import 'package:flutter/foundation.dart';
import 'package:shared_preferences/shared_preferences.dart';

/// Opt-in for reading the REAL audio level behind the waveform visualizer.
///
/// This is a sensitive-permission gate, not a cosmetic preference.
/// `VisualizadorAudio` subscribes to the native `pluriwave/audio_visualizer`
/// EventChannel only while [ondaRealHabilitada] is true, and that
/// subscription is precisely what makes `MainActivity` request
/// `RECORD_AUDIO`. So the flag must:
///
/// * default to `false`, so a fresh install never asks;
/// * flip to `true` only from a place where the user has just been told what
///   the permission is for (see `PantallaAjustesVisualizador`);
/// * be revocable at any time with no friction at all.
///
/// Without it the visualizer animates its synthetic wave, which is exactly
/// what it already did whenever the permission was denied — nothing about
/// the app breaks.
class EstadoVisualizador extends ChangeNotifier {
  EstadoVisualizador({SharedPreferences? prefs}) : _prefs = prefs {
    _cargar();
  }

  /// Persisted key. Public so tests can assert persistence without
  /// duplicating the literal.
  static const String claveOndaReal = 'visualizador_onda_real_v1';

  final SharedPreferences? _prefs;

  bool _ondaRealHabilitada = false;

  bool get ondaRealHabilitada => _ondaRealHabilitada;

  Future<void> cambiarOndaReal(bool habilitada) async {
    if (habilitada == _ondaRealHabilitada) return;
    _ondaRealHabilitada = habilitada;
    notifyListeners();
    final prefs = await _resolverPrefs();
    await prefs.setBool(claveOndaReal, habilitada);
  }

  Future<void> _cargar() async {
    final prefs = await _resolverPrefs();
    final guardado = prefs.getBool(claveOndaReal) ?? false;
    if (guardado == _ondaRealHabilitada) return;
    _ondaRealHabilitada = guardado;
    notifyListeners();
  }

  Future<SharedPreferences> _resolverPrefs() async =>
      _prefs ?? SharedPreferences.getInstance();
}