Update OOUI to v0.31.5

[lhc/web/wiklou.git] / resources / lib / ooui / oojs-ui-widgets.js

/*!
 * OOUI v0.31.5
 * https://www.mediawiki.org/wiki/OOUI
 *
 * Copyright 2011–2019 OOUI Team and other contributors.
 * Released under the MIT license
 * http://oojs.mit-license.org
 *
 * Date: 2019-04-24T18:29:08Z
 */
( function ( OO ) {

'use strict';

/**
 * DraggableElement is a mixin class used to create elements that can be clicked
 * and dragged by a mouse to a new position within a group. This class must be used
 * in conjunction with OO.ui.mixin.DraggableGroupElement, which provides a container for
 * the draggable elements.
 *
 * @abstract
 * @class
 *
 * @constructor
 * @param {Object} [config] Configuration options
 * @cfg {jQuery} [$handle] The part of the element which can be used for dragging, defaults to
 *  the whole element
 * @cfg {boolean} [draggable] The items are draggable. This can change with #toggleDraggable
 *  but the draggable state should be called from the DraggableGroupElement, which updates
 *  the whole group
 */
OO.ui.mixin.DraggableElement = function OoUiMixinDraggableElement( config ) {
        config = config || {};

        // Properties
        this.index = null;
        this.$handle = config.$handle || this.$element;
        this.wasHandleUsed = null;

        // Initialize and events
        this.$element
                .addClass( 'oo-ui-draggableElement' )
                .on( {
                        mousedown: this.onDragMouseDown.bind( this ),
                        dragstart: this.onDragStart.bind( this ),
                        dragover: this.onDragOver.bind( this ),
                        dragend: this.onDragEnd.bind( this ),
                        drop: this.onDrop.bind( this )
                } );
        this.$handle.addClass( 'oo-ui-draggableElement-handle' );
        this.toggleDraggable( config.draggable === undefined ? true : !!config.draggable );
};

OO.initClass( OO.ui.mixin.DraggableElement );

/* Events */

/**
 * @event dragstart
 *
 * A dragstart event is emitted when the user clicks and begins dragging an item.
 * @param {OO.ui.mixin.DraggableElement} item The item the user has clicked and is dragging with
 *  the mouse.
 */

/**
 * @event dragend
 * A dragend event is emitted when the user drags an item and releases the mouse,
 * thus terminating the drag operation.
 */

/**
 * @event drop
 * A drop event is emitted when the user drags an item and then releases the mouse button
 * over a valid target.
 */

/* Static Properties */

/**
 * @inheritdoc OO.ui.mixin.ButtonElement
 */
OO.ui.mixin.DraggableElement.static.cancelButtonMouseDownEvents = false;

/* Methods */

/**
 * Change the draggable state of this widget.
 * This allows users to temporarily halt the dragging operations.
 *
 * @param {boolean} isDraggable Widget supports draggable operations
 * @fires draggable
 */
OO.ui.mixin.DraggableElement.prototype.toggleDraggable = function ( isDraggable ) {
        isDraggable = isDraggable !== undefined ? !!isDraggable : !this.draggable;

        if ( this.draggable !== isDraggable ) {
                this.draggable = isDraggable;

                this.$handle.toggleClass( 'oo-ui-draggableElement-undraggable', !this.draggable );

                // We make the entire element draggable, not just the handle, so that
                // the whole element appears to move. wasHandleUsed prevents drags from
                // starting outside the handle
                this.$element.prop( 'draggable', this.draggable );
        }
};

/**
 * Check the draggable state of this widget.
 *
 * @return {boolean} Widget supports draggable operations
 */
OO.ui.mixin.DraggableElement.prototype.isDraggable = function () {
        return this.draggable;
};

/**
 * Respond to mousedown event.
 *
 * @private
 * @param {jQuery.Event} e Drag event
 */
OO.ui.mixin.DraggableElement.prototype.onDragMouseDown = function ( e ) {
        if ( !this.isDraggable() ) {
                return;
        }

        this.wasHandleUsed =
                // Optimization: if the handle is the whole element this is always true
                this.$handle[ 0 ] === this.$element[ 0 ] ||
                // Check the mousedown occurred inside the handle
                OO.ui.contains( this.$handle[ 0 ], e.target, true );
};

/**
 * Respond to dragstart event.
 *
 * @private
 * @param {jQuery.Event} e Drag event
 * @return {boolean} False if the event is cancelled
 * @fires dragstart
 */
OO.ui.mixin.DraggableElement.prototype.onDragStart = function ( e ) {
        var element = this,
                dataTransfer = e.originalEvent.dataTransfer;

        if ( !this.wasHandleUsed || !this.isDraggable() ) {
                return false;
        }

        // Define drop effect
        dataTransfer.dropEffect = 'none';
        dataTransfer.effectAllowed = 'move';
        // Support: Firefox
        // We must set up a dataTransfer data property or Firefox seems to
        // ignore the fact the element is draggable.
        try {
                dataTransfer.setData( 'application-x/OOUI-draggable', this.getIndex() );
        } catch ( err ) {
                // The above is only for Firefox. Move on if it fails.
        }
        // Briefly add a 'clone' class to style the browser's native drag image
        this.$element.addClass( 'oo-ui-draggableElement-clone' );
        // Add placeholder class after the browser has rendered the clone
        setTimeout( function () {
                element.$element
                        .removeClass( 'oo-ui-draggableElement-clone' )
                        .addClass( 'oo-ui-draggableElement-placeholder' );
        } );
        // Emit event
        this.emit( 'dragstart', this );
        return true;
};

/**
 * Respond to dragend event.
 *
 * @private
 * @fires dragend
 */
OO.ui.mixin.DraggableElement.prototype.onDragEnd = function () {
        this.$element.removeClass( 'oo-ui-draggableElement-placeholder' );
        this.emit( 'dragend' );
};

/**
 * Handle drop event.
 *
 * @private
 * @param {jQuery.Event} e Drop event
 * @fires drop
 */
OO.ui.mixin.DraggableElement.prototype.onDrop = function ( e ) {
        e.preventDefault();
        this.emit( 'drop', e );
};

/**
 * In order for drag/drop to work, the dragover event must
 * return false and stop propogation.
 *
 * @param {jQuery.Event} e Drag event
 * @private
 */
OO.ui.mixin.DraggableElement.prototype.onDragOver = function ( e ) {
        e.preventDefault();
};

/**
 * Set item index.
 * Store it in the DOM so we can access from the widget drag event.
 *
 * @private
 * @param {number} index Item index
 */
OO.ui.mixin.DraggableElement.prototype.setIndex = function ( index ) {
        if ( this.index !== index ) {
                this.index = index;
                this.$element.data( 'index', index );
        }
};

/**
 * Get item index.
 *
 * @private
 * @return {number} Item index
 */
OO.ui.mixin.DraggableElement.prototype.getIndex = function () {
        return this.index;
};

/**
 * DraggableGroupElement is a mixin class used to create a group element to
 * contain draggable elements, which are items that can be clicked and dragged by a mouse.
 * The class is used with OO.ui.mixin.DraggableElement.
 *
 * @abstract
 * @class
 * @mixins OO.ui.mixin.GroupElement
 *
 * @constructor
 * @param {Object} [config] Configuration options
 * @cfg {string} [orientation] Item orientation: 'horizontal' or 'vertical'. The orientation
 *  should match the layout of the items. Items displayed in a single row
 *  or in several rows should use horizontal orientation. The vertical orientation should only be
 *  used when the items are displayed in a single column. Defaults to 'vertical'
 * @cfg {boolean} [draggable] The items are draggable. This can change with #toggleDraggable
 */
OO.ui.mixin.DraggableGroupElement = function OoUiMixinDraggableGroupElement( config ) {
        // Configuration initialization
        config = config || {};

        // Parent constructor
        OO.ui.mixin.GroupElement.call( this, config );

        // Properties
        this.orientation = config.orientation || 'vertical';
        this.dragItem = null;
        this.itemKeys = {};
        this.dir = null;
        this.itemsOrder = null;
        this.draggable = config.draggable === undefined ? true : !!config.draggable;

        // Events
        this.aggregate( {
                dragstart: 'itemDragStart',
                dragend: 'itemDragEnd',
                drop: 'itemDrop'
        } );
        this.connect( this, {
                itemDragStart: 'onItemDragStart',
                itemDrop: 'onItemDropOrDragEnd',
                itemDragEnd: 'onItemDropOrDragEnd'
        } );

        // Initialize
        if ( Array.isArray( config.items ) ) {
                this.addItems( config.items );
        }
        this.$element
                .addClass( 'oo-ui-draggableGroupElement' )
                .toggleClass( 'oo-ui-draggableGroupElement-horizontal', this.orientation === 'horizontal' );
};

/* Setup */
OO.mixinClass( OO.ui.mixin.DraggableGroupElement, OO.ui.mixin.GroupElement );

/* Events */

/**
 * An item has been dragged to a new position, but not yet dropped.
 *
 * @event drag
 * @param {OO.ui.mixin.DraggableElement} item Dragged item
 * @param {number} [newIndex] New index for the item
 */

/**
 * An item has been dropped at a new position.
 *
 * @event reorder
 * @param {OO.ui.mixin.DraggableElement} item Reordered item
 * @param {number} [newIndex] New index for the item
 */

/**
 * Draggable state of this widget has changed.
 *
 * @event draggable
 * @param {boolean} [draggable] Widget is draggable
 */

/* Methods */

/**
 * Change the draggable state of this widget.
 * This allows users to temporarily halt the dragging operations.
 *
 * @param {boolean} isDraggable Widget supports draggable operations
 * @fires draggable
 */
OO.ui.mixin.DraggableGroupElement.prototype.toggleDraggable = function ( isDraggable ) {
        isDraggable = isDraggable !== undefined ? !!isDraggable : !this.draggable;

        if ( this.draggable !== isDraggable ) {
                this.draggable = isDraggable;

                // Tell the items their draggable state changed
                this.getItems().forEach( function ( item ) {
                        item.toggleDraggable( this.draggable );
                }.bind( this ) );

                // Emit event
                this.emit( 'draggable', this.draggable );
        }
};

/**
 * Check the draggable state of this widget
 *
 * @return {boolean} Widget supports draggable operations
 */
OO.ui.mixin.DraggableGroupElement.prototype.isDraggable = function () {
        return this.draggable;
};

/**
 * Respond to item drag start event
 *
 * @private
 * @param {OO.ui.mixin.DraggableElement} item Dragged item
 */
OO.ui.mixin.DraggableGroupElement.prototype.onItemDragStart = function ( item ) {
        if ( !this.isDraggable() ) {
                return;
        }
        // Make a shallow copy of this.items so we can re-order it during previews
        // without affecting the original array.
        this.itemsOrder = this.items.slice();
        this.updateIndexes();
        if ( this.orientation === 'horizontal' ) {
                // Calculate and cache directionality on drag start - it's a little
                // expensive and it shouldn't change while dragging.
                this.dir = this.$element.css( 'direction' );
        }
        this.setDragItem( item );
};

/**
 * Update the index properties of the items
 */
OO.ui.mixin.DraggableGroupElement.prototype.updateIndexes = function () {
        var i, len;

        // Map the index of each object
        for ( i = 0, len = this.itemsOrder.length; i < len; i++ ) {
                this.itemsOrder[ i ].setIndex( i );
        }
};

/**
 * Handle drop or dragend event and switch the order of the items accordingly
 *
 * @private
 * @param {OO.ui.mixin.DraggableElement} item Dropped item
 * @return {OO.ui.Element} The element, for chaining
 */
OO.ui.mixin.DraggableGroupElement.prototype.onItemDropOrDragEnd = function () {
        var targetIndex, originalIndex,
                item = this.getDragItem();

        // TODO: Figure out a way to configure a list of legally droppable
        // elements even if they are not yet in the list
        if ( item ) {
                originalIndex = this.items.indexOf( item );
                // If the item has moved forward, add one to the index to account for the left shift
                targetIndex = item.getIndex() + ( item.getIndex() > originalIndex ? 1 : 0 );
                if ( targetIndex !== originalIndex ) {
                        this.reorder( this.getDragItem(), targetIndex );
                        this.emit( 'reorder', this.getDragItem(), targetIndex );
                }
                this.updateIndexes();
        }
        this.unsetDragItem();
        // Return false to prevent propogation
        return false;
};

/**
 * Respond to dragover event
 *
 * @private
 * @param {jQuery.Event} e Dragover event
 * @fires reorder
 */
OO.ui.mixin.DraggableGroupElement.prototype.onDragOver = function ( e ) {
        var overIndex, targetIndex,
                item = this.getDragItem(),
                dragItemIndex = item.getIndex();

        // Get the OptionWidget item we are dragging over
        overIndex = $( e.target ).closest( '.oo-ui-draggableElement' ).data( 'index' );

        if ( overIndex !== undefined && overIndex !== dragItemIndex ) {
                targetIndex = overIndex + ( overIndex > dragItemIndex ? 1 : 0 );

                if ( targetIndex > 0 ) {
                        this.$group.children().eq( targetIndex - 1 ).after( item.$element );
                } else {
                        this.$group.prepend( item.$element );
                }
                // Move item in itemsOrder array
                this.itemsOrder.splice( overIndex, 0,
                        this.itemsOrder.splice( dragItemIndex, 1 )[ 0 ]
                );
                this.updateIndexes();
                this.emit( 'drag', item, targetIndex );
        }
        // Prevent default
        e.preventDefault();
};

/**
 * Reorder the items in the group
 *
 * @param {OO.ui.mixin.DraggableElement} item Reordered item
 * @param {number} newIndex New index
 */
OO.ui.mixin.DraggableGroupElement.prototype.reorder = function ( item, newIndex ) {
        this.addItems( [ item ], newIndex );
};

/**
 * Set a dragged item
 *
 * @param {OO.ui.mixin.DraggableElement} item Dragged item
 */
OO.ui.mixin.DraggableGroupElement.prototype.setDragItem = function ( item ) {
        if ( this.dragItem !== item ) {
                this.dragItem = item;
                this.$element.on( 'dragover', this.onDragOver.bind( this ) );
                this.$element.addClass( 'oo-ui-draggableGroupElement-dragging' );
        }
};

/**
 * Unset the current dragged item
 */
OO.ui.mixin.DraggableGroupElement.prototype.unsetDragItem = function () {
        if ( this.dragItem ) {
                this.dragItem = null;
                this.$element.off( 'dragover' );
                this.$element.removeClass( 'oo-ui-draggableGroupElement-dragging' );
        }
};

/**
 * Get the item that is currently being dragged.
 *
 * @return {OO.ui.mixin.DraggableElement|null} The currently dragged item, or `null` if no item is
 *  being dragged
 */
OO.ui.mixin.DraggableGroupElement.prototype.getDragItem = function () {
        return this.dragItem;
};

/**
 * RequestManager is a mixin that manages the lifecycle of a promise-backed request for a widget,
 * such as the {@link OO.ui.mixin.LookupElement}.
 *
 * @class
 * @abstract
 *
 * @constructor
 * @param {Object} [config] Configuration options
 * @cfg {boolean} [showPendingRequest=true] Show pending state while request data is being fetched.
 *  Requires widget to have also mixed in {@link OO.ui.mixin.PendingElement}.
 */
OO.ui.mixin.RequestManager = function OoUiMixinRequestManager( config ) {
        this.requestCache = {};
        this.requestQuery = null;
        this.requestRequest = null;
        this.showPendingRequest = !!this.pushPending && config.showPendingRequest !== false;
};

/* Setup */

OO.initClass( OO.ui.mixin.RequestManager );

/**
 * Get request results for the current query.
 *
 * @return {jQuery.Promise} Promise object which will be passed response data as the first argument
 *  of the done event. If the request was aborted to make way for a subsequent request, this
 *  promise may not be rejected, depending on what jQuery feels like doing.
 */
OO.ui.mixin.RequestManager.prototype.getRequestData = function () {
        var widget = this,
                value = this.getRequestQuery(),
                deferred = $.Deferred(),
                ourRequest;

        this.abortRequest();
        if ( Object.prototype.hasOwnProperty.call( this.requestCache, value ) ) {
                deferred.resolve( this.requestCache[ value ] );
        } else {
                if ( this.showPendingRequest ) {
                        this.pushPending();
                }
                this.requestQuery = value;
                ourRequest = this.requestRequest = this.getRequest();
                ourRequest
                        .always( function () {
                                // We need to pop pending even if this is an old request, otherwise
                                // the widget will remain pending forever.
                                // TODO: this assumes that an aborted request will fail or succeed soon after
                                // being aborted, or at least eventually. It would be nice if we could popPending()
                                // at abort time, but only if we knew that we hadn't already called popPending()
                                // for that request.
                                if ( widget.showPendingRequest ) {
                                        widget.popPending();
                                }
                        } )
                        .done( function ( response ) {
                                // If this is an old request (and aborting it somehow caused it to still succeed),
                                // ignore its success completely
                                if ( ourRequest === widget.requestRequest ) {
                                        widget.requestQuery = null;
                                        widget.requestRequest = null;
                                        widget.requestCache[ value ] =
                                                widget.getRequestCacheDataFromResponse( response );
                                        deferred.resolve( widget.requestCache[ value ] );
                                }
                        } )
                        .fail( function () {
                                // If this is an old request (or a request failing because it's being aborted),
                                // ignore its failure completely
                                if ( ourRequest === widget.requestRequest ) {
                                        widget.requestQuery = null;
                                        widget.requestRequest = null;
                                        deferred.reject();
                                }
                        } );
        }
        return deferred.promise();
};

/**
 * Abort the currently pending request, if any.
 *
 * @private
 */
OO.ui.mixin.RequestManager.prototype.abortRequest = function () {
        var oldRequest = this.requestRequest;
        if ( oldRequest ) {
                // First unset this.requestRequest to the fail handler will notice
                // that the request is no longer current
                this.requestRequest = null;
                this.requestQuery = null;
                oldRequest.abort();
        }
};

/**
 * Get the query to be made.
 *
 * @protected
 * @method
 * @abstract
 * @return {string} query to be used
 */
OO.ui.mixin.RequestManager.prototype.getRequestQuery = null;

/**
 * Get a new request object of the current query value.
 *
 * @protected
 * @method
 * @abstract
 * @return {jQuery.Promise} jQuery AJAX object, or promise object with an .abort() method
 */
OO.ui.mixin.RequestManager.prototype.getRequest = null;

/**
 * Pre-process data returned by the request from #getRequest.
 *
 * The return value of this function will be cached, and any further queries for the given value
 * will use the cache rather than doing API requests.
 *
 * @protected
 * @method
 * @abstract
 * @param {Mixed} response Response from server
 * @return {Mixed} Cached result data
 */
OO.ui.mixin.RequestManager.prototype.getRequestCacheDataFromResponse = null;

/**
 * LookupElement is a mixin that creates a {@link OO.ui.MenuSelectWidget menu} of suggested
 * values for a {@link OO.ui.TextInputWidget text input widget}. Suggested values are based on
 * the characters the user types into the text input field and, in general, the menu is only
 * displayed when the user types. If a suggested value is chosen from the lookup menu, that value
 * becomes the value of the input field.
 *
 * Note that a new menu of suggested items is displayed when a value is chosen from the
 * lookup menu. If this is not the desired behavior, disable lookup menus with the
 * #setLookupsDisabled method, then set the value, then re-enable lookups.
 *
 * See the [OOUI demos][1] for an example.
 *
 * [1]: https://doc.wikimedia.org/oojs-ui/master/demos/#LookupElement-try-inputting-an-integer
 *
 * @class
 * @abstract
 * @mixins OO.ui.mixin.RequestManager
 *
 * @constructor
 * @param {Object} [config] Configuration options
 * @cfg {jQuery} [$overlay] Overlay for the lookup menu; defaults to relative positioning.
 *  See <https://www.mediawiki.org/wiki/OOUI/Concepts#Overlays>.
 * @cfg {jQuery} [$container=this.$element] The container element. The lookup menu is rendered
 *  beneath the specified element.
 * @cfg {Object} [menu] Configuration options to pass to
 *  {@link OO.ui.MenuSelectWidget menu select widget}
 * @cfg {boolean} [allowSuggestionsWhenEmpty=false] Request and display a lookup menu when the
 *  text input is empty.
 *  By default, the lookup menu is not generated and displayed until the user begins to type.
 * @cfg {boolean} [highlightFirst=true] Whether the first lookup result should be highlighted
 *  (so, that the user can take it over into the input with simply pressing return) automatically
 *  or not.
 */
OO.ui.mixin.LookupElement = function OoUiMixinLookupElement( config ) {
        // Configuration initialization
        config = $.extend( { highlightFirst: true }, config );

        // Mixin constructors
        OO.ui.mixin.RequestManager.call( this, config );

        // Properties
        this.$overlay = ( config.$overlay === true ?
                OO.ui.getDefaultOverlay() : config.$overlay ) || this.$element;
        this.lookupMenu = new OO.ui.MenuSelectWidget( $.extend( {
                widget: this,
                input: this,
                $floatableContainer: config.$container || this.$element
        }, config.menu ) );

        this.allowSuggestionsWhenEmpty = config.allowSuggestionsWhenEmpty || false;

        this.lookupsDisabled = false;
        this.lookupInputFocused = false;
        this.lookupHighlightFirstItem = config.highlightFirst;

        // Events
        this.$input.on( {
                focus: this.onLookupInputFocus.bind( this ),
                blur: this.onLookupInputBlur.bind( this ),
                mousedown: this.onLookupInputMouseDown.bind( this )
        } );
        this.connect( this, {
                change: 'onLookupInputChange'
        } );
        this.lookupMenu.connect( this, {
                toggle: 'onLookupMenuToggle',
                choose: 'onLookupMenuItemChoose'
        } );

        // Initialization
        this.$input.attr( {
                role: 'combobox',
                'aria-owns': this.lookupMenu.getElementId(),
                'aria-autocomplete': 'list'
        } );
        this.$element.addClass( 'oo-ui-lookupElement' );
        this.lookupMenu.$element.addClass( 'oo-ui-lookupElement-menu' );
        this.$overlay.append( this.lookupMenu.$element );
};

/* Setup */

OO.mixinClass( OO.ui.mixin.LookupElement, OO.ui.mixin.RequestManager );

/* Methods */

/**
 * Handle input focus event.
 *
 * @protected
 * @param {jQuery.Event} e Input focus event
 */
OO.ui.mixin.LookupElement.prototype.onLookupInputFocus = function () {
        this.lookupInputFocused = true;
        this.populateLookupMenu();
};

/**
 * Handle input blur event.
 *
 * @protected
 * @param {jQuery.Event} e Input blur event
 */
OO.ui.mixin.LookupElement.prototype.onLookupInputBlur = function () {
        this.closeLookupMenu();
        this.lookupInputFocused = false;
};

/**
 * Handle input mouse down event.
 *
 * @protected
 * @param {jQuery.Event} e Input mouse down event
 */
OO.ui.mixin.LookupElement.prototype.onLookupInputMouseDown = function () {
        // Only open the menu if the input was already focused.
        // This way we allow the user to open the menu again after closing it with Escape (esc)
        // by clicking in the input. Opening (and populating) the menu when initially
        // clicking into the input is handled by the focus handler.
        if ( this.lookupInputFocused && !this.lookupMenu.isVisible() ) {
                this.populateLookupMenu();
        }
};

/**
 * Handle input change event.
 *
 * @protected
 * @param {string} value New input value
 */
OO.ui.mixin.LookupElement.prototype.onLookupInputChange = function () {
        if ( this.lookupInputFocused ) {
                this.populateLookupMenu();
        }
};

