feat: Add initial backend server with user authentication, session management, and playlist CRUD functionality.

lib/core/api/api_client.dart

@@ -0,0 +1,83 @@
+import 'package:dio/dio.dart';
+import 'dart:html' as html;
+
+/// API Client for communicating with the backend
+class ApiClient {
+  static final ApiClient _instance = ApiClient._internal();
+  factory ApiClient() => _instance;
+  
+  late final Dio _dio;
+  String? _token;
+
+  ApiClient._internal() {
+    _dio = Dio(BaseOptions(
+      baseUrl: _getBaseUrl(),
+      headers: {'Content-Type': 'application/json'},
+      connectTimeout: const Duration(seconds: 10),
+      receiveTimeout: const Duration(seconds: 10),
+    ));
+    
+    // Add interceptor for logging
+    _dio.interceptors.add(LogInterceptor(
+      requestBody: true,
+      responseBody: true,
+    ));
+  }
+
+  /// Get base URL (same origin for production)
+  String _getBaseUrl() {
+    // Use current origin for API calls
+    return '';
+  }
+
+  /// Set authentication token
+  void setToken(String? token) {
+    _token = token;
+    if (token != null) {
+      _dio.options.headers['Authorization'] = 'Bearer $token';
+      // Store in localStorage for persistence
+      html.window.localStorage['auth_token'] = token;
+    } else {
+      _dio.options.headers.remove('Authorization');
+      html.window.localStorage.remove('auth_token');
+    }
+  }
+
+  /// Get stored token from localStorage
+  String? getStoredToken() {
+    return html.window.localStorage['auth_token'];
+  }
+
+  /// Restore token from localStorage
+  void restoreToken() {
+    final storedToken = getStoredToken();
+    if (storedToken != null) {
+      setToken(storedToken);
+    }
+  }
+
+  /// Clear token
+  void clearToken() {
+    setToken(null);
+  }
+
+  /// GET request
+  Future<Response> get(String path) async {
+    return _dio.get(path);
+  }
+
+  /// POST request
+  Future<Response> post(String path, {dynamic data}) async {
+    return _dio.post(path, data: data);
+  }
+
+  /// PUT request
+  Future<Response> put(String path, {dynamic data}) async {
+    return _dio.put(path, data: data);
+  }
+
+  /// DELETE request
+  Future<Response> delete(String path) async {
+    return _dio.delete(path);
+  }
+}

lib/core/router/app_router.dart

@@ -9,15 +9,20 @@ import '../../features/admin/screens/admin_panel.dart';
 import '../models/playlist_config.dart';
 
 final routerProvider = Provider<GoRouter>((ref) {
-  final authNotifier = ref.watch(authProvider.notifier);
   final authState = ref.watch(authProvider);
 
   return GoRouter(
     initialLocation: '/login',
+    refreshListenable: RouterRefreshNotifier(ref),
     redirect: (context, state) {
       final isLoggedIn = authState.isAuthenticated;
       final isLoginRoute = state.matchedLocation == '/login';
 
+      // Wait for initial auth check to complete
+      if (!authState.isInitialized) {
+        return null;
+      }
+
       // Redirect to login if not authenticated
       if (!isLoggedIn && !isLoginRoute) {
         return '/login';
@@ -67,3 +72,14 @@ final routerProvider = Provider<GoRouter>((ref) {
     ],
   );
 });
+
+/// Notifier that triggers router refresh when auth state changes
+class RouterRefreshNotifier extends ChangeNotifier {
+  RouterRefreshNotifier(this._ref) {
+    _ref.listen(authProvider, (_, __) {
+      notifyListeners();
+    });
+  }
+
+  final Ref _ref;
+}

