import 'dart:async';

import 'package:audio_service/audio_service.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:just_audio/just_audio.dart';
import 'package:pluriwave/modelos/preset_ecualizador.dart';
import 'package:pluriwave/servicios/servicio_audio.dart';

import '../helpers/handlers_audio.dart';

/// eq-coche — the equalizer toggle pressed FROM ANDROID AUTO.
///
/// Reported by the owner: the toggle behaves correctly from the phone screen
/// but from the car it «sometimes sounds like a doubled equalization and
/// sometimes does nothing».
///
/// Three independent causes, one per group below:
///
///  A. The handler's `_presetActual` was hardcoded to `PresetEcualizador.flat`
///     and had NO disk seam. The on/off flag got one (`leerEqActivoPersistido`,
///     `eq-estado-unico` item A); the preset never did. On a headless Android
///     Auto engine — no Activity, no Provider tree, so no `EstadoEcualizador`
///     to push the real preset — enabling the equalizer from the car applied
///     FLAT.
///
///  B. `_aplicarEcualizadorActivo` called `setEnabled(activo)` BEFORE pushing
///     the preset's gains, so the native effect was re-activated carrying
///     whatever band levels the previous preset had left in it and only
///     afterwards were the intended ones written, band by band. That audible
///     gap is the «doubled equalization».
///
///  C. `_recrearPlayer` dropped `_eqDisponible` to `false` on EVERY station
///     change and never restored it until the fresh player attached. Every
///     native EQ path is gated on that flag, so a car toggle landing inside
///     the window flipped the icon and the flag but never touched the audio —
///     the «does nothing» — and the EQ button itself vanished from the car's
///     now-playing screen (`controlesEcualizadorPersonalizados` returns
///     `const []` when unavailable) and came back seconds later.
void main() {
  TestWidgetsFlutterBinding.ensureInitialized();

  final crearHandler = registrarHandlersLiberables();

  late _GuionReproductorEq guion;

  setUp(() {
    guion = _GuionReproductorEq();
    PluriWaveAudioHandler.fabricaReproductorPrueba =
        (pipeline, carga) => _ReproductorFalsoEq(guion, pipeline, carga);
  });

  tearDown(() {
    PluriWaveAudioHandler.fabricaReproductorPrueba = null;
    PluriWaveAudioHandler.fabricaEcualizadorPrueba = null;
  });

  group('A — the preset is seeded from disk on a headless engine', () {
    test('registrarHandler consults the injected preset port exactly once '
        'and seeds the handler with it, with no widget tree', () async {
      final handler = crearHandler();
      var lecturas = 0;

      registrarHandler(
        handler,
        leerPresetPersistido: () async {
          lecturas++;
          return PresetEcualizador.jazz;
        },
      );
      await pumpEventQueue();

      expect(lecturas, 1, reason: 'exactly one disk read per engine start');
      expect(
        handler.presetActual,
        PresetEcualizador.jazz,
        reason:
            'from the car the handler is the ONLY owner of the preset — '
            'nothing else ever pushes one on a headless engine',
      );
    });

    test('a read failure leaves the historical default instead of '
        'propagating', () async {
      final handler = crearHandler();

      registrarHandler(
        handler,
        leerPresetPersistido: () async => throw StateError('sin disco'),
      );
      await pumpEventQueue();

      expect(handler.presetActual, PresetEcualizador.flat);
    });

    test('without a preset port the handler is left untouched (widget tests, '
        'fakes)', () async {
      final handler = crearHandler();
      await handler.aplicarPreset(PresetEcualizador.rock);

      registrarHandler(handler);
      await pumpEventQueue();

      expect(handler.presetActual, PresetEcualizador.rock);
    });

    test('a preset already chosen while the disk read was in flight WINS — '
        'seeding never clobbers a live choice', () async {
      final handler = crearHandler();
      final lectura = Completer<PresetEcualizador?>();

