( function ( mw, $ ) {
	/**
	 * Notification view model
	 *
	 * @class
	 * @mixins OO.EventEmitter
	 *
	 * @constructor
	 * @param {mw.echo.api.EchoApi} api Network handler
	 * @param {mw.echo.dm.UnreadNotificationCounter} unreadCounter Counter of unread notifications
	 * @param {Object} [config] Configuration object
	 * @cfg {string} [id] Model id, used to refer to the model specifically.
	 *  Falls back to the model's unique source
	 * @cfg {string} [title=''] An optional title for the model. This is mostly used
	 *  for nested bundled models inside group items.
	 * @cfg {string|string[]} [type='alert'] Notification type 'alert', 'message'
	 *  or an array [ 'alert', 'message' ]
	 * @cfg {string} [source='local'] Model source, 'local' or some symbolic name identifying
	 *  the source of the notification items for the network handler.
	 * @cfg {number} [limit=25] Notification limit
	 * @cfg {string} [userLang] User language
	 * @cfg {number} [timestamp] Timestamp (in MW format) to return from #getTimestamp when
	 *  there are no items; use this if the timestamp is known ahead of time (before population).
	 * @cfg {boolean} [foreign] The model's source is foreign
	 * @cfg {boolean} [removeReadNotifications=false] Remove read notifications completely. This
	 *  means the model will only contain unread notifications. This is useful for
	 *  cross-wiki bundled notifications.
	 */
	mw.echo.dm.NotificationsModel = function MwEchoDmNotificationsModel( api, unreadCounter, config ) {
		config = config || {};

		// Mixin constructor
		OO.EventEmitter.call( this );

		// Mixin constructor
		mw.echo.dm.SortedList.call( this );

		this.unreadCounter = unreadCounter;

		this.type = config.type || 'alert';
		this.source = config.source || 'local';
		this.id = config.id || this.source;
		this.title = config.title || '';
		this.fallbackTimestamp = config.timestamp;

		this.markingAllAsRead = false;
		this.autoMarkReadInProcess = false;
		this.fetchingNotifications = false;

		this.removeReadNotifications = !!config.removeReadNotifications;
		this.foreign = !!config.foreign;

		this.api = api;

		this.seenTime = mw.config.get( 'wgEchoSeenTime' ) || {};

		// Store references to unseen notifications
		this.unseenNotifications = new mw.echo.dm.NotificationList();

		// Events
		this.aggregate( {
			seen: 'itemSeen',
			read: 'itemRead',
			empty: 'itemGroupEmpty'
		} );

		this.connect( this, {
			itemSeen: 'onItemSeen',
			itemRead: 'onItemRead',
			itemGroupEmpty: 'onItemGroupEmpty'
		} );

		this.setSortingCallback( function ( a, b ) {
			var diff;

			if ( !a.isRead() && b.isRead() ) {
				return -1; // Unread items are always above read items
			} else if ( a.isRead() && !b.isRead() ) {
				return 1;
			} else if ( !a.isForeign() && b.isForeign() ) {
				return -1;
			} else if ( a.isForeign() && !b.isForeign() ) {
				return 1;
			} else {
				// Reverse sorting
				diff = Number( b.getTimestamp() ) - Number( a.getTimestamp() );
				if ( diff !== 0 ) {
					return diff;
				}

				// Fallback on IDs
				return b.getId() - a.getId();
			}
		} );
	};

	/* Initialization */

	OO.initClass( mw.echo.dm.NotificationsModel );
	OO.mixinClass( mw.echo.dm.NotificationsModel, OO.EventEmitter );
	OO.mixinClass( mw.echo.dm.NotificationsModel, mw.echo.dm.SortedList );

	/* Events */

	/**
	 * @event updateSeenTime
	 *
	 * Seen time has been updated
	 */

	/**
	 * @event unseenChange
	 * @param {mw.echo.dm.NotificationItem} items An array of the unseen items
	 *
	 * Items' seen status has changed
	 */

	/**
	 * @event allRead
	 *
	 * All items are marked as read
	 */

	/**
	 * @event empty
	 *
	 * The model is empty
	 */

	/**
	 * @event done
	 * @param {boolean} success The operation is successful
	 * @param {Object} result The result of the operation. For success, the
	 *  result includes the ids of the items. For failures, the result
	 *  includes the error code from the failed API request
	 * @param {string[]} [result.ids] An array of notification IDs that were
	 *  fetched from the API. This only appears on success.
	 * @param {string} [result.errCode] The error code from the API.
	 *  This only appears on failure.
	 * @param {Object} [result.errObj] The error object from the API.
	 *  This only appears on failure.
	 *
	 * The process of fetching notifications from the API has finished
	 */