/**
 * Handle the lookup menu being shown/hidden.
 *
 * @protected
 * @param {boolean} visible Whether the lookup menu is now visible.
 */
OO.ui.mixin.LookupElement.prototype.onLookupMenuToggle = function ( visible ) {
        if ( !visible ) {
                // When the menu is hidden, abort any active request and clear the menu.
                // This has to be done here in addition to closeLookupMenu(), because
                // MenuSelectWidget will close itself when the user presses Escape (esc).
                this.abortLookupRequest();
                this.lookupMenu.clearItems();
        }
};

/**
 * Handle menu item 'choose' event, updating the text input value to the value of the clicked item.
 *
 * @protected
 * @param {OO.ui.MenuOptionWidget} item Selected item
 */
OO.ui.mixin.LookupElement.prototype.onLookupMenuItemChoose = function ( item ) {
        this.setValue( item.getData() );
};

/**
 * Get lookup menu.
 *
 * @private
 * @return {OO.ui.MenuSelectWidget}
 */
OO.ui.mixin.LookupElement.prototype.getLookupMenu = function () {
        return this.lookupMenu;
};

/**
 * Disable or re-enable lookups.
 *
 * When lookups are disabled, calls to #populateLookupMenu will be ignored.
 *
 * @param {boolean} disabled Disable lookups
 */
OO.ui.mixin.LookupElement.prototype.setLookupsDisabled = function ( disabled ) {
        this.lookupsDisabled = !!disabled;
};

/**
 * Open the menu. If there are no entries in the menu, this does nothing.
 *
 * @private
 * @chainable
 * @return {OO.ui.Element} The element, for chaining
 */
OO.ui.mixin.LookupElement.prototype.openLookupMenu = function () {
        if ( !this.lookupMenu.isEmpty() ) {
                this.lookupMenu.toggle( true );
        }
        return this;
};

/**
 * Close the menu, empty it, and abort any pending request.
 *
 * @private
 * @chainable
 * @return {OO.ui.Element} The element, for chaining
 */
OO.ui.mixin.LookupElement.prototype.closeLookupMenu = function () {
        this.lookupMenu.toggle( false );
        this.abortLookupRequest();
        this.lookupMenu.clearItems();
        return this;
};

/**
 * Request menu items based on the input's current value, and when they arrive,
 * populate the menu with these items and show the menu.
 *
 * If lookups have been disabled with #setLookupsDisabled, this function does nothing.
 *
 * @private
 * @chainable
 * @return {OO.ui.Element} The element, for chaining
 */
OO.ui.mixin.LookupElement.prototype.populateLookupMenu = function () {
        var widget = this,
                value = this.getValue();

        if ( this.lookupsDisabled || this.isReadOnly() ) {
                return;
        }

        // If the input is empty, clear the menu, unless suggestions when empty are allowed.
        if ( !this.allowSuggestionsWhenEmpty && value === '' ) {
                this.closeLookupMenu();
        // Skip population if there is already a request pending for the current value
        } else if ( value !== this.lookupQuery ) {
                this.getLookupMenuItems()
                        .done( function ( items ) {
                                widget.lookupMenu.clearItems();
                                if ( items.length ) {
                                        widget.lookupMenu
                                                .addItems( items )
                                                .toggle( true );
                                        widget.initializeLookupMenuSelection();
                                } else {
                                        widget.lookupMenu.toggle( false );
                                }
                        } )
                        .fail( function () {
                                widget.lookupMenu.clearItems();
                                widget.lookupMenu.toggle( false );
                        } );
        }

        return this;
};

/**
 * Highlight the first selectable item in the menu, if configured.
 *
 * @private
 * @chainable
 */
OO.ui.mixin.LookupElement.prototype.initializeLookupMenuSelection = function () {
        if ( this.lookupHighlightFirstItem && !this.lookupMenu.findSelectedItem() ) {
                this.lookupMenu.highlightItem( this.lookupMenu.findFirstSelectableItem() );
        }
};

/**
 * Get lookup menu items for the current query.
 *
 * @private
 * @return {jQuery.Promise} Promise object which will be passed menu items as the first argument of
 *   the done event. If the request was aborted to make way for a subsequent request, this promise
 *   will not be rejected: it will remain pending forever.
 */
OO.ui.mixin.LookupElement.prototype.getLookupMenuItems = function () {
        return this.getRequestData().then( function ( data ) {
                return this.getLookupMenuOptionsFromData( data );
        }.bind( this ) );
};

/**
 * Abort the currently pending lookup request, if any.
 *
 * @private
 */
OO.ui.mixin.LookupElement.prototype.abortLookupRequest = function () {
        this.abortRequest();
};

/**
 * Get a new request object of the current lookup query value.
 *
 * @protected
 * @method
 * @abstract
 * @return {jQuery.Promise} jQuery AJAX object, or promise object with an .abort() method
 */
OO.ui.mixin.LookupElement.prototype.getLookupRequest = null;

/**
 * Pre-process data returned by the request from #getLookupRequest.
 *
 * The return value of this function will be cached, and any further queries for the given value
 * will use the cache rather than doing API requests.
 *
 * @protected
 * @method
 * @abstract
 * @param {Mixed} response Response from server
 * @return {Mixed} Cached result data
 */
OO.ui.mixin.LookupElement.prototype.getLookupCacheDataFromResponse = null;

/**
 * Get a list of menu option widgets from the (possibly cached) data returned by
 * #getLookupCacheDataFromResponse.
 *
 * @protected
 * @method
 * @abstract
 * @param {Mixed} data Cached result data, usually an array
 * @return {OO.ui.MenuOptionWidget[]} Menu items
 */
OO.ui.mixin.LookupElement.prototype.getLookupMenuOptionsFromData = null;

/**
 * Set the read-only state of the widget.
 *
 * This will also disable/enable the lookups functionality.
 *
 * @param {boolean} readOnly Make input read-only
 * @chainable
 * @return {OO.ui.Element} The element, for chaining
 */
OO.ui.mixin.LookupElement.prototype.setReadOnly = function ( readOnly ) {
        // Parent method
        // Note: Calling #setReadOnly this way assumes this is mixed into an OO.ui.TextInputWidget
        OO.ui.TextInputWidget.prototype.setReadOnly.call( this, readOnly );

        // During construction, #setReadOnly is called before the OO.ui.mixin.LookupElement constructor.
        if ( this.isReadOnly() && this.lookupMenu ) {
                this.closeLookupMenu();
        }

        return this;
};

/**
 * @inheritdoc OO.ui.mixin.RequestManager
 */
OO.ui.mixin.LookupElement.prototype.getRequestQuery = function () {
        return this.getValue();
};

/**
 * @inheritdoc OO.ui.mixin.RequestManager
 */
OO.ui.mixin.LookupElement.prototype.getRequest = function () {
        return this.getLookupRequest();
};

/**
 * @inheritdoc OO.ui.mixin.RequestManager
 */
OO.ui.mixin.LookupElement.prototype.getRequestCacheDataFromResponse = function ( response ) {
        return this.getLookupCacheDataFromResponse( response );
};

/**
 * TabPanelLayouts are used within {@link OO.ui.IndexLayout index layouts} to create tab panels that
 * users can select and display from the index's optional {@link OO.ui.TabSelectWidget tab}
 * navigation. TabPanels are usually not instantiated directly, rather extended to include the
 * required content and functionality.
 *
 * Each tab panel must have a unique symbolic name, which is passed to the constructor. In addition,
 * the tab panel's tab item is customized (with a label) using the #setupTabItem method. See
 * {@link OO.ui.IndexLayout IndexLayout} for an example.
 *
 * @class
 * @extends OO.ui.PanelLayout
 *
 * @constructor
 * @param {string} name Unique symbolic name of tab panel
 * @param {Object} [config] Configuration options
 * @cfg {jQuery|string|Function|OO.ui.HtmlSnippet} [label] Label for tab panel's tab
 */
OO.ui.TabPanelLayout = function OoUiTabPanelLayout( name, config ) {
        // Allow passing positional parameters inside the config object
        if ( OO.isPlainObject( name ) && config === undefined ) {
                config = name;
                name = config.name;
        }

        // Configuration initialization
        config = $.extend( { scrollable: true }, config );

        // Parent constructor
        OO.ui.TabPanelLayout.parent.call( this, config );

        // Properties
        this.name = name;
        this.label = config.label;
        this.tabItem = null;
        this.active = false;

        // Initialization
        this.$element
                .addClass( 'oo-ui-tabPanelLayout' )
                .attr( 'role', 'tabpanel' );
};

/* Setup */

OO.inheritClass( OO.ui.TabPanelLayout, OO.ui.PanelLayout );

/* Events */

/**
 * An 'active' event is emitted when the tab panel becomes active. Tab panels become active when
 * they are shown in a index layout that is configured to display only one tab panel at a time.
 *
 * @event active
 * @param {boolean} active Tab panel is active
 */

/* Methods */

/**
 * Get the symbolic name of the tab panel.
 *
 * @return {string} Symbolic name of tab panel
 */
OO.ui.TabPanelLayout.prototype.getName = function () {
        return this.name;
};

/**
 * Check if tab panel is active.
 *
 * Tab panels become active when they are shown in a {@link OO.ui.IndexLayout index layout} that is
 * configured to display only one tab panel at a time. Additional CSS is applied to the tab panel's
 * tab item to reflect the active state.
 *
 * @return {boolean} Tab panel is active
 */
OO.ui.TabPanelLayout.prototype.isActive = function () {
        return this.active;
};

/**
 * Get tab item.
 *
 * The tab item allows users to access the tab panel from the index's tab
 * navigation. The tab item itself can be customized (with a label, level, etc.) using the
 * #setupTabItem method.
 *
 * @return {OO.ui.TabOptionWidget|null} Tab option widget
 */
OO.ui.TabPanelLayout.prototype.getTabItem = function () {
        return this.tabItem;
};

/**
 * Set or unset the tab item.
 *
 * Specify a {@link OO.ui.TabOptionWidget tab option} to set it,
 * or `null` to clear the tab item. To customize the tab item itself (e.g., to set a label or tab
 * level), use #setupTabItem instead of this method.
 *
 * @param {OO.ui.TabOptionWidget|null} tabItem Tab option widget, null to clear
 * @chainable
 * @return {OO.ui.TabPanelLayout} The layout, for chaining
 */
OO.ui.TabPanelLayout.prototype.setTabItem = function ( tabItem ) {
        this.tabItem = tabItem || null;
        if ( tabItem ) {
                this.setupTabItem();
        }
        return this;
};

/**
 * Set up the tab item.
 *
 * Use this method to customize the tab item (e.g., to add a label or tab level). To set or unset
 * the tab item itself (with a {@link OO.ui.TabOptionWidget tab option} or `null`), use
 * the #setTabItem method instead.
 *
 * @param {OO.ui.TabOptionWidget} tabItem Tab option widget to set up
 * @chainable
 * @return {OO.ui.TabPanelLayout} The layout, for chaining
 */
OO.ui.TabPanelLayout.prototype.setupTabItem = function () {
        this.$element.attr( 'aria-labelledby', this.tabItem.getElementId() );

        this.tabItem.$element.attr( 'aria-controls', this.getElementId() );

        if ( this.label ) {
                this.tabItem.setLabel( this.label );
        }
        return this;
};

/**
 * Set the tab panel to its 'active' state.
 *
 * Tab panels become active when they are shown in a index layout that is configured to display only
 * one tab panel at a time. Additional CSS is applied to the tab item to reflect the tab panel's
 * active state. Outside of the index context, setting the active state on a tab panel does nothing.
 *
 * @param {boolean} active Tab panel is active
 * @fires active
 */
OO.ui.TabPanelLayout.prototype.setActive = function ( active ) {
        active = !!active;

        if ( active !== this.active ) {
                this.active = active;
                this.$element.toggleClass( 'oo-ui-tabPanelLayout-active', this.active );
                this.emit( 'active', this.active );
        }
};

/**
 * PageLayouts are used within {@link OO.ui.BookletLayout booklet layouts} to create pages that
 * users can select and display from the booklet's optional
 * {@link OO.ui.OutlineSelectWidget outline} navigation. Pages are usually not instantiated
 * directly, rather extended to include the required content and functionality.
 *
 * Each page must have a unique symbolic name, which is passed to the constructor. In addition, the
 * page's outline item is customized (with a label, outline level, etc.) using the
 * #setupOutlineItem method. See {@link OO.ui.BookletLayout BookletLayout} for an example.
 *
 * @class
 * @extends OO.ui.PanelLayout
 *
 * @constructor
 * @param {string} name Unique symbolic name of page
 * @param {Object} [config] Configuration options
 */
OO.ui.PageLayout = function OoUiPageLayout( name, config ) {
        // Allow passing positional parameters inside the config object
        if ( OO.isPlainObject( name ) && config === undefined ) {
                config = name;
                name = config.name;
        }

        // Configuration initialization
        config = $.extend( { scrollable: true }, config );

        // Parent constructor
        OO.ui.PageLayout.parent.call( this, config );

        // Properties
        this.name = name;
        this.outlineItem = null;
        this.active = false;

        // Initialization
        this.$element.addClass( 'oo-ui-pageLayout' );
};

/* Setup */

OO.inheritClass( OO.ui.PageLayout, OO.ui.PanelLayout );

/* Events */

/**
 * An 'active' event is emitted when the page becomes active. Pages become active when they are
 * shown in a booklet layout that is configured to display only one page at a time.
 *
 * @event active
 * @param {boolean} active Page is active
 */

/* Methods */

/**
 * Get the symbolic name of the page.
 *
 * @return {string} Symbolic name of page
 */
OO.ui.PageLayout.prototype.getName = function () {
        return this.name;
};

/**
 * Check if page is active.
 *
 * Pages become active when they are shown in a {@link OO.ui.BookletLayout booklet layout} that is
 * configured to display only one page at a time. Additional CSS is applied to the page's outline
 * item to reflect the active state.
 *
 * @return {boolean} Page is active
 */
OO.ui.PageLayout.prototype.isActive = function () {
        return this.active;
};

/**
 * Get outline item.
 *
 * The outline item allows users to access the page from the booklet's outline
 * navigation. The outline item itself can be customized (with a label, level, etc.) using the
 * #setupOutlineItem method.
 *
 * @return {OO.ui.OutlineOptionWidget|null} Outline option widget
 */
OO.ui.PageLayout.prototype.getOutlineItem = function () {
        return this.outlineItem;
};

/**
 * Set or unset the outline item.
 *
 * Specify an {@link OO.ui.OutlineOptionWidget outline option} to set it,
 * or `null` to clear the outline item. To customize the outline item itself (e.g., to set a label
 * or outline level), use #setupOutlineItem instead of this method.
 *
 * @param {OO.ui.OutlineOptionWidget|null} outlineItem Outline option widget, null to clear
 * @chainable
 * @return {OO.ui.PageLayout} The layout, for chaining
 */
OO.ui.PageLayout.prototype.setOutlineItem = function ( outlineItem ) {
        this.outlineItem = outlineItem || null;
        if ( outlineItem ) {
                this.setupOutlineItem();
        }
        return this;
};

/**
 * Set up the outline item.
 *
 * Use this method to customize the outline item (e.g., to add a label or outline level). To set or
 * unset the outline item itself (with an {@link OO.ui.OutlineOptionWidget outline option} or
 * `null`), use the #setOutlineItem method instead.
 *
 * @param {OO.ui.OutlineOptionWidget} outlineItem Outline option widget to set up
 * @chainable
 * @return {OO.ui.PageLayout} The layout, for chaining
 */
OO.ui.PageLayout.prototype.setupOutlineItem = function () {
        return this;
};

/**
 * Set the page to its 'active' state.
 *
 * Pages become active when they are shown in a booklet layout that is configured to display only
 * one page at a time. Additional CSS is applied to the outline item to reflect the page's active
 * state. Outside of the booklet context, setting the active state on a page does nothing.
 *
 * @param {boolean} active Page is active
 * @fires active
 */
OO.ui.PageLayout.prototype.setActive = function ( active ) {
        active = !!active;

        if ( active !== this.active ) {
                this.active = active;
                this.$element.toggleClass( 'oo-ui-pageLayout-active', active );
                this.emit( 'active', this.active );
        }
};

/**
 * StackLayouts contain a series of {@link OO.ui.PanelLayout panel layouts}. By default, only one
 * panel is displayed at a time, though the stack layout can also be configured to show all
 * contained panels, one after another, by setting the #continuous option to 'true'.
 *
 *     @example
 *     // A stack layout with two panels, configured to be displayed continuously
 *     var myStack = new OO.ui.StackLayout( {
 *         items: [
 *             new OO.ui.PanelLayout( {
 *                 $content: $( '<p>Panel One</p>' ),
 *                 padded: true,
 *                 framed: true
 *             } ),
 *             new OO.ui.PanelLayout( {
 *                 $content: $( '<p>Panel Two</p>' ),
 *                 padded: true,
 *                 framed: true
 *             } )
 *         ],
 *         continuous: true
 *     } );
 *     $( document.body ).append( myStack.$element );
 *
 * @class
 * @extends OO.ui.PanelLayout
 * @mixins OO.ui.mixin.GroupElement
 *
 * @constructor
 * @param {Object} [config] Configuration options
 * @cfg {boolean} [continuous=false] Show all panels, one after another. By default, only one panel
 *  is displayed at a time.
 * @cfg {OO.ui.Layout[]} [items] Panel layouts to add to the stack layout.
 */
OO.ui.StackLayout = function OoUiStackLayout( config ) {
        // Configuration initialization
        // Make the layout scrollable in continuous mode, otherwise each
        // panel is responsible for its own scrolling.
        config = $.extend( { scrollable: !!( config && config.continuous ) }, config );

        // Parent constructor
        OO.ui.StackLayout.parent.call( this, config );

        // Mixin constructors
        OO.ui.mixin.GroupElement.call( this, $.extend( { $group: this.$element }, config ) );

        // Properties
        this.currentItem = null;
        this.continuous = !!config.continuous;

        // Initialization
        this.$element.addClass( 'oo-ui-stackLayout' );
        if ( this.continuous ) {
                this.$element.addClass( 'oo-ui-stackLayout-continuous' );
                this.$element.on( 'scroll', OO.ui.debounce( this.onScroll.bind( this ), 250 ) );
        }
        if ( Array.isArray( config.items ) ) {
                this.addItems( config.items );
        }
};

/* Setup */

OO.inheritClass( OO.ui.StackLayout, OO.ui.PanelLayout );
OO.mixinClass( OO.ui.StackLayout, OO.ui.mixin.GroupElement );

/* Events */

/**
 * A 'set' event is emitted when panels are {@link #addItems added}, {@link #removeItems removed},
 * {@link #clearItems cleared} or {@link #setItem displayed}.
 *
 * @event set
 * @param {OO.ui.Layout|null} item Current panel or `null` if no panel is shown
 */

/**
 * When used in continuous mode, this event is emitted when the user scrolls down
 * far enough such that currentItem is no longer visible.
 *
 * @event visibleItemChange
 * @param {OO.ui.PanelLayout} panel The next visible item in the layout
 */

/* Methods */

/**
 * Handle scroll events from the layout element
 *
 * @param {jQuery.Event} e
 * @fires visibleItemChange
 */
OO.ui.StackLayout.prototype.onScroll = function () {
        var currentRect,
                len = this.items.length,
                currentIndex = this.items.indexOf( this.currentItem ),
                newIndex = currentIndex,
                containerRect = this.$element[ 0 ].getBoundingClientRect();

        if ( !containerRect || ( !containerRect.top && !containerRect.bottom ) ) {
                // Can't get bounding rect, possibly not attached.
                return;
        }

        function getRect( item ) {
                return item.$element[ 0 ].getBoundingClientRect();
        }

        function isVisible( item ) {
                var rect = getRect( item );
                return rect.bottom > containerRect.top && rect.top < containerRect.bottom;
        }

        currentRect = getRect( this.currentItem );

        if ( currentRect.bottom < containerRect.top ) {
                // Scrolled down past current item
                while ( ++newIndex < len ) {
                        if ( isVisible( this.items[ newIndex ] ) ) {
                                break;
                        }
                }
        } else if ( currentRect.top > containerRect.bottom ) {
                // Scrolled up past current item
                while ( --newIndex >= 0 ) {
                        if ( isVisible( this.items[ newIndex ] ) ) {
                                break;
                        }
                }
        }

        if ( newIndex !== currentIndex ) {
                this.emit( 'visibleItemChange', this.items[ newIndex ] );
        }
};

/**
 * Get the current panel.
 *
 * @return {OO.ui.Layout|null}
 */
OO.ui.StackLayout.prototype.getCurrentItem = function () {
        return this.currentItem;
};

/**
 * Unset the current item.
 *
 * @private
 * @param {OO.ui.StackLayout} layout
 * @fires set
 */
OO.ui.StackLayout.prototype.unsetCurrentItem = function () {
        var prevItem = this.currentItem;
        if ( prevItem === null ) {
                return;
        }

        this.currentItem = null;
        this.emit( 'set', null );
};

/**
 * Add panel layouts to the stack layout.
 *
 * Panels will be added to the end of the stack layout array unless the optional index parameter
 * specifies a different insertion point. Adding a panel that is already in the stack will move it
 * to the end of the array or the point specified by the index.
 *
 * @param {OO.ui.Layout[]} items Panels to add
 * @param {number} [index] Index of the insertion point
 * @chainable
 * @return {OO.ui.StackLayout} The layout, for chaining
 */
OO.ui.StackLayout.prototype.addItems = function ( items, index ) {
        // Update the visibility
        this.updateHiddenState( items, this.currentItem );

        // Mixin method
        OO.ui.mixin.GroupElement.prototype.addItems.call( this, items, index );

        if ( !this.currentItem && items.length ) {
                this.setItem( items[ 0 ] );
        }

        return this;
};

/**
 * Remove the specified panels from the stack layout.
 *
 * Removed panels are detached from the DOM, not removed, so that they may be reused. To remove all
 * panels, you may wish to use the #clearItems method instead.
 *
 * @param {OO.ui.Layout[]} items Panels to remove
 * @chainable
 * @return {OO.ui.StackLayout} The layout, for chaining
 * @fires set
 */
OO.ui.StackLayout.prototype.removeItems = function ( items ) {
        // Mixin method
        OO.ui.mixin.GroupElement.prototype.removeItems.call( this, items );

        if ( items.indexOf( this.currentItem ) !== -1 ) {
                if ( this.items.length ) {
                        this.setItem( this.items[ 0 ] );
                } else {
                        this.unsetCurrentItem();
                }
        }

        return this;
};

/**
 * Clear all panels from the stack layout.
 *
 * Cleared panels are detached from the DOM, not removed, so that they may be reused. To remove only
 * a subset of panels, use the #removeItems method.
 *
 * @chainable
 * @return {OO.ui.StackLayout} The layout, for chaining
 * @fires set
 */
OO.ui.StackLayout.prototype.clearItems = function () {
        this.unsetCurrentItem();
        OO.ui.mixin.GroupElement.prototype.clearItems.call( this );

        return this;
};

/**
 * Show the specified panel.
 *
 * If another panel is currently displayed, it will be hidden.
 *
 * @param {OO.ui.Layout} item Panel to show
 * @chainable
 * @return {OO.ui.StackLayout} The layout, for chaining
 * @fires set
 */
OO.ui.StackLayout.prototype.setItem = function ( item ) {
        if ( item !== this.currentItem ) {
                this.updateHiddenState( this.items, item );

                if ( this.items.indexOf( item ) !== -1 ) {
                        this.currentItem = item;
                        this.emit( 'set', item );
                } else {
                        this.unsetCurrentItem();
                }
        }

        return this;
};

