mileograph_flutter/lib/services/theme_mode_service.dart

import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';

class ThemeModeService extends ChangeNotifier {
  static const _prefsKey = 'theme_mode_preference';

  ThemeMode _mode = ThemeMode.system;
  bool _loaded = false;

  ThemeMode get mode => _mode;
  bool get isLoaded => _loaded;

  ThemeModeService() {
    _load();
  }

  Future<void> _load() async {
    final prefs = await SharedPreferences.getInstance();
    final saved = prefs.getString(_prefsKey);
    if (saved != null) {
      switch (saved) {
        case 'light':
          _mode = ThemeMode.light;
          break;
        case 'dark':
          _mode = ThemeMode.dark;
          break;
        default:
          _mode = ThemeMode.system;
      }
    }
    _loaded = true;
    notifyListeners();
  }

  Future<void> setMode(ThemeMode mode) async {
    _mode = mode;
    final prefs = await SharedPreferences.getInstance();
    final value = switch (mode) {
      ThemeMode.light => 'light',
      ThemeMode.dark => 'dark',
      _ => 'system',
    };
    await prefs.setString(_prefsKey, value);
    notifyListeners();
  }
}