUR: parseNumericValue.bind(undefined, 'BYHOUR', 0, 23),
+  BYDAY: function(value) {
+    if (VALID_BYDAY_PART.test(value)) {
+      return value;
+    } else {
+      throw new Error('invalid BYDAY value "' + value + '"');
+    }
+  },
+  BYMONTHDAY: parseNumericValue.bind(undefined, 'BYMONTHDAY', -31, 31),
+  BYYEARDAY: parseNumericValue.bind(undefined, 'BYYEARDAY', -366, 366),
+  BYWEEKNO: parseNumericValue.bind(undefined, 'BYWEEKNO', -53, 53),
+  BYMONTH: parseNumericValue.bind(undefined, 'BYMONTH', 1, 12),
+  BYSETPOS: parseNumericValue.bind(undefined, 'BYSETPOS', -366, 366)
+};
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ * Portions Copyright (C) Philipp Kewisch */
+
+/**
+ * This lets typescript resolve our custom types in the
+ * generated d.ts files (jsdoc typedefs are converted to typescript types).
+ * Ignore prevents the typedefs from being documented more than once.
+ * @ignore
+ * @typedef {import("./types.js").jCalComponent} jCalComponent
+ * Imports the 'occurrenceDetails' type from the "types.js" module
+ */
+
+/**
+ * This class represents the "period" value type, with various calculation and manipulation methods.
+ *
+ * @memberof ICAL
+ */
+class Period {
+  /**
+   * Creates a new {@link ICAL.Period} instance from the passed string.
+   *
+   * @param {String} str            The string to parse
+   * @param {Property} prop         The property this period will be on
+   * @return {Period}               The created period instance
+   */
+  static fromString(str, prop) {
+    let parts = str.split('/');
+
+    if (parts.length !== 2) {
+      throw new Error(
+        'Invalid string value: "' + str + '" must contain a "/" char.'
+      );
+    }
+
+    let options = {
+      start: Time.fromDateTimeString(parts[0], prop)
+    };
+
+    let end = parts[1];
+
+    if (Duration.isValueString(end)) {
+      options.duration = Duration.fromString(end);
+    } else {
+      options.end = Time.fromDateTimeString(end, prop);
+    }
+
+    return new Period(options);
+  }
+
+  /**
+   * Creates a new {@link ICAL.Period} instance from the given data object.
+   * The passed data object cannot contain both and end date and a duration.
+   *
+   * @param {Object} aData                  An object with members of the period
+   * @param {Time=} aData.start             The start of the period
+   * @param {Time=} aData.end               The end of the period
+   * @param {Duration=} aData.duration      The duration of the period
+   * @return {Period}                       The period instance
+   */
+  static fromData(aData) {
+    return new Period(aData);
+  }
+
+  /**
+   * Returns a new period instance from the given jCal data array. The first
+   * member is always the start date string, the second member is either a
+   * duration or end date string.
+   *
+   * @param {jCalComponent} aData           The jCal data array
+   * @param {Property} aProp                The property this jCal data is on
+   * @param {Boolean} aLenient              If true, data value can be both date and date-time
+   * @return {Period}                       The period instance
+   */
+  static fromJSON(aData, aProp, aLenient) {
+    function fromDateOrDateTimeString(aValue, dateProp) {
+      if (aLenient) {
+        return Time.fromString(aValue, dateProp);
+      } else {
+        return Time.fromDateTimeString(aValue, dateProp);
+      }
+    }
+
+    if (Duration.isValueString(aData[1])) {
+      return Period.fromData({
+        start: fromDateOrDateTimeString(aData[0], aProp),
+        duration: Duration.fromString(aData[1])
+      });
+    } else {
+      return Period.fromData({
+        start: fromDateOrDateTimeString(aData[0], aProp),
+        end: fromDateOrDateTimeString(aData[1], aProp)
+      });
+    }
+  }
+
+  /**
+   * Creates a new ICAL.Period instance. The passed data object cannot contain both and end date and
+   * a duration.
+   *
+   * @param {Object} aData                  An object with members of the period
+   * @param {Time=} aData.start             The start of the period
+   * @param {Time=} aData.end               The end of the period
+   * @param {Duration=} aData.duration      The duration of the period
+   */
+  constructor(aData) {
+    this.wrappedJSObject = this;
+
+    if (aData && 'start' in aData) {
+      if (aData.start && !(aData.start instanceof Time)) {
+        throw new TypeError('.start must be an instance of ICAL.Time');
+      }
+      this.start = aData.start;
+    }
+
+    if (aData && aData.end && aData.duration) {
+      throw new Error('cannot accept both end and duration');
+    }
+
+    if (aData && 'end' in aData) {
+      if (aData.end && !(aData.end instanceof Time)) {
+        throw new TypeError('.end must be an instance of ICAL.Time');
+      }
+      this.end = aData.end;
+    }
+
+    if (aData && 'duration' in aData) {
+      if (aData.duration && !(aData.duration instanceof Duration)) {
+        throw new TypeError('.duration must be an instance of ICAL.Duration');
+      }
+      this.duration = aData.duration;
+    }
+  }
+
+
+  /**
+   * The start of the period
+   * @type {Time}
+   */
+  start = null;
+
+  /**
+   * The end of the period
+   * @type {Time}
+   */
+  end = null;
+
+  /**
+   * The duration of the period
+   * @type {Duration}
+   */
+  duration = null;
+
+  /**
+   * The class identifier.
+   * @constant
+   * @type {String}
+   * @default "icalperiod"
+   */
+  icalclass = "icalperiod";
+
+  /**
+   * The type name, to be used in the jCal object.
+   * @constant
+   * @type {String}
+   * @default "period"
+   */
+  icaltype = "period";
+
+  /**
+   * Returns a clone of the duration object.
+   *
+   * @return {Period}      The cloned object
+   */
+  clone() {
+    return Period.fromData({
+      start: this.start ? this.start.clone() : null,
+      end: this.end ? this.end.clone() : null,
+      duration: this.duration ? this.duration.clone() : null
+    });
+  }
+
+  /**
+   * Calculates the duration of the period, either directly or by subtracting
+   * start from end date.
+   *
+   * @return {Duration}      The calculated duration
+   */
+  getDuration() {
+    if (this.duration) {
+      return this.duration;
+    } else {
+      return this.end.subtractDate(this.start);
+    }
+  }
+
+  /**
+   * Calculates the end date of the period, either directly or by adding
+   * duration to start date.
+   *
+   * @return {Time}          The calculated end date
+   */
+  getEnd() {
+    if (this.end) {
+      return this.end;
+    } else {
+      let end = this.start.clone();
+      end.addDuration(this.duration);
+      return end;
+    }
+  }
+
+  /**
+   * The string representation of this period.
+   * @return {String}
+   */
+  toString() {
+    return this.start + "/" + (this.end || this.duration);
+  }
+
+  /**
+   * The jCal representation of this period type.
+   * @return {Object}
+   */
+  toJSON() {
+    return [this.start.toString(), (this.end || this.duration).toString()];
+  }
+
+  /**
+   * The iCalendar string representation of this period.
+   * @return {String}
+   */
+  toICALString() {
+    return this.start.toICALString() + "/" +
+           (this.end || this.duration).toICALString();
+  }
+}
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ * Portions Copyright (C) Philipp Kewisch */
+
+/**
+ * This lets typescript resolve our custom types in the
+ * generated d.ts files (jsdoc typedefs are converted to typescript types).
+ * Ignore prevents the typedefs from being documented more than once.
+ * @ignore
+ * @typedef {import("./types.js").designSet} designSet
+ * Imports the 'designSet' type from the "types.js" module
+ */
+
+/** @module ICAL.design */
+
+const FROM_ICAL_NEWLINE = /\\\\|\\;|\\,|\\[Nn]/g;
+const TO_ICAL_NEWLINE = /\\|;|,|\n/g;
+const FROM_VCARD_NEWLINE = /\\\\|\\,|\\[Nn]/g;
+const TO_VCARD_NEWLINE = /\\|,|\n/g;
+
+function createTextType(fromNewline, toNewline) {
+  let result = {
+    matches: /.*/,
+
+    fromICAL: function(aValue, structuredEscape) {
+      return replaceNewline(aValue, fromNewline, structuredEscape);
+    },
+
+    toICAL: function(aValue, structuredEscape) {
+      let regEx = toNewline;
+      if (structuredEscape)
+         regEx = new RegExp(regEx.source + '|' + structuredEscape, regEx.flags);
+      return aValue.replace(regEx, function(str) {
+        switch (str) {
+        case "\\":
+          return "\\\\";
+        case ";":
+          return "\\;";
+        case ",":
+          return "\\,";
+        case "\n":
+          return "\\n";
+        /* c8 ignore next 2 */
+        default:
+          return str;
+        }
+      });
+    }
+  };
+  return result;
+}
+
+// default types used multiple times
+const DEFAULT_TYPE_TEXT = { defaultType: "text" };
+const DEFAULT_TYPE_TEXT_MULTI = { defaultType: "text", multiValue: "," };
+const DEFAULT_TYPE_TEXT_STRUCTURED = { defaultType: "text", structuredValue: ";" };
+const DEFAULT_TYPE_INTEGER = { defaultType: "integer" };
+const DEFAULT_TYPE_DATETIME_DATE = { defaultType: "date-time", allowedTypes: ["date-time", "date"] };
+const DEFAULT_TYPE_DATETIME = { defaultType: "date-time" };
+const DEFAULT_TYPE_URI = { defaultType: "uri" };
+const DEFAULT_TYPE_UTCOFFSET = { defaultType: "utc-offset" };
+const DEFAULT_TYPE_RECUR = { defaultType: "recur" };
+const DEFAULT_TYPE_DATE_ANDOR_TIME = { defaultType: "date-and-or-time", allowedTypes: ["date-time", "date", "text"] };
+
+function replaceNewlineReplace(string) {
+  switch (string) {
+    case "\\\\":
+      return "\\";
+    case "\\;":
+      return ";";
+    case "\\,":
+      return ",";
+    case "\\n":
+    case "\\N":
+      return "\n";
+    /* c8 ignore next 2 */
+    default:
+      return string;
+  }
+}
+
+function replaceNewline(value, newline, structuredEscape) {
+  // avoid regex when possible.
+  if (value.indexOf('\\') === -1) {
+    return value;
+  }
+  if (structuredEscape)
+     newline = new RegExp(newline.source + '|\\\\' + structuredEscape, newline.flags);
+  return value.replace(newline, replaceNewlineReplace);
+}
+
+let commonProperties = {
+  "categories": DEFAULT_TYPE_TEXT_MULTI,
+  "url": DEFAULT_TYPE_URI,
+  "version": DEFAULT_TYPE_TEXT,
+  "uid": DEFAULT_TYPE_TEXT
+};
+
+let commonValues = {
+  "boolean": {
+    values: ["TRUE", "FALSE"],
+
+    fromICAL: function(aValue) {
+      switch (aValue) {
+        case 'TRUE':
+          return true;
+        case 'FALSE':
+          return false;
+        default:
+          //TODO: parser warning
+          return false;
+      }
+    },
+
+    toICAL: function(aValue) {
+      if (aValue) {
+        return 'TRUE';
+      }
+      return 'FALSE';
+    }
+
+  },
+  float: {
+    matches: /^[+-]?\d+\.\d+$/,
+
+    fromICAL: function(aValue) {
+      let parsed = parseFloat(aValue);
+      if (isStrictlyNaN(parsed)) {
+        // TODO: parser warning
+        return 0.0;
+      }
+      return parsed;
+    },
+
+    toICAL: function(aValue) {
+      return String(aValue);
+    }
+  },
+  integer: {
+    fromICAL: function(aValue) {
+      let parsed = parseInt(aValue);
+      if (isStrictlyNaN(parsed)) {
+        return 0;
+      }
+      return parsed;
+    },
+
+    toICAL: function(aValue) {
+      return String(aValue);
+    }
+  },
+  "utc-offset": {
+    toICAL: function(aValue) {
+      if (aValue.length < 7) {
+        // no seconds
+        // -0500
+        return aValue.slice(0, 3) +
+               aValue.slice(4, 6);
+      } else {
+        // seconds
+        // -050000
+        return aValue.slice(0, 3) +
+               aValue.slice(4, 6) +
+               aValue.slice(7, 9);
+      }
+    },
+
+    fromICAL: function(aValue) {
+      if (aValue.length < 6) {
+        // no seconds
+        // -05:00
+        return aValue.slice(0, 3) + ':' +
+               aValue.slice(3, 5);
+      } else {
+        // seconds
+        // -05:00:00
+        return aValue.slice(0, 3) + ':' +
+               aValue.slice(3, 5) + ':' +
+               aValue.slice(5, 7);
+      }
+    },
+
+    decorate: function(aValue) {
+      return UtcOffset.fromString(aValue);
+    },
+
+    undecorate: function(aValue) {
+      return aValue.toString();
+    }
+  }
+};
+
+let icalParams = {
+  // Although the syntax is DQUOTE uri DQUOTE, I don't think we should
+  // enforce anything aside from it being a valid content line.