/**
 * Reset the scroll offset of all panels, or the container if continuous
 *
 * @inheritdoc
 */
OO.ui.StackLayout.prototype.resetScroll = function () {
        if ( this.continuous ) {
                // Parent method
                return OO.ui.StackLayout.parent.prototype.resetScroll.call( this );
        }
        // Reset each panel
        this.getItems().forEach( function ( panel ) {
                var hidden = panel.$element.hasClass( 'oo-ui-element-hidden' );
                // Scroll can only be reset when panel is visible
                panel.$element.removeClass( 'oo-ui-element-hidden' );
                panel.resetScroll();
                if ( hidden ) {
                        panel.$element.addClass( 'oo-ui-element-hidden' );
                }
        } );

        return this;
};

/**
 * Update the visibility of all items in case of non-continuous view.
 *
 * Ensure all items are hidden except for the selected one.
 * This method does nothing when the stack is continuous.
 *
 * @private
 * @param {OO.ui.Layout[]} items Item list iterate over
 * @param {OO.ui.Layout} [selectedItem] Selected item to show
 */
OO.ui.StackLayout.prototype.updateHiddenState = function ( items, selectedItem ) {
        var i, len;

        if ( !this.continuous ) {
                for ( i = 0, len = items.length; i < len; i++ ) {
                        if ( !selectedItem || selectedItem !== items[ i ] ) {
                                items[ i ].$element.addClass( 'oo-ui-element-hidden' );
                                items[ i ].$element.attr( 'aria-hidden', 'true' );
                        }
                }
                if ( selectedItem ) {
                        selectedItem.$element.removeClass( 'oo-ui-element-hidden' );
                        selectedItem.$element.removeAttr( 'aria-hidden' );
                }
        }
};

/**
 * MenuLayouts combine a menu and a content {@link OO.ui.PanelLayout panel}. The menu is positioned
 * relative to the content (after, before, top, or bottom) and its size is customized with the
 * #menuSize config. The content area will fill all remaining space.
 *
 *     @example
 *     var menuLayout,
 *         menuPanel = new OO.ui.PanelLayout( {
 *             padded: true,
 *             expanded: true,
 *             scrollable: true
 *         } ),
 *         contentPanel = new OO.ui.PanelLayout( {
 *             padded: true,
 *             expanded: true,
 *             scrollable: true
 *         } ),
 *         select = new OO.ui.SelectWidget( {
 *             items: [
 *                 new OO.ui.OptionWidget( {
 *                     data: 'before',
 *                     label: 'Before'
 *                 } ),
 *                 new OO.ui.OptionWidget( {
 *                     data: 'after',
 *                     label: 'After'
 *                 } ),
 *                 new OO.ui.OptionWidget( {
 *                     data: 'top',
 *                     label: 'Top'
 *                 } ),
 *                 new OO.ui.OptionWidget( {
 *                     data: 'bottom',
 *                     label: 'Bottom'
 *                 } )
 *              ]
 *         } ).on( 'select', function ( item ) {
 *            menuLayout.setMenuPosition( item.getData() );
 *         } );
 *
 *     menuLayout = new OO.ui.MenuLayout( {
 *         position: 'top',
 *         menuPanel: menuPanel,
 *         contentPanel: contentPanel
 *     } );
 *     menuLayout.$menu.append(
 *         menuPanel.$element.append( '<b>Menu panel</b>', select.$element )
 *     );
 *     menuLayout.$content.append(
 *         contentPanel.$element.append(
 *             '<b>Content panel</b>',
 *             '<p>Note that the menu is positioned relative to the content panel: ' +
 *             'top, bottom, after, before.</p>'
 *          )
 *     );
 *     $( document.body ).append( menuLayout.$element );
 *
 * If menu size needs to be overridden, it can be accomplished using CSS similar to the snippet
 * below. MenuLayout's CSS will override the appropriate values with 'auto' or '0' to display the
 * menu correctly. If `menuPosition` is known beforehand, CSS rules corresponding to other positions
 * may be omitted.
 *
 *     .oo-ui-menuLayout-menu {
 *         width: 200px;
 *         height: 200px;
 *     }
 *
 *     .oo-ui-menuLayout-content {
 *         top: 200px;
 *         left: 200px;
 *         right: 200px;
 *         bottom: 200px;
 *     }
 *
 * @class
 * @extends OO.ui.Layout
 *
 * @constructor
 * @param {Object} [config] Configuration options
 * @cfg {OO.ui.PanelLayout} [menuPanel] Menu panel
 * @cfg {OO.ui.PanelLayout} [contentPanel] Content panel
 * @cfg {boolean} [expanded=true] Expand the layout to fill the entire parent element.
 * @cfg {boolean} [showMenu=true] Show menu
 * @cfg {string} [menuPosition='before'] Position of menu: `top`, `after`, `bottom` or `before`
 */
OO.ui.MenuLayout = function OoUiMenuLayout( config ) {
        // Configuration initialization
        config = $.extend( {
                expanded: true,
                showMenu: true,
                menuPosition: 'before'
        }, config );

        // Parent constructor
        OO.ui.MenuLayout.parent.call( this, config );

        this.menuPanel = null;
        this.contentPanel = null;
        this.expanded = !!config.expanded;
        /**
         * Menu DOM node
         *
         * @property {jQuery}
         */
        this.$menu = $( '<div>' );
        /**
         * Content DOM node
         *
         * @property {jQuery}
         */
        this.$content = $( '<div>' );

        // Initialization
        this.$menu.addClass( 'oo-ui-menuLayout-menu' );
        this.$content.addClass( 'oo-ui-menuLayout-content' );
        this.$element.addClass( 'oo-ui-menuLayout' );
        if ( config.expanded ) {
                this.$element.addClass( 'oo-ui-menuLayout-expanded' );
        } else {
                this.$element.addClass( 'oo-ui-menuLayout-static' );
        }
        if ( config.menuPanel ) {
                this.setMenuPanel( config.menuPanel );
        }
        if ( config.contentPanel ) {
                this.setContentPanel( config.contentPanel );
        }
        this.setMenuPosition( config.menuPosition );
        this.toggleMenu( config.showMenu );
};

/* Setup */

OO.inheritClass( OO.ui.MenuLayout, OO.ui.Layout );

/* Methods */

/**
 * Toggle menu.
 *
 * @param {boolean} showMenu Show menu, omit to toggle
 * @chainable
 * @return {OO.ui.MenuLayout} The layout, for chaining
 */
OO.ui.MenuLayout.prototype.toggleMenu = function ( showMenu ) {
        showMenu = showMenu === undefined ? !this.showMenu : !!showMenu;

        if ( this.showMenu !== showMenu ) {
                this.showMenu = showMenu;
                this.$element
                        .toggleClass( 'oo-ui-menuLayout-showMenu', this.showMenu )
                        .toggleClass( 'oo-ui-menuLayout-hideMenu', !this.showMenu );
                this.$menu.attr( 'aria-hidden', this.showMenu ? 'false' : 'true' );
        }

        return this;
};

/**
 * Check if menu is visible
 *
 * @return {boolean} Menu is visible
 */
OO.ui.MenuLayout.prototype.isMenuVisible = function () {
        return this.showMenu;
};

/**
 * Set menu position.
 *
 * @param {string} position Position of menu, either `top`, `after`, `bottom` or `before`
 * @chainable
 * @return {OO.ui.MenuLayout} The layout, for chaining
 */
OO.ui.MenuLayout.prototype.setMenuPosition = function ( position ) {
        if ( [ 'top', 'bottom', 'before', 'after' ].indexOf( position ) === -1 ) {
                position = 'before';
        }

        this.$element.removeClass( 'oo-ui-menuLayout-' + this.menuPosition );
        this.menuPosition = position;
        if ( this.menuPosition === 'top' || this.menuPosition === 'before' ) {
                this.$element.append( this.$menu, this.$content );
        } else {
                this.$element.append( this.$content, this.$menu );
        }
        this.$element.addClass( 'oo-ui-menuLayout-' + position );

        return this;
};

/**
 * Get menu position.
 *
 * @return {string} Menu position
 */
OO.ui.MenuLayout.prototype.getMenuPosition = function () {
        return this.menuPosition;
};

/**
 * Set the menu panel.
 *
 * @param {OO.ui.PanelLayout} menuPanel Menu panel
 */
OO.ui.MenuLayout.prototype.setMenuPanel = function ( menuPanel ) {
        this.menuPanel = menuPanel;
        this.$menu.append( this.menuPanel.$element );
};

/**
 * Set the content panel.
 *
 * @param {OO.ui.PanelLayout} contentPanel Content panel
 */
OO.ui.MenuLayout.prototype.setContentPanel = function ( contentPanel ) {
        this.contentPanel = contentPanel;
        this.$content.append( this.contentPanel.$element );
};

/**
 * Clear the menu panel.
 */
OO.ui.MenuLayout.prototype.clearMenuPanel = function () {
        this.menuPanel = null;
        this.$menu.empty();
};

/**
 * Clear the content panel.
 */
OO.ui.MenuLayout.prototype.clearContentPanel = function () {
        this.contentPanel = null;
        this.$content.empty();
};

/**
 * Reset the scroll offset of all panels and the tab select widget
 *
 * @inheritdoc
 */
OO.ui.MenuLayout.prototype.resetScroll = function () {
        if ( this.menuPanel ) {
                this.menuPanel.resetScroll();
        }
        if ( this.contentPanel ) {
                this.contentPanel.resetScroll();
        }

        return this;
};

/**
 * BookletLayouts contain {@link OO.ui.PageLayout page layouts} as well as
 * an {@link OO.ui.OutlineSelectWidget outline} that allows users to easily navigate
 * through the pages and select which one to display. By default, only one page is
 * displayed at a time and the outline is hidden. When a user navigates to a new page,
 * the booklet layout automatically focuses on the first focusable element, unless the
 * default setting is changed. Optionally, booklets can be configured to show
 * {@link OO.ui.OutlineControlsWidget controls} for adding, moving, and removing items.
 *
 *     @example
 *     // Example of a BookletLayout that contains two PageLayouts.
 *
 *     function PageOneLayout( name, config ) {
 *         PageOneLayout.parent.call( this, name, config );
 *         this.$element.append( '<p>First page</p><p>(This booklet has an outline, displayed on ' +
 *         'the left)</p>' );
 *     }
 *     OO.inheritClass( PageOneLayout, OO.ui.PageLayout );
 *     PageOneLayout.prototype.setupOutlineItem = function () {
 *         this.outlineItem.setLabel( 'Page One' );
 *     };
 *
 *     function PageTwoLayout( name, config ) {
 *         PageTwoLayout.parent.call( this, name, config );
 *         this.$element.append( '<p>Second page</p>' );
 *     }
 *     OO.inheritClass( PageTwoLayout, OO.ui.PageLayout );
 *     PageTwoLayout.prototype.setupOutlineItem = function () {
 *         this.outlineItem.setLabel( 'Page Two' );
 *     };
 *
 *     var page1 = new PageOneLayout( 'one' ),
 *         page2 = new PageTwoLayout( 'two' );
 *
 *     var booklet = new OO.ui.BookletLayout( {
 *         outlined: true
 *     } );
 *
 *     booklet.addPages( [ page1, page2 ] );
 *     $( document.body ).append( booklet.$element );
 *
 * @class
 * @extends OO.ui.MenuLayout
 *
 * @constructor
 * @param {Object} [config] Configuration options
 * @cfg {boolean} [continuous=false] Show all pages, one after another
 * @cfg {boolean} [autoFocus=true] Focus on the first focusable element when a new page is
 *  displayed. Disabled on mobile.
 * @cfg {boolean} [outlined=false] Show the outline. The outline is used to navigate through the
 *  pages of the booklet.
 * @cfg {boolean} [editable=false] Show controls for adding, removing and reordering pages.
 */
OO.ui.BookletLayout = function OoUiBookletLayout( config ) {
        // Configuration initialization
        config = config || {};

        // Parent constructor
        OO.ui.BookletLayout.parent.call( this, config );

        // Properties
        this.currentPageName = null;
        this.pages = {};
        this.ignoreFocus = false;
        this.stackLayout = new OO.ui.StackLayout( {
                continuous: !!config.continuous,
                expanded: this.expanded
        } );
        this.setContentPanel( this.stackLayout );
        this.autoFocus = config.autoFocus === undefined || !!config.autoFocus;
        this.outlineVisible = false;
        this.outlined = !!config.outlined;
        if ( this.outlined ) {
                this.editable = !!config.editable;
                this.outlineControlsWidget = null;
                this.outlineSelectWidget = new OO.ui.OutlineSelectWidget();
                this.outlinePanel = new OO.ui.PanelLayout( {
                        expanded: this.expanded,
                        scrollable: true
                } );
                this.setMenuPanel( this.outlinePanel );
                this.outlineVisible = true;
                if ( this.editable ) {
                        this.outlineControlsWidget = new OO.ui.OutlineControlsWidget(
                                this.outlineSelectWidget
                        );
                }
        }
        this.toggleMenu( this.outlined );

        // Events
        this.stackLayout.connect( this, {
                set: 'onStackLayoutSet'
        } );
        if ( this.outlined ) {
                this.outlineSelectWidget.connect( this, {
                        select: 'onOutlineSelectWidgetSelect'
                } );
                this.scrolling = false;
                this.stackLayout.connect( this, {
                        visibleItemChange: 'onStackLayoutVisibleItemChange'
                } );
        }
        if ( this.autoFocus ) {
                // Event 'focus' does not bubble, but 'focusin' does
                this.stackLayout.$element.on( 'focusin', this.onStackLayoutFocus.bind( this ) );
        }

        // Initialization
        this.$element.addClass( 'oo-ui-bookletLayout' );
        this.stackLayout.$element.addClass( 'oo-ui-bookletLayout-stackLayout' );
        if ( this.outlined ) {
                this.outlinePanel.$element
                        .addClass( 'oo-ui-bookletLayout-outlinePanel' )
                        .append( this.outlineSelectWidget.$element );
                if ( this.editable ) {
                        this.outlinePanel.$element
                                .addClass( 'oo-ui-bookletLayout-outlinePanel-editable' )
                                .append( this.outlineControlsWidget.$element );
                }
        }
};

/* Setup */

OO.inheritClass( OO.ui.BookletLayout, OO.ui.MenuLayout );

/* Events */

/**
 * A 'set' event is emitted when a page is {@link #setPage set} to be displayed by the
 * booklet layout.
 * @event set
 * @param {OO.ui.PageLayout} page Current page
 */

/**
 * An 'add' event is emitted when pages are {@link #addPages added} to the booklet layout.
 *
 * @event add
 * @param {OO.ui.PageLayout[]} page Added pages
 * @param {number} index Index pages were added at
 */

/**
 * A 'remove' event is emitted when pages are {@link #clearPages cleared} or
 * {@link #removePages removed} from the booklet.
 *
 * @event remove
 * @param {OO.ui.PageLayout[]} pages Removed pages
 */

/* Methods */

/**
 * Handle stack layout focus.
 *
 * @private
 * @param {jQuery.Event} e Focusin event
 */
OO.ui.BookletLayout.prototype.onStackLayoutFocus = function ( e ) {
        var name, $target;

        // Find the page that an element was focused within
        $target = $( e.target ).closest( '.oo-ui-pageLayout' );
        for ( name in this.pages ) {
                // Check for page match, exclude current page to find only page changes
                if ( this.pages[ name ].$element[ 0 ] === $target[ 0 ] && name !== this.currentPageName ) {
                        this.setPage( name );
                        break;
                }
        }
};

/**
 * Handle visibleItemChange events from the stackLayout
 *
 * The next visible page is set as the current page by selecting it
 * in the outline
 *
 * @param {OO.ui.PageLayout} page The next visible page in the layout
 */
OO.ui.BookletLayout.prototype.onStackLayoutVisibleItemChange = function ( page ) {
        // Set a flag to so that the resulting call to #onStackLayoutSet doesn't
        // try and scroll the item into view again.
        this.scrolling = true;
        this.outlineSelectWidget.selectItemByData( page.getName() );
        this.scrolling = false;
};

/**
 * Handle stack layout set events.
 *
 * @private
 * @param {OO.ui.PanelLayout|null} page The page panel that is now the current panel
 */
OO.ui.BookletLayout.prototype.onStackLayoutSet = function ( page ) {
        var promise, layout = this;
        // If everything is unselected, do nothing
        if ( !page ) {
                return;
        }
        // For continuous BookletLayouts, scroll the selected page into view first
        if ( this.stackLayout.continuous && !this.scrolling ) {
                promise = page.scrollElementIntoView();
        } else {
                promise = $.Deferred().resolve();
        }
        // Focus the first element on the newly selected panel.
        // Don't focus if the page was set by scrolling.
        if ( this.autoFocus && !OO.ui.isMobile() && !this.scrolling ) {
                promise.done( function () {
                        layout.focus();
                } );
        }
};

/**
 * Focus the first input in the current page.
 *
 * If no page is selected, the first selectable page will be selected.
 * If the focus is already in an element on the current page, nothing will happen.
 *
 * @param {number} [itemIndex] A specific item to focus on
 */
OO.ui.BookletLayout.prototype.focus = function ( itemIndex ) {
        var page,
                items = this.stackLayout.getItems();

        if ( itemIndex !== undefined && items[ itemIndex ] ) {
                page = items[ itemIndex ];
        } else {
                page = this.stackLayout.getCurrentItem();
        }

        if ( !page && this.outlined ) {
                this.selectFirstSelectablePage();
                page = this.stackLayout.getCurrentItem();
        }
        if ( !page ) {
                return;
        }
        // Only change the focus if is not already in the current page
        if ( !OO.ui.contains( page.$element[ 0 ], this.getElementDocument().activeElement, true ) ) {
                page.focus();
        }
};

/**
 * Find the first focusable input in the booklet layout and focus
 * on it.
 */
OO.ui.BookletLayout.prototype.focusFirstFocusable = function () {
        OO.ui.findFocusable( this.stackLayout.$element ).focus();
};

/**
 * Handle outline widget select events.
 *
 * @private
 * @param {OO.ui.OptionWidget|null} item Selected item
 */
OO.ui.BookletLayout.prototype.onOutlineSelectWidgetSelect = function ( item ) {
        if ( item ) {
                this.setPage( item.getData() );
        }
};

/**
 * Check if booklet has an outline.
 *
 * @return {boolean} Booklet has an outline
 */
OO.ui.BookletLayout.prototype.isOutlined = function () {
        return this.outlined;
};

/**
 * Check if booklet has editing controls.
 *
 * @return {boolean} Booklet is editable
 */
OO.ui.BookletLayout.prototype.isEditable = function () {
        return this.editable;
};

/**
 * Check if booklet has a visible outline.
 *
 * @return {boolean} Outline is visible
 */
OO.ui.BookletLayout.prototype.isOutlineVisible = function () {
        return this.outlined && this.outlineVisible;
};

/**
 * Hide or show the outline.
 *
 * @param {boolean} [show] Show outline, omit to invert current state
 * @chainable
 * @return {OO.ui.BookletLayout} The layout, for chaining
 */
OO.ui.BookletLayout.prototype.toggleOutline = function ( show ) {
        var booklet = this;

        if ( this.outlined ) {
                show = show === undefined ? !this.outlineVisible : !!show;
                this.outlineVisible = show;
                this.toggleMenu( show );
                if ( show && this.editable ) {
                        // HACK: Kill dumb scrollbars when the sidebar stops animating, see T161798.
                        // Only necessary when outline controls are present, delay matches transition on
                        // `.oo-ui-menuLayout-menu`.
                        setTimeout( function () {
                                OO.ui.Element.static.reconsiderScrollbars( booklet.outlinePanel.$element[ 0 ] );
                        }, OO.ui.theme.getDialogTransitionDuration() );
                }
        }

        return this;
};

/**
 * Find the page closest to the specified page.
 *
 * @param {OO.ui.PageLayout} page Page to use as a reference point
 * @return {OO.ui.PageLayout|null} Page closest to the specified page
 */
OO.ui.BookletLayout.prototype.findClosestPage = function ( page ) {
        var next, prev, level,
                pages = this.stackLayout.getItems(),
                index = pages.indexOf( page );

        if ( index !== -1 ) {
                next = pages[ index + 1 ];
                prev = pages[ index - 1 ];
                // Prefer adjacent pages at the same level
                if ( this.outlined ) {
                        level = this.outlineSelectWidget.findItemFromData( page.getName() ).getLevel();
                        if (
                                prev &&
                                level === this.outlineSelectWidget.findItemFromData( prev.getName() ).getLevel()
                        ) {
                                return prev;
                        }
                        if (
                                next &&
                                level === this.outlineSelectWidget.findItemFromData( next.getName() ).getLevel()
                        ) {
                                return next;
                        }
                }
        }
        return prev || next || null;
};

/**
 * Get the outline widget.
 *
 * If the booklet is not outlined, the method will return `null`.
 *
 * @return {OO.ui.OutlineSelectWidget|null} Outline widget, or null if the booklet is not outlined
 */
OO.ui.BookletLayout.prototype.getOutline = function () {
        return this.outlineSelectWidget;
};

/**
 * Get the outline controls widget.
 *
 * If the outline is not editable, the method will return `null`.
 *
 * @return {OO.ui.OutlineControlsWidget|null} The outline controls widget.
 */
OO.ui.BookletLayout.prototype.getOutlineControls = function () {
        return this.outlineControlsWidget;
};

/**
 * Get a page by its symbolic name.
 *
 * @param {string} name Symbolic name of page
 * @return {OO.ui.PageLayout|undefined} Page, if found
 */
OO.ui.BookletLayout.prototype.getPage = function ( name ) {
        return this.pages[ name ];
};

/**
 * Get the current page.
 *
 * @return {OO.ui.PageLayout|undefined} Current page, if found
 */
OO.ui.BookletLayout.prototype.getCurrentPage = function () {
        var name = this.getCurrentPageName();
        return name ? this.getPage( name ) : undefined;
};

/**
 * Get the symbolic name of the current page.
 *
 * @return {string|null} Symbolic name of the current page
 */
OO.ui.BookletLayout.prototype.getCurrentPageName = function () {
        return this.currentPageName;
};

/**
 * Add pages to the booklet layout
 *
 * When pages are added with the same names as existing pages, the existing pages will be
 * automatically removed before the new pages are added.
 *
 * @param {OO.ui.PageLayout[]} pages Pages to add
 * @param {number} index Index of the insertion point
 * @fires add
 * @chainable
 * @return {OO.ui.BookletLayout} The layout, for chaining
 */
OO.ui.BookletLayout.prototype.addPages = function ( pages, index ) {
        var i, len, name, page, item, currentIndex,
                stackLayoutPages = this.stackLayout.getItems(),
                remove = [],
                items = [];

        // Remove pages with same names
        for ( i = 0, len = pages.length; i < len; i++ ) {
                page = pages[ i ];
                name = page.getName();

                if ( Object.prototype.hasOwnProperty.call( this.pages, name ) ) {
                        // Correct the insertion index
                        currentIndex = stackLayoutPages.indexOf( this.pages[ name ] );
                        if ( currentIndex !== -1 && currentIndex + 1 < index ) {
                                index--;
                        }
                        remove.push( this.pages[ name ] );
                }
        }
        if ( remove.length ) {
                this.removePages( remove );
        }

        // Add new pages
        for ( i = 0, len = pages.length; i < len; i++ ) {
                page = pages[ i ];
                name = page.getName();
                this.pages[ page.getName() ] = page;
                if ( this.outlined ) {
                        item = new OO.ui.OutlineOptionWidget( { data: name } );
                        page.setOutlineItem( item );
                        items.push( item );
                }
        }

        if ( this.outlined && items.length ) {
                this.outlineSelectWidget.addItems( items, index );
                this.selectFirstSelectablePage();
        }
        this.stackLayout.addItems( pages, index );
        this.emit( 'add', pages, index );

        return this;
};

