yanting/lib/theme/theme_controller.dart

import 'dart:async';

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

const _themeModeKey = 'theme_mode';

final themeModeProvider = StateNotifierProvider<ThemeModeController, ThemeMode>(
  (ref) => ThemeModeController(),
);

class ThemeModeController extends StateNotifier<ThemeMode> {
  ThemeModeController() : super(ThemeMode.system) {
    unawaited(_loadSavedMode());
  }

  Future<void> _loadSavedMode() async {
    final prefs = await SharedPreferences.getInstance();
    final raw = prefs.getString(_themeModeKey);
    if (raw == null) return;
    state = _decode(raw);
  }

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

  ThemeMode _decode(String raw) => switch (raw) {
    'light' => ThemeMode.light,
    'dark' => ThemeMode.dark,
    _ => ThemeMode.system,
  };

  String _encode(ThemeMode mode) => switch (mode) {
    ThemeMode.light => 'light',
    ThemeMode.dark => 'dark',
    ThemeMode.system => 'system',
  };
}