+  //
+  // At least some params require - if multi values are used - DQUOTEs
+  // for each of its values - e.g. delegated-from="uri1","uri2"
+  // To indicate this, I introduced the new k/v pair
+  // multiValueSeparateDQuote: true
+  //
+  // "ALTREP": { ... },
+
+  // CN just wants a param-value
+  // "CN": { ... }
+
+  "cutype": {
+    values: ["INDIVIDUAL", "GROUP", "RESOURCE", "ROOM", "UNKNOWN"],
+    allowXName: true,
+    allowIanaToken: true
+  },
+
+  "delegated-from": {
+    valueType: "cal-address",
+    multiValue: ",",
+    multiValueSeparateDQuote: true
+  },
+  "delegated-to": {
+    valueType: "cal-address",
+    multiValue: ",",
+    multiValueSeparateDQuote: true
+  },
+  // "DIR": { ... }, // See ALTREP
+  "encoding": {
+    values: ["8BIT", "BASE64"]
+  },
+  // "FMTTYPE": { ... }, // See ALTREP
+  "fbtype": {
+    values: ["FREE", "BUSY", "BUSY-UNAVAILABLE", "BUSY-TENTATIVE"],
+    allowXName: true,
+    allowIanaToken: true
+  },
+  // "LANGUAGE": { ... }, // See ALTREP
+  "member": {
+    valueType: "cal-address",
+    multiValue: ",",
+    multiValueSeparateDQuote: true
+  },
+  "partstat": {
+    // TODO These values are actually different per-component
+    values: ["NEEDS-ACTION", "ACCEPTED", "DECLINED", "TENTATIVE",
+             "DELEGATED", "COMPLETED", "IN-PROCESS"],
+    allowXName: true,
+    allowIanaToken: true
+  },
+  "range": {
+    values: ["THISANDFUTURE"]
+  },
+  "related": {
+    values: ["START", "END"]
+  },
+  "reltype": {
+    values: ["PARENT", "CHILD", "SIBLING"],
+    allowXName: true,
+    allowIanaToken: true
+  },
+  "role": {
+    values: ["REQ-PARTICIPANT", "CHAIR",
+             "OPT-PARTICIPANT", "NON-PARTICIPANT"],
+    allowXName: true,
+    allowIanaToken: true
+  },
+  "rsvp": {
+    values: ["TRUE", "FALSE"]
+  },
+  "sent-by": {
+    valueType: "cal-address"
+  },
+  "tzid": {
+    matches: /^\//
+  },
+  "value": {
+    // since the value here is a 'type' lowercase is used.
+    values: ["binary", "boolean", "cal-address", "date", "date-time",
+             "duration", "float", "integer", "period", "recur", "text",
+             "time", "uri", "utc-offset"],
+    allowXName: true,
+    allowIanaToken: true
+  }
+};
+
+// When adding a value here, be sure to add it to the parameter types!
+const icalValues = extend(commonValues, {
+  text: createTextType(FROM_ICAL_NEWLINE, TO_ICAL_NEWLINE),
+
+  uri: {
+    // TODO
+    /* ... */
+  },
+
+  "binary": {
+    decorate: function(aString) {
+      return Binary.fromString(aString);
+    },
+
+    undecorate: function(aBinary) {
+      return aBinary.toString();
+    }
+  },
+  "cal-address": {
+    // needs to be an uri
+  },
+  "date": {
+    decorate: function(aValue, aProp) {
+      if (design.strict) {
+        return Time.fromDateString(aValue, aProp);
+      } else {
+        return Time.fromString(aValue, aProp);
+      }
+    },
+
+    /**
+     * undecorates a time object.
+     */
+    undecorate: function(aValue) {
+      return aValue.toString();
+    },
+
+    fromICAL: function(aValue) {
+      // from: 20120901
+      // to: 2012-09-01
+      if (!design.strict && aValue.length >= 15) {
+        // This is probably a date-time, e.g. 20120901T130000Z
+        return icalValues["date-time"].fromICAL(aValue);
+      } else {
+        return aValue.slice(0, 4) + '-' +
+               aValue.slice(4, 6) + '-' +
+               aValue.slice(6, 8);
+      }
+    },
+
+    toICAL: function(aValue) {
+      // from: 2012-09-01
+      // to: 20120901
+      let len = aValue.length;
+
+      if (len == 10) {
+        return aValue.slice(0, 4) +
+               aValue.slice(5, 7) +
+               aValue.slice(8, 10);
+      } else if (len >= 19) {
+        return icalValues["date-time"].toICAL(aValue);
+      } else {
+        //TODO: serialize warning?
+        return aValue;
+      }
+
+    }
+  },
+  "date-time": {
+    fromICAL: function(aValue) {
+      // from: 20120901T130000
+      // to: 2012-09-01T13:00:00
+      if (!design.strict && aValue.length == 8) {
+        // This is probably a date, e.g. 20120901
+        return icalValues.date.fromICAL(aValue);
+      } else {
+        let result = aValue.slice(0, 4) + '-' +
+                     aValue.slice(4, 6) + '-' +
+                     aValue.slice(6, 8) + 'T' +
+                     aValue.slice(9, 11) + ':' +
+                     aValue.slice(11, 13) + ':' +
+                     aValue.slice(13, 15);
+
+        if (aValue[15] && aValue[15] === 'Z') {
+          result += 'Z';
+        }
+
+        return result;
+      }
+    },
+
+    toICAL: function(aValue) {
+      // from: 2012-09-01T13:00:00
+      // to: 20120901T130000
+      let len = aValue.length;
+
+      if (len == 10 && !design.strict) {
+        return icalValues.date.toICAL(aValue);
+      } else if (len >= 19) {
+        let result = aValue.slice(0, 4) +
+                     aValue.slice(5, 7) +
+                     // grab the (DDTHH) segment
+                     aValue.slice(8, 13) +
+                     // MM
+                     aValue.slice(14, 16) +
+                     // SS
+                     aValue.slice(17, 19);
+
+        if (aValue[19] && aValue[19] === 'Z') {
+          result += 'Z';
+        }
+        return result;
+      } else {
+        // TODO: error
+        return aValue;
+      }
+    },
+
+    decorate: function(aValue, aProp) {
+      if (design.strict) {
+        return Time.fromDateTimeString(aValue, aProp);
+      } else {
+        return Time.fromString(aValue, aProp);
+      }
+    },
+
+    undecorate: function(aValue) {
+      return aValue.toString();
+    }
+  },
+  duration: {
+    decorate: function(aValue) {
+      return Duration.fromString(aValue);
+    },
+    undecorate: function(aValue) {
+      return aValue.toString();
+    }
+  },
+  period: {
+    fromICAL: function(string) {
+      let parts = string.split('/');
+      parts[0] = icalValues['date-time'].fromICAL(parts[0]);
+
+      if (!Duration.isValueString(parts[1])) {
+        parts[1] = icalValues['date-time'].fromICAL(parts[1]);
+      }
+
+      return parts;
+    },
+
+    toICAL: function(parts) {
+      parts = parts.slice();
+      if (!design.strict && parts[0].length == 10) {
+        parts[0] = icalValues.date.toICAL(parts[0]);
+      } else {
+        parts[0] = icalValues['date-time'].toICAL(parts[0]);
+      }
+
+      if (!Duration.isValueString(parts[1])) {
+        if (!design.strict && parts[1].length == 10) {
+          parts[1] = icalValues.date.toICAL(parts[1]);
+        } else {
+          parts[1] = icalValues['date-time'].toICAL(parts[1]);
+        }
+      }
+
+      return parts.join("/");
+    },
+
+    decorate: function(aValue, aProp) {
+      return Period.fromJSON(aValue, aProp, !design.strict);
+    },
+
+    undecorate: function(aValue) {
+      return aValue.toJSON();
+    }
+  },
+  recur: {
+    fromICAL: function(string) {
+      return Recur._stringToData(string, true);
+    },
+
+    toICAL: function(data) {
+      let str = "";
+      for (let [k, val] of Object.entries(data)) {
+        if (k == "until") {
+          if (val.length > 10) {
+            val = icalValues['date-time'].toICAL(val);
+          } else {
+            val = icalValues.date.toICAL(val);
+          }
+        } else if (k == "wkst") {
+          if (typeof val === 'number') {
+            val = Recur.numericDayToIcalDay(val);
+          }
+        } else if (Array.isArray(val)) {
+          val = val.join(",");
+        }
+        str += k.toUpperCase() + "=" + val + ";";
+      }
+      return str.slice(0, Math.max(0, str.length - 1));
+    },
+
+    decorate: function decorate(aValue) {
+      return Recur.fromData(aValue);
+    },
+
+    undecorate: function(aRecur) {
+      return aRecur.toJSON();
+    }
+  },
+
+  time: {
+    fromICAL: function(aValue) {
+      // from: MMHHSS(Z)?
+      // to: HH:MM:SS(Z)?
+      if (aValue.length < 6) {
+        // TODO: parser exception?
+        return aValue;
+      }
+
+      // HH::MM::SSZ?
+      let result = aValue.slice(0, 2) + ':' +
+                   aValue.slice(2, 4) + ':' +
+                   aValue.slice(4, 6);
+
+      if (aValue[6] === 'Z') {
+        result += 'Z';
+      }
+
+      return result;
+    },
+
+    toICAL: function(aValue) {
+      // from: HH:MM:SS(Z)?
+      // to: MMHHSS(Z)?
+      if (aValue.length < 8) {
+        //TODO: error
+        return aValue;
+      }
+
+      let result = aValue.slice(0, 2) +
+                   aValue.slice(3, 5) +
+                   aValue.slice(6, 8);
+
+      if (aValue[8] === 'Z') {
+        result += 'Z';
+      }
+
+      return result;
+    }
+  }
+});
+
+let icalProperties = extend(commonProperties, {
+
+  "action": DEFAULT_TYPE_TEXT,
+  "attach": { defaultType: "uri" },
+  "attendee": { defaultType: "cal-address" },
+  "calscale": DEFAULT_TYPE_TEXT,
+  "class": DEFAULT_TYPE_TEXT,
+  "comment": DEFAULT_TYPE_TEXT,
+  "completed": DEFAULT_TYPE_DATETIME,
+  "contact": DEFAULT_TYPE_TEXT,
+  "created": DEFAULT_TYPE_DATETIME,
+  "description": DEFAULT_TYPE_TEXT,
+  "dtend": DEFAULT_TYPE_DATETIME_DATE,
+  "dtstamp": DEFAULT_TYPE_DATETIME,
+  "dtstart": DEFAULT_TYPE_DATETIME_DATE,
+  "due": DEFAULT_TYPE_DATETIME_DATE,
+  "duration": { defaultType: "duration" },
+  "exdate": {
+    defaultType: "date-time",
+    allowedTypes: ["date-time", "date"],
+    multiValue: ','
+  },
+  "exrule": DEFAULT_TYPE_RECUR,
+  "freebusy": { defaultType: "period", multiValue: "," },
+  "geo": { defaultType: "float", structuredValue: ";" },
+  "last-modified": DEFAULT_TYPE_DATETIME,
+  "location": DEFAULT_TYPE_TEXT,
+  "method": DEFAULT_TYPE_TEXT,
+  "organizer": { defaultType: "cal-address" },
+  "percent-complete": DEFAULT_TYPE_INTEGER,
+  "priority": DEFAULT_TYPE_INTEGER,
+  "prodid": DEFAULT_TYPE_TEXT,
+  "related-to": DEFAULT_TYPE_TEXT,
+  "repeat": DEFAULT_TYPE_INTEGER,
+  "rdate": {
+    defaultType: "date-time",
+    allowedTypes: ["date-time", "date", "period"],
+    multiValue: ',',
+    detectType: function(string) {
+      if (string.indexOf('/') !== -1) {
+        return 'period';
+      }
+      return (string.indexOf('T') === -1) ? 'date' : 'date-time';
+    }
+  },
+  "recurrence-id": DEFAULT_TYPE_DATETIME_DATE,
+  "resources": DEFAULT_TYPE_TEXT_MULTI,
+  "request-status": DEFAULT_TYPE_TEXT_STRUCTURED,
+  "rrule": DEFAULT_TYPE_RECUR,
+  "sequence": DEFAULT_TYPE_INTEGER,
+  "status": DEFAULT_TYPE_TEXT,
+  "summary": DEFAULT_TYPE_TEXT,
+  "transp": DEFAULT_TYPE_TEXT,
+  "trigger": { defaultType: "duration", allowedTypes: ["duration", "date-time"] },
+  "tzoffsetfrom": DEFAULT_TYPE_UTCOFFSET,
+  "tzoffsetto": DEFAULT_TYPE_UTCOFFSET,
+  "tzurl": DEFAULT_TYPE_URI,
+  "tzid": DEFAULT_TYPE_TEXT,
+  "tzname": DEFAULT_TYPE_TEXT
+});
+
+// When adding a value here, be sure to add it to the parameter types!
