class ChromeNotifications extends ChromeApi {
 static final JsObject _notifications = chrome['notifications'];

 ChromeNotifications._();

 bool get available => _notifications != null;

 /**
  * Creates and displays a notification.
  * [notificationId]: Identifier of the notification. If it is empty, this
  * method generates an id. If it matches an existing notification, this method
  * first clears that notification before proceeding with the create operation.
  * [options]: Contents of the notification.
  * [callback]: Returns the notification id (either supplied or generated) that
  * represents the created notification.
  */
 Future<String> create(String notificationId, NotificationOptions options) {
   if (_notifications == null) _throwNotAvailable();

   var completer = new ChromeCompleter<String>.oneArg();
   _notifications.callMethod('create', [notificationId, jsify(options), completer.callback]);
   return completer.future;
 }

 /**
  * Updates an existing notification.
  * [notificationId]: The id of the notification to be updated. This is
  * returned by [notifications.create] method.
  * [options]: Contents of the notification to update to.
  * [callback]: Called to indicate whether a matching notification existed.
  */
 Future<bool> update(String notificationId, NotificationOptions options) {
   if (_notifications == null) _throwNotAvailable();

   var completer = new ChromeCompleter<bool>.oneArg();
   _notifications.callMethod('update', [notificationId, jsify(options), completer.callback]);
   return completer.future;
 }

 /**
  * Clears the specified notification.
  * [notificationId]: The id of the notification to be cleared. This is
  * returned by [notifications.create] method.
  * [callback]: Called to indicate whether a matching notification existed.
  */
 Future<bool> clear(String notificationId) {
   if (_notifications == null) _throwNotAvailable();

   var completer = new ChromeCompleter<bool>.oneArg();
   _notifications.callMethod('clear', [notificationId, completer.callback]);
   return completer.future;
 }

 /**
  * Retrieves all the notifications.
  * [callback]: Returns the set of notification_ids currently in the system.
  */
 Future<dynamic> getAll() {
   if (_notifications == null) _throwNotAvailable();

   var completer = new ChromeCompleter<dynamic>.oneArg();
   _notifications.callMethod('getAll', [completer.callback]);
   return completer.future;
 }

 /**
  * Retrieves whether the user has enabled notifications from this app or
  * extension.
  * [callback]: Returns the current permission level.
  */
 Future<PermissionLevel> getPermissionLevel() {
   if (_notifications == null) _throwNotAvailable();

   var completer = new ChromeCompleter<PermissionLevel>.oneArg(_createPermissionLevel);
   _notifications.callMethod('getPermissionLevel', [completer.callback]);
   return completer.future;
 }

 Stream<OnClosedEvent> get onClosed => _onClosed.stream;

 final ChromeStreamController<OnClosedEvent> _onClosed =
     new ChromeStreamController<OnClosedEvent>.twoArgs(_notifications, 'onClosed', _createOnClosedEvent);

 Stream<String> get onClicked => _onClicked.stream;

 final ChromeStreamController<String> _onClicked =
     new ChromeStreamController<String>.oneArg(_notifications, 'onClicked', selfConverter);

 Stream<OnButtonClickedEvent> get onButtonClicked => _onButtonClicked.stream;

 final ChromeStreamController<OnButtonClickedEvent> _onButtonClicked =
     new ChromeStreamController<OnButtonClickedEvent>.twoArgs(_notifications, 'onButtonClicked', _createOnButtonClickedEvent);

 Stream<PermissionLevel> get onPermissionLevelChanged => _onPermissionLevelChanged.stream;

 final ChromeStreamController<PermissionLevel> _onPermissionLevelChanged =
     new ChromeStreamController<PermissionLevel>.oneArg(_notifications, 'onPermissionLevelChanged', _createPermissionLevel);

 void _throwNotAvailable() {
   throw new UnsupportedError("'chrome.notifications' is not available");
 }
}