Display the number of unread notifications

lib/ui/routes/main_route/tablet_route.dart

@@ -1,6 +1,7 @@
 import 'package:comunic/ui/routes/main_route/main_route.dart';
 import 'package:comunic/ui/widgets/tablet_mode/current_user_panel.dart';
 import 'package:comunic/ui/widgets/tablet_mode/memberships_panel.dart';
+import 'package:comunic/ui/widgets/tablet_mode/tablet_navbar_widget.dart';
 import 'package:flutter/material.dart';
 
 /// Main tablet route
@@ -21,14 +22,7 @@ class _TabletRouteState extends State<TabletRoute> {
     );
   }
 
-  Widget _buildAppBar() => AppBar(
-        title: Text("Comunic"),
-        actions: <Widget>[
-          IconButton(icon: Icon(Icons.notifications), onPressed: () {}),
-          IconButton(icon: Icon(Icons.message), onPressed: () {}),
-          PopupMenuButton(itemBuilder: (c) => []),
-        ],
-      );
+  Widget _buildAppBar() => ComunicTabletNavbarWidget();
 
   Widget _buildBody() => Row(
         children: <Widget>[_buildLeftPane(), _buildRightPane()],

lib/ui/widgets/icon_button_badge.dart

@@ -0,0 +1,50 @@
+import 'package:flutter/material.dart';
+
+/// Display an icon button with a badge
+///
+/// Based from Medium article called "Notification Badge in Flutter"
+///
+/// @author Pierre Hubert
+
+class IconButtonWithBadge extends StatelessWidget {
+  final Widget icon;
+  final void Function() onPressed;
+  final int number;
+
+  const IconButtonWithBadge({
+    Key key,
+    @required this.icon,
+    @required this.onPressed,
+    this.number = 0,
+  })  : assert(icon != null),
+        assert(number != null),
+        super(key: key);
+
+  @override
+  Widget build(BuildContext context) {
+    return Stack(
+      alignment: AlignmentDirectional.center,
+      children: <Widget>[
+        IconButton(icon: icon, onPressed: onPressed),
+        number != 0
+            ? Positioned(
+                right: 6,
+                top: 6,
+                child: Container(
+                  padding: EdgeInsets.all(2),
+                  decoration: BoxDecoration(
+                    color: Colors.red,
+                    borderRadius: BorderRadius.circular(6),
+                  ),
+                  constraints: BoxConstraints(minWidth: 14, minHeight: 14),
+                  child: Text(
+                    "$number",
+                    style: TextStyle(color: Colors.white, fontSize: 12),
+                    textAlign: TextAlign.center,
+                  ),
+                ))
+            : Container()
+      ],
+    );
+  }
+}

lib/ui/widgets/tablet_mode/tablet_navbar_widget.dart

@@ -0,0 +1,71 @@
+import 'package:comunic/helpers/events_helper.dart';
+import 'package:comunic/helpers/notifications_helper.dart';
+import 'package:comunic/models/count_unread_notifications.dart';
+import 'package:comunic/ui/widgets/icon_button_badge.dart';
+import 'package:comunic/ui/widgets/safe_state.dart';
+import 'package:flutter/material.dart';
+
+/// Comunic tablet navbar widget
+///
+/// @author Pierre Hubert
+
+class ComunicTabletNavbarWidget extends StatefulWidget
+    implements PreferredSizeWidget {
+  @override
+  _ComunicTabletNavbarWidgetState createState() =>
+      _ComunicTabletNavbarWidgetState();
+
+  @override
+  Size get preferredSize => Size.fromHeight(kToolbarHeight);
+}
+
+class _ComunicTabletNavbarWidgetState
+    extends SafeState<ComunicTabletNavbarWidget> {
+  var _unreadNotifications =
+      CountUnreadNotifications(notifications: 0, conversations: 0);
+
+  void _refreshCountUnread() async {
+    try {
+      final count = await NotificationsHelper().countUnread();
+
+      setState(() {
+        _unreadNotifications = count;
+      });
+    } catch (e, s) {
+      print("Could not refresh the number of unread notifications: $e\n$s");
+    }
+  }
+
+  @override
+  void initState() {
+    super.initState();
+
+    _refreshCountUnread();
+
+    // Listen to notifications number update
+    this.listenChangeState<NewNumberNotifsEvent>(
+        (d) => _unreadNotifications.notifications = d.newNum);
+    this.listenChangeState<NewNumberUnreadConversations>(
+        (d) => _unreadNotifications.conversations = d.newNum);
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return AppBar(
+      title: Text("Comunic"),
+      actions: <Widget>[
+        IconButtonWithBadge(
+          icon: Icon(Icons.notifications),
+          onPressed: () {},
+          number: _unreadNotifications.notifications,
+        ),
+        IconButtonWithBadge(
+          icon: Icon(Icons.message),
+          onPressed: () {},
+          number: _unreadNotifications.conversations,
+        ),
+        PopupMenuButton(itemBuilder: (c) => []),
+      ],
+    );
+  }
+}