+const vcardValues = extend(commonValues, {
+  text: createTextType(FROM_VCARD_NEWLINE, TO_VCARD_NEWLINE),
+  uri: createTextType(FROM_VCARD_NEWLINE, TO_VCARD_NEWLINE),
+
+  date: {
+    decorate: function(aValue) {
+      return VCardTime.fromDateAndOrTimeString(aValue, "date");
+    },
+    undecorate: function(aValue) {
+      return aValue.toString();
+    },
+    fromICAL: function(aValue) {
+      if (aValue.length == 8) {
+        return icalValues.date.fromICAL(aValue);
+      } else if (aValue[0] == '-' && aValue.length == 6) {
+        return aValue.slice(0, 4) + '-' + aValue.slice(4);
+      } else {
+        return aValue;
+      }
+    },
+    toICAL: function(aValue) {
+      if (aValue.length == 10) {
+        return icalValues.date.toICAL(aValue);
+      } else if (aValue[0] == '-' && aValue.length == 7) {
+        return aValue.slice(0, 4) + aValue.slice(5);
+      } else {
+        return aValue;
+      }
+    }
+  },
+
+  time: {
+    decorate: function(aValue) {
+      return VCardTime.fromDateAndOrTimeString("T" + aValue, "time");
+    },
+    undecorate: function(aValue) {
+      return aValue.toString();
+    },
+    fromICAL: function(aValue) {
+      let splitzone = vcardValues.time._splitZone(aValue, true);
+      let zone = splitzone[0], value = splitzone[1];
+
+      //console.log("SPLIT: ",splitzone);
+
+      if (value.length == 6) {
+        value = value.slice(0, 2) + ':' +
+                value.slice(2, 4) + ':' +
+                value.slice(4, 6);
+      } else if (value.length == 4 && value[0] != '-') {
+        value = value.slice(0, 2) + ':' + value.slice(2, 4);
+      } else if (value.length == 5) {
+        value = value.slice(0, 3) + ':' + value.slice(3, 5);
+      }
+
+      if (zone.length == 5 && (zone[0] == '-' || zone[0] == '+')) {
+        zone = zone.slice(0, 3) + ':' + zone.slice(3);
+      }
+
+      return value + zone;
+    },
+
+    toICAL: function(aValue) {
+      let splitzone = vcardValues.time._splitZone(aValue);
+      let zone = splitzone[0], value = splitzone[1];
+
+      if (value.length == 8) {
+        value = value.slice(0, 2) +
+                value.slice(3, 5) +
+                value.slice(6, 8);
+      } else if (value.length == 5 && value[0] != '-') {
+        value = value.slice(0, 2) + value.slice(3, 5);
+      } else if (value.length == 6) {
+        value = value.slice(0, 3) + value.slice(4, 6);
+      }
+
+      if (zone.length == 6 && (zone[0] == '-' || zone[0] == '+')) {
+        zone = zone.slice(0, 3) + zone.slice(4);
+      }
+
+      return value + zone;
+    },
+
+    _splitZone: function(aValue, isFromIcal) {
+      let lastChar = aValue.length - 1;
+      let signChar = aValue.length - (isFromIcal ? 5 : 6);
+      let sign = aValue[signChar];
+      let zone, value;
+
+      if (aValue[lastChar] == 'Z') {
+        zone = aValue[lastChar];
+        value = aValue.slice(0, Math.max(0, lastChar));
+      } else if (aValue.length > 6 && (sign == '-' || sign == '+')) {
+        zone = aValue.slice(signChar);
+        value = aValue.slice(0, Math.max(0, signChar));
+      } else {
+        zone = "";
+        value = aValue;
+      }
+
+      return [zone, value];
+    }
+  },
+
+  "date-time": {
+    decorate: function(aValue) {
+      return VCardTime.fromDateAndOrTimeString(aValue, "date-time");
+    },
+
+    undecorate: function(aValue) {
+      return aValue.toString();
+    },
+
+    fromICAL: function(aValue) {
+      return vcardValues['date-and-or-time'].fromICAL(aValue);
+    },
+
+    toICAL: function(aValue) {
+      return vcardValues['date-and-or-time'].toICAL(aValue);
+    }
+  },
+
+  "date-and-or-time": {
+    decorate: function(aValue) {
+      return VCardTime.fromDateAndOrTimeString(aValue, "date-and-or-time");
+    },
+
+    undecorate: function(aValue) {
+      return aValue.toString();
+    },
+
+    fromICAL: function(aValue) {
+      let parts = aValue.split('T');
+      return (parts[0] ? vcardValues.date.fromICAL(parts[0]) : '') +
+             (parts[1] ? 'T' + vcardValues.time.fromICAL(parts[1]) : '');
+    },
+
+    toICAL: function(aValue) {
+      let parts = aValue.split('T');
+      return vcardValues.date.toICAL(parts[0]) +
+             (parts[1] ? 'T' + vcardValues.time.toICAL(parts[1]) : '');
+
+    }
+  },
+  timestamp: icalValues['date-time'],
+  "language-tag": {
+    matches: /^[a-zA-Z0-9-]+$/ // Could go with a more strict regex here
+  },
+  "phone-number": {
+    fromICAL: function(aValue) {
+      return Array.from(aValue).filter(function(c) {
+          return c === '\\' ? undefined : c;
+        }).join('');
+    },
+    toICAL: function(aValue) {
+      return Array.from(aValue).map(function(c) {
+        return c === ',' || c === ";" ? '\\' + c : c;
+      }).join('');
+    }
+  }
+});
+
+let vcardParams = {
+  "type": {
+    valueType: "text",
+    multiValue: ","
+  },
+  "value": {
+    // since the value here is a 'type' lowercase is used.
+    values: ["text", "uri", "date", "time", "date-time", "date-and-or-time",
+             "timestamp", "boolean", "integer", "float", "utc-offset",
+             "language-tag"],
+    allowXName: true,
+    allowIanaToken: true
+  }
+};
+
+let vcardProperties = extend(commonProperties, {
+  "adr": { defaultType: "text", structuredValue: ";", multiValue: "," },
+  "anniversary": DEFAULT_TYPE_DATE_ANDOR_TIME,
+  "bday": DEFAULT_TYPE_DATE_ANDOR_TIME,
+  "caladruri": DEFAULT_TYPE_URI,
+  "caluri": DEFAULT_TYPE_URI,
+  "clientpidmap": DEFAULT_TYPE_TEXT_STRUCTURED,
+  "email": DEFAULT_TYPE_TEXT,
+  "fburl": DEFAULT_TYPE_URI,
+  "fn": DEFAULT_TYPE_TEXT,
+  "gender": DEFAULT_TYPE_TEXT_STRUCTURED,
+  "geo": DEFAULT_TYPE_URI,
+  "impp": DEFAULT_TYPE_URI,
+  "key": DEFAULT_TYPE_URI,
+  "kind": DEFAULT_TYPE_TEXT,
+  "lang": { defaultType: "language-tag" },
+  "logo": DEFAULT_TYPE_URI,
+  "member": DEFAULT_TYPE_URI,
+  "n": { defaultType: "text", structuredValue: ";", multiValue: "," },
+  "nickname": DEFAULT_TYPE_TEXT_MULTI,
+  "note": DEFAULT_TYPE_TEXT,
+  "org": { defaultType: "text", structuredValue: ";" },
+  "photo": DEFAULT_TYPE_URI,
+  "related": DEFAULT_TYPE_URI,
+  "rev": { defaultType: "timestamp" },
+  "role": DEFAULT_TYPE_TEXT,
+  "sound": DEFAULT_TYPE_URI,
+  "source": DEFAULT_TYPE_URI,
+  "tel": { defaultType: "uri", allowedTypes: ["uri", "text"] },
+  "title": DEFAULT_TYPE_TEXT,
+  "tz": { defaultType: "text", allowedTypes: ["text", "utc-offset", "uri"] },
+  "xml": DEFAULT_TYPE_TEXT
+});
+
+let vcard3Values = extend(commonValues, {
+  binary: icalValues.binary,
+  date: vcardValues.date,
+  "date-time": vcardValues["date-time"],
+  "phone-number": vcardValues["phone-number"],
+  uri: icalValues.uri,
+  text: icalValues.text,
+  time: icalValues.time,
+  vcard: icalValues.text,
+  "utc-offset": {
+    toICAL: function(aValue) {
+      return aValue.slice(0, 7);
+    },
+
+    fromICAL: function(aValue) {
+      return aValue.slice(0, 7);
+    },
+
+    decorate: function(aValue) {
+      return UtcOffset.fromString(aValue);
+    },
+
+    undecorate: function(aValue) {
+      return aValue.toString();
+    }
+  }
+});
+
+let vcard3Params = {
+  "type": {
+    valueType: "text",
+    multiValue: ","
+  },
+  "value": {
+    // since the value here is a 'type' lowercase is used.
+    values: ["text", "uri", "date", "date-time", "phone-number", "time",
+             "boolean", "integer", "float", "utc-offset", "vcard", "binary"],
+    allowXName: true,
+    allowIanaToken: true
+  }
+};
+
+let vcard3Properties = extend(commonProperties, {
+  fn: DEFAULT_TYPE_TEXT,
+  n: { defaultType: "text", structuredValue: ";", multiValue: "," },
+  nickname: DEFAULT_TYPE_TEXT_MULTI,
+  photo: { defaultType: "binary", allowedTypes: ["binary", "uri"] },
+  bday: {
+    defaultType: "date-time",
+    allowedTypes: ["date-time", "date"],
+    detectType: function(string) {
+      return (string.indexOf('T') === -1) ? 'date' : 'date-time';
+    }
+  },
+
+  adr: { defaultType: "text", structuredValue: ";", multiValue: "," },
+  label: DEFAULT_TYPE_TEXT,
+
+  tel: { defaultType: "phone-number" },
+  email: DEFAULT_TYPE_TEXT,
+  mailer: DEFAULT_TYPE_TEXT,
+
+  tz: { defaultType: "utc-offset", allowedTypes: ["utc-offset", "text"] },
+  geo: { defaultType: "float", structuredValue: ";" },
+
+  title: DEFAULT_TYPE_TEXT,
+  role: DEFAULT_TYPE_TEXT,
+  logo: { defaultType: "binary", allowedTypes: ["binary", "uri"] },
+  agent: { defaultType: "vcard", allowedTypes: ["vcard", "text", "uri"] },
+  org: DEFAULT_TYPE_TEXT_STRUCTURED,
+
+  note: DEFAULT_TYPE_TEXT_MULTI,
+  prodid: DEFAULT_TYPE_TEXT,
+  rev: {
+    defaultType: "date-time",
+    allowedTypes: ["date-time", "date"],
+    detectType: function(string) {
+      return (string.indexOf('T') === -1) ? 'date' : 'date-time';
+    }
+  },
+  "sort-string": DEFAULT_TYPE_TEXT,
+  sound: { defaultType: "binary", allowedTypes: ["binary", "uri"] },
+
+  class: DEFAULT_TYPE_TEXT,
+  key: { defaultType: "binary", allowedTypes: ["binary", "text"] }
+});
+
+/**
+ * iCalendar design set
+ * @type {designSet}
+ */
+let icalSet = {
+  value: icalValues,
+  param: icalParams,
+  property: icalProperties,
+  propertyGroups: false
+};
+
+/**
+ * vCard 4.0 design set
+ * @type {designSet}
+ */
+let vcardSet = {
+  value: vcardValues,
+  param: vcardParams,
+  property: vcardProperties,
+  propertyGroups: true
+};
+
+/**
+ * vCard 3.0 design set
+ * @type {designSet}
+ */
+let vcard3Set = {
+  value: vcard3Values,
+  param: vcard3Params,
+  property: vcard3Properties,
+  propertyGroups: true
+};
+
+/**
+ * The design data, used by the parser to determine types for properties and
+ * other metadata needed to produce correct jCard/jCal data.
+ *
+ * @alias ICAL.design
+ * @exports module:ICAL.design
+ */
+const design = {
+  /**
+   * Can be set to false to make the parser more lenient.
+   */
+  strict: true,
+
+  /**
+   * The default set for new properties and components if none is specified.
+   * @type {designSet}
+   */
+  defaultSet: icalSet,
+
+  /**
+   * The default type for unknown properties
+   * @type {String}
+   */
+  defaultType: 'unknown',
+
+  /**
+   * Holds the design set for known top-level components
+   *
+   * @type {Object}
+   * @property {designSet} vcard       vCard VCARD
+   * @property {designSet} vevent      iCalendar VEVENT
+   * @property {designSet} vtodo       iCalendar VTODO
+   * @property {designSet} vjournal    iCalendar VJOURNAL
+   * @property {designSet} valarm      iCalendar VALARM
+   * @property {designSet} vtimezone   iCalendar VTIMEZONE
+   * @property {designSet} daylight    iCalendar DAYLIGHT
+   * @property {designSet} standard    iCalendar STANDARD
+   *
+   * @example
+   * let propertyName = 'fn';
+   * let componentDesign = ICAL.design.components.vcard;
+   * let propertyDetails = componentDesign.property[propertyName];
+   * if (propertyDetails.defaultType == 'text') {
+   *   // Yep, sure is...
+   * }
+   */
+  components: {
+    vcard: vcardSet,
+    vcard3: vcard3Set,
+    vevent: icalSet,
+    vtodo: icalSet,
+    vjournal: icalSet,
+    valarm: icalSet,
+    vtimezone: icalSet,
+    daylight: icalSet,
+    standard: icalSet
+  },
+
+
+  /**
+   * The design set for iCalendar (rfc5545/rfc7265) components.
+   * @type {designSet}
+   */
+  icalendar: icalSet,
+
+  /**
+   * The design set for vCard (rfc6350/rfc7095) components.
+   * @type {designSet}
+   */
+  vcard: vcardSet,
+
+  /**
+   * The design set for vCard (rfc2425/rfc2426/rfc7095) components.
+   * @type {designSet}
+   */
+  vcard3: vcard3Set,
+
+  /**
+   * Gets the design set for the given component name.
+   *
+   * @param {String} componentName        The name of the component
+   * @return {designSet}      The design set for the component
+   */
+  getDesignSet: function(componentName) {
+    let isInDesign = componentName && componentName in design.components;
+    return isInDesign ? design.components[componentName] : design.defaultSet;
+  }
+};
+var design$1 = design;
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ * Portions Copyright (C) Philipp Kewisch */
+
+/**
+ * This lets typescript resolve our custom types in the
+ * generated d.ts files (jsdoc typedefs are converted to typescript types).
+ * Ignore prevents the typedefs from being documented more than once.
