import 'package:flutter/widgets.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:nontonki/core/config/locale_controller.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:shared_preferences_platform_interface/in_memory_shared_preferences_async.dart';
import 'package:shared_preferences_platform_interface/shared_preferences_async_platform_interface.dart';

void main() {
  setUp(() {
    SharedPreferencesAsyncPlatform.instance =
        InMemorySharedPreferencesAsync.empty();
  });

  test('no stored choice keeps the device locale', () async {
    final controller = LocaleController();
    var notifications = 0;
    controller.addListener(() => notifications++);

    await controller.load();

    expect(controller.locale, isNull);
    expect(notifications, 1);
  });

  test('a chosen language survives a restart', () async {
    final first = LocaleController();
    await first.select('zh');
    expect(first.locale, const Locale('zh'));

    final reopened = LocaleController();
    await reopened.load();
    expect(reopened.locale, const Locale('zh'));
  });

  test('selecting english clears a stored chinese preference', () async {
    await LocaleController().select('zh');

    final reopened = LocaleController();
    await reopened.load();
    await reopened.select('en');

    final third = LocaleController();
    await third.load();
    expect(third.locale, const Locale('en'));
  });

  test('an unsupported code clears the locale instead of throwing', () async {
    final controller = LocaleController();
    await controller.select('zh');
    expect(controller.locale, const Locale('zh'));

    await controller.select('tlh');

    expect(controller.locale, isNull);
  });

  test('an unsupported stored code resolves to the device locale', () async {
    await SharedPreferencesAsync().setString('ui.locale', 'fr');

    final controller = LocaleController();
    await controller.load();

    expect(controller.locale, isNull);
  });

  test('a broken preference store never breaks load or select', () async {
    SharedPreferencesAsyncPlatform.instance = _BrokenPreferences();
    final controller = LocaleController();

    await controller.load();
    expect(controller.locale, isNull);

    await controller.select('zh');
    expect(controller.locale, const Locale('zh'));
  });
}

/// Stands in for a platform whose preference store is unavailable.
base class _BrokenPreferences extends InMemorySharedPreferencesAsync {
  _BrokenPreferences() : super.empty();

  @override
  Future<String?> getString(String key, SharedPreferencesOptions options) =>
      Future<String?>.error(StateError('preferences unavailable'));

  @override
  Future<bool> setString(
    String key,
    String value,
    SharedPreferencesOptions options,
  ) => Future<bool>.error(StateError('preferences unavailable'));
}