import {$, _, key} from 'common';
import ko from 'ko';
import {EventKeyCode} from 'Common/Enums';
import Utils from 'Common/Utils';

class Selector
{
	/**
	 * @constructor
	 * @param {koProperty} koList
	 * @param {koProperty} koSelectedItem
	 * @param {koProperty} koFocusedItem
	 * @param {string} sItemSelector
	 * @param {string} sItemSelectedSelector
	 * @param {string} sItemCheckedSelector
	 * @param {string} sItemFocusedSelector
	 */
	constructor(koList, koSelectedItem, koFocusedItem,
		sItemSelector, sItemSelectedSelector, sItemCheckedSelector, sItemFocusedSelector)
	{
		this.list = koList;

		this.listChecked = ko.computed(() => {
			return _.filter(this.list(), (item) => item.checked());
		}, this).extend({'rateLimit': 0});

		this.isListChecked = ko.computed(() => 0 < this.listChecked().length);

		this.focusedItem = koFocusedItem || ko.observable(null);
		this.selectedItem = koSelectedItem || ko.observable(null);
		this.selectedItemUseCallback = true;

		this.itemSelectedThrottle = _.debounce(_.bind(this.itemSelected, this), 300);

		this.listChecked.subscribe((items) => {
			if (0 < items.length)
			{
				if (null === this.selectedItem())
				{
					if (this.selectedItem.valueHasMutated)
					{
						this.selectedItem.valueHasMutated();
					}
				}
				else
				{
					this.selectedItem(null);
				}
			}
			else if (this.autoSelect() && this.focusedItem())
			{
				this.selectedItem(this.focusedItem());
			}
		}, this);

		this.selectedItem.subscribe((item) => {

			if (item)
			{
				if (this.isListChecked())
				{
					_.each(this.listChecked(), (subItem) => {
						subItem.checked(false);
					});
				}

				if (this.selectedItemUseCallback)
				{
					this.itemSelectedThrottle(item);
				}
			}
			else if (this.selectedItemUseCallback)
			{
				this.itemSelected(null);
			}

		}, this);

		this.selectedItem = this.selectedItem.extend({'toggleSubscribe': [null,
			(prev) => {
				if (prev)
				{
					prev.selected(false);
				}
			}, (next) => {
				if (next)
				{
					next.selected(true);
				}
			}
		]});

		this.focusedItem = this.focusedItem.extend({'toggleSubscribe': [null,
			(prev) => {
				if (prev)
				{
					prev.focused(false);
				}
			}, (next) => {
				if (next)
				{
					next.focused(true);
				}
			}
		]});

		this.iSelectNextHelper = 0;
		this.iFocusedNextHelper = 0;
		this.oContentVisible = null;
		this.oContentScrollable = null;

		this.sItemSelector = sItemSelector;
		this.sItemSelectedSelector = sItemSelectedSelector;
		this.sItemCheckedSelector = sItemCheckedSelector;
		this.sItemFocusedSelector = sItemFocusedSelector;

		this.sLastUid = '';
		this.oCallbacks = {};

		this.emptyFunction = () => {};
		this.emptyTrueFunction = () => true;

		this.focusedItem.subscribe((item) => {
			if (item)
			{
				this.sLastUid = this.getItemUid(item);
			}
		}, this);

		let
			aCache = [],
			aCheckedCache = [],
			mFocused = null,
			mSelected = null
		;

		this.list.subscribe((items) => {

			if (Utils.isArray(items))
			{
				_.each(items, (item) => {
					if (item)
					{
						const uid = this.getItemUid(item);

						aCache.push(uid);
						if (item.checked())
						{
							aCheckedCache.push(uid);
						}
						if (null === mFocused && item.focused())
						{
							mFocused = uid;
						}
						if (null === mSelected && item.selected())
						{
							mSelected = uid;
						}
					}
				});
			}
		}, this, 'beforeChange');

		this.list.subscribe((aItems) => {

			var
				oTemp = null,
				bGetNext = false,
				aUids = [],
				mNextFocused = mFocused,
				bChecked = false,
				bSelected = false,
				iLen = 0
			;

			this.selectedItemUseCallback = false;

			this.focusedItem(null);
			this.selectedItem(null);

			if (Utils.isArray(aItems))
			{
				iLen = aCheckedCache.length;