/**
 * Remove the specified pages from the booklet layout.
 *
 * To remove all pages from the booklet, you may wish to use the #clearPages method instead.
 *
 * @param {OO.ui.PageLayout[]} pages An array of pages to remove
 * @fires remove
 * @chainable
 * @return {OO.ui.BookletLayout} The layout, for chaining
 */
OO.ui.BookletLayout.prototype.removePages = function ( pages ) {
        var i, len, name, page,
                items = [];

        for ( i = 0, len = pages.length; i < len; i++ ) {
                page = pages[ i ];
                name = page.getName();
                delete this.pages[ name ];
                if ( this.outlined ) {
                        items.push( this.outlineSelectWidget.findItemFromData( name ) );
                        page.setOutlineItem( null );
                }
        }
        if ( this.outlined && items.length ) {
                this.outlineSelectWidget.removeItems( items );
                this.selectFirstSelectablePage();
        }
        this.stackLayout.removeItems( pages );
        this.emit( 'remove', pages );

        return this;
};

/**
 * Clear all pages from the booklet layout.
 *
 * To remove only a subset of pages from the booklet, use the #removePages method.
 *
 * @fires remove
 * @chainable
 * @return {OO.ui.BookletLayout} The layout, for chaining
 */
OO.ui.BookletLayout.prototype.clearPages = function () {
        var i, len,
                pages = this.stackLayout.getItems();

        this.pages = {};
        this.currentPageName = null;
        if ( this.outlined ) {
                this.outlineSelectWidget.clearItems();
                for ( i = 0, len = pages.length; i < len; i++ ) {
                        pages[ i ].setOutlineItem( null );
                }
        }
        this.stackLayout.clearItems();

        this.emit( 'remove', pages );

        return this;
};

/**
 * Set the current page by symbolic name.
 *
 * @fires set
 * @param {string} name Symbolic name of page
 */
OO.ui.BookletLayout.prototype.setPage = function ( name ) {
        var selectedItem,
                $focused,
                page = this.pages[ name ],
                previousPage = this.currentPageName && this.pages[ this.currentPageName ];

        if ( name !== this.currentPageName ) {
                if ( this.outlined ) {
                        selectedItem = this.outlineSelectWidget.findSelectedItem();
                        if ( selectedItem && selectedItem.getData() !== name ) {
                                this.outlineSelectWidget.selectItemByData( name );
                        }
                }
                if ( page ) {
                        if ( previousPage ) {
                                previousPage.setActive( false );
                                // Blur anything focused if the next page doesn't have anything focusable.
                                // This is not needed if the next page has something focusable (because once it is
                                // focused this blur happens automatically). If the layout is non-continuous, this
                                // check is meaningless because the next page is not visible yet and thus can't
                                // hold focus.
                                if (
                                        this.autoFocus &&
                                        !OO.ui.isMobile() &&
                                        this.stackLayout.continuous &&
                                        OO.ui.findFocusable( page.$element ).length !== 0
                                ) {
                                        $focused = previousPage.$element.find( ':focus' );
                                        if ( $focused.length ) {
                                                $focused[ 0 ].blur();
                                        }
                                }
                        }
                        this.currentPageName = name;
                        page.setActive( true );
                        this.stackLayout.setItem( page );
                        if ( !this.stackLayout.continuous && previousPage ) {
                                // This should not be necessary, since any inputs on the previous page should have
                                // been blurred when it was hidden, but browsers are not very consistent about
                                // this.
                                $focused = previousPage.$element.find( ':focus' );
                                if ( $focused.length ) {
                                        $focused[ 0 ].blur();
                                }
                        }
                        this.emit( 'set', page );
                }
        }
};

/**
 * For outlined-continuous booklets, also reset the outlineSelectWidget to the first item.
 *
 * @inheritdoc
 */
OO.ui.BookletLayout.prototype.resetScroll = function () {
        // Parent method
        OO.ui.BookletLayout.parent.prototype.resetScroll.call( this );

        if (
                this.outlined &&
                this.stackLayout.continuous &&
                this.outlineSelectWidget.findFirstSelectableItem()
        ) {
                this.scrolling = true;
                this.outlineSelectWidget.selectItem( this.outlineSelectWidget.findFirstSelectableItem() );
                this.scrolling = false;
        }
        return this;
};

/**
 * Select the first selectable page.
 *
 * @chainable
 * @return {OO.ui.BookletLayout} The layout, for chaining
 */
OO.ui.BookletLayout.prototype.selectFirstSelectablePage = function () {
        if ( !this.outlineSelectWidget.findSelectedItem() ) {
                this.outlineSelectWidget.selectItem( this.outlineSelectWidget.findFirstSelectableItem() );
        }

        return this;
};

/**
 * IndexLayouts contain {@link OO.ui.TabPanelLayout tab panel layouts} as well as
 * {@link OO.ui.TabSelectWidget tabs} that allow users to easily navigate through the tab panels
 * and select which one to display. By default, only one tab panel is displayed at a time. When a
 * user navigates to a new tab panel, the index layout automatically focuses on the first focusable
 * element, unless the default setting is changed.
 *
 * TODO: This class is similar to BookletLayout, we may want to refactor to reduce duplication
 *
 *     @example
 *     // Example of a IndexLayout that contains two TabPanelLayouts.
 *
 *     function TabPanelOneLayout( name, config ) {
 *         TabPanelOneLayout.parent.call( this, name, config );
 *         this.$element.append( '<p>First tab panel</p>' );
 *     }
 *     OO.inheritClass( TabPanelOneLayout, OO.ui.TabPanelLayout );
 *     TabPanelOneLayout.prototype.setupTabItem = function () {
 *         this.tabItem.setLabel( 'Tab panel one' );
 *     };
 *
 *     var tabPanel1 = new TabPanelOneLayout( 'one' ),
 *         tabPanel2 = new OO.ui.TabPanelLayout( 'two', { label: 'Tab panel two' } );
 *
 *     tabPanel2.$element.append( '<p>Second tab panel</p>' );
 *
 *     var index = new OO.ui.IndexLayout();
 *
 *     index.addTabPanels( [ tabPanel1, tabPanel2 ] );
 *     $( document.body ).append( index.$element );
 *
 * @class
 * @extends OO.ui.MenuLayout
 *
 * @constructor
 * @param {Object} [config] Configuration options
 * @cfg {OO.ui.StackLayout} [contentPanel] Content stack (see MenuLayout)
 * @cfg {boolean} [continuous=false] Show all tab panels, one after another
 * @cfg {boolean} [autoFocus=true] Focus on the first focusable element when a new tab panel is
 *  displayed. Disabled on mobile.
 */
OO.ui.IndexLayout = function OoUiIndexLayout( config ) {
        // Configuration initialization
        config = $.extend( {}, config, { menuPosition: 'top' } );

        // Parent constructor
        OO.ui.IndexLayout.parent.call( this, config );

        // Properties
        this.currentTabPanelName = null;
        // Allow infused widgets to pass existing tabPanels
        this.tabPanels = config.tabPanels || {};

        this.ignoreFocus = false;
        this.stackLayout = this.contentPanel || new OO.ui.StackLayout( {
                continuous: !!config.continuous,
                expanded: this.expanded
        } );
        this.setContentPanel( this.stackLayout );
        this.autoFocus = config.autoFocus === undefined || !!config.autoFocus;

        // Allow infused widgets to pass an existing tabSelectWidget
        this.tabSelectWidget = config.tabSelectWidget || new OO.ui.TabSelectWidget();
        this.tabPanel = this.menuPanel || new OO.ui.PanelLayout( {
                expanded: this.expanded
        } );
        this.setMenuPanel( this.tabPanel );

        this.toggleMenu( true );

        // Events
        this.stackLayout.connect( this, {
                set: 'onStackLayoutSet'
        } );
        this.tabSelectWidget.connect( this, {
                select: 'onTabSelectWidgetSelect'
        } );
        if ( this.autoFocus ) {
                // Event 'focus' does not bubble, but 'focusin' does.
                this.stackLayout.$element.on( 'focusin', this.onStackLayoutFocus.bind( this ) );
        }

        // Initialization
        this.$element.addClass( 'oo-ui-indexLayout' );
        this.stackLayout.$element.addClass( 'oo-ui-indexLayout-stackLayout' );
        this.tabPanel.$element
                .addClass( 'oo-ui-indexLayout-tabPanel' )
                .append( this.tabSelectWidget.$element );

        this.selectFirstSelectableTabPanel();
};

/* Setup */

OO.inheritClass( OO.ui.IndexLayout, OO.ui.MenuLayout );

/* Events */

/**
 * A 'set' event is emitted when a tab panel is {@link #setTabPanel set} to be displayed by the
 * index layout.
 *
 * @event set
 * @param {OO.ui.TabPanelLayout} tabPanel Current tab panel
 */

/**
 * An 'add' event is emitted when tab panels are {@link #addTabPanels added} to the index layout.
 *
 * @event add
 * @param {OO.ui.TabPanelLayout[]} tabPanel Added tab panels
 * @param {number} index Index tab panels were added at
 */

/**
 * A 'remove' event is emitted when tab panels are {@link #clearTabPanels cleared} or
 * {@link #removeTabPanels removed} from the index.
 *
 * @event remove
 * @param {OO.ui.TabPanelLayout[]} tabPanel Removed tab panels
 */

/* Methods */

/**
 * Handle stack layout focus.
 *
 * @private
 * @param {jQuery.Event} e Focusing event
 */
OO.ui.IndexLayout.prototype.onStackLayoutFocus = function ( e ) {
        var name, $target;

        // Find the tab panel that an element was focused within
        $target = $( e.target ).closest( '.oo-ui-tabPanelLayout' );
        for ( name in this.tabPanels ) {
                // Check for tab panel match, exclude current tab panel to find only tab panel changes
                if ( this.tabPanels[ name ].$element[ 0 ] === $target[ 0 ] &&
                                name !== this.currentTabPanelName ) {
                        this.setTabPanel( name );
                        break;
                }
        }
};

/**
 * Handle stack layout set events.
 *
 * @private
 * @param {OO.ui.PanelLayout|null} tabPanel The tab panel that is now the current panel
 */
OO.ui.IndexLayout.prototype.onStackLayoutSet = function ( tabPanel ) {
        // If everything is unselected, do nothing
        if ( !tabPanel ) {
                return;
        }
        // Focus the first element on the newly selected panel
        if ( this.autoFocus && !OO.ui.isMobile() ) {
                this.focus();
        }
};

/**
 * Focus the first input in the current tab panel.
 *
 * If no tab panel is selected, the first selectable tab panel will be selected.
 * If the focus is already in an element on the current tab panel, nothing will happen.
 *
 * @param {number} [itemIndex] A specific item to focus on
 */
OO.ui.IndexLayout.prototype.focus = function ( itemIndex ) {
        var tabPanel,
                items = this.stackLayout.getItems();

        if ( itemIndex !== undefined && items[ itemIndex ] ) {
                tabPanel = items[ itemIndex ];
        } else {
                tabPanel = this.stackLayout.getCurrentItem();
        }

        if ( !tabPanel ) {
                this.selectFirstSelectableTabPanel();
                tabPanel = this.stackLayout.getCurrentItem();
        }
        if ( !tabPanel ) {
                return;
        }
        // Only change the focus if is not already in the current page
        if ( !OO.ui.contains(
                tabPanel.$element[ 0 ],
                this.getElementDocument().activeElement,
                true
        ) ) {
                tabPanel.focus();
        }
};

/**
 * Find the first focusable input in the index layout and focus
 * on it.
 */
OO.ui.IndexLayout.prototype.focusFirstFocusable = function () {
        OO.ui.findFocusable( this.stackLayout.$element ).focus();
};

/**
 * Handle tab widget select events.
 *
 * @private
 * @param {OO.ui.OptionWidget|null} item Selected item
 */
OO.ui.IndexLayout.prototype.onTabSelectWidgetSelect = function ( item ) {
        if ( item ) {
                this.setTabPanel( item.getData() );
        }
};

/**
 * Get the tab panel closest to the specified tab panel.
 *
 * @param {OO.ui.TabPanelLayout} tabPanel Tab panel to use as a reference point
 * @return {OO.ui.TabPanelLayout|null} Tab panel closest to the specified
 */
OO.ui.IndexLayout.prototype.getClosestTabPanel = function ( tabPanel ) {
        var next, prev, level,
                tabPanels = this.stackLayout.getItems(),
                index = tabPanels.indexOf( tabPanel );

        if ( index !== -1 ) {
                next = tabPanels[ index + 1 ];
                prev = tabPanels[ index - 1 ];
                // Prefer adjacent tab panels at the same level
                level = this.tabSelectWidget.findItemFromData( tabPanel.getName() ).getLevel();
                if (
                        prev &&
                        level === this.tabSelectWidget.findItemFromData( prev.getName() ).getLevel()
                ) {
                        return prev;
                }
                if (
                        next &&
                        level === this.tabSelectWidget.findItemFromData( next.getName() ).getLevel()
                ) {
                        return next;
                }
        }
        return prev || next || null;
};

/**
 * Get the tabs widget.
 *
 * @return {OO.ui.TabSelectWidget} Tabs widget
 */
OO.ui.IndexLayout.prototype.getTabs = function () {
        return this.tabSelectWidget;
};

/**
 * Get a tab panel by its symbolic name.
 *
 * @param {string} name Symbolic name of tab panel
 * @return {OO.ui.TabPanelLayout|undefined} Tab panel, if found
 */
OO.ui.IndexLayout.prototype.getTabPanel = function ( name ) {
        return this.tabPanels[ name ];
};

/**
 * Get the current tab panel.
 *
 * @return {OO.ui.TabPanelLayout|undefined} Current tab panel, if found
 */
OO.ui.IndexLayout.prototype.getCurrentTabPanel = function () {
        var name = this.getCurrentTabPanelName();
        return name ? this.getTabPanel( name ) : undefined;
};

/**
 * Get the symbolic name of the current tab panel.
 *
 * @return {string|null} Symbolic name of the current tab panel
 */
OO.ui.IndexLayout.prototype.getCurrentTabPanelName = function () {
        return this.currentTabPanelName;
};

/**
 * Add tab panels to the index layout.
 *
 * When tab panels are added with the same names as existing tab panels, the existing tab panels
 * will be automatically removed before the new tab panels are added.
 *
 * @param {OO.ui.TabPanelLayout[]} tabPanels Tab panels to add
 * @param {number} index Index of the insertion point
 * @fires add
 * @chainable
 * @return {OO.ui.BookletLayout} The layout, for chaining
 */
OO.ui.IndexLayout.prototype.addTabPanels = function ( tabPanels, index ) {
        var i, len, name, tabPanel, item, currentIndex,
                stackLayoutTabPanels = this.stackLayout.getItems(),
                remove = [],
                items = [];

        // Remove tab panels with same names
        for ( i = 0, len = tabPanels.length; i < len; i++ ) {
                tabPanel = tabPanels[ i ];
                name = tabPanel.getName();

                if ( Object.prototype.hasOwnProperty.call( this.tabPanels, name ) ) {
                        // Correct the insertion index
                        currentIndex = stackLayoutTabPanels.indexOf( this.tabPanels[ name ] );
                        if ( currentIndex !== -1 && currentIndex + 1 < index ) {
                                index--;
                        }
                        remove.push( this.tabPanels[ name ] );
                }
        }
        if ( remove.length ) {
                this.removeTabPanels( remove );
        }

        // Add new tab panels
        for ( i = 0, len = tabPanels.length; i < len; i++ ) {
                tabPanel = tabPanels[ i ];
                name = tabPanel.getName();
                this.tabPanels[ tabPanel.getName() ] = tabPanel;
                item = new OO.ui.TabOptionWidget( { data: name } );
                tabPanel.setTabItem( item );
                items.push( item );
        }

        if ( items.length ) {
                this.tabSelectWidget.addItems( items, index );
                this.selectFirstSelectableTabPanel();
        }
        this.stackLayout.addItems( tabPanels, index );
        this.emit( 'add', tabPanels, index );

        return this;
};

/**
 * Remove the specified tab panels from the index layout.
 *
 * To remove all tab panels from the index, you may wish to use the #clearTabPanels method instead.
 *
 * @param {OO.ui.TabPanelLayout[]} tabPanels An array of tab panels to remove
 * @fires remove
 * @chainable
 * @return {OO.ui.BookletLayout} The layout, for chaining
 */
OO.ui.IndexLayout.prototype.removeTabPanels = function ( tabPanels ) {
        var i, len, name, tabPanel,
                items = [];

        for ( i = 0, len = tabPanels.length; i < len; i++ ) {
                tabPanel = tabPanels[ i ];
                name = tabPanel.getName();
                delete this.tabPanels[ name ];
                items.push( this.tabSelectWidget.findItemFromData( name ) );
                tabPanel.setTabItem( null );
        }
        if ( items.length ) {
                this.tabSelectWidget.removeItems( items );
                this.selectFirstSelectableTabPanel();
        }
        this.stackLayout.removeItems( tabPanels );
        this.emit( 'remove', tabPanels );

        return this;
};

/**
 * Clear all tab panels from the index layout.
 *
 * To remove only a subset of tab panels from the index, use the #removeTabPanels method.
 *
 * @fires remove
 * @chainable
 * @return {OO.ui.BookletLayout} The layout, for chaining
 */
OO.ui.IndexLayout.prototype.clearTabPanels = function () {
        var i, len,
                tabPanels = this.stackLayout.getItems();

        this.tabPanels = {};
        this.currentTabPanelName = null;
        this.tabSelectWidget.clearItems();
        for ( i = 0, len = tabPanels.length; i < len; i++ ) {
                tabPanels[ i ].setTabItem( null );
        }
        this.stackLayout.clearItems();

        this.emit( 'remove', tabPanels );

        return this;
};

/**
 * Set the current tab panel by symbolic name.
 *
 * @fires set
 * @param {string} name Symbolic name of tab panel
 */
OO.ui.IndexLayout.prototype.setTabPanel = function ( name ) {
        var selectedItem,
                $focused,
                previousTabPanel,
                tabPanel = this.tabPanels[ name ];

        if ( name !== this.currentTabPanelName ) {
                previousTabPanel = this.getCurrentTabPanel();
                selectedItem = this.tabSelectWidget.findSelectedItem();
                if ( selectedItem && selectedItem.getData() !== name ) {
                        this.tabSelectWidget.selectItemByData( name );
                }
                if ( tabPanel ) {
                        if ( previousTabPanel ) {
                                previousTabPanel.setActive( false );
                                // Blur anything focused if the next tab panel doesn't have anything focusable.
                                // This is not needed if the next tab panel has something focusable (because once
                                // it is focused this blur happens automatically). If the layout is non-continuous,
                                // this check is meaningless because the next tab panel is not visible yet and thus
                                // can't hold focus.
                                if (
                                        this.autoFocus &&
                                        !OO.ui.isMobile() &&
                                        this.stackLayout.continuous &&
                                        OO.ui.findFocusable( tabPanel.$element ).length !== 0
                                ) {
                                        $focused = previousTabPanel.$element.find( ':focus' );
                                        if ( $focused.length ) {
                                                $focused[ 0 ].blur();
                                        }
                                }
                        }
                        this.currentTabPanelName = name;
                        tabPanel.setActive( true );
                        this.stackLayout.setItem( tabPanel );
                        if ( !this.stackLayout.continuous && previousTabPanel ) {
                                // This should not be necessary, since any inputs on the previous tab panel should
                                // have been blurred when it was hidden, but browsers are not very consistent about
                                // this.
                                $focused = previousTabPanel.$element.find( ':focus' );
                                if ( $focused.length ) {
                                        $focused[ 0 ].blur();
                                }
                        }
                        this.emit( 'set', tabPanel );
                }
        }
};

/**
 * Select the first selectable tab panel.
 *
 * @chainable
 * @return {OO.ui.BookletLayout} The layout, for chaining
 */
OO.ui.IndexLayout.prototype.selectFirstSelectableTabPanel = function () {
        if ( !this.tabSelectWidget.findSelectedItem() ) {
                this.tabSelectWidget.selectItem( this.tabSelectWidget.findFirstSelectableItem() );
        }

        return this;
};

/**
 * ToggleWidget implements basic behavior of widgets with an on/off state.
 * Please see OO.ui.ToggleButtonWidget and OO.ui.ToggleSwitchWidget for examples.
 *
 * @abstract
 * @class
 * @extends OO.ui.Widget
 * @mixins OO.ui.mixin.TitledElement
 *
 * @constructor
 * @param {Object} [config] Configuration options
 * @cfg {boolean} [value=false] The toggle’s initial on/off state.
 *  By default, the toggle is in the 'off' state.
 */
OO.ui.ToggleWidget = function OoUiToggleWidget( config ) {
        // Configuration initialization
        config = config || {};

        // Parent constructor
        OO.ui.ToggleWidget.parent.call( this, config );

        // Mixin constructor
        OO.ui.mixin.TitledElement.call( this, config );

        // Properties
        this.value = null;

        // Initialization
        this.$element.addClass( 'oo-ui-toggleWidget' );
        this.setValue( !!config.value );
};

/* Setup */

OO.inheritClass( OO.ui.ToggleWidget, OO.ui.Widget );
OO.mixinClass( OO.ui.ToggleWidget, OO.ui.mixin.TitledElement );

/* Events */

/**
 * @event change
 *
 * A change event is emitted when the on/off state of the toggle changes.
 *
 * @param {boolean} value Value representing the new state of the toggle
 */

/* Methods */

/**
 * Get the value representing the toggle’s state.
 *
 * @return {boolean} The on/off state of the toggle
 */
OO.ui.ToggleWidget.prototype.getValue = function () {
        return this.value;
};

/**
 * Set the state of the toggle: `true` for 'on', `false` for 'off'.
 *
 * @param {boolean} value The state of the toggle
 * @fires change
 * @chainable
 * @return {OO.ui.Widget} The widget, for chaining
 */
OO.ui.ToggleWidget.prototype.setValue = function ( value ) {
        value = !!value;
        if ( this.value !== value ) {
                this.value = value;
                this.emit( 'change', value );
                this.$element.toggleClass( 'oo-ui-toggleWidget-on', value );
                this.$element.toggleClass( 'oo-ui-toggleWidget-off', !value );
        }
        return this;
};

/**
 * ToggleButtons are buttons that have a state (‘on’ or ‘off’) that is represented by a
 * Boolean value. Like other {@link OO.ui.ButtonWidget buttons}, toggle buttons can be
 * configured with {@link OO.ui.mixin.IconElement icons},
 * {@link OO.ui.mixin.IndicatorElement indicators},
 * {@link OO.ui.mixin.TitledElement titles}, {@link OO.ui.mixin.FlaggedElement styling flags},
 * and {@link OO.ui.mixin.LabelElement labels}. Please see
 * the [OOUI documentation][1] on MediaWiki for more information.
 *
 *     @example
 *     // Toggle buttons in the 'off' and 'on' state.
 *     var toggleButton1 = new OO.ui.ToggleButtonWidget( {
 *             label: 'Toggle Button off'
 *         } ),
 *         toggleButton2 = new OO.ui.ToggleButtonWidget( {
 *             label: 'Toggle Button on',
 *             value: true
 *         } );
 *     // Append the buttons to the DOM.
 *     $( document.body ).append( toggleButton1.$element, toggleButton2.$element );
 *
 * [1]: https://www.mediawiki.org/wiki/OOUI/Widgets/Buttons_and_Switches#Toggle_buttons
 *
 * @class
 * @extends OO.ui.ToggleWidget
 * @mixins OO.ui.mixin.ButtonElement
 * @mixins OO.ui.mixin.IconElement
 * @mixins OO.ui.mixin.IndicatorElement
 * @mixins OO.ui.mixin.LabelElement
 * @mixins OO.ui.mixin.FlaggedElement
 * @mixins OO.ui.mixin.TabIndexedElement
 *
 * @constructor
 * @param {Object} [config] Configuration options
 * @cfg {boolean} [value=false] The toggle button’s initial on/off
 *  state. By default, the button is in the 'off' state.
 */
OO.ui.ToggleButtonWidget = function OoUiToggleButtonWidget( config ) {
        // Configuration initialization
        config = config || {};