+ *
+ * @ignore
+ * @typedef {import("./types.js").designSet} designSet
+ * Imports the 'designSet' type from the "types.js" module
+ */
+
+const LINE_ENDING = '\r\n';
+const DEFAULT_VALUE_TYPE = 'unknown';
+const RFC6868_REPLACE_MAP = { '"': "^'", "\n": "^n", "^": "^^" };
+
+/**
+ * Convert a full jCal/jCard array into a iCalendar/vCard string.
+ *
+ * @function ICAL.stringify
+ * @variation function
+ * @param {Array} jCal    The jCal/jCard document
+ * @return {String}       The stringified iCalendar/vCard document
+ */
+function stringify(jCal) {
+  if (typeof jCal[0] == "string") {
+    // This is a single component
+    jCal = [jCal];
+  }
+
+  let i = 0;
+  let len = jCal.length;
+  let result = '';
+
+  for (; i < len; i++) {
+    result += stringify.component(jCal[i]) + LINE_ENDING;
+  }
+
+  return result;
+}
+
+/**
+ * Converts an jCal component array into a ICAL string.
+ * Recursive will resolve sub-components.
+ *
+ * Exact component/property order is not saved all
+ * properties will come before subcomponents.
+ *
+ * @function ICAL.stringify.component
+ * @param {Array} component
+ *        jCal/jCard fragment of a component
+ * @param {designSet} designSet
+ *        The design data to use for this component
+ * @return {String}       The iCalendar/vCard string
+ */
+stringify.component = function(component, designSet) {
+  let name = component[0].toUpperCase();
+  let result = 'BEGIN:' + name + LINE_ENDING;
+
+  let props = component[1];
+  let propIdx = 0;
+  let propLen = props.length;
+
+  let designSetName = component[0];
+  // rfc6350 requires that in vCard 4.0 the first component is the VERSION
+  // component with as value 4.0, note that 3.0 does not have this requirement.
+  if (designSetName === 'vcard' && component[1].length > 0 &&
+          !(component[1][0][0] === "version" && component[1][0][3] === "4.0")) {
+    designSetName = "vcard3";
+  }
+  designSet = designSet || design$1.getDesignSet(designSetName);
+
+  for (; propIdx < propLen; propIdx++) {
+    result += stringify.property(props[propIdx], designSet) + LINE_ENDING;
+  }
+
+  // Ignore subcomponents if none exist, e.g. in vCard.
+  let comps = component[2] || [];
+  let compIdx = 0;
+  let compLen = comps.length;
+
+  for (; compIdx < compLen; compIdx++) {
+    result += stringify.component(comps[compIdx], designSet) + LINE_ENDING;
+  }
+
+  result += 'END:' + name;
+  return result;
+};
+
+/**
+ * Converts a single jCal/jCard property to a iCalendar/vCard string.
+ *
+ * @function ICAL.stringify.property
+ * @param {Array} property
+ *        jCal/jCard property array
+ * @param {designSet} designSet
+ *        The design data to use for this property
+ * @param {Boolean} noFold
+ *        If true, the line is not folded
+ * @return {String}       The iCalendar/vCard string
+ */
+stringify.property = function(property, designSet, noFold) {
+  let name = property[0].toUpperCase();
+  let jsName = property[0];
+  let params = property[1];
+
+  if (!designSet) {
+    designSet = design$1.defaultSet;
+  }
+
+  let groupName = params.group;
+  let line;
+  if (designSet.propertyGroups && groupName) {
+    line = groupName.toUpperCase() + "." + name;
+  } else {
+    line = name;
+  }
+
+  for (let [paramName, value] of Object.entries(params)) {
+    if (designSet.propertyGroups && paramName == 'group') {
+      continue;
+    }
+
+    let paramDesign = designSet.param[paramName];
+    let multiValue = paramDesign && paramDesign.multiValue;
+    if (multiValue && Array.isArray(value)) {
+      value = value.map(function(val) {
+        val = stringify._rfc6868Unescape(val);
+        val = stringify.paramPropertyValue(val, paramDesign.multiValueSeparateDQuote);
+        return val;
+      });
+      value = stringify.multiValue(value, multiValue, "unknown", null, designSet);
+    } else {
+      value = stringify._rfc6868Unescape(value);
+      value = stringify.paramPropertyValue(value);
+    }
+
+    line += ';' + paramName.toUpperCase() + '=' + value;
+  }
+
+  if (property.length === 3) {
+    // If there are no values, we must assume a blank value
+    return line + ':';
+  }
+
+  let valueType = property[2];
+
+  let propDetails;
+  let multiValue = false;
+  let structuredValue = false;
+  let isDefault = false;
+
+  if (jsName in designSet.property) {
+    propDetails = designSet.property[jsName];
+
+    if ('multiValue' in propDetails) {
+      multiValue = propDetails.multiValue;
+    }
+
+    if (('structuredValue' in propDetails) && Array.isArray(property[3])) {
+      structuredValue = propDetails.structuredValue;
+    }
+
+    if ('defaultType' in propDetails) {
+      if (valueType === propDetails.defaultType) {
+        isDefault = true;
+      }
+    } else {
+      if (valueType === DEFAULT_VALUE_TYPE) {
+        isDefault = true;
+      }
+    }
+  } else {
+    if (valueType === DEFAULT_VALUE_TYPE) {
+      isDefault = true;
+    }
+  }
+
+  // push the VALUE property if type is not the default
+  // for the current property.
+  if (!isDefault) {
+    // value will never contain ;/:/, so we don't escape it here.
+    line += ';VALUE=' + valueType.toUpperCase();
+  }
+
+  line += ':';
+
+  if (multiValue && structuredValue) {
+    line += stringify.multiValue(
+      property[3], structuredValue, valueType, multiValue, designSet, structuredValue
+    );
+  } else if (multiValue) {
+    line += stringify.multiValue(
+      property.slice(3), multiValue, valueType, null, designSet, false
+    );
+  } else if (structuredValue) {
+    line += stringify.multiValue(
+      property[3], structuredValue, valueType, null, designSet, structuredValue
+    );
+  } else {
+    line += stringify.value(property[3], valueType, designSet, false);
+  }
+
+  return noFold ? line : foldline(line);
+};
+
+/**
+ * Handles escaping of property values that may contain:
+ *
+ *    COLON (:), SEMICOLON (;), or COMMA (,)
+ *
+ * If any of the above are present the result is wrapped
+ * in double quotes.
+ *
+ * @function ICAL.stringify.paramPropertyValue
+ * @param {String} value      Raw property value
+ * @param {boolean} force     If value should be escaped even when unnecessary
+ * @return {String}           Given or escaped value when needed
+ */
+stringify.paramPropertyValue = function(value, force) {
+  if (!force &&
+      (value.indexOf(',') === -1) &&
+      (value.indexOf(':') === -1) &&
+      (value.indexOf(';') === -1)) {
+
+    return value;
+  }
+
+  return '"' + value + '"';
+};
+
+/**
+ * Converts an array of ical values into a single
+ * string based on a type and a delimiter value (like ",").
+ *
+ * @function ICAL.stringify.multiValue
+ * @param {Array} values      List of values to convert
+ * @param {String} delim      Used to join the values (",", ";", ":")
+ * @param {String} type       Lowecase ical value type
+ *        (like boolean, date-time, etc..)
+ * @param {?String} innerMulti If set, each value will again be processed
+ *        Used for structured values
+ * @param {designSet} designSet
+ *        The design data to use for this property
+ *
+ * @return {String}           iCalendar/vCard string for value
+ */
+stringify.multiValue = function(values, delim, type, innerMulti, designSet, structuredValue) {
+  let result = '';
+  let len = values.length;
+  let i = 0;
+
+  for (; i < len; i++) {
+    if (innerMulti && Array.isArray(values[i])) {
+      result += stringify.multiValue(values[i], innerMulti, type, null, designSet, structuredValue);
+    } else {
+      result += stringify.value(values[i], type, designSet, structuredValue);
+    }
+
+    if (i !== (len - 1)) {
+      result += delim;
+    }
+  }
+
+  return result;
+};
+
+/**
+ * Processes a single ical value runs the associated "toICAL" method from the
+ * design value type if available to convert the value.
+ *
+ * @function ICAL.stringify.value
+ * @param {String|Number} value       A formatted value
+ * @param {String} type               Lowercase iCalendar/vCard value type
+ *  (like boolean, date-time, etc..)
+ * @return {String}                   iCalendar/vCard value for single value
+ */
+stringify.value = function(value, type, designSet, structuredValue) {
+  if (type in designSet.value && 'toICAL' in designSet.value[type]) {
+    return designSet.value[type].toICAL(value, structuredValue);
+  }
+  return value;
+};
+
+/**
+ * Internal helper for rfc6868. Exposing this on ICAL.stringify so that
+ * hackers can disable the rfc6868 parsing if the really need to.
+ *
+ * @param {String} val        The value to unescape
+ * @return {String}           The escaped value
+ */
+stringify._rfc6868Unescape = function(val) {
+  return val.replace(/[\n^"]/g, function(x) {
+    return RFC6868_REPLACE_MAP[x];
+  });
+};
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ * Portions Copyright (C) Philipp Kewisch */
+
+const NAME_INDEX$1 = 0;
+const PROP_INDEX = 1;
+const TYPE_INDEX = 2;
+const VALUE_INDEX = 3;
+
+/**
+ * This lets typescript resolve our custom types in the
+ * generated d.ts files (jsdoc typedefs are converted to typescript types).
+ * Ignore prevents the typedefs from being documented more than once.
+ * @ignore
+ * @typedef {import("./types.js").designSet} designSet
+ * Imports the 'designSet' type from the "types.js" module
+ * @typedef {import("./types.js").Geo} Geo
+ * Imports the 'Geo' type from the "types.js" module
+ */
+
+/**
+ * Provides a layer on top of the raw jCal object for manipulating a single property, with its
+ * parameters and value.
+ *
+ * @memberof ICAL
+ */
+class Property {
+  /**
+   * Create an {@link ICAL.Property} by parsing the passed iCalendar string.
+   *
+   * @param {String} str            The iCalendar string to parse
+   * @param {designSet=} designSet  The design data to use for this property
+   * @return {Property}             The created iCalendar property
+   */
+  static fromString(str, designSet) {
+    return new Property(parse.property(str, designSet));
+  }
+
+  /**
+   * Creates a new ICAL.Property instance.
+   *
+   * It is important to note that mutations done in the wrapper directly mutate the jCal object used
+   * to initialize.
+   *
+   * Can also be used to create new properties by passing the name of the property (as a String).
+   *
+   * @param {Array|String} jCal         Raw jCal representation OR the new name of the property
+   * @param {Component=} parent         Parent component
+   */
+  constructor(jCal, parent) {
+    this._parent = parent || null;
+
+    if (typeof(jCal) === 'string') {
+      // We are creating the property by name and need to detect the type
+      this.jCal = [jCal, {}, design$1.defaultType];
+      this.jCal[TYPE_INDEX] = this.getDefaultType();
+    } else {
+      this.jCal = jCal;
+    }
+    this._updateType();
+  }
+
+  /**
+   * The value type for this property
+   * @type {String}
+   */
+  get type() {
+    return this.jCal[TYPE_INDEX];
+  }
+
+  /**
+   * The name of this property, in lowercase.
+   * @type {String}
+   */
+  get name() {
+    return this.jCal[NAME_INDEX$1];
+  }
+
+  /**
+   * The parent component for this property.
+   * @type {Component}
+   */
+  get parent() {
+    return this._parent;
+  }
+
+  set parent(p) {
+    // Before setting the parent, check if the design set has changed. If it
+    // has, we later need to update the type if it was unknown before.
+    let designSetChanged = !this._parent || (p && p._designSet != this._parent._designSet);
+
+    this._parent = p;
+
+    if (this.type == design$1.defaultType && designSetChanged) {
+      this.jCal[TYPE_INDEX] = this.getDefaultType();
+      this._updateType();
+    }
+  }
+
+  /**
+   * The design set for this property, e.g. icalendar vs vcard
+   *
+   * @type {designSet}
+   * @private
+   */
+  get _designSet() {
+    return this.parent ? this.parent._designSet : design$1.defaultSet;
+  }
+
+  /**
+   * Updates the type metadata from the current jCal type and design set.
+   *
+   * @private
+   */
+  _updateType() {
+    let designSet = this._designSet;
+
+    if (this.type in designSet.value) {
+      if ('decorate' in designSet.value[this.type]) {
+        this.isDecorated = true;
+      } else {
+        this.isDecorated = false;
+      }
+
+      if (this.name in designSet.property) {
+        this.isMultiValue = ('multiValue' in designSet.property[this.name]);
+        this.isStructuredValue = ('structuredValue' in designSet.property[this.name]);
+      }
+    }
+  }
+
+  /**
+   * Hydrate a single value. The act of hydrating means turning the raw jCal
+   * value into a potentially wrapped object, for example {@link ICAL.Time}.
+   *
+   * @private
+   * @param {Number} index        The index of the value to hydrate
+   * @return {?Object}             The decorated value.
+   */
+  _hydrateValue(index) {
+    if (this._values && this._values[index]) {
+      return this._values[index];
+    }
+
+    // for the case where there is no value.
+    if (this.jCal.length <= (VALUE_INDEX + index)) {
+      return null;
+    }
+
+    if (this.isDecorated) {
+      if (!this._values) {
+        this._values = [];
+      }
+      return (this._values[index] = this._decorate(
+        this.jCal[VALUE_INDEX + index]
+      ));
+    } else {
+      return this.jCal[VALUE_INDEX + index];
+    }
+  }
+
+  /**
+   * Decorate a single value, returning its wrapped object. This is used by
+   * the hydrate function to actually wrap the value.