				_.each(aItems, (oItem) => {

					var sUid = this.getItemUid(oItem);
					aUids.push(sUid);

					if (null !== mFocused && mFocused === sUid)
					{
						this.focusedItem(oItem);
						mFocused = null;
					}

					if (0 < iLen && -1 < Utils.inArray(sUid, aCheckedCache))
					{
						bChecked = true;
						oItem.checked(true);
						iLen--;
					}

					if (!bChecked && null !== mSelected && mSelected === sUid)
					{
						bSelected = true;
						this.selectedItem(oItem);
						mSelected = null;
					}
				});

				this.selectedItemUseCallback = true;

				if (!bChecked && !bSelected && this.autoSelect())
				{
					if (this.focusedItem())
					{
						this.selectedItem(this.focusedItem());
					}
					else if (0 < aItems.length)
					{
						if (null !== mNextFocused)
						{
							bGetNext = false;
							mNextFocused = _.find(aCache, (sUid) => {
								if (bGetNext && -1 < Utils.inArray(sUid, aUids))
								{
									return sUid;
								}
								else if (mNextFocused === sUid)
								{
									bGetNext = true;
								}
								return false;
							});

							if (mNextFocused)
							{
								oTemp = _.find(aItems, (oItem) => mNextFocused === this.getItemUid(oItem));
							}
						}

						this.selectedItem(oTemp || null);
						this.focusedItem(this.selectedItem());
					}
				}

				if ((0 !== this.iSelectNextHelper || 0 !== this.iFocusedNextHelper) && 0 < aItems.length && !this.focusedItem())
				{
					oTemp = null;
					if (0 !== this.iFocusedNextHelper)
					{
						oTemp = aItems[-1 === this.iFocusedNextHelper ? aItems.length - 1 : 0] || null;
					}

					if (!oTemp && 0 !== this.iSelectNextHelper)
					{
						oTemp = aItems[-1 === this.iSelectNextHelper ? aItems.length - 1 : 0] || null;
					}

					if (oTemp)
					{
						if (0 !== this.iSelectNextHelper)
						{
							this.selectedItem(oTemp || null);
						}

						this.focusedItem(oTemp || null);

						this.scrollToFocused();

						_.delay(() => this.scrollToFocused(), 100);
					}

					this.iSelectNextHelper = 0;
					this.iFocusedNextHelper = 0;
				}
			}

			aCache = [];
			aCheckedCache = [];
			mFocused = null;
			mSelected = null;

		}, this);
	}

	itemSelected(item) {

		if (this.isListChecked())
		{
			if (!item)
			{
				(this.oCallbacks['onItemSelect'] || this.emptyFunction)(item || null);
			}
		}
		else
		{
			if (item)
			{
				(this.oCallbacks['onItemSelect'] || this.emptyFunction)(item);
			}
		}
	}

	/**
	 * @param {boolean} forceSelect
	 */
	goDown(forceSelect) {
		this.newSelectPosition(EventKeyCode.Down, false, forceSelect);
	}

	/**
	 * @param {boolean} forceSelect
	 */
	goUp(forceSelect) {
		this.newSelectPosition(EventKeyCode.Up, false, forceSelect);
	}

	unselect() {
		this.selectedItem(null);
		this.focusedItem(null);
	}

	init(contentVisible, contentScrollable, keyScope = 'all') {

		this.oContentVisible = contentVisible;
		this.oContentScrollable = contentScrollable;

		if (this.oContentVisible && this.oContentScrollable)
		{
			$(this.oContentVisible)
				.on('selectstart', (event) => {
					if (event && event.preventDefault)
					{
						event.preventDefault();
					}
				})
				.on('click', this.sItemSelector, (event) => {
					this.actionClick(ko.dataFor(event.currentTarget), event);
				})
				.on('click', this.sItemCheckedSelector, (event) => {
					const item = ko.dataFor(event.currentTarget);
					if (item)
					{
						if (event && event.shiftKey)
						{
							this.actionClick(item, event);
						}
						else
						{
							this.focusedItem(item);
							item.checked(!item.checked());
						}
					}
				})
			;

			key('enter', keyScope, () => {
				if (this.focusedItem() && !this.focusedItem().selected())
				{
					this.actionClick(this.focusedItem());
					return false;
				}

				return true;
			});

			key('ctrl+up, command+up, ctrl+down, command+down', keyScope, () => false);

			key('up, shift+up, down, shift+down, home, end, pageup, pagedown, insert, space', keyScope, (event, handler) => {
				if (event && handler && handler.shortcut)
				{
					let eventKey = 0;
					switch (handler.shortcut)
					{
						case 'up':
						case 'shift+up':
							eventKey = EventKeyCode.Up;
							break;
						case 'down':
						case 'shift+down':
							eventKey = EventKeyCode.Down;
							break;
						case 'insert':
							eventKey = EventKeyCode.Insert;
							break;
						case 'space':
							eventKey = EventKeyCode.Space;
							break;
						case 'home':
							eventKey = EventKeyCode.Home;
							break;
						case 'end':
							eventKey = EventKeyCode.End;
							break;
						case 'pageup':
							eventKey = EventKeyCode.PageUp;
							break;
						case 'pagedown':
							eventKey = EventKeyCode.PageDown;
							break;
					}

					if (0 < eventKey)
					{
						this.newSelectPosition(eventKey, key.shift);
						return false;
					}
				}
			});
		}
	}

