import 'package:shared_preferences/shared_preferences.dart';

/// Persists whether the 9-screen help/tutorial carousel (`PantallaTutorialAyuda`)
/// has already been shown, so it renders once on the genuine first-run
/// sequence rather than on every launch.
///
/// Same injectable-`SharedPreferences`, versioned-key convention as
/// `ServicioBienvenida` -- a plain one-time boolean flag, not a per-app-version
/// "due again" scheme like `ServicioContenidoApp` uses: no existing user has
/// this flag set yet, regardless of whether they are a fresh install or an
/// upgrade, so a single flag already satisfies "show once, ever".
class ServicioTutorialAyuda {
  ServicioTutorialAyuda({SharedPreferences? prefs}) : _prefs = prefs;

  static const _keyTutorialVisto = 'pluri_tutorial_visto_v1';

  final SharedPreferences? _prefs;

  /// Injected startup instance (S3-R4); getInstance() is only a fallback.
  Future<SharedPreferences> _resolverPrefs() async =>
      _prefs ?? SharedPreferences.getInstance();

  Future<bool> debeMostrarTutorial() async {
    final prefs = await _resolverPrefs();
    return !(prefs.getBool(_keyTutorialVisto) ?? false);
  }

  Future<void> marcarTutorialVisto() async {
    final prefs = await _resolverPrefs();
    await prefs.setBool(_keyTutorialVisto, true);
  }
}