Can delete notifications from notifications screen

lib/ui/screens/notifications_screen.dart

@@ -17,6 +17,8 @@ import 'package:flutter/material.dart';
 
 enum _Status { LOADING, ERROR, NONE }
 
+enum _PopupMenuActions { DELETE }
+
 class NotificationsScreen extends StatefulWidget {
   @override
   _NotificationsScreenState createState() => _NotificationsScreenState();
@@ -93,6 +95,7 @@ class _NotificationsScreenState extends State<NotificationsScreen> {
                 notification: f,
                 usersList: _users,
                 groupsList: _groups,
+                onDelete: _deleteNotification,
               ))
           .toList(),
     );
@@ -118,19 +121,33 @@ class _NotificationsScreenState extends State<NotificationsScreen> {
         ),
       );
   }
+
+  /// Delete a notification
+  void _deleteNotification(n.Notification notif) async {
+    setState(() {
+      _list.remove(notif);
+    });
+
+    NotificationsHelper().markSeen(notif);
+  }
 }
 
 class _NotificationTile extends StatelessWidget {
   final n.Notification notification;
   final UsersList usersList;
   final GroupsList groupsList;
+  final void Function(n.Notification) onDelete;
 
   const _NotificationTile({
     Key key,
     @required this.notification,
     @required this.usersList,
     @required this.groupsList,
+    @required this.onDelete,
   })  : assert(notification != null),
+        assert(usersList != null),
+        assert(groupsList != null),
+        assert(onDelete != null),
         super(key: key);
 
   @override
@@ -227,6 +244,23 @@ class _NotificationTile extends StatelessWidget {
       ),
       title: Text(message),
       subtitle: Text(diffTimeFromNowToStr(notification.timeCreate)),
+      trailing: PopupMenuButton<_PopupMenuActions>(
+        onSelected: _popupMenuAction,
+        itemBuilder: (c) => [
+          PopupMenuItem(
+            child: Text(tr("Delete")),
+            value: _PopupMenuActions.DELETE,
+          ),
+        ],
+      ),
     );
   }
+
+  void _popupMenuAction(_PopupMenuActions value) {
+    switch (value) {
+      case _PopupMenuActions.DELETE:
+        onDelete(notification);
+        break;
+    }
+  }
 }