added persisted app settings

lib/service/json_file_service.dart

@@ -14,21 +14,10 @@ class JsonFileService {
     required List<Bookmark> bookmarks,
   }) async {
     try {
-      final dir = await _directoryPath;
+      final dir = await selectDirectoryPath();
       if (dir.isEmpty) return false;
 
-      final data = {
-        'collections': collections.map((c) => c.toJson()).toList(),
-        'bookmarks': bookmarks.map((b) => b.toJson()).toList(),
-      };
-      final json = jsonEncode(data).codeUnits;
-      final file = XFile.fromData(
-        Uint8List.fromList(json),
-        mimeType: 'application/json',
-        name: constants.jsonFileName,
-      );
-
-      file.saveTo('$dir/${constants.jsonFileName}');
+      saveDataToFile(collections, bookmarks, dir);
     } catch (e) {
       return false;
     }
@@ -65,7 +54,31 @@ class JsonFileService {
     }
   }
 
-  static Future<String> get _directoryPath async {
+  static Future<bool> saveDataToFile(
+    List<Collection> collections,
+    List<Bookmark> bookmarks,
+    String directory,
+  ) async {
+    try {
+      final data = jsonEncode({
+        'collections': collections.map((c) => c.toJson()).toList(),
+        'bookmarks': bookmarks.map((b) => b.toJson()).toList(),
+      }).codeUnits;
+
+      final file = XFile.fromData(
+        Uint8List.fromList(data),
+        mimeType: 'application/json',
+        name: constants.jsonFileName,
+      );
+
+      file.saveTo('$directory/${constants.jsonFileName}');
+    } catch (e) {
+      return false;
+    }
+    return true;
+  }
+
+  static Future<String> selectDirectoryPath() async {
     if (Platform.isAndroid) {
       return await getDirectoryPath(
             initialDirectory: constants.defaultAndroidExportDirectory,

lib/service/settings_provider.dart

@@ -12,9 +12,13 @@ class SettingsProvider extends ChangeNotifier {
 
   void setExportDirectoryPath(String path, {bool silent = false}) {
     _settings = _settings.copyWith(exportDirectoryPath: path);
-    _saveSettings();
+    Storage.saveSettings(_settings);
     if (!silent) notifyListeners();
   }
 
-  void _saveSettings() => Storage.saveSettings(_settings);
+  void setAlwaysExportEnabled(bool enabled, {bool silent = false}) {
+    _settings = _settings.copyWith(alwaysExportEnabled: enabled);
+    Storage.saveSettings(_settings);
+    if (!silent) notifyListeners();
+  }
 }

lib/service/storage.dart

@@ -13,6 +13,7 @@ class Storage {
   static SharedPreferencesWithCache? _prefsWithCache;
   static const String _settingsKey = 'settings';
   static const String _statsKey = 'stats';
+  static Settings _currentSettings = Settings.defaults();
 
   static Future<void> initialize() async {
     _prefsWithCache = await SharedPreferencesWithCache.create(
@@ -31,7 +32,8 @@ class Storage {
     final jsonString = _prefs.getString(_settingsKey);
     if (jsonString != null) {
       final json = jsonDecode(jsonString) as Map<String, dynamic>;
-      return Settings.fromJson(json);
+      _currentSettings = Settings.fromJson(json);
+      return _currentSettings;
     } else {
       final settings = Settings.defaults();
       saveSettings(settings);
@@ -41,6 +43,7 @@ class Storage {
 
   static Future<void> saveSettings(Settings settings) {
     final json = jsonEncode(settings.toJson());
+    _currentSettings = settings;
     return _prefs.setString(_settingsKey, json);
   }
 
@@ -63,11 +66,13 @@ class Storage {
   static Future<void> saveCollections(List<Collection> collections) async {
     final jsonList = collections.map((c) => c.toJson()).toList();
     await _prefs.setString(_collectionsKey, jsonEncode(jsonList));
+    if (_currentSettings.alwaysExportEnabled) saveDataToFile();
   }
 
   static Future<void> saveBookmarks(List<Bookmark> bookmarks) async {
     final jsonList = bookmarks.map((b) => b.toJson()).toList();
     await _prefs.setString(_bookmarksKey, jsonEncode(jsonList));
+    if (_currentSettings.alwaysExportEnabled) saveDataToFile();
   }
 
   static List<Bookmark> loadBookmarksForCollection(int collectionId) {
@@ -196,6 +201,15 @@ class Storage {
     return false;
   }
 
+  static Future<String> selectDirectoryPath() =>
+      JsonFileService.selectDirectoryPath();
+
+  static Future<bool> saveDataToFile() => JsonFileService.saveDataToFile(
+    loadCollections(),
+    loadBookmarks(),
+    _currentSettings.exportDirectoryPath,
+  );
+
   static SharedPreferencesWithCache get _prefs {
     if (_prefsWithCache == null) {
       throw StateError(