	/* Methods */

	/**
	 * Respond to item seen state change
	 *
	 * @param {mw.echo.dm.NotificationItem} item Notification item
	 * @param {boolean} isSeen Notification is seen
	 * @fires unseenChange
	 */
	mw.echo.dm.NotificationsModel.prototype.onItemSeen = function ( item, isSeen ) {
		var id = item && item.getId(),
			unseenItem = id && this.unseenNotifications.getItemById( id );

		if ( unseenItem ) {
			if ( isSeen ) {
				this.unseenNotifications.removeItems( [ unseenItem ] );
			} else {
				this.unseenNotifications.addItems( [ unseenItem ] );
			}
			this.emit( 'unseenChange', this.unseenNotifications.getItems() );
		}
	};

	/**
	 * Respond to item read state change
	 *
	 * @param {mw.echo.dm.NotificationItem} item Notification item
	 * @param {boolean} isRead Notification is read
	 */
	mw.echo.dm.NotificationsModel.prototype.onItemRead = function ( item, isRead ) {
		var model = this,
			id = item && item.getId();

		// The event 'itemRead' has different meanings depending on who fires it.
		// When fired by NotificationItem, it means: "please call the API to mark me as read"
		// When fired by NotificationsGroupItem, it means: "I've already called the API to do the work"
		if ( item instanceof mw.echo.dm.NotificationGroupItem ) {
			return;
		}

		// Update unread status and emit events
		if ( isRead ) {
			// We are skipping "mark as read" when the operation is "mark all read"
			// because the API takes a single request to mark all notifications
			// as read, and we don't need to send multiple individual requests.
			if ( !this.markingAllAsRead ) {
				this.unreadCounter.estimateChange( -1 );
				this.toggleItemsReadInApi( id, isRead ).then( function () {
					model.unreadCounter.update();
				} );
			}
			if ( this.removeReadNotifications ) {
				// Remove this notification from the model
				this.removeItems( [ item ] );
			}

		} else {
			this.unreadCounter.estimateChange( 1 );
			this.toggleItemsReadInApi( id, isRead ).then( function () {
				model.unreadCounter.update();
			} );
		}

		if ( !this.countUnreadTalkPageNotifications() ) {
			this.emit( 'allTalkRead' );
		}
	};

	/**
	 * Respond to grouped item being empty
	 *
	 * @param {mw.echo.dm.NotificationItem} item Group item
	 */
	mw.echo.dm.NotificationsModel.prototype.onItemGroupEmpty = function ( item ) {
		// TODO: When we have other types of bundles, we should check how to handle
		// empty bundles (and bundles with only 1 item left)
		// In this case, the notification is a "cross wiki" notification, which
		// goes away when it is empty
		this.removeItems( [ item ] );
	};

	/**
	 * Count the unread messages that originate from the user talk page.
	 *
	 * @return {number} Number of unread talk page messages
	 */
	mw.echo.dm.NotificationsModel.prototype.countUnreadTalkPageNotifications = function () {
		var i, len,
			talk = 0,
			item,
			items = this.getItems();

		for ( i = 0, len = items.length; i < len; i++ ) {
			item = items[ i ];
			if ( !item.isRead() && item.getCategory() === 'edit-user-talk' ) {
				talk++;
			}
		}
		return talk;
	};

	/**
	 * Get the type of the notifications that this model deals with.
	 * Notifications types can be 'alert', 'message' or an array of both.
	 *
	 * @return {string|string[]} Notifications type
	 */
	mw.echo.dm.NotificationsModel.prototype.getType = function () {
		return this.type;
	};

	/**
	 * Get the counter of how many notifications are unseen
	 *
	 * @return {number} Number of unseen notifications
	 */
	mw.echo.dm.NotificationsModel.prototype.getUnseenCount = function () {
		return this.unseenNotifications.getItemCount();
	};