lib/core/services/auth_api_service.dart

@@ -0,0 +1,98 @@
+import '../api/api_client.dart';
+import '../models/app_user.dart';
+
+/// Service for authentication via API
+class AuthApiService {
+  final ApiClient _api = ApiClient();
+
+  /// Login with username and password
+  Future<AuthResult> login(String username, String password) async {
+    try {
+      final response = await _api.post('/api/auth/login', data: {
+        'username': username,
+        'password': password,
+      });
+
+      final data = response.data as Map<String, dynamic>;
+      
+      if (data['success'] == true) {
+        final token = data['token'] as String;
+        final userData = data['user'] as Map<String, dynamic>;
+        
+        _api.setToken(token);
+        
+        return AuthResult(
+          success: true,
+          user: AppUser(
+            id: userData['id'] as String,
+            username: userData['username'] as String,
+            passwordHash: '', // Not needed for API auth
+            isAdmin: userData['isAdmin'] as bool? ?? false,
+            createdAt: DateTime.now(),
+          ),
+          token: token,
+        );
+      } else {
+        return AuthResult(
+          success: false,
+          error: data['error'] as String? ?? 'Login failed',
+        );
+      }
+    } catch (e) {
+      return AuthResult(
+        success: false,
+        error: 'Network error: $e',
+      );
+    }
+  }
+
+  /// Logout
+  Future<void> logout() async {
+    try {
+      await _api.post('/api/auth/logout');
+    } finally {
+      _api.clearToken();
+    }
+  }
+
+  /// Get current user from token
+  Future<AppUser?> getCurrentUser() async {
+    _api.restoreToken();
+    
+    if (_api.getStoredToken() == null) {
+      return null;
+    }
+
+    try {
+      final response = await _api.get('/api/auth/me');
+      final data = response.data as Map<String, dynamic>;
+      final userData = data['user'] as Map<String, dynamic>;
+      
+      return AppUser(
+        id: userData['id'] as String,
+        username: userData['username'] as String,
+        passwordHash: '',
+        isAdmin: userData['isAdmin'] as bool? ?? false,
+        createdAt: DateTime.now(),
+      );
+    } catch (e) {
+      _api.clearToken();
+      return null;
+    }
+  }
+}
+
+/// Result of authentication attempt
+class AuthResult {
+  final bool success;
+  final AppUser? user;
+  final String? token;
+  final String? error;
+
+  AuthResult({
+    required this.success,
+    this.user,
+    this.token,
+    this.error,
+  });
+}

lib/core/services/playlist_api_service.dart

@@ -0,0 +1,116 @@
+import '../api/api_client.dart';
+import '../models/playlist_config.dart';
+
+/// Service for managing playlists via API
+class PlaylistApiService {
+  final ApiClient _api = ApiClient();
+
+  /// Get all playlists for current user
+  Future<List<PlaylistConfig>> getPlaylists() async {
+    try {
+      final response = await _api.get('/api/playlists');
+      final data = response.data as Map<String, dynamic>;
+      final playlistsData = data['playlists'] as List<dynamic>;
+
+      return playlistsData.map((p) {
+        final playlist = p as Map<String, dynamic>;
+        return PlaylistConfig(
+          id: playlist['id'] as String,
+          name: playlist['name'] as String,
+          dns: playlist['serverUrl'] as String? ?? playlist['dns'] as String,
+          username: playlist['username'] as String,
+          password: playlist['password'] as String,
+          createdAt: DateTime.tryParse(playlist['createdAt'] as String? ?? '') ?? DateTime.now(),
+        );
+      }).toList();
+    } catch (e) {
+      print('Error fetching playlists: $e');
+      return [];
+    }
+  }
+
+  /// Create a new playlist
+  Future<PlaylistConfig?> createPlaylist({
+    required String name,
+    required String dns,
+    required String username,
+    required String password,
+  }) async {
+    try {
+      final response = await _api.post('/api/playlists', data: {
+        'name': name,
+        'serverUrl': dns,
+        'username': username,
+        'password': password,
+        'dns': dns,
+      });
+
+      final data = response.data as Map<String, dynamic>;
+      
+      if (data['success'] == true) {
+        final playlist = data['playlist'] as Map<String, dynamic>;
+        return PlaylistConfig(
+          id: playlist['id'] as String,
+          name: playlist['name'] as String,
+          dns: playlist['serverUrl'] as String? ?? playlist['dns'] as String,
+          username: playlist['username'] as String,
+          password: playlist['password'] as String,
+          createdAt: DateTime.tryParse(playlist['createdAt'] as String? ?? '') ?? DateTime.now(),
+        );
+      }
+      return null;
+    } catch (e) {
+      print('Error creating playlist: $e');
+      return null;
+    }
+  }
+
+  /// Update a playlist
+  Future<PlaylistConfig?> updatePlaylist({
+    required String id,
+    required String name,
+    required String dns,
+    required String username,
+    required String password,
+  }) async {
+    try {
+      final response = await _api.put('/api/playlists/$id', data: {
+        'name': name,
+        'serverUrl': dns,
+        'username': username,
+        'password': password,
+        'dns': dns,
+      });
+
+      final data = response.data as Map<String, dynamic>;
+      
+      if (data['success'] == true) {
+        final playlist = data['playlist'] as Map<String, dynamic>;
+        return PlaylistConfig(
+          id: playlist['id'] as String,
+          name: playlist['name'] as String,
+          dns: playlist['serverUrl'] as String? ?? playlist['dns'] as String,
+          username: playlist['username'] as String,
+          password: playlist['password'] as String,
+          createdAt: DateTime.tryParse(playlist['createdAt'] as String? ?? '') ?? DateTime.now(),
+        );
+      }
+      return null;
+    } catch (e) {
+      print('Error updating playlist: $e');
+      return null;
+    }
+  }
+
+  /// Delete a playlist
+  Future<bool> deletePlaylist(String id) async {
+    try {
+      final response = await _api.delete('/api/playlists/$id');
+      final data = response.data as Map<String, dynamic>;
+      return data['success'] == true;
+    } catch (e) {
+      print('Error deleting playlist: $e');
+      return false;
+    }
+  }
+}