import 'package:flutter/foundation.dart';

import '../models/settings.dart';
import '../services/settings_service.dart';

class SettingsViewModel extends ChangeNotifier {
  final SettingsService settingsService;

  SettingsViewModel({required this.settingsService});

  AppSettings _settings = AppSettings.defaults;
  bool _isLoading = false;
  bool _hasLoaded = false;
  String? _errorMessage;

  AppSettings get settings => _settings;
  bool get isLoading => _isLoading;
  bool get hasLoaded => _hasLoaded;
  String? get errorMessage => _errorMessage;

  Future<void> ensureLoaded() async {
    if (_hasLoaded || _isLoading) return;
    await load();
  }

  Future<void> load() async {
    if (_isLoading) return;

    _isLoading = true;
    _errorMessage = null;
    notifyListeners();

    try {
      _settings = await settingsService.getSettings();
    } catch (_) {
      _errorMessage = 'Could not load settings.';
    } finally {
      _hasLoaded = true;
      _isLoading = false;
      notifyListeners();
    }
  }

  /// Just flips the preference flag. Caller is responsible for having
  /// already set/verified the actual PIN via PinLockViewModel first.
  Future<void> updatePinRequired(bool value) =>
      _save(_settings.copyWith(pinRequired: value));

  Future<void> updateThemeMode(AppThemeMode mode) =>
      _save(_settings.copyWith(themeMode: mode));

  Future<void> _save(AppSettings updated) async {
    final previous = _settings;
    _settings = updated;
    _errorMessage = null;
    notifyListeners();

    try {
      await settingsService.saveSettings(updated);
    } catch (_) {
      _settings = previous;
      _errorMessage = 'Could not save settings.';
      notifyListeners();
    }
  }
}