	/**
	 * Get the counter of how many regular, non bundled notifications are unread
	 *
	 * @return {number} Number of non bundled unread notifications
	 */
	mw.echo.dm.NotificationsModel.prototype.getNonbundledUnreadCount = function () {
		var i,
			nonBundleItems = 0,
			items = this.getItems();

		for ( i = 0; i < items.length; i++ ) {
			if (
				!( items[ i ] instanceof mw.echo.dm.NotificationGroupItem ) &&
				!items[ i ].isRead()
			) {
				nonBundleItems++;
			}
		}
		return nonBundleItems;
	};

	/**
	 * Set the system seen time - the last time we've marked notification as seen
	 *
	 * @private
	 * @param {string} type Notification type; 'alert', 'message' or 'all'
	 * @param {string} time Mediawiki seen timestamp in Mediawiki timestamp format
	 */
	mw.echo.dm.NotificationsModel.prototype.setSeenTime = function ( type, time ) {
		var i, types;

		// Normalize if using 'all'
		types = type === 'all' ? [ 'alert', 'message' ] : [ type ];

		for ( i = 0; i < type.length; i++ ) {
			// Update all types
			this.seenTime[ type[ i ] ] = time;
		}
	};

	/**
	 * Get the system seen time
	 *
	 * @param {string} [type] Notification type
	 * @return {string} Mediawiki seen timestamp in Mediawiki timestamp format
	 */
	mw.echo.dm.NotificationsModel.prototype.getSeenTime = function ( type ) {
		var normalizedType;

		type = type || this.type;

		normalizedType = type === 'all' ?
			[ 'alert', 'message' ] : [ type ];

		return this.seenTime[ normalizedType[ 0 ] ];
	};

	/**
	 * Update the seen timestamp
	 *
	 * @param {string|string[]} [type] Notification type
	 * @fires updateSeenTime
	 */
	mw.echo.dm.NotificationsModel.prototype.updateSeenTime = function ( type ) {
		var i, len, types,
			items = this.unseenNotifications.getItems();

		type = type || this.type;

		// If type is "all" or is not given, update both
		types = type === 'all' ? [ 'alert', 'message' ] : [ type || this.type ];

		// Update the notifications seen status
		for ( i = 0, len = items.length; i < len; i++ ) {
			items[ i ].toggleSeen( true );
		}
		this.emit( 'updateSeenTime' );

		// Only update seenTime in the API locally
		if ( !this.isForeign() ) {
			for ( i = 0; i < types.length; i++ ) {
				this.api.updateSeenTime( this.getSource(), types[ i ] )
					.then( this.setSeenTime.bind( this, types[ i ] ) );
			}
		}
	};

	/**
	 * Mark all notifications as read
	 *
	 * @return {jQuery.Promise} A promise that resolves when all notifications
	 * were marked as read.
	 * @fires empty
	 */
	mw.echo.dm.NotificationsModel.prototype.markAllRead = function () {
		var model = this,
			i, len, item,
			items = this.getItems(),
			itemIds = [],
			length = items.length;

		// Skip if this is an automatic "mark as read" and this model is
		// foreign
		if ( this.foreign && this.autoMarkReadInProcess ) {
			return $.Deferred().resolve( 0 ).promise();
		}

		// In some cases our model is empty out of technicalities -- that is,
		// we didn't fetch its items yet. In that case, when markAllRead is
		// called, we should emit the empty event (that would have been
		// emitted if there were items that were then marked as read and removed)
		// and return a resolved promise
		if ( length === 0 ) {
			if ( this.removeReadNotifications ) {
				this.emit( 'empty' );
			}
			return $.Deferred().resolve( 0 ).promise();
		}

		this.markingAllAsRead = true;
		for ( i = 0, len = items.length; i < len; i++ ) {
			item = items[ i ];
			// Skip items that are foreign if we are in automatic 'mark all as read'
			if ( !item.isForeign() && !item.isRead() ) {
				item.toggleRead( true );
				item.toggleSeen( true );
				itemIds.push( items[ i ].getId() );
			}
		}
		this.markingAllAsRead = false;

		if ( itemIds ) {
			this.unreadCounter.estimateChange( -itemIds.length );
			return this.api.markItemsRead( itemIds, this.getSource(), true ).then( function () {
				model.unreadCounter.update();
			} );
		}
	};

