Multiple improvements in authentication functionality

frontend/lib/app_menu.dart

@@ -1,5 +1,8 @@
 import 'package:flutter/material.dart';
+import 'package:flutter_secure_storage/flutter_secure_storage.dart';
 import 'chat_list_screen.dart';
+import 'user_checker.dart';
+import 'backend.dart';
 
 class AppMenu extends StatelessWidget {
   const AppMenu({super.key});
@@ -21,6 +24,22 @@ class AppMenu extends StatelessWidget {
               );
             },
           ),
+          ListTile(
+            title: const Text('Logout'),
+            onTap: () async {
+              final storage = const FlutterSecureStorage();
+              await storage.delete(key: 'username');
+              await storage.delete(key: 'password');
+              Backend.disconnect();
+
+              Navigator.push(
+                context,
+                MaterialPageRoute(
+                  builder: (context) => UserChecker(),
+                ),
+              );
+            },
+          ),
           // Add other settings options here
         ],
       ),

frontend/lib/backend.dart

@@ -6,26 +6,46 @@ import 'dart:async'; // Import for handling Completers
 class Backend {
   static WebSocket? _socket;
   static String? _url;
-  static String? _username;
   static Map<int, Completer> _pendingActions = {};
   static Map<int, StreamController<Map<String, dynamic>>> _chatControllers = {};
   static int _nextNonce = 0; // Tracking nonce for each action
   static StreamController<Map<String, dynamic>> _packetStreamController = StreamController.broadcast();
   
+  // Authentication
+  static ({String username, String password})? _credentials;
+  static Completer? _loginCompleter;
+  static Completer? _credentialsCompleter;
+
   static void setup(String url) {
     _url = url;
     connect();
   }
 
-  static void auth(String username, String password) {
+  static Future<void> auth(String username, String password) {
     _socket!.send(json.encode({'username': username, 'password': password}));
-    _username = username;
+    _credentials = (username: username, password: password);
+    if (_credentialsCompleter != null) {
+      _credentialsCompleter!.complete(_credentials);
+      _credentialsCompleter = null;
+    }
+    _loginCompleter = Completer();
+    return _loginCompleter!.future;
   }
 
   static void connect() {
     _socket = WebSocket(_url!);
     _socket!.onOpen.listen((event) {
       print('Connected to the WebSocket server');
+      print('Logging in...');
+      if (_credentials != null) {
+        _socket!.send(json.encode({'username': _credentials!.username, 'password': _credentials!.password}));
+      } else {
+        _credentialsCompleter = Completer();
+        _credentialsCompleter!.future.then((credentials) {
+          _socket!.send(json.encode({'username': credentials.username, 'password': credentials.password}));
+        });
+      }
+      _loginCompleter?.complete();
     });
     _socket!.onError.listen((event) {
       print('Error: $event');
@@ -40,6 +60,11 @@ class Backend {
     });
   }
 
+  static void disconnect() {
+    _socket?.close();
+    _loginCompleter = null;
+  }
+
   static void _reconnect() {
     Future.delayed(Duration(seconds: 5), () {
       connect();

frontend/lib/login_screen.dart

@@ -8,6 +8,13 @@ class LoginScreen extends StatelessWidget {
   final TextEditingController usernameController = TextEditingController();
   final TextEditingController passwordController = TextEditingController();
 
+  final FocusNode usernameFocusNode = FocusNode();
+  final FocusNode passwordFocusNode = FocusNode();
+
+  void _handleLogin() {
+    onLogin(usernameController.text, passwordController.text);
+  }
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(
@@ -18,18 +25,29 @@ class LoginScreen extends StatelessWidget {
           child: Column(
             mainAxisAlignment: MainAxisAlignment.center,
             children: [
-              TextField(controller: usernameController, decoration: InputDecoration(labelText: 'Username')),
+              TextField(
+                controller: usernameController,
+                focusNode: usernameFocusNode,
+                decoration: InputDecoration(labelText: 'Username'),
+                textInputAction: TextInputAction.next,
+                onSubmitted: (_) {
+                  FocusScope.of(context).requestFocus(passwordFocusNode);
+                },
+              ),
               SizedBox(height: 20),
               TextField(
                 controller: passwordController,
+                focusNode: passwordFocusNode,
                 decoration: InputDecoration(labelText: 'Password'),
-                obscureText: true, // Hide password characters
+                obscureText: true,
+                textInputAction: TextInputAction.done,
+                onSubmitted: (_) {
+                  _handleLogin();
+                },
               ),
               SizedBox(height: 20),
               ElevatedButton(
-                onPressed: () {
-                  onLogin(usernameController.text, passwordController.text);
-                },
+                onPressed: _handleLogin,
                 child: Text('Login'),
               ),
             ],

frontend/lib/user_checker.dart

@@ -1,4 +1,5 @@
 import 'package:flutter/material.dart';
+import 'package:flutter_secure_storage/flutter_secure_storage.dart';
 import 'backend.dart';
 import 'login_screen.dart';
 import 'chat_screen.dart';
@@ -11,12 +12,26 @@ class UserChecker extends StatefulWidget {
 
 class _UserCheckerState extends State<UserChecker> {
   String? username;
-  bool isLoading = false;
+  bool isLoading = true;
+  final _storage = const FlutterSecureStorage();
 
