implement auth state mgmt and navigation flow

Author: Anish-Chanda

app/lib/main.dart

@@ -1,21 +1,21 @@
 import 'package:ferna/providers/auth_provider.dart';
-import 'package:ferna/screens/login_screen.dart';
+import 'package:ferna/router.dart';
 import 'package:ferna/theme/theme_data.dart';
 import 'package:flutter/material.dart';
 import 'package:provider/provider.dart';
 
 void main() async {
   WidgetsFlutterBinding.ensureInitialized();
 
-  // Initialzie auth provider
+  // Initialize auth provider
   final authProvider = await AuthProvider.initialize();
 
   runApp(
     MultiProvider(
       providers: [
         ChangeNotifierProvider<AuthProvider>.value(value: authProvider),
       ],
-      child: FernaApp(),
+      child: const FernaApp(),
     ),
   );
 }
@@ -31,18 +31,7 @@ class FernaApp extends StatelessWidget {
       theme: FernaTheme.light,
       darkTheme: FernaTheme.dark,
       themeMode: ThemeMode.system,
-      // TODO: Replace with router
-      home: const LoginScreen(),
-      routes: {'/home': (_) => const HomeScreen()},
+      home: const AppNavigator(),
     );
   }
 }
-
-class HomeScreen extends StatelessWidget {
-  const HomeScreen({super.key});
-
-  @override
-  Widget build(BuildContext context) {
-    return const Placeholder(child: Text(":)"));
-  }
-}

app/lib/providers/auth_provider.dart

@@ -9,8 +9,16 @@ import '../services/storage_service.dart';
 class AuthProvider with ChangeNotifier {
   final AuthService _authService = AuthService.instance;
   AuthProvider._();
+  
   bool _isLoading = false;
   bool get isLoading => _isLoading;
+  
+  bool _isCheckingAuthState = false;
+  bool get isCheckingAuthState => _isCheckingAuthState;
+  
+  bool _isAuthenticated = false;
+  bool get isAuthenticated => _isAuthenticated;
+  
   String _serverUrl = '';
   String get serverUrl => _serverUrl;
 
@@ -25,9 +33,27 @@ class AuthProvider with ChangeNotifier {
     // Initialize AuthService (sets up Dio & loads any persisted cookies).
     await provider._authService.initialize(serverUrl: provider._serverUrl);
 
+    // Check if user is already authenticated
+    await provider._checkAuthState();
+
     return provider;
   }
 
+  /// Check authentication state by making a test API call
+  Future<void> _checkAuthState() async {
+    _isCheckingAuthState = true;
+    notifyListeners();
+
+    try {
+      _isAuthenticated = await _authService.checkAuthState();
+    } catch (e) {
+      _isAuthenticated = false;
+    }
+
+    _isCheckingAuthState = false;
+    notifyListeners();
+  }
+
   /// Change serverUrl, persist it, and re-initialize Dio so its baseUrl updates.
   Future<void> updateServerUrl(String newUrl) async {
     if (newUrl == _serverUrl) return;
@@ -50,9 +76,11 @@ class AuthProvider with ChangeNotifier {
 
     try {
       await _authService.login(email: email, password: password);
+      _isAuthenticated = true;
       _isLoading = false;
       notifyListeners();
     } catch (e) {
+      _isAuthenticated = false;
       _isLoading = false;
       notifyListeners();
       rethrow;
@@ -68,13 +96,32 @@ class AuthProvider with ChangeNotifier {
         email: email,
         password: password,
       );
+      _isAuthenticated = true;
       _isLoading = false;
       notifyListeners();
       return userId;
     } catch (e) {
+      _isAuthenticated = false;
       _isLoading = false;
       notifyListeners();
       rethrow;
     }
   }
+
+  /// Logout user and clear authentication state
+  Future<void> logout() async {
+    _isLoading = true;
+    notifyListeners();
+
+    try {
+      await _authService.logout();
+      _isAuthenticated = false;
+    } catch (e) {
+      // Even if logout fails, clear local state
+      _isAuthenticated = false;
+    }
+
+    _isLoading = false;
+    notifyListeners();
+  }
 }

app/lib/router.dart

@@ -0,0 +1,15 @@
+import 'package:ferna/screens/home_screen.dart';
+import 'package:flutter/material.dart';
+import 'widgets/auth_wrapper.dart';
+
+/// Main app navigation widget and handles auth state
+class AppNavigator extends StatelessWidget {
+  const AppNavigator({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return const AuthWrapper(
+      authenticatedChild: HomeScreen(),
+    );
+  }
+}

app/lib/screens/home_screen.dart

@@ -0,0 +1,10 @@
+import 'package:flutter/material.dart';
+
+class HomeScreen extends StatelessWidget {
+  const HomeScreen({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Placeholder(child: Text("home screen"));
+  }
+}

app/lib/screens/login_screen.dart

@@ -105,9 +105,8 @@ class _LoginScreenState extends State<LoginScreen>
         await auth.signUp(email: email, password: password);
       }
 
-      // On success, navigate to your home screen:
-      if (!mounted) return;
-      Navigator.of(context).pushReplacementNamed('/home');
+      // AuthWrapper will automatically handle navigation to home screen
+      // when auth.isAuthenticated becomes true
     } catch (error) {
       if (!mounted) return;
       ScaffoldMessenger.of(context).showSnackBar(

app/lib/services/auth_service.dart

@@ -35,7 +35,7 @@ class AuthService {
   Future<void> login({required String email, required String password}) async {
     final dio = HttpClient.instance.dio;
     final response = await dio.post(
-      '/auth/local/login',
+      '/auth/local/login?session=1',
       data: {'user': email, 'passwd': password},
     );
 
@@ -48,4 +48,27 @@ class AuthService {
       );
     }
   }
+
+  /// Check if user is currently authenticated by making a test API call
+  Future<bool> checkAuthState() async {
+    try {
+      final dio = HttpClient.instance.dio;
+      // Try to access a protected endpoint - the backend should return 401 if not authenticated
+      // TODO: add /api/me for this pupose
+      final response = await dio.get('/api/plants');
+
+      // If we get a successful response (200-299), user is authenticated
+      return response.statusCode != null &&
+          response.statusCode! >= 200 &&
+          response.statusCode! < 300;
+    } catch (e) {
+      // Any error (network, 401, 403, etc.) means not authenticated
+      return false;
+    }
+  }
+
+  /// Logout user by clearing cookies
+  Future<void> logout() async {
+    await HttpClient.instance.clearCookies();
+  }
 }

app/lib/widgets/auth_wrapper.dart

@@ -0,0 +1,35 @@
+import 'dart:developer';
+
+import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
+import '../providers/auth_provider.dart';
+import '../screens/login_screen.dart';
+
+/// Wrapper that checks authentication state and routes to appropriate screen
+class AuthWrapper extends StatelessWidget {
+  final Widget authenticatedChild;
+
+  const AuthWrapper({super.key, required this.authenticatedChild});
+
+  @override
+  Widget build(BuildContext context) {
+    return Consumer<AuthProvider>(
+      builder: (context, auth, _) {
+        // Show loading indicator while checking auth state
+        if (auth.isCheckingAuthState) {
+          return const Scaffold(
+            body: Center(child: CircularProgressIndicator()),
+          );
+        }
+
+        // Route based on authentication state
+        if (auth.isAuthenticated) {
+          log('User is authenticated, navigating to home screen');
+          return authenticatedChild;
+        } else {
+          return const LoginScreen();
+        }
+      },
+    );
+  }
+}