feat: add alot

lib/viewmodels/settings_view_model.dart

@@ -1,10 +1,11 @@
 import 'package:flutter/foundation.dart';
-import 'package:kooltab2/utils/app_update_util.dart';
 import 'package:ota_update/ota_update.dart';
 
+import '../models/app_error.dart';
 import '../models/settings.dart';
 import '../services/settings_service.dart';
 import '../utils/app_config.dart';
+import '../utils/app_update_util.dart';
 
 class SettingsViewModel extends ChangeNotifier {
   final SettingsService settingsService;
@@ -14,7 +15,7 @@ class SettingsViewModel extends ChangeNotifier {
   AppSettings _settings = AppSettings.defaults;
   bool _isLoading = false;
   bool _hasLoaded = false;
-  String? _errorMessage;
+  AppError? _error;
 
   final AppUpdateUtil _updater = AppUpdateUtil(serverUrl: kUpdateServerUrl);
 
@@ -28,7 +29,7 @@ class SettingsViewModel extends ChangeNotifier {
 
   bool get hasLoaded => _hasLoaded;
 
-  String? get errorMessage => _errorMessage;
+  AppError? get error => _error;
 
   Future<void> ensureLoaded() async {
     if (_hasLoaded || _isLoading) return;
@@ -39,14 +40,14 @@ class SettingsViewModel extends ChangeNotifier {
     if (_isLoading) return;
 
     _isLoading = true;
-    _errorMessage = null;
+    _error = null;
     notifyListeners();
 
     try {
       _settings = await settingsService.getSettings();
     } catch (e) {
       debugPrint('SettingsViewModel: load error: $e');
-      _errorMessage = 'Could not load settings.';
+      _error = AppError.loadSettings;
     } finally {
       _hasLoaded = true;
       _isLoading = false;
@@ -72,33 +73,33 @@ class SettingsViewModel extends ChangeNotifier {
     UpdateInfo update, {
     void Function(double progress)? onProgress,
   }) async {
-    final url = update.download.startsWith("http")
+    final url = update.download.startsWith('http')
         ? update.download
-        : "$kUpdateServerUrl${update.download}";
+        : '$kUpdateServerUrl${update.download}';
 
-    debugPrint("Download Url: $url");
+    debugPrint('Download Url: $url');
 
     final stream = OtaUpdate().execute(
       url,
-      destinationFilename: "update.apk",
+      destinationFilename: 'update.apk',
       sha256checksum: update.sha256,
     );
 
     await for (final event in stream) {
-      debugPrint("OTA: ${event.status} ${event.value}");
+      debugPrint('OTA: ${event.status} ${event.value}');
 
       if (event.status == OtaStatus.DOWNLOADING) {
-        final progress = double.tryParse(event.value ?? "0") ?? 0;
+        final progress = double.tryParse(event.value ?? '0') ?? 0;
 
         onProgress?.call(progress / 100);
       }
 
       if (event.status == OtaStatus.DOWNLOAD_ERROR) {
-        throw Exception("Download failed: ${event.value}");
+        throw Exception('Download failed: ${event.value}');
       }
 
       if (event.status == OtaStatus.INSTALLATION_ERROR) {
-        throw Exception("Installation failed: ${event.value}");
+        throw Exception('Installation failed: ${event.value}');
       }
     }
   }
@@ -121,7 +122,7 @@ class SettingsViewModel extends ChangeNotifier {
   Future<void> _save(AppSettings updated) async {
     final previous = _settings;
     _settings = updated;
-    _errorMessage = null;
+    _error = null;
     notifyListeners();
 
     try {
@@ -129,7 +130,7 @@ class SettingsViewModel extends ChangeNotifier {
     } catch (e) {
       debugPrint('SettingsViewModel: save error: $e');
       _settings = previous;
-      _errorMessage = 'Could not save settings.';
+      _error = AppError.saveSettings;
       notifyListeners();
     }
   }