        // Parent constructor
        OO.ui.ToggleButtonWidget.parent.call( this, config );

        // Mixin constructors
        OO.ui.mixin.ButtonElement.call( this, $.extend( {
                active: this.active
        }, config ) );
        OO.ui.mixin.IconElement.call( this, config );
        OO.ui.mixin.IndicatorElement.call( this, config );
        OO.ui.mixin.LabelElement.call( this, config );
        OO.ui.mixin.FlaggedElement.call( this, config );
        OO.ui.mixin.TabIndexedElement.call( this, $.extend( {
                $tabIndexed: this.$button
        }, config ) );

        // Events
        this.connect( this, {
                click: 'onAction'
        } );

        // Initialization
        this.$button.append( this.$icon, this.$label, this.$indicator );
        this.$element
                .addClass( 'oo-ui-toggleButtonWidget' )
                .append( this.$button );
        this.setTitledElement( this.$button );
};

/* Setup */

OO.inheritClass( OO.ui.ToggleButtonWidget, OO.ui.ToggleWidget );
OO.mixinClass( OO.ui.ToggleButtonWidget, OO.ui.mixin.ButtonElement );
OO.mixinClass( OO.ui.ToggleButtonWidget, OO.ui.mixin.IconElement );
OO.mixinClass( OO.ui.ToggleButtonWidget, OO.ui.mixin.IndicatorElement );
OO.mixinClass( OO.ui.ToggleButtonWidget, OO.ui.mixin.LabelElement );
OO.mixinClass( OO.ui.ToggleButtonWidget, OO.ui.mixin.FlaggedElement );
OO.mixinClass( OO.ui.ToggleButtonWidget, OO.ui.mixin.TabIndexedElement );

/* Static Properties */

/**
 * @static
 * @inheritdoc
 */
OO.ui.ToggleButtonWidget.static.tagName = 'span';

/* Methods */

/**
 * Handle the button action being triggered.
 *
 * @private
 */
OO.ui.ToggleButtonWidget.prototype.onAction = function () {
        this.setValue( !this.value );
};

/**
 * @inheritdoc
 */
OO.ui.ToggleButtonWidget.prototype.setValue = function ( value ) {
        value = !!value;
        if ( value !== this.value ) {
                // Might be called from parent constructor before ButtonElement constructor
                if ( this.$button ) {
                        this.$button.attr( 'aria-pressed', value.toString() );
                }
                this.setActive( value );
        }

        // Parent method
        OO.ui.ToggleButtonWidget.parent.prototype.setValue.call( this, value );

        return this;
};

/**
 * @inheritdoc
 */
OO.ui.ToggleButtonWidget.prototype.setButtonElement = function ( $button ) {
        if ( this.$button ) {
                this.$button.removeAttr( 'aria-pressed' );
        }
        OO.ui.mixin.ButtonElement.prototype.setButtonElement.call( this, $button );
        this.$button.attr( 'aria-pressed', this.value.toString() );
};

/**
 * ToggleSwitches are switches that slide on and off. Their state is represented by a Boolean
 * value (`true` for ‘on’, and `false` otherwise, the default). The ‘off’ state is represented
 * visually by a slider in the leftmost position.
 *
 *     @example
 *     // Toggle switches in the 'off' and 'on' position.
 *     var toggleSwitch1 = new OO.ui.ToggleSwitchWidget(),
 *         toggleSwitch2 = new OO.ui.ToggleSwitchWidget( {
 *             value: true
 *         } );
 *         // Create a FieldsetLayout to layout and label switches.
 *         fieldset = new OO.ui.FieldsetLayout( {
 *             label: 'Toggle switches'
 *         } );
 *     fieldset.addItems( [
 *         new OO.ui.FieldLayout( toggleSwitch1, {
 *             label: 'Off',
 *             align: 'top'
 *         } ),
 *         new OO.ui.FieldLayout( toggleSwitch2, {
 *             label: 'On',
 *             align: 'top'
 *         } )
 *     ] );
 *     $( document.body ).append( fieldset.$element );
 *
 * @class
 * @extends OO.ui.ToggleWidget
 * @mixins OO.ui.mixin.TabIndexedElement
 *
 * @constructor
 * @param {Object} [config] Configuration options
 * @cfg {boolean} [value=false] The toggle switch’s initial on/off state.
 *  By default, the toggle switch is in the 'off' position.
 */
OO.ui.ToggleSwitchWidget = function OoUiToggleSwitchWidget( config ) {
        // Parent constructor
        OO.ui.ToggleSwitchWidget.parent.call( this, config );

        // Mixin constructors
        OO.ui.mixin.TabIndexedElement.call( this, config );

        // Properties
        this.dragging = false;
        this.dragStart = null;
        this.sliding = false;
        this.$glow = $( '<span>' );
        this.$grip = $( '<span>' );

        // Events
        this.$element.on( {
                click: this.onClick.bind( this ),
                keypress: this.onKeyPress.bind( this )
        } );

        // Initialization
        this.$glow.addClass( 'oo-ui-toggleSwitchWidget-glow' );
        this.$grip.addClass( 'oo-ui-toggleSwitchWidget-grip' );
        this.$element
                .addClass( 'oo-ui-toggleSwitchWidget' )
                .attr( 'role', 'checkbox' )
                .append( this.$glow, this.$grip );
};

/* Setup */

OO.inheritClass( OO.ui.ToggleSwitchWidget, OO.ui.ToggleWidget );
OO.mixinClass( OO.ui.ToggleSwitchWidget, OO.ui.mixin.TabIndexedElement );

/* Methods */

/**
 * Handle mouse click events.
 *
 * @private
 * @param {jQuery.Event} e Mouse click event
 * @return {undefined|boolean} False to prevent default if event is handled
 */
OO.ui.ToggleSwitchWidget.prototype.onClick = function ( e ) {
        if ( !this.isDisabled() && e.which === OO.ui.MouseButtons.LEFT ) {
                this.setValue( !this.value );
        }
        return false;
};

/**
 * Handle key press events.
 *
 * @private
 * @param {jQuery.Event} e Key press event
 * @return {undefined|boolean} False to prevent default if event is handled
 */
OO.ui.ToggleSwitchWidget.prototype.onKeyPress = function ( e ) {
        if ( !this.isDisabled() && ( e.which === OO.ui.Keys.SPACE || e.which === OO.ui.Keys.ENTER ) ) {
                this.setValue( !this.value );
                return false;
        }
};

/**
 * @inheritdoc
 */
OO.ui.ToggleSwitchWidget.prototype.setValue = function ( value ) {
        OO.ui.ToggleSwitchWidget.parent.prototype.setValue.call( this, value );
        this.$element.attr( 'aria-checked', this.value.toString() );
        return this;
};

/**
 * @inheritdoc
 */
OO.ui.ToggleSwitchWidget.prototype.simulateLabelClick = function () {
        if ( !this.isDisabled() ) {
                this.setValue( !this.value );
        }
        this.focus();
};

/**
 * OutlineControlsWidget is a set of controls for an
 * {@link OO.ui.OutlineSelectWidget outline select widget}.
 * Controls include moving items up and down, removing items, and adding different kinds of items.
 *
 * **Currently, this class is only used by {@link OO.ui.BookletLayout booklet layouts}.**
 *
 * @class
 * @extends OO.ui.Widget
 * @mixins OO.ui.mixin.GroupElement
 *
 * @constructor
 * @param {OO.ui.OutlineSelectWidget} outline Outline to control
 * @param {Object} [config] Configuration options
 * @cfg {Object} [abilities] List of abilties
 * @cfg {boolean} [abilities.move=true] Allow moving movable items
 * @cfg {boolean} [abilities.remove=true] Allow removing removable items
 */
OO.ui.OutlineControlsWidget = function OoUiOutlineControlsWidget( outline, config ) {
        // Allow passing positional parameters inside the config object
        if ( OO.isPlainObject( outline ) && config === undefined ) {
                config = outline;
                outline = config.outline;
        }

        // Configuration initialization
        config = config || {};

        // Parent constructor
        OO.ui.OutlineControlsWidget.parent.call( this, config );

        // Mixin constructors
        OO.ui.mixin.GroupElement.call( this, config );

        // Properties
        this.outline = outline;
        this.$movers = $( '<div>' );
        this.upButton = new OO.ui.ButtonWidget( {
                framed: false,
                icon: 'collapse',
                title: OO.ui.msg( 'ooui-outline-control-move-up' )
        } );
        this.downButton = new OO.ui.ButtonWidget( {
                framed: false,
                icon: 'expand',
                title: OO.ui.msg( 'ooui-outline-control-move-down' )
        } );
        this.removeButton = new OO.ui.ButtonWidget( {
                framed: false,
                icon: 'trash',
                title: OO.ui.msg( 'ooui-outline-control-remove' )
        } );
        this.abilities = { move: true, remove: true };

        // Events
        outline.connect( this, {
                select: 'onOutlineChange',
                add: 'onOutlineChange',
                remove: 'onOutlineChange'
        } );
        this.upButton.connect( this, {
                click: [ 'emit', 'move', -1 ]
        } );
        this.downButton.connect( this, {
                click: [ 'emit', 'move', 1 ]
        } );
        this.removeButton.connect( this, {
                click: [ 'emit', 'remove' ]
        } );

        // Initialization
        this.$element.addClass( 'oo-ui-outlineControlsWidget' );
        this.$group.addClass( 'oo-ui-outlineControlsWidget-items' );
        this.$movers
                .addClass( 'oo-ui-outlineControlsWidget-movers' )
                .append( this.removeButton.$element, this.upButton.$element, this.downButton.$element );
        this.$element.append( this.$icon, this.$group, this.$movers );
        this.setAbilities( config.abilities || {} );
};

/* Setup */

OO.inheritClass( OO.ui.OutlineControlsWidget, OO.ui.Widget );
OO.mixinClass( OO.ui.OutlineControlsWidget, OO.ui.mixin.GroupElement );

/* Events */

/**
 * @event move
 * @param {number} places Number of places to move
 */

/**
 * @event remove
 */

/* Methods */

/**
 * Set abilities.
 *
 * @param {Object} abilities List of abilties
 * @param {boolean} [abilities.move] Allow moving movable items
 * @param {boolean} [abilities.remove] Allow removing removable items
 */
OO.ui.OutlineControlsWidget.prototype.setAbilities = function ( abilities ) {
        var ability;

        for ( ability in this.abilities ) {
                if ( abilities[ ability ] !== undefined ) {
                        this.abilities[ ability ] = !!abilities[ ability ];
                }
        }

        this.onOutlineChange();
};

/**
 * Handle outline change events.
 *
 * @private
 */
OO.ui.OutlineControlsWidget.prototype.onOutlineChange = function () {
        var i, len, firstMovable, lastMovable,
                items = this.outline.getItems(),
                selectedItem = this.outline.findSelectedItem(),
                movable = this.abilities.move && selectedItem && selectedItem.isMovable(),
                removable = this.abilities.remove && selectedItem && selectedItem.isRemovable();

        if ( movable ) {
                i = -1;
                len = items.length;
                while ( ++i < len ) {
                        if ( items[ i ].isMovable() ) {
                                firstMovable = items[ i ];
                                break;
                        }
                }
                i = len;
                while ( i-- ) {
                        if ( items[ i ].isMovable() ) {
                                lastMovable = items[ i ];
                                break;
                        }
                }
        }
        this.upButton.setDisabled( !movable || selectedItem === firstMovable );
        this.downButton.setDisabled( !movable || selectedItem === lastMovable );
        this.removeButton.setDisabled( !removable );
};

/**
 * OutlineOptionWidget is an item in an {@link OO.ui.OutlineSelectWidget OutlineSelectWidget}.
 *
 * Currently, this class is only used by {@link OO.ui.BookletLayout booklet layouts}, which contain
 * {@link OO.ui.PageLayout page layouts}. See {@link OO.ui.BookletLayout BookletLayout}
 * for an example.
 *
 * @class
 * @extends OO.ui.DecoratedOptionWidget
 *
 * @constructor
 * @param {Object} [config] Configuration options
 * @cfg {number} [level] Indentation level
 * @cfg {boolean} [movable] Allow modification from
 *  {@link OO.ui.OutlineControlsWidget outline controls}.
 */
OO.ui.OutlineOptionWidget = function OoUiOutlineOptionWidget( config ) {
        // Configuration initialization
        config = config || {};

        // Parent constructor
        OO.ui.OutlineOptionWidget.parent.call( this, config );

        // Properties
        this.level = 0;
        this.movable = !!config.movable;
        this.removable = !!config.removable;

        // Initialization
        this.$element.addClass( 'oo-ui-outlineOptionWidget' );
        this.setLevel( config.level );
};

/* Setup */

OO.inheritClass( OO.ui.OutlineOptionWidget, OO.ui.DecoratedOptionWidget );

/* Static Properties */

/**
 * @static
 * @inheritdoc
 */
OO.ui.OutlineOptionWidget.static.highlightable = true;

/**
 * @static
 * @inheritdoc
 */
OO.ui.OutlineOptionWidget.static.scrollIntoViewOnSelect = true;

/**
 * @static
 * @inheritable
 * @property {string}
 */
OO.ui.OutlineOptionWidget.static.levelClass = 'oo-ui-outlineOptionWidget-level-';

/**
 * @static
 * @inheritable
 * @property {number}
 */
OO.ui.OutlineOptionWidget.static.levels = 3;

/* Methods */

/**
 * Check if item is movable.
 *
 * Movability is used by {@link OO.ui.OutlineControlsWidget outline controls}.
 *
 * @return {boolean} Item is movable
 */
OO.ui.OutlineOptionWidget.prototype.isMovable = function () {
        return this.movable;
};

/**
 * Check if item is removable.
 *
 * Removability is used by {@link OO.ui.OutlineControlsWidget outline controls}.
 *
 * @return {boolean} Item is removable
 */
OO.ui.OutlineOptionWidget.prototype.isRemovable = function () {
        return this.removable;
};

/**
 * Get indentation level.
 *
 * @return {number} Indentation level
 */
OO.ui.OutlineOptionWidget.prototype.getLevel = function () {
        return this.level;
};

/**
 * @inheritdoc
 */
OO.ui.OutlineOptionWidget.prototype.setPressed = function ( state ) {
        OO.ui.OutlineOptionWidget.parent.prototype.setPressed.call( this, state );
        return this;
};

/**
 * Set movability.
 *
 * Movability is used by {@link OO.ui.OutlineControlsWidget outline controls}.
 *
 * @param {boolean} movable Item is movable
 * @chainable
 * @return {OO.ui.Widget} The widget, for chaining
 */
OO.ui.OutlineOptionWidget.prototype.setMovable = function ( movable ) {
        this.movable = !!movable;
        this.updateThemeClasses();
        return this;
};

/**
 * Set removability.
 *
 * Removability is used by {@link OO.ui.OutlineControlsWidget outline controls}.
 *
 * @param {boolean} removable Item is removable
 * @chainable
 * @return {OO.ui.Widget} The widget, for chaining
 */
OO.ui.OutlineOptionWidget.prototype.setRemovable = function ( removable ) {
        this.removable = !!removable;
        this.updateThemeClasses();
        return this;
};

/**
 * @inheritdoc
 */
OO.ui.OutlineOptionWidget.prototype.setSelected = function ( state ) {
        OO.ui.OutlineOptionWidget.parent.prototype.setSelected.call( this, state );
        return this;
};

/**
 * Set indentation level.
 *
 * @param {number} [level=0] Indentation level, in the range of [0,#maxLevel]
 * @chainable
 * @return {OO.ui.Widget} The widget, for chaining
 */
OO.ui.OutlineOptionWidget.prototype.setLevel = function ( level ) {
        var levels = this.constructor.static.levels,
                levelClass = this.constructor.static.levelClass,
                i = levels;

        this.level = level ? Math.max( 0, Math.min( levels - 1, level ) ) : 0;
        while ( i-- ) {
                if ( this.level === i ) {
                        this.$element.addClass( levelClass + i );
                } else {
                        this.$element.removeClass( levelClass + i );
                }
        }
        this.updateThemeClasses();

        return this;
};

/**
 * OutlineSelectWidget is a structured list that contains
 * {@link OO.ui.OutlineOptionWidget outline options}
 * A set of controls can be provided with an {@link OO.ui.OutlineControlsWidget outline controls}
 * widget.
 *
 * **Currently, this class is only used by {@link OO.ui.BookletLayout booklet layouts}.**
 *
 * @class
 * @extends OO.ui.SelectWidget
 * @mixins OO.ui.mixin.TabIndexedElement
 *
 * @constructor
 * @param {Object} [config] Configuration options
 */
OO.ui.OutlineSelectWidget = function OoUiOutlineSelectWidget( config ) {
        // Parent constructor
        OO.ui.OutlineSelectWidget.parent.call( this, config );

        // Mixin constructors
        OO.ui.mixin.TabIndexedElement.call( this, config );

        // Events
        this.$element.on( {
                focus: this.bindDocumentKeyDownListener.bind( this ),
                blur: this.unbindDocumentKeyDownListener.bind( this )
        } );

        // Initialization
        this.$element.addClass( 'oo-ui-outlineSelectWidget' );
};

/* Setup */

OO.inheritClass( OO.ui.OutlineSelectWidget, OO.ui.SelectWidget );
OO.mixinClass( OO.ui.OutlineSelectWidget, OO.ui.mixin.TabIndexedElement );

/**
 * ButtonOptionWidget is a special type of {@link OO.ui.mixin.ButtonElement button element} that
 * can be selected and configured with data. The class is
 * used with OO.ui.ButtonSelectWidget to create a selection of button options. Please see the
 * [OOUI documentation on MediaWiki] [1] for more information.
 *
 * [1]: https://www.mediawiki.org/wiki/OOUI/Widgets/Selects_and_Options#Button_selects_and_options
 *
 * @class
 * @extends OO.ui.OptionWidget
 * @mixins OO.ui.mixin.ButtonElement
 * @mixins OO.ui.mixin.IconElement
 * @mixins OO.ui.mixin.IndicatorElement
 *
 * @constructor
 * @param {Object} [config] Configuration options
 */
OO.ui.ButtonOptionWidget = function OoUiButtonOptionWidget( config ) {
        // Configuration initialization
        config = config || {};

        // Parent constructor
        OO.ui.ButtonOptionWidget.parent.call( this, config );

        // Mixin constructors
        OO.ui.mixin.ButtonElement.call( this, config );
        OO.ui.mixin.IconElement.call( this, config );
        OO.ui.mixin.IndicatorElement.call( this, config );

        // Initialization
        this.$element.addClass( 'oo-ui-buttonOptionWidget' );
        this.$button.append( this.$icon, this.$label, this.$indicator );
        this.$element.append( this.$button );
        this.setTitledElement( this.$button );
};

/* Setup */

OO.inheritClass( OO.ui.ButtonOptionWidget, OO.ui.OptionWidget );
OO.mixinClass( OO.ui.ButtonOptionWidget, OO.ui.mixin.ButtonElement );
OO.mixinClass( OO.ui.ButtonOptionWidget, OO.ui.mixin.IconElement );
OO.mixinClass( OO.ui.ButtonOptionWidget, OO.ui.mixin.IndicatorElement );

/* Static Properties */

/**
 * Allow button mouse down events to pass through so they can be handled by the parent select widget
 *
 * @static
 * @inheritdoc
 */
OO.ui.ButtonOptionWidget.static.cancelButtonMouseDownEvents = false;

/**
 * @static
 * @inheritdoc
 */
OO.ui.ButtonOptionWidget.static.highlightable = false;

/* Methods */

/**
 * @inheritdoc
 */
OO.ui.ButtonOptionWidget.prototype.setSelected = function ( state ) {
        OO.ui.ButtonOptionWidget.parent.prototype.setSelected.call( this, state );

        if ( this.constructor.static.selectable ) {
                this.setActive( state );
        }

        return this;
};

/**
 * ButtonSelectWidget is a {@link OO.ui.SelectWidget select widget} that contains
 * button options and is used together with
 * OO.ui.ButtonOptionWidget. The ButtonSelectWidget provides an interface for
 * highlighting, choosing, and selecting mutually exclusive options. Please see
 * the [OOUI documentation on MediaWiki] [1] for more information.
 *
 *     @example
 *     // A ButtonSelectWidget that contains three ButtonOptionWidgets.
 *     var option1 = new OO.ui.ButtonOptionWidget( {
 *             data: 1,
 *             label: 'Option 1',
 *             title: 'Button option 1'
 *         } ),
 *         option2 = new OO.ui.ButtonOptionWidget( {
 *             data: 2,
 *             label: 'Option 2',
 *             title: 'Button option 2'
 *         } ),
 *         option3 = new OO.ui.ButtonOptionWidget( {
 *             data: 3,
 *             label: 'Option 3',
 *             title: 'Button option 3'
 *         } ),
 *         buttonSelect = new OO.ui.ButtonSelectWidget( {
 *             items: [ option1, option2, option3 ]
 *         } );
 *     $( document.body ).append( buttonSelect.$element );
 *
 * [1]: https://www.mediawiki.org/wiki/OOUI/Widgets/Selects_and_Options
 *
 * @class
 * @extends OO.ui.SelectWidget
 * @mixins OO.ui.mixin.TabIndexedElement
 *
 * @constructor
 * @param {Object} [config] Configuration options
 */
OO.ui.ButtonSelectWidget = function OoUiButtonSelectWidget( config ) {
        // Parent constructor
        OO.ui.ButtonSelectWidget.parent.call( this, config );

        // Mixin constructors
        OO.ui.mixin.TabIndexedElement.call( this, config );

        // Events
        this.$element.on( {
                focus: this.bindDocumentKeyDownListener.bind( this ),
                blur: this.unbindDocumentKeyDownListener.bind( this )
        } );

        // Initialization
        this.$element.addClass( 'oo-ui-buttonSelectWidget' );
};

/* Setup */

OO.inheritClass( OO.ui.ButtonSelectWidget, OO.ui.SelectWidget );
OO.mixinClass( OO.ui.ButtonSelectWidget, OO.ui.mixin.TabIndexedElement );

/**
 * TabOptionWidget is an item in a {@link OO.ui.TabSelectWidget TabSelectWidget}.
 *
 * Currently, this class is only used by {@link OO.ui.IndexLayout index layouts}, which contain
 * {@link OO.ui.TabPanelLayout tab panel layouts}. See {@link OO.ui.IndexLayout IndexLayout}
 * for an example.
 *
 * @class
 * @extends OO.ui.OptionWidget
 *
 * @constructor
 * @param {Object} [config] Configuration options
 */
OO.ui.TabOptionWidget = function OoUiTabOptionWidget( config ) {
        // Configuration initialization
        config = config || {};

        // Parent constructor
        OO.ui.TabOptionWidget.parent.call( this, config );

        // Initialization
        this.$element
                .addClass( 'oo-ui-tabOptionWidget' )
                .attr( 'role', 'tab' );
};

/* Setup */

OO.inheritClass( OO.ui.TabOptionWidget, OO.ui.OptionWidget );

/* Static Properties */

/**
 * @static
 * @inheritdoc
 */
OO.ui.TabOptionWidget.static.highlightable = false;

/**
 * TabSelectWidget is a list that contains {@link OO.ui.TabOptionWidget tab options}
 *
 * **Currently, this class is only used by {@link OO.ui.IndexLayout index layouts}.**
 *
 * @class
 * @extends OO.ui.SelectWidget
 * @mixins OO.ui.mixin.TabIndexedElement
 *
 * @constructor
 * @param {Object} [config] Configuration options
 */
OO.ui.TabSelectWidget = function OoUiTabSelectWidget( config ) {
        // Parent constructor
        OO.ui.TabSelectWidget.parent.call( this, config );

