import ko from 'ko';
import { koComputable } from 'External/ko';
import { doc, $htmlCL, elementById } from 'Common/Globals';
import { isFunction, forEachObjectValue, forEachObjectEntry } from 'Common/Utils';

let
	SCREENS = {},
	currentScreen = null,
	defaultScreenName = '';

const
	autofocus = dom => {
		const af = dom.querySelector('[autofocus]');
		af && af.focus();
	},

	visiblePopups = new Set,

	/**
	 * @param {string} screenName
	 * @returns {?Object}
	 */
	screen = screenName => screenName && null != SCREENS[screenName] ? SCREENS[screenName] : null,

	/**
	 * @param {Function} ViewModelClass
	 * @param {Object=} vmScreen
	 * @returns {*}
	 */
	buildViewModel = (ViewModelClass, vmScreen) => {
		if (ViewModelClass && !ViewModelClass.__builded) {
			let vmDom = null;
			const vm = new ViewModelClass(vmScreen),
				position = vm.viewType || '',
				dialog = ViewType.Popup === position,
				vmPlace = position ? doc.getElementById('rl-' + position.toLowerCase()) : null;

			ViewModelClass.__builded = true;
			ViewModelClass.__vm = vm;

			if (vmPlace) {
				vmDom = dialog
					? Element.fromHTML('<dialog id="V-'+ vm.viewModelTemplateID + '"></dialog>')
					: Element.fromHTML('<div id="V-'+ vm.viewModelTemplateID + '" hidden=""></div>');
				vmPlace.append(vmDom);

				vm.viewModelDom = vmDom;
				ViewModelClass.__dom = vmDom;

				if (ViewType.Popup === position) {
					vm.cancelCommand = vm.closeCommand = createCommand(() => hideScreenPopup(ViewModelClass));

					// Firefox / Safari HTMLDialogElement not defined
					if (!vmDom.showModal) {
						vmDom.classList.add('polyfill');
						vmDom.showModal = () => {
							if (!vmDom.backdrop) {
								vmDom.before(vmDom.backdrop = Element.fromHTML('<div class="dialog-backdrop"></div>'));
							}
							vmDom.setAttribute('open','');
							vmDom.open = true;
							vmDom.returnValue = null;
							vmDom.backdrop.hidden = false;
						};
						vmDom.close = v => {
							vmDom.backdrop.hidden = true;
							vmDom.returnValue = v;
							vmDom.removeAttribute('open', null);
							vmDom.open = false;
						};
					}

					// show/hide popup/modal
					const endShowHide = e => {
						if (e.target === vmDom) {
							if (vmDom.classList.contains('animate')) {
								autofocus(vmDom);
								vm.onShowWithDelay && vm.onShowWithDelay();
							} else {
								vmDom.close();
								vm.onHideWithDelay && vm.onHideWithDelay();
							}
						}
					};

					vm.modalVisibility.subscribe(value => {
						if (value) {
							visiblePopups.add(vm);
							vmDom.style.zIndex = 3000 + (visiblePopups.size * 2);
							vmDom.showModal();
							if (vmDom.backdrop) {
								vmDom.backdrop.style.zIndex = 3000 + visiblePopups.size;
							}
							vm.keyScope.set();
							requestAnimationFrame(() => { // wait just before the next paint
								vmDom.offsetHeight; // force a reflow
								vmDom.classList.add('animate'); // trigger the transitions
							});
						} else {
							visiblePopups.delete(vm);
							vm.onHide && vm.onHide();
							vm.keyScope.unset();
							vmDom.classList.remove('animate'); // trigger the transitions
						}
						arePopupsVisible(0 < visiblePopups.size);
/*
						// the old ko.bindingHandlers.modal
						const close = vmDom.querySelector('.close'),
							click = () => vm.modalVisibility(false);
						if (close) {
							close.addEventListener('click.koModal', click);
							ko.utils.domNodeDisposal.addDisposeCallback(vmDom, () =>
								close.removeEventListener('click.koModal', click)
							);
						}
*/
					});
					if ('ontransitionend' in vmDom) {
						vmDom.addEventListener('transitionend', endShowHide);
					} else {
						// For Edge < 79 and mobile browsers
						vm.modalVisibility.subscribe(() => ()=>setTimeout(endShowHide({target:vmDom}), 500));
					}
				}

				ko.applyBindingAccessorsToNode(
					vmDom,
					{
						i18nInit: true,
						template: () => ({ name: vm.viewModelTemplateID })
					},
					vm
				);

				vm.onBuild && vm.onBuild(vmDom);
				if (vm && ViewType.Popup === position) {
					vm.registerPopupKeyDown();
				}

				dispatchEvent(new CustomEvent('rl-view-model', {detail:vm}));
			} else {
				console.log('Cannot find view model position: ' + position);
			}
		}

		return ViewModelClass && ViewModelClass.__vm;
	},

	forEachViewModel = (screen, fn) => {
		screen.viewModels.forEach(ViewModelClass => {
			if (
				ViewModelClass.__vm &&
				ViewModelClass.__dom &&
				ViewType.Popup !== ViewModelClass.__vm.viewType
			) {
				fn(ViewModelClass.__vm, ViewModelClass.__dom);
			}
		});
	},

	hideScreen = (screenToHide, destroy) => {
		screenToHide.onHide && screenToHide.onHide();
		forEachViewModel(screenToHide, (vm, dom) => {
			dom.hidden = true;
			vm.onHide && vm.onHide();
			destroy && vm.viewModelDom.remove();
		});
	},

