/*!
 * MediaWiki Widgets - CategoryMultiselectWidget class.
 *
 * @copyright 2011-2015 MediaWiki Widgets Team and others; see AUTHORS.txt
 * @license The MIT License (MIT); see LICENSE.txt
 */
( function () {
	const hasOwn = Object.prototype.hasOwnProperty,
		NS_CATEGORY = mw.config.get( 'wgNamespaceIds' ).category;

	/**
	 * @classdesc Displays an {@link OO.ui.MenuTagMultiselectWidget}
	 * and autocompletes with available categories.
	 *
	 * @example
	 * mw.loader.using( 'mediawiki.widgets.CategoryMultiselectWidget', function () {
	 *   let selector = new mw.widgets.CategoryMultiselectWidget( {
	 *     searchTypes: [
	 *       mw.widgets.CategoryMultiselectWidget.SearchType.OpenSearch,
	 *       mw.widgets.CategoryMultiselectWidget.SearchType.InternalSearch
	 *     ]
	 *   } );
	 *
	 *   $( document.body ).append( selector.$element );
	 *
	 *   selector.setSearchTypes( [ mw.widgets.CategoryMultiselectWidget.SearchType.SubCategories ] );
	 * } );
	 *
	 * @class mw.widgets.CategoryMultiselectWidget
	 * @uses mw.Api
	 * @extends OO.ui.MenuTagMultiselectWidget
	 * @mixes OO.ui.mixin.PendingElement
	 *
	 * @constructor
	 * @description Create an instance of `mw.widgets.CategoryMultiselectWidget`.
	 * @param {Object} [config] Configuration options
	 * @param {mw.Api} [config.api] Instance of mw.Api (or subclass thereof) to use for queries
	 * @param {number} [config.limit=10] Maximum number of results to load
	 * @param {mw.widgets.CategoryMultiselectWidget.SearchType[]} [config.searchTypes=[mw.widgets.CategoryMultiselectWidget.SearchType.OpenSearch]]
	 *   Default search API to use when searching.
	 */
	mw.widgets.CategoryMultiselectWidget = function MWCategoryMultiselectWidget( config ) {
		// Config initialization
		config = Object.assign( {
			limit: 10,
			searchTypes: [ mw.widgets.CategoryMultiselectWidget.SearchType.OpenSearch ],
			placeholder: mw.msg( 'mw-widgets-categoryselector-add-category-placeholder' )
		}, config );
		this.limit = config.limit;
		this.searchTypes = config.searchTypes;
		this.validateSearchTypes();

		// Parent constructor
		mw.widgets.CategoryMultiselectWidget.super.call( this, $.extend( true, {}, config, {
			menu: {
				filterFromInput: false
			},
			// This allows the user to both select non-existent categories, and prevents the selector from
			// being wiped from #onMenuItemsChange when we change the available options in the dropdown
			allowArbitrary: true
		} ) );

		// Mixin constructors
		OO.ui.mixin.PendingElement.call( this, Object.assign( {}, config, { $pending: this.$handle } ) );

		// Event handler to call the autocomplete methods
		this.input.$input.on( 'change input cut paste', OO.ui.debounce( this.updateMenuItems.bind( this ), 100 ) );

		// Initialize
		this.api = config.api || new mw.Api();
		this.searchCache = {};
	};

	/* Setup */

	OO.inheritClass( mw.widgets.CategoryMultiselectWidget, OO.ui.MenuTagMultiselectWidget );
	OO.mixinClass( mw.widgets.CategoryMultiselectWidget, OO.ui.mixin.PendingElement );

	/* Methods */

	/**
	 * Gets new items based on the input by calling
	 * {@link #getNewMenuItems getNewItems} and updates the menu
	 * after removing duplicates based on the data value.
	 *
	 * @private
	 * @method
	 */
	mw.widgets.CategoryMultiselectWidget.prototype.updateMenuItems = function () {
		this.getMenu().clearItems();
		this.getNewMenuItems( this.input.$input.val() ).then( ( items ) => {
			const menu = this.getMenu();

			// Never show the menu if the input lost focus in the meantime
			if ( !this.input.$input.is( ':focus' ) ) {
				return;
			}

			// Array of strings of the data of OO.ui.MenuOptionsWidgets
			const existingItems = menu.getItems().map( ( item ) => item.data );

			// Remove if items' data already exists
			let filteredItems = items.filter( ( item ) => !existingItems.includes( item ) );

			// Map to an array of OO.ui.MenuOptionWidgets
			filteredItems = filteredItems.map( ( item ) => new OO.ui.MenuOptionWidget( {
				data: item,
				label: item
			} ) );

			menu.addItems( filteredItems ).toggle( true );
		} );
	};