   @override
   void initState() {
     super.initState();
-    username = null;
+    _checkSavedCredentials();
+  }
+
+  Future<void> _checkSavedCredentials() async {
+    final savedUsername = await _storage.read(key: 'username');
+    final savedPassword = await _storage.read(key: 'password');
+
+    if (savedUsername != null && savedPassword != null) {
+      _handleLogin(savedUsername, savedPassword);
+    } else {
+      setState(() {
+        isLoading = false;
+      });
+    }
   }
 
   static void fetchChats(Function(List<int>) onSuccess) {
@@ -28,14 +43,16 @@ class _UserCheckerState extends State<UserChecker> {
     });
   }
 
-  void _handleLogin(String user, String password) {
-    Backend.auth(user, password);
-  
+  void _handleLogin(String user, String password) async {
     setState(() {
       username = user;
-      isLoading = true; // Show loading spinner
+      isLoading = true;
     });
   
+    await Backend.auth(user, password);
+    await _storage.write(key: 'username', value: user);
+    await _storage.write(key: 'password', value: password);
+
     fetchChats((chatIds) {
       if (chatIds.isEmpty) {
         Navigator.pushReplacement(
@@ -49,14 +66,13 @@ class _UserCheckerState extends State<UserChecker> {
         );
       }
     });
-
   }
 
   @override
   Widget build(BuildContext context) {
     print("Build UserChecker: $username $isLoading");
     if (isLoading) {
-      return Center(child: CircularProgressIndicator()); // Loading state UI
+      return Center(child: CircularProgressIndicator());
     }
 
     return LoginScreen(onLogin: _handleLogin);

frontend/linux/flutter/generated_plugin_registrant.cc

@@ -6,6 +6,10 @@
 
 #include "generated_plugin_registrant.h"
 
+#include <flutter_secure_storage_linux/flutter_secure_storage_linux_plugin.h>
 
 void fl_register_plugins(FlPluginRegistry* registry) {
+  g_autoptr(FlPluginRegistrar) flutter_secure_storage_linux_registrar =
+      fl_plugin_registry_get_registrar_for_plugin(registry, "FlutterSecureStorageLinuxPlugin");
+  flutter_secure_storage_linux_plugin_register_with_registrar(flutter_secure_storage_linux_registrar);
 }

frontend/linux/flutter/generated_plugins.cmake

@@ -3,6 +3,7 @@
 #
 
 list(APPEND FLUTTER_PLUGIN_LIST
+  flutter_secure_storage_linux
 )
 
 list(APPEND FLUTTER_FFI_PLUGIN_LIST

frontend/macos/Flutter/GeneratedPluginRegistrant.swift

@@ -5,6 +5,10 @@
 import FlutterMacOS
 import Foundation
 
+import flutter_secure_storage_macos
+import path_provider_foundation
 
 func RegisterGeneratedPlugins(registry: FlutterPluginRegistry) {
+  FlutterSecureStoragePlugin.register(with: registry.registrar(forPlugin: "FlutterSecureStoragePlugin"))
+  PathProviderPlugin.register(with: registry.registrar(forPlugin: "PathProviderPlugin"))
 }

