/// [ChangeNotifier] that owns [ThemeMode] and persists it locally.
library;

import 'package:flutter/material.dart';

import '../services/storage_service.dart';

/// Provides [themeMode] to [MaterialApp] and writes changes to storage.
class ThemeController extends ChangeNotifier {
  ThemeController(this._storage) {
    _themeMode = _fromName(_storage.themeModeName);
  }

  final StorageService _storage;
  late ThemeMode _themeMode;

  ThemeMode get themeMode => _themeMode;

  bool get isDark =>
      _themeMode == ThemeMode.dark ||
      (_themeMode == ThemeMode.system &&
          WidgetsBinding.instance.platformDispatcher.platformBrightness ==
              Brightness.dark);

  Future<void> setThemeMode(ThemeMode mode) async {
    if (mode == _themeMode) return;
    _themeMode = mode;
    notifyListeners();
    await _storage.setThemeModeName(_toName(mode));
  }

  /// Toggles between light and dark (moon / sun control).
  Future<void> toggleLightDark() {
    return setThemeMode(isDark ? ThemeMode.light : ThemeMode.dark);
  }
}

ThemeMode _fromName(String name) {
  return switch (name) {
    'dark' => ThemeMode.dark,
    'system' => ThemeMode.system,
    _ => ThemeMode.light,
  };
}

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