Add initialization layer

lib/helpers/websocket_helper.dart

@@ -0,0 +1,15 @@
+/// User web socket helper
+///
+/// @author Pierre Hubert
+
+class WebSocketHelper {
+  /// Check out whether we are currently connected to websocket or not
+  static bool isConnected() {
+    return true;
+  }
+
+  /// Connect to WebSocket
+  static connect() async {
+    if (isConnected()) return;
+  }
+}

lib/main.dart

@@ -1,8 +1,8 @@
 import 'package:comunic/helpers/account_helper.dart';
 import 'package:comunic/helpers/database/database_helper.dart';
 import 'package:comunic/helpers/preferences_helper.dart';
-import 'package:comunic/ui/routes/home_route.dart';
 import 'package:comunic/ui/routes/login_route.dart';
+import 'package:comunic/ui/widgets/init_widget.dart';
 import 'package:comunic/utils/intl_utils.dart';
 import 'package:comunic/utils/ui_utils.dart';
 import 'package:flutter/material.dart';
@@ -68,7 +68,7 @@ class _ComunicApplicationHomeState extends State<ComunicApplicationHome> {
     if (_signedIn == null) return buildLoadingPage();
 
     if (_signedIn)
-      return HomeRoute();
+      return InitializeWidget();
     else
       return LoginRoute();
   }

lib/ui/routes/login_route.dart

@@ -1,7 +1,7 @@
 import 'package:comunic/helpers/account_helper.dart';
 import 'package:comunic/models/authentication_details.dart';
 import 'package:comunic/ui/routes/create_account_route.dart';
-import 'package:comunic/ui/routes/home_route.dart';
+import 'package:comunic/ui/widgets/init_widget.dart';
 import 'package:comunic/utils/input_utils.dart';
 import 'package:comunic/utils/intl_utils.dart';
 import 'package:comunic/utils/ui_utils.dart';
@@ -52,7 +52,7 @@ class _LoginRouteState extends State<LoginRoute> {
 
     if (loginResult == AuthResult.SUCCESS)
       Navigator.pushReplacement(
-          context, MaterialPageRoute(builder: (b) => HomeRoute()));
+          context, MaterialPageRoute(builder: (b) => InitializeWidget()));
     else
       setState(() {
         _authResult = loginResult;

lib/ui/widgets/init_widget.dart

@@ -0,0 +1,105 @@
+import 'package:comunic/helpers/websocket_helper.dart';
+import 'package:comunic/ui/routes/home_route.dart';
+import 'package:comunic/utils/intl_utils.dart';
+import 'package:flutter/material.dart';
+
+/// Comunic account initialization widget
+///
+/// Application screens should only appears as children of this widget
+///
+/// This widget ensures that the application is correctly initialized before
+/// starting it
+///
+/// @author Pierre Hubert
+
+class InitializeWidget extends StatefulWidget {
+  @override
+  _InitializeWidgetState createState() => _InitializeWidgetState();
+}
+
+class _InitializeWidgetState extends State<InitializeWidget> {
+  bool _error = false;
+
+  @override
+  void initState() {
+    _tryConnect();
+
+    super.initState();
+  }
+
+  /// Try to connect to server
+  void _tryConnect() async {
+    try {
+      setState(() {
+        _error = false;
+      });
+
+      await WebSocketHelper.connect();
+
+      setState(() {});
+    } catch (e, stack) {
+      print("Could not connect to server! $e");
+      print(stack);
+
+      setState(() {
+        _error = true;
+      });
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return WebSocketHelper.isConnected() ? HomeRoute() : _buildNonReadyWidget();
+  }
+
+  /// Build loading widget
+  Widget _buildNonReadyWidget() {
+    return Scaffold(
+      backgroundColor: Colors.indigo.shade900,
+      body: Center(
+        child: Column(
+          mainAxisAlignment: MainAxisAlignment.center,
+          crossAxisAlignment: CrossAxisAlignment.center,
+          children: <Widget>[
+            Spacer(
+              flex: 4,
+            ),
+            Text(
+              tr("Comunic"),
+              style: TextStyle(fontSize: 50),
+            ),
+            Spacer(
+              flex: 2,
+            ),
+            _error ? _buildErrorWidget() : _buildConnectingWidget(),
+            Spacer(
+              flex: 2,
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+
+  Widget _buildConnectingWidget() {
+    return CircularProgressIndicator();
+  }
+
+  Widget _buildErrorWidget() {
+    return Column(
+      children: <Widget>[
+        Icon(Icons.error),
+        SizedBox(height: 30),
+        Text(tr("Could not connect to server!")),
+        SizedBox(
+          height: 30,
+        ),
+        RaisedButton(
+          color: Colors.indigo,
+          onPressed: () => _tryConnect(),
+          child: Text(tr("Try again")),
+        ),
+      ],
+    );
+  }
+}

pubspec.lock

@@ -441,6 +441,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "2.0.8"
+  web_socket_channel:
+    dependency: "direct main"
+    description:
+      name: web_socket_channel
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.1.0"
   xml:
     dependency: transitive
     description:

pubspec.yaml

@@ -69,6 +69,9 @@ dependencies:
   # Check Internet connection
   connectivity: ^0.4.8+2
 
+  # Establish WebSocket connections
+  web_socket_channel: ^1.1.0
+
 dev_dependencies:
   flutter_test:
     sdk: flutter