frontend/pubspec.lock

@@ -57,6 +57,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.3.2"
+  ffi:
+    dependency: transitive
+    description:
+      name: ffi
+      sha256: "289279317b4b16eb2bb7e271abccd4bf84ec9bdcbe999e278a94b804f5630418"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.1.4"
   flutter:
     dependency: "direct main"
     description: flutter
@@ -70,11 +78,72 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "5.0.0"
+  flutter_secure_storage:
+    dependency: "direct main"
+    description:
+      name: flutter_secure_storage
+      sha256: "9cad52d75ebc511adfae3d447d5d13da15a55a92c9410e50f67335b6d21d16ea"
+      url: "https://pub.dev"
+    source: hosted
+    version: "9.2.4"
+  flutter_secure_storage_linux:
+    dependency: transitive
+    description:
+      name: flutter_secure_storage_linux
+      sha256: be76c1d24a97d0b98f8b54bce6b481a380a6590df992d0098f868ad54dc8f688
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.2.3"
+  flutter_secure_storage_macos:
+    dependency: transitive
+    description:
+      name: flutter_secure_storage_macos
+      sha256: "6c0a2795a2d1de26ae202a0d78527d163f4acbb11cde4c75c670f3a0fc064247"
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.1.3"
+  flutter_secure_storage_platform_interface:
+    dependency: transitive
+    description:
+      name: flutter_secure_storage_platform_interface
+      sha256: cf91ad32ce5adef6fba4d736a542baca9daf3beac4db2d04be350b87f69ac4a8
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.1.2"
+  flutter_secure_storage_web:
+    dependency: transitive
+    description:
+      name: flutter_secure_storage_web
+      sha256: f4ebff989b4f07b2656fb16b47852c0aab9fed9b4ec1c70103368337bc1886a9
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.2.1"
+  flutter_secure_storage_windows:
+    dependency: transitive
+    description:
+      name: flutter_secure_storage_windows
+      sha256: b20b07cb5ed4ed74fc567b78a72936203f587eba460af1df11281c9326cd3709
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.1.2"
   flutter_test:
     dependency: "direct dev"
     description: flutter
     source: sdk
     version: "0.0.0"
+  flutter_web_plugins:
+    dependency: transitive
+    description: flutter
+    source: sdk
+    version: "0.0.0"
+  js:
+    dependency: transitive
+    description:
+      name: js
+      sha256: f2c445dce49627136094980615a031419f7f3eb393237e4ecd97ac15dea343f3
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.6.7"
   leak_tracker:
     dependency: transitive
     description:
@@ -139,6 +208,70 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.9.1"
+  path_provider:
+    dependency: transitive
+    description:
+      name: path_provider
+      sha256: "50c5dd5b6e1aaf6fb3a78b33f6aa3afca52bf903a8a5298f53101fdaee55bbcd"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.1.5"
+  path_provider_android:
+    dependency: transitive
+    description:
+      name: path_provider_android
+      sha256: d0d310befe2c8ab9e7f393288ccbb11b60c019c6b5afc21973eeee4dda2b35e9
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.2.17"
+  path_provider_foundation:
+    dependency: transitive
+    description:
+      name: path_provider_foundation
+      sha256: "4843174df4d288f5e29185bd6e72a6fbdf5a4a4602717eed565497429f179942"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.4.1"
+  path_provider_linux:
+    dependency: transitive
+    description:
+      name: path_provider_linux
+      sha256: f7a1fe3a634fe7734c8d3f2766ad746ae2a2884abe22e241a8b301bf5cac3279
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.2.1"
+  path_provider_platform_interface:
+    dependency: transitive
+    description:
+      name: path_provider_platform_interface
+      sha256: "88f5779f72ba699763fa3a3b06aa4bf6de76c8e5de842cf6f29e2e06476c2334"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.1.2"
+  path_provider_windows:
+    dependency: transitive
+    description:
+      name: path_provider_windows
+      sha256: bd6f00dbd873bfb70d0761682da2b3a2c2fccc2b9e84c495821639601d81afe7
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.3.0"
+  platform:
+    dependency: transitive
+    description:
+      name: platform
+      sha256: "5d6b1b0036a5f331ebc77c850ebc8506cbc1e9416c27e59b439f917a902a4984"
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.1.6"
+  plugin_platform_interface:
+    dependency: transitive
+    description:
+      name: plugin_platform_interface
+      sha256: "4820fbfdb9478b1ebae27888254d445073732dae3d6ea81f0b7e06d5dedc3f02"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.1.8"
   sky_engine:
     dependency: transitive
     description: flutter
@@ -208,6 +341,22 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "14.3.1"
+  win32:
+    dependency: transitive
+    description:
+      name: win32
+      sha256: "329edf97fdd893e0f1e3b9e88d6a0e627128cc17cc316a8d67fda8f1451178ba"
+      url: "https://pub.dev"
+    source: hosted
+    version: "5.13.0"
+  xdg_directories:
+    dependency: transitive
+    description:
+      name: xdg_directories
+      sha256: "7a3f37b05d989967cdddcbb571f1ea834867ae2faa29725fd085180e0883aa15"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.1.0"
 sdks:
   dart: ">=3.7.2 <4.0.0"
-  flutter: ">=3.18.0-18.0.pre.54"
+  flutter: ">=3.27.0"

frontend/pubspec.yaml

@@ -35,6 +35,9 @@ dependencies:
   # Use with the CupertinoIcons class for iOS style icons.
   cupertino_icons: ^1.0.8
 
+  # For user credentials and sensitive data
+  flutter_secure_storage: ^9.2.4
+
 dev_dependencies:
   flutter_test:
     sdk: flutter

frontend/windows/flutter/generated_plugin_registrant.cc

@@ -6,6 +6,9 @@
 
 #include "generated_plugin_registrant.h"
 
+#include <flutter_secure_storage_windows/flutter_secure_storage_windows_plugin.h>
 
 void RegisterPlugins(flutter::PluginRegistry* registry) {
+  FlutterSecureStorageWindowsPluginRegisterWithRegistrar(
+      registry->GetRegistrarForPlugin("FlutterSecureStorageWindowsPlugin"));
 }

frontend/windows/flutter/generated_plugins.cmake

@@ -3,6 +3,7 @@
 #
 
 list(APPEND FLUTTER_PLUGIN_LIST
+  flutter_secure_storage_windows
 )
 
 list(APPEND FLUTTER_FFI_PLUGIN_LIST