        // Mixin constructors
        OO.ui.mixin.TabIndexedElement.call( this, config );

        // Events
        this.$element.on( {
                focus: this.bindDocumentKeyDownListener.bind( this ),
                blur: this.unbindDocumentKeyDownListener.bind( this )
        } );

        // Initialization
        this.$element
                .addClass( 'oo-ui-tabSelectWidget' )
                .attr( 'role', 'tablist' );
};

/* Setup */

OO.inheritClass( OO.ui.TabSelectWidget, OO.ui.SelectWidget );
OO.mixinClass( OO.ui.TabSelectWidget, OO.ui.mixin.TabIndexedElement );

/**
 * TagItemWidgets are used within a {@link OO.ui.TagMultiselectWidget
 * TagMultiselectWidget} to display the selected items.
 *
 * @class
 * @extends OO.ui.Widget
 * @mixins OO.ui.mixin.ItemWidget
 * @mixins OO.ui.mixin.LabelElement
 * @mixins OO.ui.mixin.FlaggedElement
 * @mixins OO.ui.mixin.TabIndexedElement
 * @mixins OO.ui.mixin.DraggableElement
 *
 * @constructor
 * @param {Object} [config] Configuration object
 * @cfg {boolean} [valid=true] Item is valid
 * @cfg {boolean} [fixed] Item is fixed. This means the item is
 *  always included in the values and cannot be removed.
 */
OO.ui.TagItemWidget = function OoUiTagItemWidget( config ) {
        config = config || {};

        // Parent constructor
        OO.ui.TagItemWidget.parent.call( this, config );

        // Mixin constructors
        OO.ui.mixin.ItemWidget.call( this );
        OO.ui.mixin.LabelElement.call( this, config );
        OO.ui.mixin.FlaggedElement.call( this, config );
        OO.ui.mixin.TabIndexedElement.call( this, config );
        OO.ui.mixin.DraggableElement.call( this, config );

        this.valid = config.valid === undefined ? true : !!config.valid;
        this.fixed = !!config.fixed;

        this.closeButton = new OO.ui.ButtonWidget( {
                framed: false,
                icon: 'close',
                tabIndex: -1,
                title: OO.ui.msg( 'ooui-item-remove' )
        } );
        this.closeButton.setDisabled( this.isDisabled() );

        // Events
        this.closeButton.connect( this, {
                click: 'remove'
        } );
        this.$element
                .on( 'click', this.select.bind( this ) )
                .on( 'keydown', this.onKeyDown.bind( this ) )
                // Prevent propagation of mousedown; the tag item "lives" in the
                // clickable area of the TagMultiselectWidget, which listens to
                // mousedown to open the menu or popup. We want to prevent that
                // for clicks specifically on the tag itself, so the actions taken
                // are more deliberate. When the tag is clicked, it will emit the
                // selection event (similar to how #OO.ui.MultioptionWidget emits 'change')
                // and can be handled separately.
                .on( 'mousedown', function ( e ) { e.stopPropagation(); } );

        // Initialization
        this.$element
                .addClass( 'oo-ui-tagItemWidget' )
                .append( this.$label, this.closeButton.$element );
};

/* Initialization */

OO.inheritClass( OO.ui.TagItemWidget, OO.ui.Widget );
OO.mixinClass( OO.ui.TagItemWidget, OO.ui.mixin.ItemWidget );
OO.mixinClass( OO.ui.TagItemWidget, OO.ui.mixin.LabelElement );
OO.mixinClass( OO.ui.TagItemWidget, OO.ui.mixin.FlaggedElement );
OO.mixinClass( OO.ui.TagItemWidget, OO.ui.mixin.TabIndexedElement );
OO.mixinClass( OO.ui.TagItemWidget, OO.ui.mixin.DraggableElement );

/* Events */

/**
 * @event remove
 *
 * A remove action was performed on the item
 */

/**
 * @event navigate
 * @param {string} direction Direction of the movement, forward or backwards
 *
 * A navigate action was performed on the item
 */

/**
 * @event select
 *
 * The tag widget was selected. This can occur when the widget
 * is either clicked or enter was pressed on it.
 */

/**
 * @event valid
 * @param {boolean} isValid Item is valid
 *
 * Item validity has changed
 */

/**
 * @event fixed
 * @param {boolean} isFixed Item is fixed
 *
 * Item fixed state has changed
 */

/* Methods */

/**
 * Set this item as fixed, meaning it cannot be removed
 *
 * @param {string} [state] Item is fixed
 * @fires fixed
 * @return {OO.ui.Widget} The widget, for chaining
 */
OO.ui.TagItemWidget.prototype.setFixed = function ( state ) {
        state = state === undefined ? !this.fixed : !!state;

        if ( this.fixed !== state ) {
                this.fixed = state;
                if ( this.closeButton ) {
                        this.closeButton.toggle( !this.fixed );
                }

                if ( !this.fixed && this.elementGroup && !this.elementGroup.isDraggable() ) {
                        // Only enable the state of the item if the
                        // entire group is draggable
                        this.toggleDraggable( !this.fixed );
                }
                this.$element.toggleClass( 'oo-ui-tagItemWidget-fixed', this.fixed );

                this.emit( 'fixed', this.isFixed() );
        }
        return this;
};

/**
 * Check whether the item is fixed
 * @return {boolean}
 */
OO.ui.TagItemWidget.prototype.isFixed = function () {
        return this.fixed;
};

/**
 * @inheritdoc
 */
OO.ui.TagItemWidget.prototype.setDisabled = function ( state ) {
        if ( state && this.elementGroup && !this.elementGroup.isDisabled() ) {
                OO.ui.warnDeprecation( 'TagItemWidget#setDisabled: Disabling individual items is deprecated and will result in inconsistent behavior. Use #setFixed instead. See T193571.' );
        }
        // Parent method
        OO.ui.TagItemWidget.parent.prototype.setDisabled.call( this, state );
        if (
                !state &&
                // Verify we have a group, and that the widget is ready
                this.toggleDraggable && this.elementGroup &&
                !this.isFixed() &&
                !this.elementGroup.isDraggable()
        ) {
                // Only enable the draggable state of the item if the
                // entire group is draggable to begin with, and if the
                // item is not fixed
                this.toggleDraggable( !state );
        }

        if ( this.closeButton ) {
                this.closeButton.setDisabled( state );
        }

        return this;
};

/**
 * Handle removal of the item
 *
 * This is mainly for extensibility concerns, so other children
 * of this class can change the behavior if they need to. This
 * is called by both clicking the 'remove' button but also
 * on keypress, which is harder to override if needed.
 *
 * @fires remove
 */
OO.ui.TagItemWidget.prototype.remove = function () {
        if ( !this.isDisabled() && !this.isFixed() ) {
                this.emit( 'remove' );
        }
};

/**
 * Handle a keydown event on the widget
 *
 * @fires navigate
 * @fires remove
 * @param {jQuery.Event} e Key down event
 * @return {boolean|undefined} false to stop the operation
 */
OO.ui.TagItemWidget.prototype.onKeyDown = function ( e ) {
        var movement;

        if (
                !this.isDisabled() &&
                !this.isFixed() &&
                ( e.keyCode === OO.ui.Keys.BACKSPACE || e.keyCode === OO.ui.Keys.DELETE )
        ) {
                this.remove();
                return false;
        } else if ( e.keyCode === OO.ui.Keys.ENTER ) {
                this.select();
                return false;
        } else if (
                e.keyCode === OO.ui.Keys.LEFT ||
                e.keyCode === OO.ui.Keys.RIGHT
        ) {
                if ( OO.ui.Element.static.getDir( this.$element ) === 'rtl' ) {
                        movement = {
                                left: 'forwards',
                                right: 'backwards'
                        };
                } else {
                        movement = {
                                left: 'backwards',
                                right: 'forwards'
                        };
                }

                this.emit(
                        'navigate',
                        e.keyCode === OO.ui.Keys.LEFT ?
                                movement.left : movement.right
                );
                return false;
        }
};

/**
 * Select this item
 *
 * @fires select
 */
OO.ui.TagItemWidget.prototype.select = function () {
        if ( !this.isDisabled() ) {
                this.emit( 'select' );
        }
};

/**
 * Set the valid state of this item
 *
 * @param {boolean} [valid] Item is valid
 * @fires valid
 */
OO.ui.TagItemWidget.prototype.toggleValid = function ( valid ) {
        valid = valid === undefined ? !this.valid : !!valid;

        if ( this.valid !== valid ) {
                this.valid = valid;

                this.setFlags( { invalid: !this.valid } );

                this.emit( 'valid', this.valid );
        }
};

/**
 * Check whether the item is valid
 *
 * @return {boolean} Item is valid
 */
OO.ui.TagItemWidget.prototype.isValid = function () {
        return this.valid;
};

/**
 * A basic tag multiselect widget, similar in concept to
 * {@link OO.ui.ComboBoxInputWidget combo box widget} that allows the user to add multiple values
 * that are displayed in a tag area.
 *
 * This widget is a base widget; see {@link OO.ui.MenuTagMultiselectWidget MenuTagMultiselectWidget}
 * and {@link OO.ui.PopupTagMultiselectWidget PopupTagMultiselectWidget} for the implementations
 * that use a menu and a popup respectively.
 *
 *     @example
 *     // A TagMultiselectWidget.
 *     var widget = new OO.ui.TagMultiselectWidget( {
 *         inputPosition: 'outline',
 *         allowedValues: [ 'Option 1', 'Option 2', 'Option 3' ],
 *         selected: [ 'Option 1' ]
 *     } );
 *     $( document.body ).append( widget.$element );
 *
 * @class
 * @extends OO.ui.Widget
 * @mixins OO.ui.mixin.GroupWidget
 * @mixins OO.ui.mixin.DraggableGroupElement
 * @mixins OO.ui.mixin.IndicatorElement
 * @mixins OO.ui.mixin.IconElement
 * @mixins OO.ui.mixin.TabIndexedElement
 * @mixins OO.ui.mixin.FlaggedElement
 * @mixins OO.ui.mixin.TitledElement
 *
 * @constructor
 * @param {Object} config Configuration object
 * @cfg {Object} [input] Configuration options for the input widget
 * @cfg {OO.ui.InputWidget} [inputWidget] An optional input widget. If given, it will
 *  replace the input widget used in the TagMultiselectWidget. If not given,
 *  TagMultiselectWidget creates its own.
 * @cfg {boolean} [inputPosition='inline'] Position of the input. Options are:
 *  - inline: The input is invisible, but exists inside the tag list, so
 *    the user types into the tag groups to add tags.
 *  - outline: The input is underneath the tag area.
 *  - none: No input supplied
 * @cfg {boolean} [allowEditTags=true] Allow editing of the tags by clicking them
 * @cfg {boolean} [allowArbitrary=false] Allow data items to be added even if
 *  not present in the menu.
 * @cfg {Object[]} [allowedValues] An array representing the allowed items
 *  by their datas.
 * @cfg {boolean} [allowDuplicates=false] Allow duplicate items to be added
 * @cfg {boolean} [allowDisplayInvalidTags=false] Allow the display of
 *  invalid tags. These tags will display with an invalid state, and
 *  the widget as a whole will have an invalid state if any invalid tags
 *  are present.
 * @cfg {number} [tagLimit] An optional limit on the number of selected options.
 *  If 'tagLimit' is set and is reached, the input is disabled, not allowing any
 *  additions. If 'tagLimit' is unset or is 0, an unlimited number of items can be
 *  added.
 * @cfg {boolean} [allowReordering=true] Allow reordering of the items
 * @cfg {Object[]|String[]} [selected] A set of selected tags. If given,
 *  these will appear in the tag list on initialization, as long as they
 *  pass the validity tests.
 */
OO.ui.TagMultiselectWidget = function OoUiTagMultiselectWidget( config ) {
        var inputEvents,
                rAF = window.requestAnimationFrame || setTimeout,
                widget = this,
                $tabFocus = $( '<span>' ).addClass( 'oo-ui-tagMultiselectWidget-focusTrap' );

        config = config || {};

        // Parent constructor
        OO.ui.TagMultiselectWidget.parent.call( this, config );

        // Mixin constructors
        OO.ui.mixin.GroupWidget.call( this, config );
        OO.ui.mixin.IndicatorElement.call( this, config );
        OO.ui.mixin.IconElement.call( this, config );
        OO.ui.mixin.TabIndexedElement.call( this, config );
        OO.ui.mixin.FlaggedElement.call( this, config );
        OO.ui.mixin.DraggableGroupElement.call( this, config );
        OO.ui.mixin.TitledElement.call( this, config );

        this.toggleDraggable(
                config.allowReordering === undefined ?
                        true : !!config.allowReordering
        );

        this.inputPosition =
                this.constructor.static.allowedInputPositions.indexOf( config.inputPosition ) > -1 ?
                        config.inputPosition : 'inline';
        this.allowEditTags = config.allowEditTags === undefined ? true : !!config.allowEditTags;
        this.allowArbitrary = !!config.allowArbitrary;
        this.allowDuplicates = !!config.allowDuplicates;
        this.allowedValues = config.allowedValues || [];
        this.allowDisplayInvalidTags = config.allowDisplayInvalidTags;
        this.hasInput = this.inputPosition !== 'none';
        this.tagLimit = config.tagLimit;
        this.height = null;
        this.valid = true;

        this.$content = $( '<div>' ).addClass( 'oo-ui-tagMultiselectWidget-content' );
        this.$handle = $( '<div>' )
                .addClass( 'oo-ui-tagMultiselectWidget-handle' )
                .append(
                        this.$indicator,
                        this.$icon,
                        this.$content
                                .append(
                                        this.$group.addClass( 'oo-ui-tagMultiselectWidget-group' )
                                )
                );

        // Events
        this.aggregate( {
                remove: 'itemRemove',
                navigate: 'itemNavigate',
                select: 'itemSelect',
                fixed: 'itemFixed'
        } );
        this.connect( this, {
                itemRemove: 'onTagRemove',
                itemSelect: 'onTagSelect',
                itemFixed: 'onTagFixed',
                itemNavigate: 'onTagNavigate',
                change: 'onChangeTags'
        } );
        this.$handle.on( {
                mousedown: this.onMouseDown.bind( this )
        } );

        // Initialize
        this.$element
                .addClass( 'oo-ui-tagMultiselectWidget' )
                .append( this.$handle );

        if ( this.hasInput ) {
                if ( config.inputWidget ) {
                        this.input = config.inputWidget;
                } else {
                        this.input = new OO.ui.TextInputWidget( $.extend( {
                                placeholder: config.placeholder,
                                classes: [ 'oo-ui-tagMultiselectWidget-input' ]
                        }, config.input ) );
                }
                this.input.setDisabled( this.isDisabled() );

                inputEvents = {
                        focus: this.onInputFocus.bind( this ),
                        blur: this.onInputBlur.bind( this ),
                        'propertychange change click mouseup keydown keyup input cut paste select focus':
                                OO.ui.debounce( this.updateInputSize.bind( this ) ),
                        keydown: this.onInputKeyDown.bind( this ),
                        keypress: this.onInputKeyPress.bind( this )
                };

                this.input.$input.on( inputEvents );
                this.inputPlaceholder = this.input.$input.attr( 'placeholder' );

                if ( this.inputPosition === 'outline' ) {
                        // Override max-height for the input widget
                        // in the case the widget is outline so it can
                        // stretch all the way if the widget is wide
                        this.input.$element.css( 'max-width', 'inherit' );
                        this.$element
                                .addClass( 'oo-ui-tagMultiselectWidget-outlined' )
                                .append( this.input.$element );
                } else {
                        this.$element.addClass( 'oo-ui-tagMultiselectWidget-inlined' );
                        // HACK: When the widget is using 'inline' input, the
                        // behavior needs to only use the $input itself
                        // so we style and size it accordingly (otherwise
                        // the styling and sizing can get very convoluted
                        // when the wrapping divs and other elements)
                        // We are taking advantage of still being able to
                        // call the widget itself for operations like
                        // .getValue() and setDisabled() and .focus() but
                        // having only the $input attached to the DOM
                        this.$content.append( this.input.$input );
                }
        } else {
                this.$content.append( $tabFocus );
        }

        this.setTabIndexedElement(
                this.hasInput ?
                        this.input.$input :
                        $tabFocus
        );

        if ( config.selected ) {
                this.setValue( config.selected );
        }

        // HACK: Input size needs to be calculated after everything
        // else is rendered
        rAF( function () {
                if ( widget.hasInput ) {
                        widget.updateInputSize();
                }
        } );
};

/* Initialization */

OO.inheritClass( OO.ui.TagMultiselectWidget, OO.ui.Widget );
OO.mixinClass( OO.ui.TagMultiselectWidget, OO.ui.mixin.GroupWidget );
OO.mixinClass( OO.ui.TagMultiselectWidget, OO.ui.mixin.DraggableGroupElement );
OO.mixinClass( OO.ui.TagMultiselectWidget, OO.ui.mixin.IndicatorElement );
OO.mixinClass( OO.ui.TagMultiselectWidget, OO.ui.mixin.IconElement );
OO.mixinClass( OO.ui.TagMultiselectWidget, OO.ui.mixin.TabIndexedElement );
OO.mixinClass( OO.ui.TagMultiselectWidget, OO.ui.mixin.FlaggedElement );
OO.mixinClass( OO.ui.TagMultiselectWidget, OO.ui.mixin.TitledElement );

/* Static properties */

/**
 * Allowed input positions.
 * - inline: The input is inside the tag list
 * - outline: The input is under the tag list
 * - none: There is no input
 *
 * @property {Array}
 */
OO.ui.TagMultiselectWidget.static.allowedInputPositions = [ 'inline', 'outline', 'none' ];

/* Methods */

/**
 * Handle mouse down events.
 *
 * @private
 * @param {jQuery.Event} e Mouse down event
 * @return {boolean} False to prevent defaults
 */
OO.ui.TagMultiselectWidget.prototype.onMouseDown = function ( e ) {
        if (
                !this.isDisabled() &&
                ( !this.hasInput || e.target !== this.input.$input[ 0 ] ) &&
                e.which === OO.ui.MouseButtons.LEFT
        ) {
                this.focus();
                return false;
        }
};

/**
 * Handle key press events.
 *
 * @private
 * @param {jQuery.Event} e Key press event
 * @return {boolean} Whether to prevent defaults
 */
OO.ui.TagMultiselectWidget.prototype.onInputKeyPress = function ( e ) {
        var stopOrContinue,
                withMetaKey = e.metaKey || e.ctrlKey;

        if ( !this.isDisabled() ) {
                if ( e.which === OO.ui.Keys.ENTER ) {
                        stopOrContinue = this.doInputEnter( e, withMetaKey );
                }

                // Make sure the input gets resized.
                setTimeout( this.updateInputSize.bind( this ), 0 );
                return stopOrContinue;
        }
};

/**
 * Handle key down events.
 *
 * @private
 * @param {jQuery.Event} e Key down event
 * @return {boolean}
 */
OO.ui.TagMultiselectWidget.prototype.onInputKeyDown = function ( e ) {
        var movement, direction,
                widget = this,
                withMetaKey = e.metaKey || e.ctrlKey,
                isMovementInsideInput = function ( direction ) {
                        var inputRange = widget.input.getRange(),
                                inputValue = widget.hasInput && widget.input.getValue();

                        if ( direction === 'forwards' && inputRange.to > inputValue.length - 1 ) {
                                return false;
                        }

                        if ( direction === 'backwards' && inputRange.from <= 0 ) {
                                return false;
                        }

                        return true;
                };

        if ( !this.isDisabled() ) {
                // 'keypress' event is not triggered for Backspace key
                if ( e.keyCode === OO.ui.Keys.BACKSPACE ) {
                        return this.doInputBackspace( e, withMetaKey );
                } else if ( e.keyCode === OO.ui.Keys.ESCAPE ) {
                        return this.doInputEscape( e );
                } else if (
                        e.keyCode === OO.ui.Keys.LEFT ||
                        e.keyCode === OO.ui.Keys.RIGHT
                ) {
                        if ( OO.ui.Element.static.getDir( this.$element ) === 'rtl' ) {
                                movement = {
                                        left: 'forwards',
                                        right: 'backwards'
                                };
                        } else {
                                movement = {
                                        left: 'backwards',
                                        right: 'forwards'
                                };
                        }
                        direction = e.keyCode === OO.ui.Keys.LEFT ?
                                movement.left : movement.right;

                        if ( !this.hasInput || !isMovementInsideInput( direction ) ) {
                                return this.doInputArrow( e, direction, withMetaKey );
                        }
                }
        }
};

/**
 * Respond to input focus event
 */
OO.ui.TagMultiselectWidget.prototype.onInputFocus = function () {
        this.$element.addClass( 'oo-ui-tagMultiselectWidget-focus' );
        // Reset validity
        this.toggleValid( true );
};

/**
 * Respond to input blur event
 */
OO.ui.TagMultiselectWidget.prototype.onInputBlur = function () {
        this.$element.removeClass( 'oo-ui-tagMultiselectWidget-focus' );

        // Set the widget as invalid if there's text in the input
        this.addTagFromInput();
        this.toggleValid( this.checkValidity() && ( !this.hasInput || !this.input.getValue() ) );
};

/**
 * Perform an action after the Enter key on the input
 *
 * @param {jQuery.Event} e Event data
 * @param {boolean} [withMetaKey] Whether this key was pressed with
 * a meta key like Control
 * @return {boolean} Whether to prevent defaults
 */
OO.ui.TagMultiselectWidget.prototype.doInputEnter = function () {
        this.addTagFromInput();
        return false;
};

/**
 * Perform an action responding to the Enter key on the input
 *
 * @param {jQuery.Event} e Event data
 * @param {boolean} [withMetaKey] Whether this key was pressed with
 * a meta key like Control
 * @return {boolean} Whether to prevent defaults
 */
OO.ui.TagMultiselectWidget.prototype.doInputBackspace = function ( e, withMetaKey ) {
        var items, item;

        if (
                this.inputPosition === 'inline' &&
                this.input.getValue() === '' &&
                !this.isEmpty()
        ) {
                // Delete the last item
                items = this.getItems();
                item = items[ items.length - 1 ];

                if ( !item.isDisabled() && !item.isFixed() ) {
                        this.removeItems( [ item ] );
                        // If Ctrl/Cmd was pressed, delete item entirely.
                        // Otherwise put it into the text field for editing.
                        if ( !withMetaKey ) {
                                this.input.setValue( item.getLabel() );
                        }
                }

                return false;
        }
};

/**
 * Perform an action after the Escape key on the input
 *
 * @param {jQuery.Event} e Event data
 */
OO.ui.TagMultiselectWidget.prototype.doInputEscape = function () {
        this.clearInput();
};

/**
 * Perform an action after the Left/Right arrow key on the input, select the previous
 * item from the input.
 * See #getPreviousItem
 *
 * @param {jQuery.Event} e Event data
 * @param {string} direction Direction of the movement; forwards or backwards
 * @param {boolean} [withMetaKey] Whether this key was pressed with
 *  a meta key like Control
 */
OO.ui.TagMultiselectWidget.prototype.doInputArrow = function ( e, direction ) {
        if (
                this.inputPosition === 'inline' &&
                !this.isEmpty() &&
                direction === 'backwards'
        ) {
                // Get previous item
                this.getPreviousItem().focus();
        }
};

/**
 * Respond to item select event
 *
 * @param {OO.ui.TagItemWidget} item Selected item
 */
OO.ui.TagMultiselectWidget.prototype.onTagSelect = function ( item ) {
        if ( this.hasInput && this.allowEditTags && !item.isFixed() ) {
                if ( this.input.getValue() ) {
                        this.addTagFromInput();
                }
                // 1. Get the label of the tag into the input
                this.input.setValue( item.getLabel() );
                // 2. Remove the tag
                this.removeItems( [ item ] );
                // 3. Focus the input
                this.focus();
        }
};