+   *
+   * @private
+   * @param {?} value         The value to decorate
+   * @return {Object}         The decorated value
+   */
+  _decorate(value) {
+    return this._designSet.value[this.type].decorate(value, this);
+  }
+
+  /**
+   * Undecorate a single value, returning its raw jCal data.
+   *
+   * @private
+   * @param {Object} value         The value to undecorate
+   * @return {?}                   The undecorated value
+   */
+  _undecorate(value) {
+    return this._designSet.value[this.type].undecorate(value, this);
+  }
+
+  /**
+   * Sets the value at the given index while also hydrating it. The passed
+   * value can either be a decorated or undecorated value.
+   *
+   * @private
+   * @param {?} value             The value to set
+   * @param {Number} index        The index to set it at
+   */
+  _setDecoratedValue(value, index) {
+    if (!this._values) {
+      this._values = [];
+    }
+
+    if (typeof(value) === 'object' && 'icaltype' in value) {
+      // decorated value
+      this.jCal[VALUE_INDEX + index] = this._undecorate(value);
+      this._values[index] = value;
+    } else {
+      // undecorated value
+      this.jCal[VALUE_INDEX + index] = value;
+      this._values[index] = this._decorate(value);
+    }
+  }
+
+  /**
+   * Gets a parameter on the property.
+   *
+   * @param {String}        name   Parameter name (lowercase)
+   * @return {Array|String}        Parameter value
+   */
+  getParameter(name) {
+    if (name in this.jCal[PROP_INDEX]) {
+      return this.jCal[PROP_INDEX][name];
+    } else {
+      return undefined;
+    }
+  }
+
+  /**
+   * Gets first parameter on the property.
+   *
+   * @param {String}        name   Parameter name (lowercase)
+   * @return {String}        Parameter value
+   */
+  getFirstParameter(name) {
+    let parameters = this.getParameter(name);
+
+    if (Array.isArray(parameters)) {
+      return parameters[0];
+    }
+
+    return parameters;
+  }
+
+  /**
+   * Sets a parameter on the property.
+   *
+   * @param {String}       name     The parameter name
+   * @param {Array|String} value    The parameter value
+   */
+  setParameter(name, value) {
+    let lcname = name.toLowerCase();
+    if (typeof value === "string" &&
+        lcname in this._designSet.param &&
+        'multiValue' in this._designSet.param[lcname]) {
+        value = [value];
+    }
+    this.jCal[PROP_INDEX][name] = value;
+  }
+
+  /**
+   * Removes a parameter
+   *
+   * @param {String} name     The parameter name
+   */
+  removeParameter(name) {
+    delete this.jCal[PROP_INDEX][name];
+  }
+
+  /**
+   * Get the default type based on this property's name.
+   *
+   * @return {String}     The default type for this property
+   */
+  getDefaultType() {
+    let name = this.jCal[NAME_INDEX$1];
+    let designSet = this._designSet;
+
+    if (name in designSet.property) {
+      let details = designSet.property[name];
+      if ('defaultType' in details) {
+        return details.defaultType;
+      }
+    }
+    return design$1.defaultType;
+  }
+
+  /**
+   * Sets type of property and clears out any existing values of the current
+   * type.
+   *
+   * @param {String} type     New iCAL type (see design.*.values)
+   */
+  resetType(type) {
+    this.removeAllValues();
+    this.jCal[TYPE_INDEX] = type;
+    this._updateType();
+  }
+
+  /**
+   * Finds the first property value.
+   *
+   * @return {Binary | Duration | Period |
+   * Recur | Time | UtcOffset | Geo | string | null}         First property value
+   */
+  getFirstValue() {
+    return this._hydrateValue(0);
+  }
+
+  /**
+   * Gets all values on the property.
+   *
+   * NOTE: this creates an array during each call.
+   *
+   * @return {Array}          List of values
+   */
+  getValues() {
+    let len = this.jCal.length - VALUE_INDEX;
+
+    if (len < 1) {
+      // it is possible for a property to have no value.
+      return [];
+    }
+
+    let i = 0;
+    let result = [];
+
+    for (; i < len; i++) {
+      result[i] = this._hydrateValue(i);
+    }
+
+    return result;
+  }
+
+  /**
+   * Removes all values from this property
+   */
+  removeAllValues() {
+    if (this._values) {
+      this._values.length = 0;
+    }
+    this.jCal.length = 3;
+  }
+
+  /**
+   * Sets the values of the property.  Will overwrite the existing values.
+   * This can only be used for multi-value properties.
+   *
+   * @param {Array} values    An array of values
+   */
+  setValues(values) {
+    if (!this.isMultiValue) {
+      throw new Error(
+        this.name + ': does not not support mulitValue.\n' +
+        'override isMultiValue'
+      );
+    }
+
+    let len = values.length;
+    let i = 0;
+    this.removeAllValues();
+
+    if (len > 0 &&
+        typeof(values[0]) === 'object' &&
+        'icaltype' in values[0]) {
+      this.resetType(values[0].icaltype);
+    }
+
+    if (this.isDecorated) {
+      for (; i < len; i++) {
+        this._setDecoratedValue(values[i], i);
+      }
+    } else {
+      for (; i < len; i++) {
+        this.jCal[VALUE_INDEX + i] = values[i];
+      }
+    }
+  }
+
+  /**
+   * Sets the current value of the property. If this is a multi-value
+   * property, all other values will be removed.
+   *
+   * @param {String|Object} value     New property value.
+   */
+  setValue(value) {
+    this.removeAllValues();
+    if (typeof(value) === 'object' && 'icaltype' in value) {
+      this.resetType(value.icaltype);
+    }
+
+    if (this.isDecorated) {
+      this._setDecoratedValue(value, 0);
+    } else {
+      this.jCal[VALUE_INDEX] = value;
+    }
+  }
+
+  /**
+   * Returns the Object representation of this component. The returned object
+   * is a live jCal object and should be cloned if modified.
+   * @return {Object}
+   */
+  toJSON() {
+    return this.jCal;
+  }
+
+  /**
+   * The string representation of this component.
+   * @return {String}
+   */
+  toICALString() {
+    return stringify.property(
+      this.jCal, this._designSet, true
+    );
+  }
+}
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ * Portions Copyright (C) Philipp Kewisch */
+
+/**
+ * This lets typescript resolve our custom types in the
+ * generated d.ts files (jsdoc typedefs are converted to typescript types).
+ * Ignore prevents the typedefs from being documented more than once.
+ * @ignore
+ * @typedef {import("./types.js").designSet} designSet
+ * Imports the 'designSet' type from the "types.js" module
+ * @typedef {import("./types.js").Geo} Geo
+ * Imports the 'Geo' type from the "types.js" module
+ */
+
+const NAME_INDEX = 0;
+const PROPERTY_INDEX = 1;
+const COMPONENT_INDEX = 2;
+
+/**
+ * Wraps a jCal component, adding convenience methods to add, remove and update subcomponents and
+ * properties.
+ *
+ * @memberof ICAL
+ */
+class Component {
+  /**
+   * Create an {@link ICAL.Component} by parsing the passed iCalendar string.
+   *
+   * @param {String} str        The iCalendar string to parse
+   */
+  static fromString(str) {
+    return new Component(parse.component(str));
+  }
+
+  /**
+   * Creates a new Component instance.
+   *
+   * @param {Array|String} jCal         Raw jCal component data OR name of new
+   *                                      component
+   * @param {Component=} parent     Parent component to associate
+   */
+  constructor(jCal, parent) {
+    if (typeof(jCal) === 'string') {
+      // jCal spec (name, properties, components)
+      jCal = [jCal, [], []];
+    }
+
+    // mostly for legacy reasons.
+    this.jCal = jCal;
+
+    this.parent = parent || null;
+
+    if (!this.parent && this.name === 'vcalendar') {
+      this._timezoneCache = new Map();
+    }
+  }
+
+  /**
+   * Hydrated properties are inserted into the _properties array at the same
+   * position as in the jCal array, so it is possible that the array contains
+   * undefined values for unhydrdated properties. To avoid iterating the
+   * array when checking if all properties have been hydrated, we save the
+   * count here.
+   *
+   * @type {Number}
+   * @private
+   */
+  _hydratedPropertyCount = 0;
+
+  /**
+   * The same count as for _hydratedPropertyCount, but for subcomponents
+   *
+   * @type {Number}
+   * @private
+   */
+  _hydratedComponentCount = 0;
+
+  /**
+   * A cache of hydrated time zone objects which may be used by consumers, keyed
+   * by time zone ID.
+   *
+   * @type {Map}
+   * @private
+   */
+  _timezoneCache = null;
+
+  /**
+   * @private
+   */
+  _components = null;
+
+  /**
+   * @private
+   */
+  _properties = null;
+
+  /**
+   * The name of this component
+   *
+   * @type {String}
+   */
+  get name() {
+    return this.jCal[NAME_INDEX];
+  }
+
+  /**
+   * The design set for this component, e.g. icalendar vs vcard
+   *
+   * @type {designSet}
+   * @private
+   */
+  get _designSet() {
+    let parentDesign = this.parent && this.parent._designSet;
+    return parentDesign || design$1.getDesignSet(this.name);
+  }
+
+  /**
+   * @private
+   */
+  _hydrateComponent(index) {
+    if (!this._components) {
+      this._components = [];
+      this._hydratedComponentCount = 0;
+    }
+
+    if (this._components[index]) {
+      return this._components[index];
+    }
+
+    let comp = new Component(
+      this.jCal[COMPONENT_INDEX][index],
+      this
+    );
+
+    this._hydratedComponentCount++;
+    return (this._components[index] = comp);
+  }
+
+  /**
+   * @private
+   */
+  _hydrateProperty(index) {
+    if (!this._properties) {
+      this._properties = [];
+      this._hydratedPropertyCount = 0;
+    }
+
+    if (this._properties[index]) {
+      return this._properties[index];
+    }
+
+    let prop = new Property(
+      this.jCal[PROPERTY_INDEX][index],
+      this
+    );
+
+    this._hydratedPropertyCount++;
+    return (this._properties[index] = prop);
+  }
+
+  /**
+   * Finds first sub component, optionally filtered by name.
+   *
+   * @param {String=} name        Optional name to filter by
+   * @return {?Component}     The found subcomponent
+   */
+  getFirstSubcomponent(name) {
+    if (name) {
+      let i = 0;
+      let comps = this.jCal[COMPONENT_INDEX];
+      let len = comps.length;
+
+      for (; i < len; i++) {
+        if (comps[i][NAME_INDEX] === name) {
+          let result = this._hydrateComponent(i);
+          return result;
+        }
+      }
+    } else {
+      if (this.jCal[COMPONENT_INDEX].length) {
+        return this._hydrateComponent(0);
+      }
+    }
+
+    // ensure we return a value (strict mode)
+    return null;
+  }
+
+  /**
+   * Finds all sub components, optionally filtering by name.
+   *
+   * @param {String=} name            Optional name to filter by
+   * @return {Component[]}       The found sub components
+   */
+  getAllSubcomponents(name) {
+    let jCalLen = this.jCal[COMPONENT_INDEX].length;
+    let i = 0;
+
+    if (name) {
+      let comps = this.jCal[COMPONENT_INDEX];
+      let result = [];
+
+      for (; i < jCalLen; i++) {
+        if (name === comps[i][NAME_INDEX]) {
+          result.push(
+            this._hydrateComponent(i)
+          );
+        }
+      }
+      return result;
+    } else {
+      if (!this._components ||
+          (this._hydratedComponentCount !== jCalLen)) {
+        for (; i < jCalLen; i++) {
+          this._hydrateComponent(i);
+        }
+      }
+
+      return this._components || [];
+    }
+  }
+
+  /**
+   * Returns true when a named property exists.
+   *
+   * @param {String} name     The property name
+   * @return {Boolean}        True, when property is found
+   */
+  hasProperty(name) {
+    let props = this.jCal[PROPERTY_INDEX];
+    let len = props.length;
+
+    let i = 0;
+    for (; i < len; i++) {
+      // 0 is property name
+      if (props[i][NAME_INDEX] === name) {
+        return true;
+      }
+    }
+
+    return false;
+  }
+
+  /**
+   * Finds the first property, optionally with the given name.
+   *
+   * @param {String=} name        Lowercase property name
+   * @return {?Property}     The found property
+   */
+  getFirstProperty(name) {
+    if (name) {
+      let i = 0;
+      let props = this.jCal[PROPERTY_INDEX];
+      let len = props.length;
+
+      for (; i < len; i++) {
+        if (props[i][NAME_INDEX] === name) {
+          let result = this._hydrateProperty(i);
+          return result;
+        }
+      }
+    } else {
+      if (this.jCal[PROPERTY_INDEX].length) {
+        return this._hydrateProperty(0);
+      }
+    }
+
+    return null;
+  }
+
+  /**
+   * Returns first property's value, if available.
+   *
+   * @param {String=} name                    Lowercase property name
+   * @return {Binary | Duration | Period |
+   * Recur | Time | UtcOffset | Geo | string | null}         The found property value.
+   */
+  getFirstPropertyValue(name) {
+    let prop = this.getFirstProperty(name);
+    if (prop) {
+      return prop.getFirstValue();
+    }
+
+    return null;
+  }
+
+  /**
+   * Get all properties in the component, optionally filtered by name.