	/**
	 * @param {Function} ViewModelClassToHide
	 * @returns {void}
	 */
	hideScreenPopup = ViewModelClassToHide => {
		if (ViewModelClassToHide && ViewModelClassToHide.__vm && ViewModelClassToHide.__dom) {
			ViewModelClassToHide.__vm.modalVisibility(false);
		}
	},

	/**
	 * @param {string} screenName
	 * @param {string} subPart
	 * @returns {void}
	 */
	screenOnRoute = (screenName, subPart) => {
		let vmScreen = null,
			isSameScreen = false;

		if (null == screenName || '' == screenName) {
			screenName = defaultScreenName;
		}

		// Close all popups
		for (let vm of visiblePopups) {
			vm.closeCommand();
		}

		if (screenName) {
			vmScreen = screen(screenName);
			if (!vmScreen) {
				vmScreen = screen(defaultScreenName);
				if (vmScreen) {
					subPart = screenName + '/' + subPart;
					screenName = defaultScreenName;
				}
			}

			if (vmScreen && vmScreen.__started) {
				isSameScreen = currentScreen && vmScreen === currentScreen;

				if (!vmScreen.__builded) {
					vmScreen.__builded = true;

					vmScreen.viewModels.forEach(ViewModelClass =>
						buildViewModel(ViewModelClass, vmScreen)
					);

					vmScreen.onBuild && vmScreen.onBuild();
				}

				setTimeout(() => {
					// hide screen
					if (currentScreen && !isSameScreen) {
						hideScreen(currentScreen);
					}
					// --

					currentScreen = vmScreen;

					// show screen
					if (!isSameScreen) {
						vmScreen.onShow && vmScreen.onShow();

						forEachViewModel(vmScreen, (vm, dom) => {
							vm.onBeforeShow && vm.onBeforeShow();
							dom.hidden = false;
							vm.onShow && vm.onShow();
							autofocus(dom);
						});
					}
					// --

					vmScreen.__cross && vmScreen.__cross.parse(subPart);
				}, 1);
			}
		}
	};

export const
	ViewType = {
		Popup: 'Popups',
		Left: 'Left',
		Right: 'Right',
		Content: 'Content'
	},

	/**
	 * @param {Function} fExecute
	 * @param {(Function|boolean|null)=} fCanExecute = true
	 * @returns {Function}
	 */
	createCommand = (fExecute, fCanExecute) => {
		let fResult = () => {
				fResult.canExecute() && fExecute.call(null);
				return false;
			};
		fResult.enabled = ko.observable(true);
		fResult.canExecute = isFunction(fCanExecute)
			? koComputable(() => fResult.enabled() && fCanExecute())
			: fResult.enabled;
		return fResult;
	},

	getScreenPopupViewModel = ViewModelClassToShow =>
		(buildViewModel(ViewModelClassToShow) && ViewModelClassToShow.__dom) && ViewModelClassToShow.__vm,

	/**
	 * @param {Function} ViewModelClassToShow
	 * @param {Array=} params
	 * @returns {void}
	 */
	showScreenPopup = (ViewModelClassToShow, params = []) => {
		const vm = getScreenPopupViewModel(ViewModelClassToShow);
		if (vm) {
			params = params || [];

			vm.onBeforeShow && vm.onBeforeShow(...params);

			vm.modalVisibility(true);

			vm.onShow && vm.onShow(...params);
		}
	},

	arePopupsVisible = ko.observable(false),

	/**
	 * @param {Function} ViewModelClassToShow
	 * @returns {boolean}
	 */
	isPopupVisible = ViewModelClassToShow =>
		ViewModelClassToShow && ViewModelClassToShow.__vm && ViewModelClassToShow.__vm.modalVisibility(),

	/**
	 * @param {Array} screensClasses
	 * @returns {void}
	 */
	startScreens = screensClasses => {
		hasher.clear();
		forEachObjectValue(SCREENS, screen => hideScreen(screen, 1));
		SCREENS = {};
		currentScreen = null,
		defaultScreenName = '';

		screensClasses.forEach(CScreen => {
			if (CScreen) {
				const vmScreen = new CScreen(),
					screenName = vmScreen.screenName;
				defaultScreenName || (defaultScreenName = screenName);
				SCREENS[screenName] = vmScreen;
			}
		});

		forEachObjectValue(SCREENS, vmScreen => vmScreen.onStart());

		const cross = new Crossroads();
		cross.addRoute(/^([a-zA-Z0-9-]*)\/?(.*)$/, screenOnRoute);

		hasher.add(cross.parse.bind(cross));
		hasher.init();

		setTimeout(() => $htmlCL.remove('rl-started-trigger'), 100);

		const c = elementById('rl-content'), l = elementById('rl-loading');
		c && (c.hidden = false);
		l && l.remove();
	},

	decorateKoCommands = (thisArg, commands) =>
		forEachObjectEntry(commands, (key, canExecute) => {
			let command = thisArg[key],
				fn = (...args) => fn.enabled() && fn.canExecute() && command.apply(thisArg, args);

	//		fn.__realCanExecute = canExecute;

			fn.enabled = ko.observable(true);

			fn.canExecute = isFunction(canExecute)
				? koComputable(() => fn.enabled() && canExecute.call(thisArg, thisArg))
				: koComputable(() => fn.enabled());

			thisArg[key] = fn;
		});

ko.decorateCommands = decorateKoCommands;