/**
 * Respond to item fixed state change
 *
 * @param {OO.ui.TagItemWidget} item Selected item
 */
OO.ui.TagMultiselectWidget.prototype.onTagFixed = function ( item ) {
        var i,
                items = this.getItems();

        // Move item to the end of the static items
        for ( i = 0; i < items.length; i++ ) {
                if ( items[ i ] !== item && !items[ i ].isFixed() ) {
                        break;
                }
        }
        this.addItems( item, i );
};
/**
 * Respond to change event, where items were added, removed, or cleared.
 */
OO.ui.TagMultiselectWidget.prototype.onChangeTags = function () {
        var isUnderLimit = this.isUnderLimit();

        // Reset validity
        this.toggleValid(
                this.checkValidity() &&
                !( this.hasInput && this.input.getValue() )
        );

        if ( this.hasInput ) {
                this.updateInputSize();
                if ( !isUnderLimit ) {
                        // Clear the input
                        this.input.setValue( '' );
                }
                if ( this.inputPosition === 'outline' ) {
                        // Show/clear the placeholder and enable/disable the input
                        // based on whether we are/aren't under the specified limit
                        this.input.$input.attr( 'placeholder', isUnderLimit ? this.inputPlaceholder : '' );
                        this.input.setDisabled( !isUnderLimit );
                } else {
                        // Show/hide the input
                        this.input.$input.toggleClass( 'oo-ui-element-hidden', !isUnderLimit );
                }
        }
        this.updateIfHeightChanged();
};

/**
 * @inheritdoc
 */
OO.ui.TagMultiselectWidget.prototype.setDisabled = function ( isDisabled ) {
        // Parent method
        OO.ui.TagMultiselectWidget.parent.prototype.setDisabled.call( this, isDisabled );

        if ( this.hasInput && this.input ) {
                if ( !isDisabled ) {
                        this.updateInputSize();
                }
                this.input.setDisabled( !!isDisabled && !this.isUnderLimit() );
        }

        if ( this.items ) {
                this.getItems().forEach( function ( item ) {
                        item.setDisabled( !!isDisabled );
                } );
        }
};

/**
 * Respond to tag remove event
 * @param {OO.ui.TagItemWidget} item Removed tag
 */
OO.ui.TagMultiselectWidget.prototype.onTagRemove = function ( item ) {
        this.removeTagByData( item.getData() );
};

/**
 * Respond to navigate event on the tag
 *
 * @param {OO.ui.TagItemWidget} item Removed tag
 * @param {string} direction Direction of movement; 'forwards' or 'backwards'
 */
OO.ui.TagMultiselectWidget.prototype.onTagNavigate = function ( item, direction ) {
        var firstItem = this.getItems()[ 0 ];

        if ( direction === 'forwards' ) {
                this.getNextItem( item ).focus();
        } else if ( !this.inputPosition === 'inline' || item !== firstItem ) {
                // If the widget has an inline input, we want to stop at the starting edge
                // of the tags
                this.getPreviousItem( item ).focus();
        }
};

/**
 * Add tag from input value
 */
OO.ui.TagMultiselectWidget.prototype.addTagFromInput = function () {
        var val = this.input.getValue(),
                isValid = this.isAllowedData( val );

        if ( !val ) {
                return;
        }

        if ( isValid || this.allowDisplayInvalidTags ) {
                this.clearInput();
                this.addTag( val );
        }
};

/**
 * Clear the input
 */
OO.ui.TagMultiselectWidget.prototype.clearInput = function () {
        this.input.setValue( '' );
};

/**
 * Check whether the given value is a duplicate of an existing
 * tag already in the list.
 *
 * @param {string|Object} data Requested value
 * @return {boolean} Value is duplicate
 */
OO.ui.TagMultiselectWidget.prototype.isDuplicateData = function ( data ) {
        return !!this.findItemFromData( data );
};

/**
 * Check whether a given value is allowed to be added
 *
 * @param {string|Object} data Requested value
 * @return {boolean} Value is allowed
 */
OO.ui.TagMultiselectWidget.prototype.isAllowedData = function ( data ) {
        if (
                !this.allowDuplicates &&
                this.isDuplicateData( data )
        ) {
                return false;
        }

        if ( this.allowArbitrary ) {
                return true;
        }

        // Check with allowed values
        if (
                this.getAllowedValues().some( function ( value ) {
                        return data === value;
                } )
        ) {
                return true;
        }

        return false;
};

/**
 * Get the allowed values list
 *
 * @return {string[]} Allowed data values
 */
OO.ui.TagMultiselectWidget.prototype.getAllowedValues = function () {
        return this.allowedValues;
};

/**
 * Add a value to the allowed values list
 *
 * @param {string} value Allowed data value
 */
OO.ui.TagMultiselectWidget.prototype.addAllowedValue = function ( value ) {
        if ( this.allowedValues.indexOf( value ) === -1 ) {
                this.allowedValues.push( value );
        }
};

/**
 * Get the datas of the currently selected items
 *
 * @return {string[]|Object[]} Datas of currently selected items
 */
OO.ui.TagMultiselectWidget.prototype.getValue = function () {
        return this.getItems()
                .filter( function ( item ) {
                        return item.isValid();
                } )
                .map( function ( item ) {
                        return item.getData();
                } );
};

/**
 * Set the value of this widget by datas.
 *
 * @param {string|string[]|Object|Object[]} valueObject An object representing the data
 *  and label of the value. If the widget allows arbitrary values,
 *  the items will be added as-is. Otherwise, the data value will
 *  be checked against allowedValues.
 *  This object must contain at least a data key. Example:
 *  { data: 'foo', label: 'Foo item' }
 *  For multiple items, use an array of objects. For example:
 *  [
 *     { data: 'foo', label: 'Foo item' },
 *     { data: 'bar', label: 'Bar item' }
 *  ]
 *  Value can also be added with plaintext array, for example:
 *  [ 'foo', 'bar', 'bla' ] or a single string, like 'foo'
 */
OO.ui.TagMultiselectWidget.prototype.setValue = function ( valueObject ) {
        valueObject = Array.isArray( valueObject ) ? valueObject : [ valueObject ];

        this.clearItems();
        valueObject.forEach( function ( obj ) {
                if ( typeof obj === 'string' ) {
                        this.addTag( obj );
                } else {
                        this.addTag( obj.data, obj.label );
                }
        }.bind( this ) );
};

/**
 * Add tag to the display area
 *
 * @param {string|Object} data Tag data
 * @param {string} [label] Tag label. If no label is provided, the
 *  stringified version of the data will be used instead.
 * @return {boolean} Item was added successfully
 */
OO.ui.TagMultiselectWidget.prototype.addTag = function ( data, label ) {
        var newItemWidget,
                isValid = this.isAllowedData( data );

        if ( this.isUnderLimit() && ( isValid || this.allowDisplayInvalidTags ) ) {
                newItemWidget = this.createTagItemWidget( data, label );
                newItemWidget.toggleValid( isValid );
                this.addItems( [ newItemWidget ] );
                return true;
        }

        return false;
};

/**
 * Check whether the number of current tags is within the limit.
 *
 * @return {boolean} True if current tag count is within the limit or
 *  if 'tagLimit' is not set
 */
OO.ui.TagMultiselectWidget.prototype.isUnderLimit = function () {
        return !this.tagLimit ||
                this.getItemCount() < this.tagLimit;
};

/**
 * Remove tag by its data property.
 *
 * @param {string|Object} data Tag data
 */
OO.ui.TagMultiselectWidget.prototype.removeTagByData = function ( data ) {
        var item = this.findItemFromData( data );

        this.removeItems( [ item ] );
};

/**
 * Construct a OO.ui.TagItemWidget (or a subclass thereof) from given label and data.
 *
 * @protected
 * @param {string} data Item data
 * @param {string} label The label text.
 * @return {OO.ui.TagItemWidget}
 */
OO.ui.TagMultiselectWidget.prototype.createTagItemWidget = function ( data, label ) {
        label = label || data;

        return new OO.ui.TagItemWidget( { data: data, label: label } );
};

/**
 * Given an item, returns the item after it. If the item is already the
 * last item, return `this.input`. If no item is passed, returns the
 * very first item.
 *
 * @protected
 * @param {OO.ui.TagItemWidget} [item] Tag item
 * @return {OO.ui.Widget} The next widget available.
 */
OO.ui.TagMultiselectWidget.prototype.getNextItem = function ( item ) {
        var itemIndex = this.items.indexOf( item );

        if ( item === undefined || itemIndex === -1 ) {
                return this.items[ 0 ];
        }

        if ( itemIndex === this.items.length - 1 ) { // Last item
                if ( this.hasInput ) {
                        return this.input;
                } else {
                        // Return first item
                        return this.items[ 0 ];
                }
        } else {
                return this.items[ itemIndex + 1 ];
        }
};

/**
 * Given an item, returns the item before it. If the item is already the
 * first item, return `this.input`. If no item is passed, returns the
 * very last item.
 *
 * @protected
 * @param {OO.ui.TagItemWidget} [item] Tag item
 * @return {OO.ui.Widget} The previous widget available.
 */
OO.ui.TagMultiselectWidget.prototype.getPreviousItem = function ( item ) {
        var itemIndex = this.items.indexOf( item );

        if ( item === undefined || itemIndex === -1 ) {
                return this.items[ this.items.length - 1 ];
        }

        if ( itemIndex === 0 ) {
                if ( this.hasInput ) {
                        return this.input;
                } else {
                        // Return the last item
                        return this.items[ this.items.length - 1 ];
                }
        } else {
                return this.items[ itemIndex - 1 ];
        }
};

/**
 * Update the dimensions of the text input field to encompass all available area.
 * This is especially relevant for when the input is at the edge of a line
 * and should get smaller. The usual operation (as an inline-block with min-width)
 * does not work in that case, pushing the input downwards to the next line.
 *
 * @private
 */
OO.ui.TagMultiselectWidget.prototype.updateInputSize = function () {
        var $lastItem, direction, contentWidth, currentWidth, bestWidth;
        if ( this.inputPosition === 'inline' && !this.isDisabled() ) {
                if ( this.input.$input[ 0 ].scrollWidth === 0 ) {
                        // Input appears to be attached but not visible.
                        // Don't attempt to adjust its size, because our measurements
                        // are going to fail anyway.
                        return;
                }
                this.input.$input.css( 'width', '1em' );
                $lastItem = this.$group.children().last();
                direction = OO.ui.Element.static.getDir( this.$handle );

                // Get the width of the input with the placeholder text as
                // the value and save it so that we don't keep recalculating
                if (
                        this.contentWidthWithPlaceholder === undefined &&
                        this.input.getValue() === '' &&
                        this.input.$input.attr( 'placeholder' ) !== undefined
                ) {
                        this.input.setValue( this.input.$input.attr( 'placeholder' ) );
                        this.contentWidthWithPlaceholder = this.input.$input[ 0 ].scrollWidth;
                        this.input.setValue( '' );

                }

                // Always keep the input wide enough for the placeholder text
                contentWidth = Math.max(
                        this.input.$input[ 0 ].scrollWidth,
                        // undefined arguments in Math.max lead to NaN
                        ( this.contentWidthWithPlaceholder === undefined ) ?
                                0 : this.contentWidthWithPlaceholder
                );
                currentWidth = this.input.$input.width();

                if ( contentWidth < currentWidth ) {
                        this.updateIfHeightChanged();
                        // All is fine, don't perform expensive calculations
                        return;
                }

                if ( $lastItem.length === 0 ) {
                        bestWidth = this.$content.innerWidth();
                } else {
                        bestWidth = direction === 'ltr' ?
                                this.$content.innerWidth() - $lastItem.position().left - $lastItem.outerWidth() :
                                $lastItem.position().left;
                }

                // Some safety margin for sanity, because I *really* don't feel like finding out where the
                // few pixels this is off by are coming from.
                bestWidth -= 13;
                if ( contentWidth > bestWidth ) {
                        // This will result in the input getting shifted to the next line
                        bestWidth = this.$content.innerWidth() - 13;
                }
                this.input.$input.width( Math.floor( bestWidth ) );
                this.updateIfHeightChanged();
        } else {
                this.updateIfHeightChanged();
        }
};

/**
 * Determine if widget height changed, and if so,
 * emit the resize event. This is useful for when there are either
 * menus or popups attached to the bottom of the widget, to allow
 * them to change their positioning in case the widget moved down
 * or up.
 *
 * @private
 */
OO.ui.TagMultiselectWidget.prototype.updateIfHeightChanged = function () {
        var height = this.$element.height();
        if ( height !== this.height ) {
                this.height = height;
                this.emit( 'resize' );
        }
};

/**
 * Check whether all items in the widget are valid
 *
 * @return {boolean} Widget is valid
 */
OO.ui.TagMultiselectWidget.prototype.checkValidity = function () {
        return this.getItems().every( function ( item ) {
                return item.isValid();
        } );
};

/**
 * Set the valid state of this item
 *
 * @param {boolean} [valid] Item is valid
 * @fires valid
 */
OO.ui.TagMultiselectWidget.prototype.toggleValid = function ( valid ) {
        valid = valid === undefined ? !this.valid : !!valid;

        if ( this.valid !== valid ) {
                this.valid = valid;

                this.setFlags( { invalid: !this.valid } );

                this.emit( 'valid', this.valid );
        }
};

/**
 * Get the current valid state of the widget
 *
 * @return {boolean} Widget is valid
 */
OO.ui.TagMultiselectWidget.prototype.isValid = function () {
        return this.valid;
};

/**
 * PopupTagMultiselectWidget is a {@link OO.ui.TagMultiselectWidget OO.ui.TagMultiselectWidget}
 * intended to use a popup. The popup can be configured to have a default input to insert values
 * into the widget.
 *
 *     @example
 *     // A PopupTagMultiselectWidget.
 *     var widget = new OO.ui.PopupTagMultiselectWidget();
 *     $( document.body ).append( widget.$element );
 *
 *     // Example: A PopupTagMultiselectWidget with an external popup.
 *     var popupInput = new OO.ui.TextInputWidget(),
 *         widget = new OO.ui.PopupTagMultiselectWidget( {
 *            popupInput: popupInput,
 *            popup: {
 *               $content: popupInput.$element
 *            }
 *         } );
 *     $( document.body ).append( widget.$element );
 *
 * @class
 * @extends OO.ui.TagMultiselectWidget
 * @mixins OO.ui.mixin.PopupElement
 *
 * @param {Object} config Configuration object
 * @cfg {jQuery} [$overlay] An overlay for the popup.
 *  See <https://www.mediawiki.org/wiki/OOUI/Concepts#Overlays>.
 * @cfg {Object} [popup] Configuration options for the popup
 * @cfg {OO.ui.InputWidget} [popupInput] An input widget inside the popup that will be
 *  focused when the popup is opened and will be used as replacement for the
 *  general input in the widget.
 * @deprecated
 */
OO.ui.PopupTagMultiselectWidget = function OoUiPopupTagMultiselectWidget( config ) {
        var defaultInput,
                defaultConfig = { popup: {} };

        config = config || {};

        // Parent constructor
        OO.ui.PopupTagMultiselectWidget.parent.call( this, $.extend( {
                inputPosition: 'none'
        }, config ) );

        this.$overlay = ( config.$overlay === true ?
                OO.ui.getDefaultOverlay() : config.$overlay ) || this.$element;

        if ( !config.popup ) {
                // For the default base implementation, we give a popup
                // with an input widget inside it. For any other use cases
                // the popup needs to be populated externally and the
                // event handled to add tags separately and manually
                defaultInput = new OO.ui.TextInputWidget();

                defaultConfig.popupInput = defaultInput;
                defaultConfig.popup.$content = defaultInput.$element;
                defaultConfig.popup.padded = true;

                this.$element.addClass( 'oo-ui-popupTagMultiselectWidget-defaultPopup' );
        }

        // Add overlay, and add that to the autoCloseIgnore
        defaultConfig.popup.$overlay = this.$overlay;
        defaultConfig.popup.$autoCloseIgnore = this.hasInput ?
                this.input.$element.add( this.$overlay ) : this.$overlay;

        // Allow extending any of the above
        config = $.extend( defaultConfig, config );

        // Mixin constructors
        OO.ui.mixin.PopupElement.call( this, config );

        if ( this.hasInput ) {
                this.input.$input.on( 'focus', this.popup.toggle.bind( this.popup, true ) );
        }

        // Configuration options
        this.popupInput = config.popupInput;
        if ( this.popupInput ) {
                this.popupInput.connect( this, {
                        enter: 'onPopupInputEnter'
                } );
        }

        // Events
        this.on( 'resize', this.popup.updateDimensions.bind( this.popup ) );
        this.popup.connect( this, {
                toggle: 'onPopupToggle'
        } );
        this.$tabIndexed.on( 'focus', this.onFocus.bind( this ) );

        // Initialize
        this.$element
                .append( this.popup.$element )
                .addClass( 'oo-ui-popupTagMultiselectWidget' );

        // Deprecation warning
        OO.ui.warnDeprecation( 'PopupTagMultiselectWidget: Deprecated widget. Use MenuTagMultiselectWidget instead. See T208821.' );
};

/* Initialization */

OO.inheritClass( OO.ui.PopupTagMultiselectWidget, OO.ui.TagMultiselectWidget );
OO.mixinClass( OO.ui.PopupTagMultiselectWidget, OO.ui.mixin.PopupElement );

/* Methods */

/**
 * Focus event handler.
 *
 * @private
 */
OO.ui.PopupTagMultiselectWidget.prototype.onFocus = function () {
        this.popup.toggle( true );
};

/**
 * Respond to popup toggle event
 *
 * @param {boolean} isVisible Popup is visible
 */
OO.ui.PopupTagMultiselectWidget.prototype.onPopupToggle = function ( isVisible ) {
        if ( isVisible && this.popupInput ) {
                this.popupInput.focus();
        }
};

/**
 * Respond to popup input enter event
 */
OO.ui.PopupTagMultiselectWidget.prototype.onPopupInputEnter = function () {
        if ( this.popupInput ) {
                this.addTagByPopupValue( this.popupInput.getValue() );
                this.popupInput.setValue( '' );
        }
};

/**
 * @inheritdoc
 */
OO.ui.PopupTagMultiselectWidget.prototype.onTagSelect = function ( item ) {
        if ( this.popupInput && this.allowEditTags ) {
                this.popupInput.setValue( item.getData() );
                this.removeItems( [ item ] );

                this.popup.toggle( true );
                this.popupInput.focus();
        } else {
                // Parent
                OO.ui.PopupTagMultiselectWidget.parent.prototype.onTagSelect.call( this, item );
        }
};

/**
 * Add a tag by the popup value.
 * Whatever is responsible for setting the value in the popup should call
 * this method to add a tag, or use the regular methods like #addTag or
 * #setValue directly.
 *
 * @param {string} data The value of item
 * @param {string} [label] The label of the tag. If not given, the data is used.
 */
OO.ui.PopupTagMultiselectWidget.prototype.addTagByPopupValue = function ( data, label ) {
        this.addTag( data, label );
};

/**
 * MenuTagMultiselectWidget is a {@link OO.ui.TagMultiselectWidget OO.ui.TagMultiselectWidget}
 * intended to use a menu of selectable options.
 *
 *     @example
 *     // A basic MenuTagMultiselectWidget.
 *     var widget = new OO.ui.MenuTagMultiselectWidget( {
 *         inputPosition: 'outline',
 *         options: [
 *            { data: 'option1', label: 'Option 1', icon: 'tag' },
 *            { data: 'option2', label: 'Option 2' },
 *            { data: 'option3', label: 'Option 3' },
 *         ],
 *         selected: [ 'option1', 'option2' ]
 *     } );
 *     $( document.body ).append( widget.$element );
 *
 * @class
 * @extends OO.ui.TagMultiselectWidget
 *
 * @constructor
 * @param {Object} [config] Configuration object
 * @cfg {boolean} [clearInputOnChoose=true] Clear the text input value when a menu option is chosen
 * @cfg {Object} [menu] Configuration object for the menu widget
 * @cfg {jQuery} [$overlay] An overlay for the menu.
 *  See <https://www.mediawiki.org/wiki/OOUI/Concepts#Overlays>.
 * @cfg {Object[]} [options=[]] Array of menu options in the format `{ data: …, label: … }`
 */
OO.ui.MenuTagMultiselectWidget = function OoUiMenuTagMultiselectWidget( config ) {
        var $autoCloseIgnore = $( [] );
        config = config || {};

        // Parent constructor
        OO.ui.MenuTagMultiselectWidget.parent.call( this, config );

        $autoCloseIgnore = $autoCloseIgnore.add( this.$group );
        if ( this.hasInput ) {
                $autoCloseIgnore = $autoCloseIgnore.add( this.input.$element );
        }

        this.$overlay = ( config.$overlay === true ?
                OO.ui.getDefaultOverlay() : config.$overlay ) || this.$element;
        this.clearInputOnChoose = config.clearInputOnChoose === undefined ||
                !!config.clearInputOnChoose;
        this.menu = this.createMenuWidget( $.extend( {
                widget: this,
                hideOnChoose: false,
                input: this.hasInput ? this.input : null,
                $input: this.hasInput ? this.input.$input : null,
                filterFromInput: !!this.hasInput,
                highlightOnFilter: !this.allowArbitrary,
                multiselect: true,
                $autoCloseIgnore: $autoCloseIgnore,
                $floatableContainer: this.hasInput && this.inputPosition === 'outline' ?
                        this.input.$element : this.$element,
                $overlay: this.$overlay,
                disabled: this.isDisabled()
        }, config.menu ) );
        this.addOptions( config.options || [] );

        // Events
        this.menu.connect( this, {
                choose: 'onMenuChoose',
                toggle: 'onMenuToggle'
        } );
        if ( this.hasInput ) {
                this.input.connect( this, {
                        change: 'onInputChange'
                } );
        }
        this.connect( this, {
                resize: 'onResize'
        } );

        // Initialization
        this.$overlay.append( this.menu.$element );
        this.$element.addClass( 'oo-ui-menuTagMultiselectWidget' );
        // Remove MenuSelectWidget's generic focus owner ARIA attribute
        // TODO: Should this widget have a `role` that is compatible with this attribute?
        this.menu.$focusOwner.removeAttr( 'aria-expanded' );
        // TagMultiselectWidget already does this, but it doesn't work right because this.menu is
        // not yet set up while the parent constructor runs, and #getAllowedValues rejects everything.
        if ( config.selected ) {
                this.setValue( config.selected );
        }
};

/* Initialization */

OO.inheritClass( OO.ui.MenuTagMultiselectWidget, OO.ui.TagMultiselectWidget );

/* Methods */

/**
 * Respond to resize event
 */
OO.ui.MenuTagMultiselectWidget.prototype.onResize = function () {
        // Reposition the menu
        this.menu.position();
};

/**
 * @inheritdoc
 */
OO.ui.MenuTagMultiselectWidget.prototype.onInputFocus = function () {
        // Parent method
        OO.ui.MenuTagMultiselectWidget.parent.prototype.onInputFocus.call( this );

        this.menu.toggle( true );
};

/**
 * Respond to input change event
 */
OO.ui.MenuTagMultiselectWidget.prototype.onInputChange = function () {
        this.menu.toggle( true );
};

/**
 * Respond to menu choose event, which is intentional by the user.
 *
 * @param {OO.ui.OptionWidget} menuItem Selected menu items
 * @param {boolean} selected Item is selected
 */
OO.ui.MenuTagMultiselectWidget.prototype.onMenuChoose = function ( menuItem, selected ) {
        if ( this.hasInput && this.clearInputOnChoose ) {
                this.input.setValue( '' );
        }

        if ( selected && !this.findItemFromData( menuItem.getData() ) ) {
                // The menu item is selected, add it to the tags
                this.addTag( menuItem.getData(), menuItem.getLabel() );
        } else {
                // The menu item was unselected, remove the tag
                this.removeTagByData( menuItem.getData() );
        }
};

/**
 * Respond to menu toggle event. Reset item highlights on hide.
 *
 * @param {boolean} isVisible The menu is visible
 */
OO.ui.MenuTagMultiselectWidget.prototype.onMenuToggle = function ( isVisible ) {
        if ( !isVisible ) {
                this.menu.highlightItem( null );
                this.menu.scrollToTop();
        }
        setTimeout( function () {
                // Remove MenuSelectWidget's generic focus owner ARIA attribute
                // TODO: Should this widget have a `role` that is compatible with this attribute?
                this.menu.$focusOwner.removeAttr( 'aria-expanded' );
        }.bind( this ) );
};

/**
 * @inheritdoc
 */
OO.ui.MenuTagMultiselectWidget.prototype.onTagSelect = function ( tagItem ) {
        var menuItem = this.menu.findItemFromData( tagItem.getData() );
        if ( !this.allowArbitrary ) {
                // Override the base behavior from TagMultiselectWidget; the base behavior
                // in TagMultiselectWidget is to remove the tag to edit it in the input,
                // but in our case, we want to utilize the menu selection behavior, and
                // definitely not remove the item.