	/**
	 * @return {boolean}
	 */
	autoSelect() {
		return !!(this.oCallbacks['onAutoSelect'] || this.emptyTrueFunction)();
	}

	/**
	 * @param {boolean} up
	 */
	doUpUpOrDownDown(up) {
		(this.oCallbacks['onUpUpOrDownDown'] || this.emptyTrueFunction)(!!up);
	}

	/**
	 * @param {Object} oItem
	 * @return {string}
	 */
	getItemUid(item) {

		let uid = '';

		const getItemUidCallback = this.oCallbacks['onItemGetUid'] || null;
		if (getItemUidCallback && item)
		{
			uid = getItemUidCallback(item);
		}

		return uid.toString();
	}

	/**
	 * @param {number} iEventKeyCode
	 * @param {boolean} bShiftKey
	 * @param {boolean=} bForceSelect = false
	 */
	newSelectPosition(iEventKeyCode, bShiftKey, bForceSelect) {

		var
			iIndex = 0,
			iPageStep = 10,
			bNext = false,
			bStop = false,
			oResult = null,
			aList = this.list(),
			iListLen = aList ? aList.length : 0,
			oFocused = this.focusedItem()
		;

		if (0 < iListLen)
		{
			if (!oFocused)
			{
				if (EventKeyCode.Down === iEventKeyCode || EventKeyCode.Insert === iEventKeyCode || EventKeyCode.Space === iEventKeyCode || EventKeyCode.Home === iEventKeyCode || EventKeyCode.PageUp === iEventKeyCode)
				{
					oResult = aList[0];
				}
				else if (EventKeyCode.Up === iEventKeyCode || EventKeyCode.End === iEventKeyCode || EventKeyCode.PageDown === iEventKeyCode)
				{
					oResult = aList[aList.length - 1];
				}
			}
			else if (oFocused)
			{
				if (EventKeyCode.Down === iEventKeyCode || EventKeyCode.Up === iEventKeyCode ||  EventKeyCode.Insert === iEventKeyCode || EventKeyCode.Space === iEventKeyCode)
				{
					_.each(aList, (item) => {
						if (!bStop)
						{
							switch (iEventKeyCode) {
							case EventKeyCode.Up:
								if (oFocused === item)
								{
									bStop = true;
								}
								else
								{
									oResult = item;
								}
								break;
							case EventKeyCode.Down:
							case EventKeyCode.Insert:
								if (bNext)
								{
									oResult = item;
									bStop = true;
								}
								else if (oFocused === item)
								{
									bNext = true;
								}
								break;
							}
						}
					});

					if (!oResult && (EventKeyCode.Down === iEventKeyCode || EventKeyCode.Up === iEventKeyCode))
					{
						this.doUpUpOrDownDown(EventKeyCode.Up === iEventKeyCode);
					}
				}
				else if (EventKeyCode.Home === iEventKeyCode || EventKeyCode.End === iEventKeyCode)
				{
					if (EventKeyCode.Home === iEventKeyCode)
					{
						oResult = aList[0];
					}
					else if (EventKeyCode.End === iEventKeyCode)
					{
						oResult = aList[aList.length - 1];
					}
				}
				else if (EventKeyCode.PageDown === iEventKeyCode)
				{
					for (; iIndex < iListLen; iIndex++)
					{
						if (oFocused === aList[iIndex])
						{
							iIndex += iPageStep;
							iIndex = iListLen - 1 < iIndex ? iListLen - 1 : iIndex;
							oResult = aList[iIndex];
							break;
						}
					}
				}
				else if (EventKeyCode.PageUp === iEventKeyCode)
				{
					for (iIndex = iListLen; iIndex >= 0; iIndex--)
					{
						if (oFocused === aList[iIndex])
						{
							iIndex -= iPageStep;
							iIndex = 0 > iIndex ? 0 : iIndex;
							oResult = aList[iIndex];
							break;
						}
					}
				}
			}
		}

		if (oResult)
		{
			this.focusedItem(oResult);

