refactor: simplify settings data layer

Remove SettingsLocalDatasource and manual codecs, implement persistence
directly in SettingsRepositoryImpl. Migrate Settings and GeneralSettings
to freezed with json_serializable for codegen-based serialization.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: hawkkiller

app/lib/src/feature/settings/data/datasources/settings_local_datasource.dart

@@ -1,21 +1,31 @@
 import 'dart:async';
 
-import 'package:sizzle_starter/src/feature/settings/data/datasources/settings_local_datasource.dart';
+import 'package:common/common.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
 import 'package:sizzle_starter/src/feature/settings/domain/model/settings.dart';
 import 'package:sizzle_starter/src/feature/settings/domain/repositories/settings_repository.dart';
 
 final class SettingsRepositoryImpl implements SettingsRepository {
-  const SettingsRepositoryImpl({required this.localDatasource});
+  const SettingsRepositoryImpl({required this.sharedPreferences});
+
+  final SharedPreferencesAsync sharedPreferences;
 
-  final SettingsLocalDatasource localDatasource;
+  SharedPreferencesColumnJson get _column => SharedPreferencesColumnJson(
+    sharedPreferences: sharedPreferences,
+    key: 'settings',
+  );
 
   @override
   Future<void> save(Settings settings) async {
-    await localDatasource.save(settings);
+    await _column.set(settings.toJson());
   }
 
   @override
   Future<Settings> read() async {
-    return await localDatasource.read();
+    final settingsMap = await _column.read();
+    if (settingsMap == null) return const Settings();
+
+    return Settings.fromJson(settingsMap);
   }
 }

app/lib/src/feature/settings/data/mappers/general_settings_codec.dart

@@ -1,36 +1,28 @@
 import 'dart:ui' show Color, Locale;
 
+import 'package:freezed_annotation/freezed_annotation.dart';
+
+part 'general.freezed.dart';
+part 'general.g.dart';
+
 /// Possible theme modes for the application.
 enum ThemeModeVO { light, dark, system }
 
 /// Class that holds values used for constructing a theme for the app.
-final class GeneralSettings {
-  const GeneralSettings({
-    this.locale = const Locale('en'),
-    this.themeMode = ThemeModeVO.system,
-    this.seedColor = const Color(0xFF6200EE),
-  });
-
-  final ThemeModeVO themeMode;
-  final Color seedColor;
-  final Locale locale;
+@freezed
+abstract class GeneralSettings with _$GeneralSettings {
+  const factory GeneralSettings({
+    @Default(Locale('en')) @JsonKey(toJson: _localeToJson, fromJson: _localeFromJson) Locale locale,
+    @Default(ThemeModeVO.system) ThemeModeVO themeMode,
+    @Default(Color(0xFF6200EE))
+    @JsonKey(toJson: _colorToARGB32, fromJson: _colorFromARGB32)
+    Color seedColor,
+  }) = _GeneralSettings;
 
-  GeneralSettings copyWith({ThemeModeVO? themeMode, Color? seedColor, Locale? locale}) {
-    return GeneralSettings(
-      themeMode: themeMode ?? this.themeMode,
-      seedColor: seedColor ?? this.seedColor,
-      locale: locale ?? this.locale,
-    );
-  }
-
-  @override
-  bool operator ==(Object other) =>
-      identical(this, other) ||
-      other is GeneralSettings &&
-          seedColor == other.seedColor &&
-          themeMode == other.themeMode &&
-          locale == other.locale;
-
-  @override
-  int get hashCode => Object.hash(seedColor, themeMode, locale);
+  factory GeneralSettings.fromJson(Map<String, Object?> json) => _$GeneralSettingsFromJson(json);
 }
+
+String _localeToJson(Locale locale) => locale.toString();
+Locale _localeFromJson(String json) => Locale(json);
+int _colorToARGB32(Color color) => color.toARGB32();
+Color _colorFromARGB32(int argb32) => Color(argb32);

app/lib/src/feature/settings/data/mappers/settings_codec.dart

@@ -1,22 +1,13 @@
+import 'package:freezed_annotation/freezed_annotation.dart';
 import 'package:sizzle_starter/src/feature/settings/domain/model/general.dart';
 
-/// Settings for the app.
-class Settings {
-  const Settings({this.general = const GeneralSettings()});
-
-  final GeneralSettings general;
-
-  Settings copyWith({GeneralSettings? general}) => Settings(
-    general: general ?? this.general,
-  );
+part 'settings.freezed.dart';
+part 'settings.g.dart';
 
-  @override
-  bool operator ==(Object other) {
-    if (identical(this, other)) return true;
-
-    return other is Settings && other.general == general;
-  }
+/// Settings for the app.
+@freezed
+abstract class Settings with _$Settings {
+  const factory Settings({@Default(GeneralSettings()) GeneralSettings general}) = _Settings;
 
-  @override
-  int get hashCode => general.hashCode;
+  factory Settings.fromJson(Map<String, Object?> json) => _$SettingsFromJson(json);
 }

app/lib/src/feature/settings/data/repositories/settings_repository_impl.dart

@@ -1,7 +1,6 @@
 import 'package:shared_preferences/shared_preferences.dart';
 
 import 'package:sizzle_starter/src/feature/settings/application/settings_service.dart';
-import 'package:sizzle_starter/src/feature/settings/data/datasources/settings_local_datasource.dart';
 import 'package:sizzle_starter/src/feature/settings/data/repositories/settings_repository_impl.dart';
 
 /// Container with global settings state.
@@ -16,9 +15,7 @@ class SettingsContainer {
     required SharedPreferencesAsync sharedPreferences,
   }) async {
     final settingsRepository = SettingsRepositoryImpl(
-      localDatasource: SettingsLocalDatasourceSharedPreferences(
-        sharedPreferences: sharedPreferences,
-      ),
+      sharedPreferences: sharedPreferences,
     );
 
     final settingsService = await SettingsServiceImpl.create(repository: settingsRepository);

app/lib/src/feature/settings/domain/model/general.dart

@@ -25,6 +25,10 @@ dependencies:
   clock: 1.1.2
   package_info_plus: ^9.0.0
 
+  # Code Generation
+  json_annotation: ^4.10.0
+  freezed_annotation: ^3.1.0
+
   # Core
   rest_client:
     path: ../core/rest_client
@@ -39,12 +43,16 @@ dependencies:
   ui_library:
     path: ../core/ui_library
 
-
 dev_dependencies:
   # Testing
   flutter_test:
     sdk: flutter
 
+  # Code Generation
+  build_runner: ^2.11.1
+  json_serializable: ^6.12.0
+  freezed: ^3.2.5
+
 flutter:
   uses-material-design: true