Added jwt authenticaation

frontend_splatournament_manager/lib/providers/auth_provider.dart

@@ -1,8 +1,11 @@
 import 'package:flutter/material.dart';
 import 'package:frontend_splatournament_manager/services/auth_service.dart';
+import 'package:flutter_secure_storage/flutter_secure_storage.dart';
+import 'package:jwt_decoder/jwt_decoder.dart';
 
 class AuthProvider extends ChangeNotifier {
   final AuthService _authService = AuthService();
+  final FlutterSecureStorage _storage = const FlutterSecureStorage();
 
   bool _isLoggedIn = false;
   String? _username;
@@ -23,6 +26,12 @@ class AuthProvider extends ChangeNotifier {
 
     try {
       final user = await _authService.login(username, password);
+      
+      final token = user['token'];
+      if (token != null) {
+        await _storage.write(key: 'jwt_token', value: token);
+      }
+
       _isLoggedIn = true;
       _username = user['username'];
       _userId = user['id'];
@@ -44,6 +53,12 @@ class AuthProvider extends ChangeNotifier {
 
     try {
       final user = await _authService.register(username, password);
+
+      final token = user['token'];
+      if (token != null) {
+        await _storage.write(key: 'jwt_token', value: token);
+      }
+
       _isLoggedIn = true;
       _username = user['username'];
       _userId = user['id'];
@@ -58,17 +73,32 @@ class AuthProvider extends ChangeNotifier {
     }
   }
 
-  void logout() {
+  Future<void> logout() async {
     _isLoggedIn = false;
     _username = null;
     _userId = null;
     _error = null;
+    await _storage.delete(key: 'jwt_token');
     notifyListeners();
   }
 
+  Future<void> checkAuthStatus() async {
+    final token = await _storage.read(key: 'jwt_token');
+    if (token != null) {
+      if (JwtDecoder.isExpired(token)) {
+        await logout();
+      } else {
+        Map<String, dynamic> decodedToken = JwtDecoder.decode(token);
+        _isLoggedIn = true;
+        _userId = decodedToken['id'];
+        _username = decodedToken['username'];
+        notifyListeners();
+      }
+    }
+  }
+
   void clearError() {
     _error = null;
     notifyListeners();
   }
 }
-