			if (oFocused)
			{
				if (bShiftKey)
				{
					if (EventKeyCode.Up === iEventKeyCode || EventKeyCode.Down === iEventKeyCode)
					{
						oFocused.checked(!oFocused.checked());
					}
				}
				else if (EventKeyCode.Insert === iEventKeyCode || EventKeyCode.Space === iEventKeyCode)
				{
					oFocused.checked(!oFocused.checked());
				}
			}

			if ((this.autoSelect() || !!bForceSelect) &&
				!this.isListChecked() && EventKeyCode.Space !== iEventKeyCode)
			{
				this.selectedItem(oResult);
			}

			this.scrollToFocused();
		}
		else if (oFocused)
		{
			if (bShiftKey && (EventKeyCode.Up === iEventKeyCode || EventKeyCode.Down === iEventKeyCode))
			{
				oFocused.checked(!oFocused.checked());
			}
			else if (EventKeyCode.Insert === iEventKeyCode || EventKeyCode.Space === iEventKeyCode)
			{
				oFocused.checked(!oFocused.checked());
			}

			this.focusedItem(oFocused);
		}
	}

	/**
	 * @return {boolean}
	 */
	scrollToFocused() {

		if (!this.oContentVisible || !this.oContentScrollable)
		{
			return false;
		}

		const
			offset = 20,
			list = this.list(),
			$focused = $(this.sItemFocusedSelector, this.oContentScrollable),
			pos = $focused.position(),
			visibleHeight = this.oContentVisible.height(),
			focusedHeight = $focused.outerHeight()
		;

		if (list && list[0] && list[0].focused())
		{
			this.oContentScrollable.scrollTop(0);
			return true;
		}
		else if (pos && (pos.top < 0 || pos.top + focusedHeight > visibleHeight))
		{
			this.oContentScrollable.scrollTop(pos.top < 0 ?
				this.oContentScrollable.scrollTop() + pos.top - offset :
				this.oContentScrollable.scrollTop() + pos.top - visibleHeight + focusedHeight + offset
			);

			return true;
		}

		return false;
	}

	/**
	 * @param {boolean=} fast = false
	 * @return {boolean}
	 */
	scrollToTop(fast = false) {

		if (!this.oContentVisible || !this.oContentScrollable)
		{
			return false;
		}

		if (fast || 50 > this.oContentScrollable.scrollTop())
		{
			this.oContentScrollable.scrollTop(0);
		}
		else
		{
			this.oContentScrollable.stop().animate({'scrollTop': 0}, 200);
		}

		return true;
	}

	eventClickFunction(item, event) {

		let
			index = 0,
			length = 0,
			changeRange = false,
			isInRange = false,
			list = [],
			checked = false,
			listItem = null,
			lineUid = ''
		;

		const uid = this.getItemUid(item);
		if (event && event.shiftKey)
		{
			if ('' !== uid && '' !== this.sLastUid && uid !== this.sLastUid)
			{
				list = this.list();
				checked = item.checked();

				for (index = 0, length = list.length; index < length; index++)
				{
					listItem = list[index];
					lineUid = this.getItemUid(listItem);

					changeRange = false;
					if (lineUid === this.sLastUid || lineUid === uid)
					{
						changeRange = true;
					}

					if (changeRange)
					{
						isInRange = !isInRange;
					}

					if (isInRange || changeRange)
					{
						listItem.checked(checked);
					}
				}
			}
		}

		this.sLastUid = '' === uid ? '' : uid;
	}

	/**
	 * @param {Object} item
	 * @param {Object=} event
	 */
	actionClick = function (item, event = null) {

		if (item)
		{
			let click = true;
			if (event)
			{
				if (event.shiftKey && !(event.ctrlKey || event.metaKey) && !event.altKey)
				{
					click = false;
					if ('' === this.sLastUid)
					{
						this.sLastUid = this.getItemUid(item);
					}

					item.checked(!item.checked());
					this.eventClickFunction(item, event);

					this.focusedItem(item);
				}
				else if ((event.ctrlKey || event.metaKey) && !event.shiftKey && !event.altKey)
				{
					click = false;
					this.focusedItem(item);

					if (this.selectedItem() && item !== this.selectedItem())
					{
						this.selectedItem().checked(true);
					}

					item.checked(!item.checked());
				}
			}

			if (click)
			{
				this.selectMessageItem(item);
			}
		}
	}

	on(eventName, callback) {
		this.oCallbacks[eventName] = callback;
	}

	selectMessageItem(messageItem) {
		this.focusedItem(messageItem);
		this.selectedItem(messageItem);
		this.scrollToFocused();
	}
}

export {Selector, Selector as default};
module.exports = Selector;