	/**
	 * @inheritdoc
	 */
	mw.widgets.CategoryMultiselectWidget.prototype.clearInput = function () {
		mw.widgets.CategoryMultiselectWidget.super.prototype.clearInput.call( this );
		// Abort all pending requests, we won't need their results
		this.api.abort();
	};

	/**
	 * Searches for categories based on the input.
	 *
	 * @private
	 * @method
	 * @param {string} input The input used to prefix search categories
	 * @return {jQuery.Promise} Resolves with an array of categories
	 */
	mw.widgets.CategoryMultiselectWidget.prototype.getNewMenuItems = function ( input ) {
		const deferred = $.Deferred();

		if ( input.trim() === '' ) {
			deferred.resolve( [] );
			return deferred.promise();
		}

		// Abort all pending requests, we won't need their results
		this.api.abort();
		const promises = [];
		for ( let i = 0; i < this.searchTypes.length; i++ ) {
			promises.push( this.searchCategories( input, this.searchTypes[ i ] ) );
		}

		this.pushPending();

		$.when( ...promises ).done( ( ...dataSets ) => {
			// Flatten array
			const allData = [].concat( ...dataSets );

			const categoryNames = allData
				// Remove duplicates
				.filter( ( value, index, arr ) => arr.indexOf( value ) === index )
				// Get Title objects
				.map( ( name ) => mw.Title.newFromText( name ) )
				// Keep only titles from 'Category' namespace
				.filter( ( title ) => title && title.getNamespaceId() === NS_CATEGORY )
				// Convert back to strings, strip 'Category:' prefix
				.map( ( title ) => title.getMainText() );

			deferred.resolve( categoryNames );

		} ).always( this.popPending.bind( this ) );

		return deferred.promise();
	};

	/**
	 * @inheritdoc
	 */
	mw.widgets.CategoryMultiselectWidget.prototype.isAllowedData = function ( data ) {
		const title = mw.Title.makeTitle( NS_CATEGORY, data );
		if ( !title ) {
			return false;
		}
		return mw.widgets.CategoryMultiselectWidget.super.prototype.isAllowedData.call( this, data );
	};

	/**
	 * @inheritdoc
	 */
	mw.widgets.CategoryMultiselectWidget.prototype.createTagItemWidget = function ( data ) {
		const title = mw.Title.makeTitle( NS_CATEGORY, data );

		return new mw.widgets.CategoryTagItemWidget( {
			apiUrl: this.api.apiUrl || undefined,
			title: title
		} );
	};

	/**
	 * @inheritdoc
	 */
	mw.widgets.CategoryMultiselectWidget.prototype.findItemFromData = function ( data ) {
		// This is a bit of a hack... We have to canonicalize the data in the same way that
		// #createItemWidget and CategoryTagItemWidget will do, otherwise we won't find duplicates.
		const title = mw.Title.makeTitle( NS_CATEGORY, data );
		if ( !title ) {
			return null;
		}
		return OO.ui.mixin.GroupElement.prototype.findItemFromData.call( this, title.getMainText() );
	};

	/**
	 * Validates the values in `this.searchType`.
	 *
	 * @private
	 * @return {boolean}
	 */
	mw.widgets.CategoryMultiselectWidget.prototype.validateSearchTypes = function () {
		let validSearchTypes = false;

		const searchTypeEnumCount = Object.keys( mw.widgets.CategoryMultiselectWidget.SearchType ).length;

		// Check if all values are in the SearchType enum
		validSearchTypes = this.searchTypes.every( ( searchType ) => searchType > -1 && searchType < searchTypeEnumCount );

		if ( validSearchTypes === false ) {
			throw new Error( 'Unknown searchType in searchTypes' );
		}

		// If the searchTypes has mw.widgets.CategoryMultiselectWidget.SearchType.SubCategories
		// it can be the only search type.
		if ( this.searchTypes.includes( mw.widgets.CategoryMultiselectWidget.SearchType.SubCategories ) &&
			this.searchTypes.length > 1
		) {
			throw new Error( 'Can\'t have additional search types with mw.widgets.CategoryMultiselectWidget.SearchType.SubCategories' );
		}

		// If the searchTypes has mw.widgets.CategoryMultiselectWidget.SearchType.ParentCategories
		// it can be the only search type.
		if ( this.searchTypes.includes( mw.widgets.CategoryMultiselectWidget.SearchType.ParentCategories ) &&
			this.searchTypes.length > 1
		) {
			throw new Error( 'Can\'t have additional search types with mw.widgets.CategoryMultiselectWidget.SearchType.ParentCategories' );
		}

		return true;
	};