+   *
+   * @param {String=} name        Lowercase property name
+   * @return {Property[]}    List of properties
+   */
+  getAllProperties(name) {
+    let jCalLen = this.jCal[PROPERTY_INDEX].length;
+    let i = 0;
+
+    if (name) {
+      let props = this.jCal[PROPERTY_INDEX];
+      let result = [];
+
+      for (; i < jCalLen; i++) {
+        if (name === props[i][NAME_INDEX]) {
+          result.push(
+            this._hydrateProperty(i)
+          );
+        }
+      }
+      return result;
+    } else {
+      if (!this._properties ||
+          (this._hydratedPropertyCount !== jCalLen)) {
+        for (; i < jCalLen; i++) {
+          this._hydrateProperty(i);
+        }
+      }
+
+      return this._properties || [];
+    }
+  }
+
+  /**
+   * @private
+   */
+  _removeObjectByIndex(jCalIndex, cache, index) {
+    cache = cache || [];
+    // remove cached version
+    if (cache[index]) {
+      let obj = cache[index];
+      if ("parent" in obj) {
+          obj.parent = null;
+      }
+    }
+
+    cache.splice(index, 1);
+
+    // remove it from the jCal
+    this.jCal[jCalIndex].splice(index, 1);
+  }
+
+  /**
+   * @private
+   */
+  _removeObject(jCalIndex, cache, nameOrObject) {
+    let i = 0;
+    let objects = this.jCal[jCalIndex];
+    let len = objects.length;
+    let cached = this[cache];
+
+    if (typeof(nameOrObject) === 'string') {
+      for (; i < len; i++) {
+        if (objects[i][NAME_INDEX] === nameOrObject) {
+          this._removeObjectByIndex(jCalIndex, cached, i);
+          return true;
+        }
+      }
+    } else if (cached) {
+      for (; i < len; i++) {
+        if (cached[i] && cached[i] === nameOrObject) {
+          this._removeObjectByIndex(jCalIndex, cached, i);
+          return true;
+        }
+      }
+    }
+
+    return false;
+  }
+
+  /**
+   * @private
+   */
+  _removeAllObjects(jCalIndex, cache, name) {
+    let cached = this[cache];
+
+    // Unfortunately we have to run through all children to reset their
+    // parent property.
+    let objects = this.jCal[jCalIndex];
+    let i = objects.length - 1;
+
+    // descending search required because splice
+    // is used and will effect the indices.
+    for (; i >= 0; i--) {
+      if (!name || objects[i][NAME_INDEX] === name) {
+        this._removeObjectByIndex(jCalIndex, cached, i);
+      }
+    }
+  }
+
+  /**
+   * Adds a single sub component.
+   *
+   * @param {Component} component        The component to add
+   * @return {Component}                 The passed in component
+   */
+  addSubcomponent(component) {
+    if (!this._components) {
+      this._components = [];
+      this._hydratedComponentCount = 0;
+    }
+
+    if (component.parent) {
+      component.parent.removeSubcomponent(component);
+    }
+
+    let idx = this.jCal[COMPONENT_INDEX].push(component.jCal);
+    this._components[idx - 1] = component;
+    this._hydratedComponentCount++;
+    component.parent = this;
+    return component;
+  }
+
+  /**
+   * Removes a single component by name or the instance of a specific
+   * component.
+   *
+   * @param {Component|String} nameOrComp    Name of component, or component
+   * @return {Boolean}                            True when comp is removed
+   */
+  removeSubcomponent(nameOrComp) {
+    let removed = this._removeObject(COMPONENT_INDEX, '_components', nameOrComp);
+    if (removed) {
+      this._hydratedComponentCount--;
+    }
+    return removed;
+  }
+
+  /**
+   * Removes all components or (if given) all components by a particular
+   * name.
+   *
+   * @param {String=} name            Lowercase component name
+   */
+  removeAllSubcomponents(name) {
+    let removed = this._removeAllObjects(COMPONENT_INDEX, '_components', name);
+    this._hydratedComponentCount = 0;
+    return removed;
+  }
+
+  /**
+   * Adds an {@link ICAL.Property} to the component.
+   *
+   * @param {Property} property      The property to add
+   * @return {Property}              The passed in property
+   */
+  addProperty(property) {
+    if (!(property instanceof Property)) {
+      throw new TypeError('must be instance of ICAL.Property');
+    }
+
+    if (!this._properties) {
+      this._properties = [];
+      this._hydratedPropertyCount = 0;
+    }
+
+    if (property.parent) {
+      property.parent.removeProperty(property);
+    }
+
+    let idx = this.jCal[PROPERTY_INDEX].push(property.jCal);
+    this._properties[idx - 1] = property;
+    this._hydratedPropertyCount++;
+    property.parent = this;
+    return property;
+  }
+
+  /**
+   * Helper method to add a property with a value to the component.
+   *
+   * @param {String}               name         Property name to add
+   * @param {String|Number|Object} value        Property value
+   * @return {Property}                    The created property
+   */
+  addPropertyWithValue(name, value) {
+    let prop = new Property(name);
+    prop.setValue(value);
+
+    this.addProperty(prop);
+
+    return prop;
+  }
+
+  /**
+   * Helper method that will update or create a property of the given name
+   * and sets its value. If multiple properties with the given name exist,
+   * only the first is updated.
+   *
+   * @param {String}               name         Property name to update
+   * @param {String|Number|Object} value        Property value
+   * @return {Property}                    The created property
+   */
+  updatePropertyWithValue(name, value) {
+    let prop = this.getFirstProperty(name);
+
+    if (prop) {
+      prop.setValue(value);
+    } else {
+      prop = this.addPropertyWithValue(name, value);
+    }
+
+    return prop;
+  }
+
+  /**
+   * Removes a single property by name or the instance of the specific
+   * property.
+   *
+   * @param {String|Property} nameOrProp     Property name or instance to remove
+   * @return {Boolean}                            True, when deleted
+   */
+  removeProperty(nameOrProp) {
+    let removed = this._removeObject(PROPERTY_INDEX, '_properties', nameOrProp);
+    if (removed) {
+      this._hydratedPropertyCount--;
+    }
+    return removed;
+  }
+
+  /**
+   * Removes all properties associated with this component, optionally
+   * filtered by name.
+   *
+   * @param {String=} name        Lowercase property name
+   * @return {Boolean}            True, when deleted
+   */
+  removeAllProperties(name) {
+    let removed = this._removeAllObjects(PROPERTY_INDEX, '_properties', name);
+    this._hydratedPropertyCount = 0;
+    return removed;
+  }
+
+  /**
+   * Returns the Object representation of this component. The returned object
+   * is a live jCal object and should be cloned if modified.
+   * @return {Object}
+   */
+  toJSON() {
+    return this.jCal;
+  }
+
+  /**
+   * The string representation of this component.
+   * @return {String}
+   */
+  toString() {
+    return stringify.component(
+      this.jCal, this._designSet
+    );
+  }
+
+  /**
+   * Retrieve a time zone definition from the component tree, if any is present.
+   * If the tree contains no time zone definitions or the TZID cannot be
+   * matched, returns null.
+   *
+   * @param {String} tzid     The ID of the time zone to retrieve
+   * @return {Timezone}  The time zone corresponding to the ID, or null
+   */
+  getTimeZoneByID(tzid) {
+    // VTIMEZONE components can only appear as a child of the VCALENDAR
+    // component; walk the tree if we're not the root.
+    if (this.parent) {
+      return this.parent.getTimeZoneByID(tzid);
+    }
+
+    // If there is no time zone cache, we are probably parsing an incomplete
+    // file and will have no time zone definitions.
+    if (!this._timezoneCache) {
+      return null;
+    }
+
+    if (this._timezoneCache.has(tzid)) {
+      return this._timezoneCache.get(tzid);
+    }
+
+    // If the time zone is not already cached, hydrate it from the
+    // subcomponents.
+    const zones = this.getAllSubcomponents('vtimezone');
+    for (const zone of zones) {
+      if (zone.getFirstProperty('tzid').getFirstValue() === tzid) {
+        const hydratedZone = new Timezone({
+          component: zone,
+          tzid: tzid,
+        });
+
+        this._timezoneCache.set(tzid, hydratedZone);
+
+        return hydratedZone;
+      }
+    }
+
+    // Per the standard, we should always have a time zone defined in a file
+    // for any referenced TZID, but don't blow up if the file is invalid.
+    return null;
+  }
+}
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ * Portions Copyright (C) Philipp Kewisch */
+
+/**
+ * Primary class for expanding recurring rules.  Can take multiple rrules, rdates, exdate(s) and
+ * iterate (in order) over each next occurrence.
+ *
+ * Once initialized this class can also be serialized saved and continue iteration from the last
+ * point.
+ *
+ * NOTE: it is intended that this class is to be used with {@link ICAL.Event} which handles recurrence
+ * exceptions.
+ *
+ * @example
+ * // assuming event is a parsed ical component
+ * var event;
+ *
+ * var expand = new ICAL.RecurExpansion({
+ *   component: event,
+ *   dtstart: event.getFirstPropertyValue('dtstart')
+ * });
+ *
+ * // remember there are infinite rules so it is a good idea to limit the scope of the iterations
+ * // then resume later on.
+ *
+ * // next is always an ICAL.Time or null
+ * var next;
+ *
+ * while (someCondition && (next = expand.next())) {
+ *   // do something with next
+ * }
+ *
+ * // save instance for later
+ * var json = JSON.stringify(expand);
+ *
+ * //...
+ *
+ * // NOTE: if the component's properties have changed you will need to rebuild the class and start
+ * // over. This only works when the component's recurrence info is the same.
+ * var expand = new ICAL.RecurExpansion(JSON.parse(json));
+ *
+ * @memberof ICAL
+ */
+class RecurExpansion {
+  /**
+   * Creates a new ICAL.RecurExpansion instance.
+   *
+   * The options object can be filled with the specified initial values. It can also contain
+   * additional members, as a result of serializing a previous expansion state, as shown in the
+   * example.
+   *
+   * @param {Object} options
+   *        Recurrence expansion options
+   * @param {Time} options.dtstart
+   *        Start time of the event
+   * @param {Component=} options.component
+   *        Component for expansion, required if not resuming.
+   */
+  constructor(options) {
+    this.ruleDates = [];
+    this.exDates = [];
+    this.fromData(options);
+  }
+
+  /**
+   * True when iteration is fully completed.
+   * @type {Boolean}
+   */
+  complete = false;
+
+  /**
+   * Array of rrule iterators.
+   *
+   * @type {RecurIterator[]}
+   * @private
+   */
+  ruleIterators = null;
+
+  /**
+   * Array of rdate instances.
+   *
+   * @type {Time[]}
+   * @private
+   */
+  ruleDates = null;
+
+  /**
+   * Array of exdate instances.
+   *
+   * @type {Time[]}
+   * @private
+   */
+  exDates = null;
+
+  /**
+   * Current position in ruleDates array.
+   * @type {Number}
+   * @private
+   */
+  ruleDateInc = 0;
+
+  /**
+   * Current position in exDates array
+   * @type {Number}
+   * @private
+   */
+  exDateInc = 0;
+
+  /**
+   * Current negative date.
+   *
+   * @type {Time}
+   * @private
+   */
+  exDate = null;
+
+  /**
+   * Current additional date.
+   *
+   * @type {Time}
+   * @private
+   */
+  ruleDate = null;
+
+  /**
+   * Start date of recurring rules.
+   *
+   * @type {Time}
+   */
+  dtstart = null;
+
+  /**
+   * Last expanded time
+   *
+   * @type {Time}
+   */
+  last = null;
+
+  /**
+   * Initialize the recurrence expansion from the data object. The options
+   * object may also contain additional members, see the
+   * {@link ICAL.RecurExpansion constructor} for more details.
+   *
+   * @param {Object} options
+   *        Recurrence expansion options
+   * @param {Time} options.dtstart
+   *        Start time of the event
+   * @param {Component=} options.component
+   *        Component for expansion, required if not resuming.
+   */
+  fromData(options) {
+    let start = formatClassType(options.dtstart, Time);
+
+    if (!start) {
+      throw new Error('.dtstart (ICAL.Time) must be given');
+    } else {
+      this.dtstart = start;
+    }
+
+    if (options.component) {
+      this._init(options.component);
+    } else {
+      this.last = formatClassType(options.last, Time) || start.clone();
+
+      if (!options.ruleIterators) {
+        throw new Error('.ruleIterators or .component must be given');
+      }
+
+      this.ruleIterators = options.ruleIterators.map(function(item) {
+        return formatClassType(item, RecurIterator);
+      });
+
+      this.ruleDateInc = options.ruleDateInc;
+      this.exDateInc = options.exDateInc;
+
+      if (options.ruleDates) {
+        this.ruleDates = options.ruleDates.map(item => formatClassType(item, Time));
+        this.ruleDate = this.ruleDates[this.ruleDateInc];
+      }
+
+      if (options.exDates) {
+        this.exDates = options.exDates.map(item => formatClassType(item, Time));
+        this.exDate = this.exDates[this.exDateInc];
+      }
+
+      if (typeof(options.complete) !== 'undefined') {
+        this.complete = options.complete;
+      }
+    }
+  }
+
+  /**
+   * Retrieve the next occurrence in the series.
+   * @return {Time}
+   */
+  next() {
+    let iter;
+    let next;
+    let compare;
+
+    let maxTries = 500;
+    let currentTry = 0;
+
+    while (true) {
+      if (currentTry++ > maxTries) {
+        throw new Error(
+          'max tries have occurred, rule may be impossible to fulfill.'
