/**
 * A widget that displays wikis and their pages to choose a filter
 *
 * @class
 * @extends OO.ui.SelectWidget
 *
 * @constructor
 * @param {mw.echo.dm.FiltersModel} filterModel Filters model
 * @param {string} source Symbolic name for the source
 * @param {Object} [config={}]
 * @param {string} [config.title] The title of this page group, usually
 *  the name of the wiki that the pages belong to
 * @param {number} [config.unreadCount] Number of unread notifications
 * @param {number} [config.initialSelection] The page title of the option to select initially
 */
mw.echo.ui.PageFilterWidget = function MwEchoUiPageFilterWidget( filterModel, source, config ) {
	config = config || {};

	// Parent constructor
	mw.echo.ui.PageFilterWidget.super.call( this, config );

	this.model = filterModel;
	this.source = source;
	// This is to be able to fetch and recognize this widget
	// according to its source. The source is, in this case,
	// unique per filter widget.
	this.data = this.source;
	this.totalCount = config.unreadCount || this.model.getSourceTotalCount( this.source );

	this.initialSelection = config.initialSelection;

	// Title option
	this.title = new mw.echo.ui.PageNotificationsOptionWidget( {
		label: config.title,
		title: config.title,
		count: this.totalCount,
		isCapped: true,
		data: null,
		classes: [ 'mw-echo-ui-pageFilterWidget-title' ]
	} );

	// Initialization
	this.populateDataFromModel();
	this.$element
		.addClass( 'mw-echo-ui-pageFilterWidget' )
		.attr( 'aria-label', mw.msg( 'echo-specialpage-pagefilterwidget-aria-label' ) );
};

/* Initialization */

OO.inheritClass( mw.echo.ui.PageFilterWidget, OO.ui.SelectWidget );

/**
 * Set the total count of this group
 *
 * @return {number} Total count
 */
mw.echo.ui.PageFilterWidget.prototype.getTotalCount = function () {
	return this.totalCount;
};

/**
 * Populate the widget from the model
 */
mw.echo.ui.PageFilterWidget.prototype.populateDataFromModel = function () {
	const optionWidgets = [],
		sourcePages = this.model.getSourcePages( this.source );

	for ( const title in sourcePages ) {
		const isUserPage = sourcePages[ title ].ns === mw.config.get( 'wgNamespaceIds' ).user;
		const widget = new mw.echo.ui.PageNotificationsOptionWidget( {
			label: isUserPage ? sourcePages[ title ].unprefixed : title,
			title: isUserPage ? sourcePages[ title ].unprefixed : title,
			icon: isUserPage ? 'userAvatar' : 'article',
			count: sourcePages[ title ].count,
			data: title,
			classes: [ 'mw-echo-ui-pageFilterWidget-page' ]
		} );
		optionWidgets.push( widget );

		if ( this.initialSelection === title ) {
			widget.setSelected( true );
		}
	}

	this.setItems( optionWidgets );
};

/**
 * Get the source associated with this filter
 *
 * @return {string} Source symbolic name
 */
mw.echo.ui.PageFilterWidget.prototype.getSource = function () {
	return this.source;
};

/**
 * Get the title item
 *
 * @return {mw.echo.ui.PageNotificationsOptionWidget} Page title item
 */
mw.echo.ui.PageFilterWidget.prototype.getTitleItem = function () {
	return this.title;
};

/**
 * Set the page items in this widget, in order
 *
 * @param {mw.echo.ui.PageNotificationsOptionWidget[]} items Item widgets to order and insert
 */
mw.echo.ui.PageFilterWidget.prototype.setItems = function ( items ) {
	this.clearItems();
	for ( let i = 0; i < items.length; i++ ) {
		const index = this.findInsertionIndex( items[ i ] );
		this.addItems( [ items[ i ] ], index );
	}

	// Add the title on top
	this.addItems( [ this.title ], 0 );
};

/**
 * Find the proper insertion index for ordering when inserting items
 *
 * @private
 * @param {mw.echo.ui.PageNotificationsOptionWidget} item Item widget
 * @return {number} Insertion index
 */
mw.echo.ui.PageFilterWidget.prototype.findInsertionIndex = function ( item ) {
	return OO.binarySearch(
		this.items,
		( otherItem ) => this.sortingFunction( item, otherItem ),
		true
	);
};

/**
 * Sorting function for item insertion
 *
 * @private
 * @param {mw.echo.ui.PageNotificationsOptionWidget} item Item widget
 * @param {mw.echo.ui.PageNotificationsOptionWidget} otherItem Another item widget
 * @return {number} Ordering value
 */
mw.echo.ui.PageFilterWidget.prototype.sortingFunction = function ( item, otherItem ) {
	return Number( otherItem.getCount() ) - Number( item.getCount() );
};