	/**
	 * Trigger an automatic mark all notifications as read. It's important to mark
	 * this process as an automatic one, because there are several cases where we
	 * don't want to mark specific notifications as automatically read (like external
	 * group items)
	 *
	 * @fires empty
	 */
	mw.echo.dm.NotificationsModel.prototype.autoMarkAllRead = function () {
		var model = this;

		this.autoMarkReadInProcess = true;
		this.markAllRead()
			.then( function () {
				model.autoMarkReadInProcess = false;
			} );
	};

	/**
	 * Update the read status of a notification item, or a list of items, in the API
	 *
	 * @param {string|string[]} itemIds Item id or an array of item Ids
	 * @return {jQuery.Promise} A promise that resolves when the notifications
	 * were marked as read.
	 */
	mw.echo.dm.NotificationsModel.prototype.toggleItemsReadInApi = function ( itemIds, isRead ) {
		itemIds = $.isArray( itemIds ) ? itemIds : [ itemIds ];

		return this.api.markItemsRead( itemIds, this.getSource(), isRead );
	};

	/**
	 * Get an array of the notification IDs of the items in this model
	 *
	 * @return {string[]} Array of notification IDs
	 */
	mw.echo.dm.NotificationsModel.prototype.getAllItemIds = function () {
		var i,
			items = this.getItems(),
			result = [];

		for ( i = 0; i < items.length; i++ ) {
			result.push( items[ i ].getId() );
		}

		return result;
	};

	/**
	 * Fetch notifications from the API and update the notifications list.
	 *
	 * @param {boolean} [isForced] Force a renewed fetching promise. If set to false, the
	 *  model will request the stored/cached fetching promise from the API. A 'true' value
	 *  will force the API to re-request that information from the server and update the
	 *  notifications.
	 * @return {jQuery.Promise} A promise that resolves with an array of notification IDs
	 */
	mw.echo.dm.NotificationsModel.prototype.fetchNotifications = function ( isForced ) {
		var model = this;

		if ( !this.isForeign() ) {
			this.unreadCounter.update();
		}

		// Rebuild the notifications promise either when it is null or when
		// it exists in a failed state
		return this.api.fetchNotifications( this.getType(), this.getSource(), !!isForced )
			.then(
				// Success
				function ( data ) {
					var notifData, id,
						notificationModel, content,
						newNotifData = {},
						sources = {},
						optionItems = [],
						idArray = [];

					data = data || {};

					for ( id in data.list ) {
						notifData = data.list[ id ];
						content = notifData[ '*' ] || {};

						// Collect common data
						newNotifData = {
							read: !!notifData.read,
							seen: !!notifData.read || notifData.timestamp.mw <= model.getSeenTime(),
							timestamp: notifData.timestamp.utcmw,
							category: notifData.category,
							content: {
								header: content.header,
								body: content.body
							},
							iconURL: content.iconUrl,
							iconType: content.icon,
							type: model.getType(),
							foreign: model.isForeign(),
							source: model.getSource(),
							primaryUrl: OO.getProp( content.links, 'primary', 'url' ),
							secondaryUrls: OO.getProp( content.links, 'secondary' ) || []
						};

						if ( notifData.type === 'foreign' ) {
							// Register sources
							sources = notifData.sources;
							model.api.registerForeignSources( sources );

							// Create model
							notificationModel = new mw.echo.dm.NotificationGroupItem(
								model.api,
								model.unreadCounter,
								sources,
								id,
								$.extend( true, {}, newNotifData, {
									// This should probably be separated by bundled
									// type. Some types don't have read messages, but
									// some do
									removeReadNotifications: true,
									// Override the foreign flag to 'true' for cross-wiki
									// notifications.
									// For bundles that are not foreign (like regular
									// bundles of notifications) this flag should be false
									foreign: true,
									type: notifData.section,
									count: notifData.count
								} )
							);
						} else {
							notificationModel = new mw.echo.dm.NotificationItem(
								id,
								newNotifData
							);
						}

						idArray.push( notifData.id );
						optionItems.push( notificationModel );
					}