+        );
+      }
+
+      next = this.ruleDate;
+      iter = this._nextRecurrenceIter(this.last);
+
+      // no more matches
+      // because we increment the rule day or rule
+      // _after_ we choose a value this should be
+      // the only spot where we need to worry about the
+      // end of events.
+      if (!next && !iter) {
+        // there are no more iterators or rdates
+        this.complete = true;
+        break;
+      }
+
+      // no next rule day or recurrence rule is first.
+      if (!next || (iter && next.compare(iter.last) > 0)) {
+        // must be cloned, recur will reuse the time element.
+        next = iter.last.clone();
+        // move to next so we can continue
+        iter.next();
+      }
+
+      // if the ruleDate is still next increment it.
+      if (this.ruleDate === next) {
+        this._nextRuleDay();
+      }
+
+      this.last = next;
+
+      // check the negative rules
+      if (this.exDate) {
+        compare = this.exDate.compare(this.last);
+
+        if (compare < 0) {
+          this._nextExDay();
+        }
+
+        // if the current rule is excluded skip it.
+        if (compare === 0) {
+          this._nextExDay();
+          continue;
+        }
+      }
+
+      //XXX: The spec states that after we resolve the final
+      //     list of dates we execute exdate this seems somewhat counter
+      //     intuitive to what I have seen most servers do so for now
+      //     I exclude based on the original date not the one that may
+      //     have been modified by the exception.
+      return this.last;
+    }
+  }
+
+  /**
+   * Converts object into a serialize-able format. This format can be passed
+   * back into the expansion to resume iteration.
+   * @return {Object}
+   */
+  toJSON() {
+    function toJSON(item) {
+      return item.toJSON();
+    }
+
+    let result = Object.create(null);
+    result.ruleIterators = this.ruleIterators.map(toJSON);
+
+    if (this.ruleDates) {
+      result.ruleDates = this.ruleDates.map(toJSON);
+    }
+
+    if (this.exDates) {
+      result.exDates = this.exDates.map(toJSON);
+    }
+
+    result.ruleDateInc = this.ruleDateInc;
+    result.exDateInc = this.exDateInc;
+    result.last = this.last.toJSON();
+    result.dtstart = this.dtstart.toJSON();
+    result.complete = this.complete;
+
+    return result;
+  }
+
+  /**
+   * Extract all dates from the properties in the given component. The
+   * properties will be filtered by the property name.
+   *
+   * @private
+   * @param {Component} component             The component to search in
+   * @param {String} propertyName             The property name to search for
+   * @return {Time[]}                         The extracted dates.
+   */
+  _extractDates(component, propertyName) {
+    let result = [];
+    let props = component.getAllProperties(propertyName);
+
+    for (let i = 0, len = props.length; i < len; i++) {
+      for (let prop of props[i].getValues()) {
+        let idx = binsearchInsert(
+          result,
+          prop,
+          (a, b) => a.compare(b)
+        );
+
+        // ordered insert
+        result.splice(idx, 0, prop);
+      }
+    }
+
+    return result;
+  }
+
+  /**
+   * Initialize the recurrence expansion.
+   *
+   * @private
+   * @param {Component} component    The component to initialize from.
+   */
+  _init(component) {
+    this.ruleIterators = [];
+
+    this.last = this.dtstart.clone();
+
+    // to provide api consistency non-recurring
+    // events can also use the iterator though it will
+    // only return a single time.
+    if (!component.hasProperty('rdate') &&
+        !component.hasProperty('rrule') &&
+        !component.hasProperty('recurrence-id')) {
+      this.ruleDate = this.last.clone();
+      this.complete = true;
+      return;
+    }
+
+    if (component.hasProperty('rdate')) {
+      this.ruleDates = this._extractDates(component, 'rdate');
+
+      // special hack for cases where first rdate is prior
+      // to the start date. We only check for the first rdate.
+      // This is mostly for google's crazy recurring date logic
+      // (contacts birthdays).
+      if ((this.ruleDates[0]) &&
+          (this.ruleDates[0].compare(this.dtstart) < 0)) {
+
+        this.ruleDateInc = 0;
+        this.last = this.ruleDates[0].clone();
+      } else {
+        this.ruleDateInc = binsearchInsert(
+          this.ruleDates,
+          this.last,
+          (a, b) => a.compare(b)
+        );
+      }
+
+      this.ruleDate = this.ruleDates[this.ruleDateInc];
+    }
+
+    if (component.hasProperty('rrule')) {
+      let rules = component.getAllProperties('rrule');
+      let i = 0;
+      let len = rules.length;
+
+      let rule;
+      let iter;
+
+      for (; i < len; i++) {
+        rule = rules[i].getFirstValue();
+        iter = rule.iterator(this.dtstart);
+        this.ruleIterators.push(iter);
+
+        // increment to the next occurrence so future
+        // calls to next return times beyond the initial iteration.
+        // XXX: I find this suspicious might be a bug?
+        iter.next();
+      }
+    }
+
+    if (component.hasProperty('exdate')) {
+      this.exDates = this._extractDates(component, 'exdate');
+      // if we have a .last day we increment the index to beyond it.
+      this.exDateInc = binsearchInsert(
+        this.exDates,
+        this.last,
+        (a, b) => a.compare(b)
+      );
+
+      this.exDate = this.exDates[this.exDateInc];
+    }
+  }
+
+  /**
+   * Advance to the next exdate
+   * @private
+   */
+  _nextExDay() {
+    this.exDate = this.exDates[++this.exDateInc];
+  }
+
+  /**
+   * Advance to the next rule date
+   * @private
+   */
+  _nextRuleDay() {
+    this.ruleDate = this.ruleDates[++this.ruleDateInc];
+  }
+
+  /**
+   * Find and return the recurrence rule with the most recent event and
+   * return it.
+   *
+   * @private
+   * @return {?RecurIterator}    Found iterator.
+   */
+  _nextRecurrenceIter() {
+    let iters = this.ruleIterators;
+
+    if (iters.length === 0) {
+      return null;
+    }
+
+    let len = iters.length;
+    let iter;
+    let iterTime;
+    let iterIdx = 0;
+    let chosenIter;
+
+    // loop through each iterator
+    for (; iterIdx < len; iterIdx++) {
+      iter = iters[iterIdx];
+      iterTime = iter.last;
+
+      // if iteration is complete
+      // then we must exclude it from
+      // the search and remove it.
+      if (iter.completed) {
+        len--;
+        if (iterIdx !== 0) {
+          iterIdx--;
+        }
+        iters.splice(iterIdx, 1);
+        continue;
+      }
+
+      // find the most recent possible choice
+      if (!chosenIter || chosenIter.last.compare(iterTime) > 0) {
+        // that iterator is saved
+        chosenIter = iter;
+      }
+    }
+
+    // the chosen iterator is returned but not mutated
+    // this iterator contains the most recent event.
+    return chosenIter;
+  }
+}
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ * Portions Copyright (C) Philipp Kewisch */
+
+/**
+ * This lets typescript resolve our custom types in the
+ * generated d.ts files (jsdoc typedefs are converted to typescript types).
+ * Ignore prevents the typedefs from being documented more than once.
+ * @ignore
+ * @typedef {import("./types.js").frequencyValues} frequencyValues
+ * Imports the 'frequencyValues' type from the "types.js" module
+ * @typedef {import("./types.js").occurrenceDetails} occurrenceDetails
+ * Imports the 'occurrenceDetails' type from the "types.js" module
+ */
+
+/**
+ * ICAL.js is organized into multiple layers. The bottom layer is a raw jCal
+ * object, followed by the component/property layer. The highest level is the
+ * event representation, which this class is part of. See the
+ * {@tutorial layers} guide for more details.
+ *
+ * @memberof ICAL
+ */
+class Event {
+  /**
+   * Creates a new ICAL.Event instance.
+   *
+   * @param {Component=} component              The ICAL.Component to base this event on
+   * @param {Object} [options]                  Options for this event
+   * @param {Boolean=} options.strictExceptions  When true, will verify exceptions are related by
+   *                                              their UUID
+   * @param {Array<Component|Event>=} options.exceptions
+   *          Exceptions to this event, either as components or events. If not
+   *            specified exceptions will automatically be set in relation of
+   *            component's parent
+   */
+  constructor(component, options) {
+    if (!(component instanceof Component)) {
+      options = component;
+      component = null;
+    }
+
+    if (component) {
+      this.component = component;
+    } else {
+      this.component = new Component('vevent');
+    }
+
+    this._rangeExceptionCache = Object.create(null);
+    this.exceptions = Object.create(null);
+    this.rangeExceptions = [];
+
+    if (options && options.strictExceptions) {
+      this.strictExceptions = options.strictExceptions;
+    }
+
+    if (options && options.exceptions) {
+      options.exceptions.forEach(this.relateException, this);
+    } else if (this.component.parent && !this.isRecurrenceException()) {
+      this.component.parent.getAllSubcomponents('vevent').forEach(function(event) {
+        if (event.hasProperty('recurrence-id')) {
+          this.relateException(event);
+        }
+      }, this);
+    }
+  }
+
+
+  static THISANDFUTURE = 'THISANDFUTURE';
+
+  /**
+   * List of related event exceptions.
+   *
+   * @type {Event[]}
+   */
+  exceptions = null;
+
+  /**
+   * When true, will verify exceptions are related by their UUID.
+   *
+   * @type {Boolean}
+   */
+  strictExceptions = false;
+
+  /**
+   * Relates a given event exception to this object.  If the given component
+   * does not share the UID of this event it cannot be related and will throw
+   * an exception.
+   *
+   * If this component is an exception it cannot have other exceptions
+   * related to it.
+   *
+   * @param {Component|Event} obj       Component or event
+   */
+  relateException(obj) {
+    if (this.isRecurrenceException()) {
+      throw new Error('cannot relate exception to exceptions');
+    }
+
+    if (obj instanceof Component) {
+      obj = new Event(obj);
+    }
+
+    if (this.strictExceptions && obj.uid !== this.uid) {
+      throw new Error('attempted to relate unrelated exception');
+    }
+
+    let id = obj.recurrenceId.toString();
+
+    // we don't sort or manage exceptions directly
+    // here the recurrence expander handles that.
+    this.exceptions[id] = obj;
+
+    // index RANGE=THISANDFUTURE exceptions so we can
+    // look them up later in getOccurrenceDetails.
+    if (obj.modifiesFuture()) {
+      let item = [
+        obj.recurrenceId.toUnixTime(), id
+      ];
+
+      // we keep them sorted so we can find the nearest
+      // value later on...
+      let idx = binsearchInsert(
+        this.rangeExceptions,
+        item,
+        compareRangeException
+      );
+
+      this.rangeExceptions.splice(idx, 0, item);
+    }
+  }
+
+  /**
+   * Checks if this record is an exception and has the RANGE=THISANDFUTURE
+   * value.
+   *
+   * @return {Boolean}        True, when exception is within range
+   */
+  modifiesFuture() {
+    if (!this.component.hasProperty('recurrence-id')) {
+      return false;
+    }
+
+    let range = this.component.getFirstProperty('recurrence-id').getParameter('range');
+    return range === Event.THISANDFUTURE;
+  }
+
+  /**
+   * Finds the range exception nearest to the given date.
+   *
+   * @param {Time} time   usually an occurrence time of an event
+   * @return {?Event}     the related event/exception or null
+   */
+  findRangeException(time) {
+    if (!this.rangeExceptions.length) {
+      return null;
+    }
+
+    let utc = time.toUnixTime();
+    let idx = binsearchInsert(
+      this.rangeExceptions,
+      [utc],
+      compareRangeException
+    );
+
+    idx -= 1;
+
+    // occurs before
+    if (idx < 0) {
+      return null;
+    }
+
+    let rangeItem = this.rangeExceptions[idx];
+
+    /* c8 ignore next 4 */
+    if (utc < rangeItem[0]) {
+      // sanity check only
+      return null;
+    }
+
+    return rangeItem[1];
+  }
+
+  /**
+   * Returns the occurrence details based on its start time.  If the
+   * occurrence has an exception will return the details for that exception.
+   *
+   * NOTE: this method is intend to be used in conjunction
+   *       with the {@link ICAL.Event#iterator iterator} method.
+   *
+   * @param {Time} occurrence               time occurrence
+   * @return {occurrenceDetails}            Information about the occurrence
+   */
+  getOccurrenceDetails(occurrence) {
+    let id = occurrence.toString();
+    let utcId = occurrence.convertToZone(Timezone.utcTimezone).toString();
+    let item;
+    let result = {
+      //XXX: Clone?
+      recurrenceId: occurrence
+    };
+
+    if (id in this.exceptions) {
+      item = result.item = this.exceptions[id];
+      result.startDate = item.startDate;
+      result.endDate = item.endDate;
+      result.item = item;
+    } else if (utcId in this.exceptions) {
+      item = this.exceptions[utcId];
+      result.startDate = item.startDate;
+      result.endDate = item.endDate;
+      result.item = item;
+    } else {
+      // range exceptions (RANGE=THISANDFUTURE) have a
+      // lower priority then direct exceptions but
+      // must be accounted for first. Their item is
+      // always the first exception with the range prop.
+      let rangeExceptionId = this.findRangeException(
+        occurrence
+      );
+      let end;
+
+      if (rangeExceptionId) {
+        let exception = this.exceptions[rangeExceptionId];
+
+        // range exception must modify standard time
+        // by the difference (if any) in start/end times.
+        result.item = exception;
+
+        let startDiff = this._rangeExceptionCache[rangeExceptionId];
+
+        if (!startDiff) {
+          let original = exception.recurrenceId.clone();
+          let newStart = exception.startDate.clone();
+
+          // zones must be same otherwise subtract may be incorrect.
