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

part 'theme_provider.g.dart';

const _themeModeKey = 'theme_mode';

@riverpod
class ThemeNotifier extends _$ThemeNotifier {
  @override
  ThemeMode build() {
    _loadPersistedThemeMode();
    return ThemeMode.system;
  }

  Future<void> _loadPersistedThemeMode() async {
    final prefs = await SharedPreferences.getInstance();
    final persisted = prefs.getString(_themeModeKey);
    if (persisted != null) {
      state = _themeModeFromString(persisted);
    }
  }

  Future<void> setThemeMode(ThemeMode mode) async {
    state = mode;
    final prefs = await SharedPreferences.getInstance();
    await prefs.setString(_themeModeKey, _themeModeToString(mode));
  }

  static ThemeMode _themeModeFromString(String? value) {
    switch (value) {
      case 'light':
        return ThemeMode.light;
      case 'dark':
        return ThemeMode.dark;
      case 'system':
      default:
        return ThemeMode.system;
    }
  }

  static String _themeModeToString(ThemeMode mode) {
    switch (mode) {
      case ThemeMode.light:
        return 'light';
      case ThemeMode.dark:
        return 'dark';
      case ThemeMode.system:
        return 'system';
    }
  }
}