					// Empty current items
					// HACK: We're turning on a 'fetchingNotifications' flag
					// so the x-wiki "empty" event is suppressed while
					// we clear items just to fill them back up.
					// Otherwise, the x-wiki notification bundle will be
					// removed from the general list before it is refilled.
					model.fetchingNotifications = true;
					model.clearItems();
					model.fetchingNotifications = false;
					// Add again to the model
					model.addItems( optionItems, 0 );

					model.emit( 'done', true, { ids: idArray } );
					return idArray;
				},
				// Failure
				function ( errCode, errObj ) {
					// TODO: The 'analysis' of which error we are working with should
					// be in the network layer of Echo's frontend code
					model.emit(
						'done',
						false,
						{
							errCode: errCode,
							errInfo: errCode === 'http' ?
								mw.msg( 'echo-api-failure-cross-wiki' ) :
								OO.getProp( errObj, 'error', 'info' )
						} );
				}
			);
	};

	/**
	 * Update the unseen tracking lists when we add items
	 *
	 * @param {mw.echo.dm.NotificationItem[]} items Items to add
	 */
	mw.echo.dm.NotificationsModel.prototype.addItems = function ( items ) {
		var i, len;

		for ( i = 0, len = items.length; i < len; i++ ) {
			if ( !items[ i ].isSeen() ) {
				this.unseenNotifications.addItems( [ items[ i ] ] );
			}
		}
		// Parent
		mw.echo.dm.SortedList.prototype.addItems.call( this, items );
	};

	/**
	 * Update the unseen tracking lists when we remove items
	 *
	 * @param {mw.echo.dm.NotificationItem[]} items Items to remove
	 */
	mw.echo.dm.NotificationsModel.prototype.removeItems = function ( items ) {
		var i, len;

		for ( i = 0, len = items.length; i < len; i++ ) {
			this.unseenNotifications.removeItems( [ items[ i ] ] );
		}

		// Parent
		mw.echo.dm.SortedList.prototype.removeItems.call( this, items );

		if ( this.isEmpty() && !this.fetchingNotifications ) {
			this.emit( 'empty' );
		}
	};

	/**
	 * Update the unseen tracking lists when we clear items
	 */
	mw.echo.dm.NotificationsModel.prototype.clearItems = function () {
		this.unseenNotifications.clearItems();

		// Parent
		mw.echo.dm.SortedList.prototype.clearItems.call( this );

		if ( !this.fetchingNotifications ) {
			this.emit( 'empty' );
		}
	};

	/**
	 * Query the API for unread count of the notifications in this model
	 *
	 * @return {jQuery.Promise} jQuery promise that's resolved when the unread count is fetched
	 */
	mw.echo.dm.NotificationsModel.prototype.fetchUnreadCountFromApi = function () {
		return this.api.fetchUnreadCount( this.getSource(), this.getType() );
	};

	/**
	 * Check whether the model has an api error state flagged
	 *
	 * @return {boolean} The model is in api error state
	 */
	mw.echo.dm.NotificationsModel.prototype.isFetchingErrorState = function () {
		return this.api.isFetchingErrorState( this.getSource(), this.getType() );
	};

	/**
	 * Return the fetch notifications promise
	 *
	 * @return {jQuery.Promise} Promise that is resolved when notifications were
	 *  fetched from the API.
	 */
	mw.echo.dm.NotificationsModel.prototype.getFetchNotificationPromise = function () {
		return this.api.getFetchNotificationPromise( this.getSource(), this.getType() );
	};

	/**
	 * Get the timestamp of the latest unread item
	 *
	 * @return {mw.echo.dm.APIHandler} API handler
	 */
	mw.echo.dm.NotificationsModel.prototype.getTimestamp = function () {
		var items = this.getItems();

		// This is a sorted list, so the top (first) item is also the 'latest'
		// item for this purpose.
		return ( items[ 0 ] && items[ 0 ].getTimestamp() ) || this.fallbackTimestamp;
	};

	/**
	 * Get the source this model is associated with
	 *
	 * @return {string} Symbolic name for the APIHandler source
	 */
	mw.echo.dm.NotificationsModel.prototype.getSource = function () {
		return this.source;
	};

	/**
	 * Get the title of this model
	 *
	 * @return {string} Title
	 */
	mw.echo.dm.NotificationsModel.prototype.getTitle = function () {
		return this.title;
	};

	/**
	 * Get the id of this model
	 *
	 * @return {string} id
	 */
	mw.echo.dm.NotificationsModel.prototype.getId = function () {
		return this.id;
	};

	/**
	 * This model is foreign
	 *
	 * @return {boolean} Model is foreign
	 */
	mw.echo.dm.NotificationsModel.prototype.isForeign = function () {
		return this.foreign;
	};

} )( mediaWiki, jQuery );