+          original.zone = newStart.zone;
+          startDiff = newStart.subtractDate(original);
+
+          this._rangeExceptionCache[rangeExceptionId] = startDiff;
+        }
+
+        let start = occurrence.clone();
+        start.zone = exception.startDate.zone;
+        start.addDuration(startDiff);
+
+        end = start.clone();
+        end.addDuration(exception.duration);
+
+        result.startDate = start;
+        result.endDate = end;
+      } else {
+        // no range exception standard expansion
+        end = occurrence.clone();
+        end.addDuration(this.duration);
+
+        result.endDate = end;
+        result.startDate = occurrence;
+        result.item = this;
+      }
+    }
+
+    return result;
+  }
+
+  /**
+   * Builds a recur expansion instance for a specific point in time (defaults
+   * to startDate).
+   *
+   * @param {Time=} startTime     Starting point for expansion
+   * @return {RecurExpansion}    Expansion object
+   */
+  iterator(startTime) {
+    return new RecurExpansion({
+      component: this.component,
+      dtstart: startTime || this.startDate
+    });
+  }
+
+  /**
+   * Checks if the event is recurring
+   *
+   * @return {Boolean}        True, if event is recurring
+   */
+  isRecurring() {
+    let comp = this.component;
+    return comp.hasProperty('rrule') || comp.hasProperty('rdate');
+  }
+
+  /**
+   * Checks if the event describes a recurrence exception. See
+   * {@tutorial terminology} for details.
+   *
+   * @return {Boolean}    True, if the event describes a recurrence exception
+   */
+  isRecurrenceException() {
+    return this.component.hasProperty('recurrence-id');
+  }
+
+  /**
+   * Returns the types of recurrences this event may have.
+   *
+   * Returned as an object with the following possible keys:
+   *
+   *    - YEARLY
+   *    - MONTHLY
+   *    - WEEKLY
+   *    - DAILY
+   *    - MINUTELY
+   *    - SECONDLY
+   *
+   * @return {Object.<frequencyValues, Boolean>}
+   *          Object of recurrence flags
+   */
+  getRecurrenceTypes() {
+    let rules = this.component.getAllProperties('rrule');
+    let i = 0;
+    let len = rules.length;
+    let result = Object.create(null);
+
+    for (; i < len; i++) {
+      let value = rules[i].getFirstValue();
+      result[value.freq] = true;
+    }
+
+    return result;
+  }
+
+  /**
+   * The uid of this event
+   * @type {String}
+   */
+  get uid() {
+    return this._firstProp('uid');
+  }
+
+  set uid(value) {
+    this._setProp('uid', value);
+  }
+
+  /**
+   * The start date
+   * @type {Time}
+   */
+  get startDate() {
+    return this._firstProp('dtstart');
+  }
+
+  set startDate(value) {
+    this._setTime('dtstart', value);
+  }
+
+  /**
+   * The end date. This can be the result directly from the property, or the
+   * end date calculated from start date and duration. Setting the property
+   * will remove any duration properties.
+   * @type {Time}
+   */
+  get endDate() {
+    let endDate = this._firstProp('dtend');
+    if (!endDate) {
+        let duration = this._firstProp('duration');
+        endDate = this.startDate.clone();
+        if (duration) {
+            endDate.addDuration(duration);
+        } else if (endDate.isDate) {
+            endDate.day += 1;
+        }
+    }
+    return endDate;
+  }
+
+  set endDate(value) {
+    if (this.component.hasProperty('duration')) {
+      this.component.removeProperty('duration');
+    }
+    this._setTime('dtend', value);
+  }
+
+  /**
+   * The duration. This can be the result directly from the property, or the
+   * duration calculated from start date and end date. Setting the property
+   * will remove any `dtend` properties.
+   * @type {Duration}
+   */
+  get duration() {
+    let duration = this._firstProp('duration');
+    if (!duration) {
+      return this.endDate.subtractDateTz(this.startDate);
+    }
+    return duration;
+  }
+
+  set duration(value) {
+    if (this.component.hasProperty('dtend')) {
+      this.component.removeProperty('dtend');
+    }
+
+    this._setProp('duration', value);
+  }
+
+  /**
+   * The location of the event.
+   * @type {String}
+   */
+  get location() {
+    return this._firstProp('location');
+  }
+
+  set location(value) {
+    this._setProp('location', value);
+  }
+
+  /**
+   * The attendees in the event
+   * @type {Property[]}
+   */
+  get attendees() {
+    //XXX: This is way lame we should have a better
+    //     data structure for this later.
+    return this.component.getAllProperties('attendee');
+  }
+
+  /**
+   * The event summary
+   * @type {String}
+   */
+  get summary() {
+    return this._firstProp('summary');
+  }
+
+  set summary(value) {
+    this._setProp('summary', value);
+  }
+
+  /**
+   * The event description.
+   * @type {String}
+   */
+  get description() {
+    return this._firstProp('description');
+  }
+
+  set description(value) {
+    this._setProp('description', value);
+  }
+
+  /**
+   * The event color from [rfc7986](https://datatracker.ietf.org/doc/html/rfc7986)
+   * @type {String}
+   */
+  get color() {
+    return this._firstProp('color');
+  }
+
+  set color(value) {
+    this._setProp('color', value);
+  }
+
+  /**
+   * The organizer value as an uri. In most cases this is a mailto: uri, but
+   * it can also be something else, like urn:uuid:...
+   * @type {String}
+   */
+  get organizer() {
+    return this._firstProp('organizer');
+  }
+
+  set organizer(value) {
+    this._setProp('organizer', value);
+  }
+
+  /**
+   * The sequence value for this event. Used for scheduling
+   * see {@tutorial terminology}.
+   * @type {Number}
+   */
+  get sequence() {
+    return this._firstProp('sequence');
+  }
+
+  set sequence(value) {
+    this._setProp('sequence', value);
+  }
+
+  /**
+   * The recurrence id for this event. See {@tutorial terminology} for details.
+   * @type {Time}
+   */
+  get recurrenceId() {
+    return this._firstProp('recurrence-id');
+  }
+
+  set recurrenceId(value) {
+    this._setTime('recurrence-id', value);
+  }
+
+  /**
+   * Set/update a time property's value.
+   * This will also update the TZID of the property.
+   *
+   * TODO: this method handles the case where we are switching
+   * from a known timezone to an implied timezone (one without TZID).
+   * This does _not_ handle the case of moving between a known
+   *  (by TimezoneService) timezone to an unknown timezone...
+   *
+   * We will not add/remove/update the VTIMEZONE subcomponents
+   *  leading to invalid ICAL data...
+   * @private
+   * @param {String} propName     The property name
+   * @param {Time} time           The time to set
+   */
+  _setTime(propName, time) {
+    let prop = this.component.getFirstProperty(propName);
+
+    if (!prop) {
+      prop = new Property(propName);
+      this.component.addProperty(prop);
+    }
+
+    // utc and local don't get a tzid
+    if (
+      time.zone === Timezone.localTimezone ||
+      time.zone === Timezone.utcTimezone
+    ) {
+      // remove the tzid
+      prop.removeParameter('tzid');
+    } else {
+      prop.setParameter('tzid', time.zone.tzid);
+    }
+
+    prop.setValue(time);
+  }
+
+  _setProp(name, value) {
+    this.component.updatePropertyWithValue(name, value);
+  }
+
+  _firstProp(name) {
+    return this.component.getFirstPropertyValue(name);
+  }
+
+  /**
+   * The string representation of this event.
+   * @return {String}
+   */
+  toString() {
+    return this.component.toString();
+  }
+}
+
+function compareRangeException(a, b) {
+  if (a[0] > b[0]) return 1;
+  if (b[0] > a[0]) return -1;
+  return 0;
+}
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ * Portions Copyright (C) Philipp Kewisch */
+
+/**
+ * The ComponentParser is used to process a String or jCal Object,
+ * firing callbacks for various found components, as well as completion.
+ *
+ * @example
+ * var options = {
+ *   // when false no events will be emitted for type
+ *   parseEvent: true,
+ *   parseTimezone: true
+ * };
+ *
+ * var parser = new ICAL.ComponentParser(options);
+ *
+ * parser.onevent(eventComponent) {
+ *   //...
+ * }
+ *
+ * // ontimezone, etc...
+ *
+ * parser.oncomplete = function() {
+ *
+ * };
+ *
+ * parser.process(stringOrComponent);
+ *
+ * @memberof ICAL
+ */
+class ComponentParser {
+  /**
+   * Creates a new ICAL.ComponentParser instance.
+   *
+   * @param {Object=} options                   Component parser options
+   * @param {Boolean} options.parseEvent        Whether events should be parsed
+   * @param {Boolean} options.parseTimezeone    Whether timezones should be parsed
+   */
+  constructor(options) {
+    if (typeof(options) === 'undefined') {
+      options = {};
+    }
+
+    for (let [key, value] of Object.entries(options)) {
+      this[key] = value;
+    }
+  }
+
+  /**
+   * When true, parse events
+   *
+   * @type {Boolean}
+   */
+  parseEvent = true;
+
+  /**
+   * When true, parse timezones
+   *
+   * @type {Boolean}
+   */
+  parseTimezone = true;
+
+
+  /* SAX like events here for reference */
+
+  /**
+   * Fired when parsing is complete
+   * @callback
+   */
+  oncomplete = /* c8 ignore next */ function() {};
+
+  /**
+   * Fired if an error occurs during parsing.
+   *
+   * @callback
+   * @param {Error} err details of error
+   */
+  onerror = /* c8 ignore next */ function(err) {};
+
+  /**
+   * Fired when a top level component (VTIMEZONE) is found
+   *
+   * @callback
+   * @param {Timezone} component     Timezone object
+   */
+  ontimezone = /* c8 ignore next */ function(component) {};
+
+  /**
+   * Fired when a top level component (VEVENT) is found.
+   *
+   * @callback
+   * @param {Event} component    Top level component
+   */
+  onevent = /* c8 ignore next */ function(component) {};
+
+  /**
+   * Process a string or parse ical object.  This function itself will return
+   * nothing but will start the parsing process.
+   *
+   * Events must be registered prior to calling this method.
+   *
+   * @param {Component|String|Object} ical      The component to process,
+   *        either in its final form, as a jCal Object, or string representation
+   */
+  process(ical) {
+    //TODO: this is sync now in the future we will have a incremental parser.
+    if (typeof(ical) === 'string') {
+      ical = parse(ical);
+    }
+
+    if (!(ical instanceof Component)) {
+      ical = new Component(ical);
+    }
+
+    let components = ical.getAllSubcomponents();
+    let i = 0;
+    let len = components.length;
+    let component;
+
+    for (; i < len; i++) {
+      component = components[i];
+
+      switch (component.name) {
+        case 'vtimezone':
+          if (this.parseTimezone) {
+            let tzid = component.getFirstPropertyValue('tzid');
+            if (tzid) {
+              this.ontimezone(new Timezone({
+                tzid: tzid,
+                component: component
+              }));
+            }
+          }
+          break;
+        case 'vevent':
+          if (this.parseEvent) {
+            this.onevent(new Event(component));
+          }
+          break;
+        default:
+          continue;
+      }
+    }
+
+    //XXX: ideally we should do a "nextTick" here
+    //     so in all cases this is actually async.
+    this.oncomplete();
+  }
+}
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ * Portions Copyright (C) Philipp Kewisch */
+
+/**
+ * The main ICAL module. Provides access to everything else.
+ *
+ * @alias ICAL
+ * @namespace ICAL
+ * @property {ICAL.design} design
+ * @property {ICAL.helpers} helpers
+ */
+var ICALmodule = {
+  /**
+   * The number of characters before iCalendar line folding should occur
+   * @type {Number}
+   * @default 75
+   */
+  foldLength: 75,
+
+  debug: false,
+
+  /**
+   * The character(s) to be used for a newline. The default value is provided by
+   * rfc5545.
+   * @type {String}
+   * @default "\r\n"
+   */
+  newLineChar: '\r\n',
+
+  Binary,
+  Component,
+  ComponentParser,
+  Duration,
+  Event,
+  Period,
+  Property,
+  Recur,
+  RecurExpansion,
+  RecurIterator,
+  Time,
+  Timezone,
+  TimezoneService,
+  UtcOffset,
+  VCardTime,
+
+  parse,
+  stringify,
+
+  design: design$1,
+  helpers
+};
+
+return ICALmodule;
+
+})();
diff --git a/plugins/ics-viewer/index.php b/plugins/ics-viewer/index.php
index 75ee7040a..591288392 100644
--- a/plugins/ics-viewer/index.php
+++ b/plugins/ics-viewer/index.php
@@ -4,7 +4,8 @@ class ICSViewerPlugin extends \RainLoop\Plugins\AbstractPlugin
 {
 	const
 		NAME = 'ICS Viewer',
-		VERSION = '1',
+		AUTHOR = 'PhieF',
+		VERSION = '1.0',
 		RELEASE  = '2024-09-17',
 		CATEGORY = 'Messages',
 		DESCRIPTION = 'Display ICS attachment using ical lib, or JSON-LD details, based on viewICS',
@@ -14,7 +15,8 @@ class ICSViewerPlugin extends \RainLoop\Plugins\AbstractPlugin
 	{
 //		$this->UseLangs(true);
 		$this->addJs('message.js');
-		$this->addJs('ical.es5.min.cjs');
 		$this->addJs('windowsZones.js');
+		// Load https://github.com/kewisch/ical.js/releases
+		$this->addJs('ical.js');
 	}
 }