                // If there is an input that is used for filtering, erase the value so we don't filter
                if ( this.hasInput && this.menu.filterFromInput ) {
                        this.input.setValue( '' );
                }

                this.focus();

                // Highlight the menu item
                this.menu.highlightItem( menuItem );
                this.menu.scrollItemIntoView( menuItem );

        } else {
                // Use the default
                OO.ui.MenuTagMultiselectWidget.parent.prototype.onTagSelect.call( this, tagItem );
        }
};

/**
 * @inheritdoc
 */
OO.ui.MenuTagMultiselectWidget.prototype.removeItems = function ( items ) {
        var widget = this;

        // Parent
        OO.ui.MenuTagMultiselectWidget.parent.prototype.removeItems.call( this, items );

        items.forEach( function ( tagItem ) {
                var menuItem = widget.menu.findItemFromData( tagItem.getData() );
                if ( menuItem ) {
                        // Synchronize the menu selection - unselect the removed tag
                        widget.menu.unselectItem( menuItem );
                }
        } );
};

/**
 * @inheritdoc
 */
OO.ui.MenuTagMultiselectWidget.prototype.setValue = function ( valueObject ) {
        valueObject = Array.isArray( valueObject ) ? valueObject : [ valueObject ];

        // We override this method from the parent, to make sure we are adding proper
        // menu items, and are accounting for cases where we have this widget with
        // a menu but also 'allowArbitrary'
        if ( !this.menu ) {
                return;
        }

        this.clearItems();
        valueObject.forEach( function ( obj ) {
                var data, label, menuItem;

                if ( typeof obj === 'string' ) {
                        data = label = obj;
                } else {
                        data = obj.data;
                        label = obj.label;
                }

                // Check if the item is in the menu
                menuItem = this.menu.getItemFromLabel( label ) || this.menu.findItemFromData( data );
                if ( menuItem ) {
                        // Menu item found, add the menu item
                        this.addTag( menuItem.getData(), menuItem.getLabel() );
                        // Make sure that item is also selected
                        this.menu.selectItem( menuItem );
                } else if ( this.allowArbitrary ) {
                        // If the item isn't in the menu, only add it if we
                        // allow for arbitrary values
                        this.addTag( data, label );
                }
        }.bind( this ) );
};

/**
 * @inheritdoc
 */
OO.ui.MenuTagMultiselectWidget.prototype.setDisabled = function ( isDisabled ) {
        // Parent method
        OO.ui.MenuTagMultiselectWidget.parent.prototype.setDisabled.call( this, isDisabled );

        if ( this.menu ) {
                // Protect against calling setDisabled() before the menu was initialized
                this.menu.setDisabled( isDisabled );
        }
};

/**
 * Highlight the first selectable item in the menu, if configured.
 *
 * @private
 * @chainable
 */
OO.ui.MenuTagMultiselectWidget.prototype.initializeMenuSelection = function () {
        var highlightedItem;
        this.menu.highlightItem(
                this.allowArbitrary ?
                        null :
                        this.menu.findFirstSelectableItem()
        );

        highlightedItem = this.menu.findHighlightedItem();
        // Scroll to the highlighted item, if it exists
        if ( highlightedItem ) {
                this.menu.scrollItemIntoView( highlightedItem );
        }
};

/**
 * @inheritdoc
 */
OO.ui.MenuTagMultiselectWidget.prototype.addTagFromInput = function () {
        var val = this.input.getValue(),
                // Look for a highlighted item first
                // Then look for the element that fits the data
                item = this.menu.findHighlightedItem() || this.menu.findItemFromData( val ),
                data = item ? item.getData() : val,
                isValid = this.isAllowedData( data );

        // Override the parent method so we add from the menu
        // rather than directly from the input

        if ( !val ) {
                return;
        }

        if ( isValid || this.allowDisplayInvalidTags ) {
                this.clearInput();
                if ( item ) {
                        this.addTag( data, item.getLabel() );
                } else {
                        this.addTag( val );
                }
        }
};

/**
 * Return the visible items in the menu. This is mainly used for when
 * the menu is filtering results.
 *
 * @return {OO.ui.MenuOptionWidget[]} Visible results
 */
OO.ui.MenuTagMultiselectWidget.prototype.getMenuVisibleItems = function () {
        return this.menu.getItems().filter( function ( menuItem ) {
                return menuItem.isVisible();
        } );
};

/**
 * Create the menu for this widget. This is in a separate method so that
 * child classes can override this without polluting the constructor with
 * unnecessary extra objects that will be overidden.
 *
 * @param {Object} menuConfig Configuration options
 * @return {OO.ui.MenuSelectWidget} Menu widget
 */
OO.ui.MenuTagMultiselectWidget.prototype.createMenuWidget = function ( menuConfig ) {
        return new OO.ui.MenuSelectWidget( menuConfig );
};

/**
 * Add options to the menu
 *
 * @param {Object[]} menuOptions Object defining options
 */
OO.ui.MenuTagMultiselectWidget.prototype.addOptions = function ( menuOptions ) {
        var widget = this,
                items = menuOptions.map( function ( obj ) {
                        return widget.createMenuOptionWidget( obj.data, obj.label, obj.icon );
                } );

        this.menu.addItems( items );
};

/**
 * Create a menu option widget.
 *
 * @param {string} data Item data
 * @param {string} [label] Item label
 * @param {string} [icon] Symbolic icon name
 * @return {OO.ui.OptionWidget} Option widget
 */
OO.ui.MenuTagMultiselectWidget.prototype.createMenuOptionWidget = function ( data, label, icon ) {
        return new OO.ui.MenuOptionWidget( {
                data: data,
                label: label || data,
                icon: icon
        } );
};

/**
 * Get the menu
 *
 * @return {OO.ui.MenuSelectWidget} Menu
 */
OO.ui.MenuTagMultiselectWidget.prototype.getMenu = function () {
        return this.menu;
};

/**
 * Get the allowed values list
 *
 * @return {string[]} Allowed data values
 */
OO.ui.MenuTagMultiselectWidget.prototype.getAllowedValues = function () {
        var menuDatas = [];
        if ( this.menu ) {
                // If the parent constructor is calling us, we're not ready yet, this.menu is not set up.
                menuDatas = this.menu.getItems().map( function ( menuItem ) {
                        return menuItem.getData();
                } );
        }
        return this.allowedValues.concat( menuDatas );
};

/**
 * SelectFileWidgets allow for selecting files, using the HTML5 File API. These
 * widgets can be configured with {@link OO.ui.mixin.IconElement icons}, {@link
 * OO.ui.mixin.IndicatorElement indicators} and {@link OO.ui.mixin.TitledElement titles}.
 * Please see the [OOUI documentation on MediaWiki] [1] for more information and examples.
 *
 * Although SelectFileWidget inherits from SelectFileInputWidget, it does not
 * behave as an InputWidget, and can't be used in HTML forms.
 *
 *     @example
 *     // A file select widget.
 *     var selectFile = new OO.ui.SelectFileWidget();
 *     $( document.body ).append( selectFile.$element );
 *
 * [1]: https://www.mediawiki.org/wiki/OOUI/Widgets
 *
 * @class
 * @extends OO.ui.SelectFileInputWidget
 * @mixins OO.ui.mixin.PendingElement
 *
 * @constructor
 * @param {Object} [config] Configuration options
 * @cfg {string} [notsupported] Text to display when file support is missing in the browser.
 * @cfg {boolean} [droppable=true] Whether to accept files by drag and drop.
 * @cfg {boolean} [buttonOnly=false] Show only the select file button, no info field. Requires
 *  showDropTarget to be false.
 * @cfg {boolean} [showDropTarget=false] Whether to show a drop target. Requires droppable to be
 *  true. Not yet supported in multiple file mode.
 * @cfg {number} [thumbnailSizeLimit=20] File size limit in MiB above which to not try and show a
 *  preview (for performance).
 */
OO.ui.SelectFileWidget = function OoUiSelectFileWidget( config ) {
        var dragHandler, droppable,
                isSupported = this.constructor.static.isSupported();

        // Configuration initialization
        config = $.extend( {
                notsupported: OO.ui.msg( 'ooui-selectfile-not-supported' ),
                droppable: true,
                buttonOnly: false,
                showDropTarget: false,
                thumbnailSizeLimit: 20
        }, config );

        if ( !isSupported ) {
                config.disabled = true;
        }

        // Parent constructor
        OO.ui.SelectFileWidget.parent.call( this, config );

        // Mixin constructors
        OO.ui.mixin.PendingElement.call( this );

        if ( !isSupported ) {
                this.info.setValue( config.notsupported );
        }

        // Properties
        droppable = config.droppable && isSupported;
        // TODO: Support drop target when multiple is set
        this.showDropTarget = droppable && config.showDropTarget && !this.multiple;
        this.thumbnailSizeLimit = config.thumbnailSizeLimit;

        // Events
        if ( droppable ) {
                dragHandler = this.onDragEnterOrOver.bind( this );
                this.$element.on( {
                        dragenter: dragHandler,
                        dragover: dragHandler,
                        dragleave: this.onDragLeave.bind( this ),
                        drop: this.onDrop.bind( this )
                } );
        }

        // Initialization
        if ( this.showDropTarget ) {
                this.selectButton.setIcon( 'upload' );
                this.$thumbnail = $( '<div>' ).addClass( 'oo-ui-selectFileWidget-thumbnail' );
                this.setPendingElement( this.$thumbnail );
                this.$element
                        .addClass( 'oo-ui-selectFileWidget-dropTarget' )
                        .on( {
                                click: this.onDropTargetClick.bind( this )
                        } )
                        .append(
                                this.$thumbnail,
                                this.info.$element,
                                this.selectButton.$element,
                                $( '<span>' )
                                        .addClass( 'oo-ui-selectFileWidget-dropLabel' )
                                        .text( OO.ui.msg( 'ooui-selectfile-dragdrop-placeholder' ) )
                        );
                this.fieldLayout.$element.remove();
        } else if ( config.buttonOnly ) {
                this.$element.append( this.selectButton.$element );
                this.fieldLayout.$element.remove();
        }

        this.$input
                .on( 'click', function ( e ) {
                        // Prevents dropTarget to get clicked which calls
                        // a click on this input
                        e.stopPropagation();
                } );

        this.$element.addClass( 'oo-ui-selectFileWidget' );

        this.updateUI();
};

/* Setup */

OO.inheritClass( OO.ui.SelectFileWidget, OO.ui.SelectFileInputWidget );
OO.mixinClass( OO.ui.SelectFileWidget, OO.ui.mixin.PendingElement );

/* Static Properties */

/**
 * Check if this widget is supported
 *
 * @static
 * @return {boolean}
 */
OO.ui.SelectFileWidget.static.isSupported = function () {
        var $input;
        if ( OO.ui.SelectFileWidget.static.isSupportedCache === null ) {
                $input = $( '<input>' ).attr( 'type', 'file' );
                OO.ui.SelectFileWidget.static.isSupportedCache = $input[ 0 ].files !== undefined;
        }
        return OO.ui.SelectFileWidget.static.isSupportedCache;
};

OO.ui.SelectFileWidget.static.isSupportedCache = null;

/* Events */

/**
 * @event change
 *
 * A change event is emitted when the on/off state of the toggle changes.
 *
 * @param {File|null} value New value
 */

/* Methods */

/**
 * Get the current value of the field
 *
 * For single file widgets returns a File or null.
 * For multiple file widgets returns a list of Files.
 *
 * @return {File|File[]|null}
 */
OO.ui.SelectFileWidget.prototype.getValue = function () {
        return this.multiple ? this.currentFiles : this.currentFiles[ 0 ];
};

/**
 * Set the current value of the field
 *
 * @param {File[]|null} files Files to select
 */
OO.ui.SelectFileWidget.prototype.setValue = function ( files ) {
        if ( files && !this.multiple ) {
                files = files.slice( 0, 1 );
        }

        function comparableFile( file ) {
                // Use extend to convert to plain objects so they can be compared.
                return $.extend( {}, file );
        }

        if ( !OO.compare(
                files && files.map( comparableFile ),
                this.currentFiles && this.currentFiles.map( comparableFile )
        ) ) {
                this.currentFiles = files || [];
                this.emit( 'change', this.currentFiles );
        }
};

/**
 * @inheritdoc
 */
OO.ui.SelectFileWidget.prototype.getFilename = function () {
        return this.currentFiles.map( function ( file ) {
                return file.name;
        } ).join( ', ' );
};

/**
 * Disable InputWidget#onEdit listener, onFileSelected is used instead.
 * @inheritdoc
 */
OO.ui.SelectFileWidget.prototype.onEdit = function () {};

/**
 * @inheritdoc
 */
OO.ui.SelectFileWidget.prototype.updateUI = function () {
        // Too early, or not supported
        if ( !this.selectButton || !this.constructor.static.isSupported() ) {
                return;
        }

        // Parent method
        OO.ui.SelectFileWidget.super.prototype.updateUI.call( this );

        if ( this.currentFiles.length ) {
                this.$element.removeClass( 'oo-ui-selectFileInputWidget-empty' );

                if ( this.showDropTarget ) {
                        this.pushPending();
                        this.loadAndGetImageUrl( this.currentFiles[ 0 ] ).done( function ( url ) {
                                this.$thumbnail.css( 'background-image', 'url( ' + url + ' )' );
                        }.bind( this ) ).fail( function () {
                                this.$thumbnail.append(
                                        new OO.ui.IconWidget( {
                                                icon: 'attachment',
                                                classes: [ 'oo-ui-selectFileWidget-noThumbnail-icon' ]
                                        } ).$element
                                );
                        }.bind( this ) ).always( function () {
                                this.popPending();
                        }.bind( this ) );
                        this.$element.off( 'click' );
                }
        } else {
                if ( this.showDropTarget ) {
                        this.$element.off( 'click' );
                        this.$element.on( {
                                click: this.onDropTargetClick.bind( this )
                        } );
                        this.$thumbnail
                                .empty()
                                .css( 'background-image', '' );
                }
                this.$element.addClass( 'oo-ui-selectFileInputWidget-empty' );
        }
};

/**
 * If the selected file is an image, get its URL and load it.
 *
 * @param {File} file File
 * @return {jQuery.Promise} Promise resolves with the image URL after it has loaded
 */
OO.ui.SelectFileWidget.prototype.loadAndGetImageUrl = function ( file ) {
        var deferred = $.Deferred(),
                reader = new FileReader();

        if (
                ( OO.getProp( file, 'type' ) || '' ).indexOf( 'image/' ) === 0 &&
                file.size < this.thumbnailSizeLimit * 1024 * 1024
        ) {
                reader.onload = function ( event ) {
                        var img = document.createElement( 'img' );
                        img.addEventListener( 'load', function () {
                                if (
                                        img.naturalWidth === 0 ||
                                        img.naturalHeight === 0 ||
                                        img.complete === false
                                ) {
                                        deferred.reject();
                                } else {
                                        deferred.resolve( event.target.result );
                                }
                        } );
                        img.src = event.target.result;
                };
                reader.readAsDataURL( file );
        } else {
                deferred.reject();
        }

        return deferred.promise();
};

/**
 * @inheritdoc
 */
OO.ui.SelectFileWidget.prototype.onFileSelected = function ( e ) {
        var files;

        if ( this.inputClearing ) {
                return;
        }

        files = this.filterFiles( e.target.files || [] );

        // After a file is selected clear the native widget to avoid confusion
        this.inputClearing = true;
        this.$input[ 0 ].value = '';
        this.inputClearing = false;

        this.setValue( files );
};

/**
 * Handle drop target click events.
 *
 * @private
 * @param {jQuery.Event} e Key press event
 * @return {undefined|boolean} False to prevent default if event is handled
 */
OO.ui.SelectFileWidget.prototype.onDropTargetClick = function () {
        if ( !this.isDisabled() && this.$input ) {
                this.$input.trigger( 'click' );
                return false;
        }
};

/**
 * Handle drag enter and over events
 *
 * @private
 * @param {jQuery.Event} e Drag event
 * @return {undefined|boolean} False to prevent default if event is handled
 */
OO.ui.SelectFileWidget.prototype.onDragEnterOrOver = function ( e ) {
        var itemsOrFiles,
                hasDroppableFile = false,
                dt = e.originalEvent.dataTransfer;

        e.preventDefault();
        e.stopPropagation();

        if ( this.isDisabled() ) {
                this.$element.removeClass( 'oo-ui-selectFileWidget-canDrop' );
                dt.dropEffect = 'none';
                return false;
        }

        // DataTransferItem and File both have a type property, but in Chrome files
        // have no information at this point.
        itemsOrFiles = dt.items || dt.files;
        if ( itemsOrFiles && itemsOrFiles.length ) {
                if ( this.filterFiles( itemsOrFiles ).length ) {
                        hasDroppableFile = true;
                }
        // dt.types is Array-like, but not an Array
        } else if ( Array.prototype.indexOf.call( OO.getProp( dt, 'types' ) || [], 'Files' ) !== -1 ) {
                // File information is not available at this point for security so just assume
                // it is acceptable for now.
                // https://bugzilla.mozilla.org/show_bug.cgi?id=640534
                hasDroppableFile = true;
        }

        this.$element.toggleClass( 'oo-ui-selectFileWidget-canDrop', hasDroppableFile );
        if ( !hasDroppableFile ) {
                dt.dropEffect = 'none';
        }

        return false;
};

/**
 * Handle drag leave events
 *
 * @private
 * @param {jQuery.Event} e Drag event
 */
OO.ui.SelectFileWidget.prototype.onDragLeave = function () {
        this.$element.removeClass( 'oo-ui-selectFileWidget-canDrop' );
};

/**
 * Handle drop events
 *
 * @private
 * @param {jQuery.Event} e Drop event
 * @return {undefined|boolean} False to prevent default if event is handled
 */
OO.ui.SelectFileWidget.prototype.onDrop = function ( e ) {
        var files,
                dt = e.originalEvent.dataTransfer;

        e.preventDefault();
        e.stopPropagation();
        this.$element.removeClass( 'oo-ui-selectFileWidget-canDrop' );

        if ( this.isDisabled() ) {
                return false;
        }

        files = this.filterFiles( dt.files || [] );
        this.setValue( files );

        return false;
};

/**
 * @inheritdoc
 */
OO.ui.SelectFileWidget.prototype.setDisabled = function ( disabled ) {
        disabled = disabled || !this.constructor.static.isSupported();

        // Parent method
        OO.ui.SelectFileWidget.parent.prototype.setDisabled.call( this, disabled );
};

/**
 * SearchWidgets combine a {@link OO.ui.TextInputWidget text input field},
 * where users can type a search query, and a menu of search results,
 * which is displayed beneath the query field.
 * Unlike {@link OO.ui.mixin.LookupElement lookup menus}, search result menus are always visible
 * to the user. Users can choose an item from the menu or type a query into the text field to
 * search for a matching result item.
 * In general, search widgets are used inside a separate {@link OO.ui.Dialog dialog} window.
 *
 * Each time the query is changed, the search result menu is cleared and repopulated. Please see
 * the [OOUI demos][1] for an example.
 *
 * [1]: https://doc.wikimedia.org/oojs-ui/master/demos/#SearchInputWidget-type-search
 *
 * @class
 * @extends OO.ui.Widget
 *
 * @constructor
 * @param {Object} [config] Configuration options
 * @cfg {string|jQuery} [placeholder] Placeholder text for query input
 * @cfg {string} [value] Initial query value
 */
OO.ui.SearchWidget = function OoUiSearchWidget( config ) {
        // Configuration initialization
        config = config || {};

        // Parent constructor
        OO.ui.SearchWidget.parent.call( this, config );

        // Properties
        this.query = new OO.ui.TextInputWidget( {
                icon: 'search',
                placeholder: config.placeholder,
                value: config.value
        } );
        this.results = new OO.ui.SelectWidget();
        this.$query = $( '<div>' );
        this.$results = $( '<div>' );

        // Events
        this.query.connect( this, {
                change: 'onQueryChange',
                enter: 'onQueryEnter'
        } );
        this.query.$input.on( 'keydown', this.onQueryKeydown.bind( this ) );

        // Initialization
        this.$query
                .addClass( 'oo-ui-searchWidget-query' )
                .append( this.query.$element );
        this.$results
                .addClass( 'oo-ui-searchWidget-results' )
                .append( this.results.$element );
        this.$element
                .addClass( 'oo-ui-searchWidget' )
                .append( this.$results, this.$query );
};

/* Setup */

OO.inheritClass( OO.ui.SearchWidget, OO.ui.Widget );

/* Methods */

/**
 * Handle query key down events.
 *
 * @private
 * @param {jQuery.Event} e Key down event
 */
OO.ui.SearchWidget.prototype.onQueryKeydown = function ( e ) {
        var highlightedItem, nextItem,
                dir = e.which === OO.ui.Keys.DOWN ? 1 : ( e.which === OO.ui.Keys.UP ? -1 : 0 );

        if ( dir ) {
                highlightedItem = this.results.findHighlightedItem();
                if ( !highlightedItem ) {
                        highlightedItem = this.results.findSelectedItem();
                }
                nextItem = this.results.findRelativeSelectableItem( highlightedItem, dir );
                this.results.highlightItem( nextItem );
                nextItem.scrollElementIntoView();
        }
};

/**
 * Handle select widget select events.
 *
 * Clears existing results. Subclasses should repopulate items according to new query.
 *
 * @private
 * @param {string} value New value
 */
OO.ui.SearchWidget.prototype.onQueryChange = function () {
        // Reset
        this.results.clearItems();
};

/**
 * Handle select widget enter key events.
 *
 * Chooses highlighted item.
 *
 * @private
 * @param {string} value New value
 */
OO.ui.SearchWidget.prototype.onQueryEnter = function () {
        var highlightedItem = this.results.findHighlightedItem();
        if ( highlightedItem ) {
                this.results.chooseItem( highlightedItem );
        }
};

/**
 * Get the query input.
 *
 * @return {OO.ui.TextInputWidget} Query input
 */
OO.ui.SearchWidget.prototype.getQuery = function () {
        return this.query;
};

/**
 * Get the search results menu.
 *
 * @return {OO.ui.SelectWidget} Menu of search results
 */
OO.ui.SearchWidget.prototype.getResults = function () {
        return this.results;
};

}( OO ) );

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