	/**
	 * Sets and validates the value of `this.searchType`.
	 *
	 * @param {mw.widgets.CategoryMultiselectWidget.SearchType[]} searchTypes
	 */
	mw.widgets.CategoryMultiselectWidget.prototype.setSearchTypes = function ( searchTypes ) {
		this.searchTypes = searchTypes;
		this.validateSearchTypes();
	};

	/**
	 * Searches categories based on input and searchType.
	 *
	 * @private
	 * @method
	 * @param {string} input The input used to prefix search categories
	 * @param {mw.widgets.CategoryMultiselectWidget.SearchType} searchType
	 * @return {jQuery.Promise} Resolves with an array of categories
	 */
	mw.widgets.CategoryMultiselectWidget.prototype.searchCategories = function ( input, searchType ) {
		const deferred = $.Deferred(),
			cacheKey = input + searchType.toString();

		// Check cache
		if ( hasOwn.call( this.searchCache, cacheKey ) ) {
			return this.searchCache[ cacheKey ];
		}

		switch ( searchType ) {
			case mw.widgets.CategoryMultiselectWidget.SearchType.OpenSearch:
				this.api.get( {
					formatversion: 2,
					action: 'opensearch',
					namespace: NS_CATEGORY,
					limit: this.limit,
					search: input
				} ).done( ( res ) => {
					const categories = res[ 1 ];
					deferred.resolve( categories );
				} ).fail( deferred.reject.bind( deferred ) );
				break;

			case mw.widgets.CategoryMultiselectWidget.SearchType.InternalSearch:
				this.api.get( {
					formatversion: 2,
					action: 'query',
					list: 'allpages',
					apnamespace: NS_CATEGORY,
					aplimit: this.limit,
					apfrom: input,
					apprefix: input
				} ).done( ( res ) => {
					const categories = res.query.allpages.map( ( page ) => page.title );
					deferred.resolve( categories );
				} ).fail( deferred.reject.bind( deferred ) );
				break;

			case mw.widgets.CategoryMultiselectWidget.SearchType.Exists:
				if ( input.includes( '|' ) ) {
					deferred.resolve( [] );
					break;
				}

				this.api.get( {
					formatversion: 2,
					action: 'query',
					prop: 'info',
					titles: 'Category:' + input
				} ).done( ( res ) => {
					const categories = [];

					res.query.pages.forEach( ( page ) => {
						if ( !page.missing ) {
							categories.push( page.title );
						}
					} );

					deferred.resolve( categories );
				} ).fail( deferred.reject.bind( deferred ) );
				break;

			case mw.widgets.CategoryMultiselectWidget.SearchType.SubCategories:
				if ( input.includes( '|' ) ) {
					deferred.resolve( [] );
					break;
				}

				this.api.get( {
					formatversion: 2,
					action: 'query',
					list: 'categorymembers',
					cmtype: 'subcat',
					cmlimit: this.limit,
					cmtitle: 'Category:' + input
				} ).done( ( res ) => {
					const categories = res.query.categorymembers.map( ( category ) => category.title );
					deferred.resolve( categories );
				} ).fail( deferred.reject.bind( deferred ) );
				break;

			case mw.widgets.CategoryMultiselectWidget.SearchType.ParentCategories:
				if ( input.includes( '|' ) ) {
					deferred.resolve( [] );
					break;
				}

				this.api.get( {
					formatversion: 2,
					action: 'query',
					prop: 'categories',
					cllimit: this.limit,
					titles: 'Category:' + input
				} ).done( ( res ) => {
					const categories = [];

					res.query.pages.forEach( ( page ) => {
						if ( !page.missing && Array.isArray( page.categories ) ) {
							categories.push( ...page.categories.map( ( category ) => category.title ) );
						}
					} );

					deferred.resolve( categories );
				} ).fail( deferred.reject.bind( deferred ) );
				break;

			default:
				throw new Error( 'Unknown searchType' );
		}

		// Cache the result
		this.searchCache[ cacheKey ] = deferred.promise();

		return deferred.promise();
	};

	/**
	 * @enum mw.widgets.CategoryMultiselectWidget.SearchType
	 * Types of search available.
	 */
	mw.widgets.CategoryMultiselectWidget.SearchType = {
		/** Search using action=opensearch */
		OpenSearch: 0,

		/** Search using action=query */
		InternalSearch: 1,

		/** Search for existing categories with the exact title */
		Exists: 2,

		/** Search only subcategories */
		SubCategories: 3,

		/** Search only parent categories */
		ParentCategories: 4
	};
}() );