      registrarHandler(handler, leerPresetPersistido: () => lectura.future);
      // The phone UI (`EstadoEcualizador`) resolves a per-station preset and
      // pushes it while the seed's disk read is still pending.
      await handler.aplicarPreset(PresetEcualizador.pop);
      lectura.complete(PresetEcualizador.jazz);
      await pumpEventQueue();

      expect(
        handler.presetActual,
        PresetEcualizador.pop,
        reason:
            'the seed exists to fill a VOID, not to overrule the richer '
            'per-station/per-device preset the phone UI resolves',
      );
    });
  });

  group('B — the preset is pushed BEFORE the effect is enabled', () {
    test('enabling applies the gains first and only then flips the native '
        'effect on', () {
      expect(
        PluriWaveAudioHandler.pasosEcualizador(activo: true),
        [PasoEcualizador.ganancias, PasoEcualizador.habilitacion],
        reason:
            'enabling first would re-activate the native Equalizer carrying '
            'the PREVIOUS preset gains, which is the doubled equalization '
            'the owner hears',
      );
    });

    test('disabling only flips the effect off — the band gains are NOT '
        'reset', () {
      expect(
        PluriWaveAudioHandler.pasosEcualizador(activo: false),
        [PasoEcualizador.habilitacion],
        reason:
            'android.media.audiofx.AudioEffect.setEnabled(false) bypasses '
            'the effect and RETAINS its band levels, and the enable path '
            'rewrites them before re-enabling anyway — zeroing them would be '
            'one native round trip per band for no audible difference',
      );
    });

    test('the real toggle path executes those steps IN THAT ORDER', () async {
      final handler = crearHandler();
      registrarHandler(handler);
      handler.simularEcualizadorDisponible(true);

      await handler.setEcualizadorActivo(true);

      expect(
        handler.pasosEcualizadorEjecutados,
        [PasoEcualizador.ganancias, PasoEcualizador.habilitacion],
        reason:
            'the ORDER is the fix; asserting only that both happened would '
            'stay green against the exact bug being fixed',
      );
    });

    test('the real disable path executes only the habilitacion step', () async {
      final handler = crearHandler();
      registrarHandler(handler);
      handler.simularEcualizadorDisponible(true);

      await handler.setEcualizadorActivo(false);

      expect(handler.pasosEcualizadorEjecutados, [
        PasoEcualizador.habilitacion,
      ]);
    });
  });

  group('C — a station change no longer drops the equalizer', () {
    test('once the EQ was available, no state published across a station '
        'change and a car toggle has zero custom actions', () async {
      final handler = crearHandler();
      registrarHandler(handler);
      handler.simularEcualizadorDisponible(true);
      // The EQ action is on the car's now-playing screen before the station
      // changes — that is the state the driver is looking at.
      await handler.setEcualizadorActivo(true);

      final acciones = <int>[];
      final sub = handler.playbackState.listen(
        (estado) => acciones.add(
          estado.controls.where((c) => c.customAction != null).length,
        ),
      );

      await handler.playMediaItem(
        const MediaItem(id: 'https://a', title: 'A'),
      );
      await pumpEventQueue();
      // The car tap that used to land inside the window `_recrearPlayer`
      // opened. It republishes the controls from `_eqDisponible`, so a flag
      // reset to `false` shows up here as an EQ button that disappeared.
      await handler.customAction(accionEqToggle);
      await sub.cancel();

      expect(
        acciones,
        isNotEmpty,
        reason: 'the station change must publish at least one state',
      );
      expect(
        acciones.every((n) => n > 0),
        isTrue,
        reason:
            'the EQ button vanished and reappeared on every station change '
            'because `_recrearPlayer` reset `_eqDisponible`; availability is '
            'a DEVICE property and does not change with the station. Got '
            '$acciones',
      );
    });

    test('the availability flag survives the player rebuild, so a car toggle '
        'inside the window still reaches the native effect', () async {
      final handler = crearHandler();
      registrarHandler(handler);
      handler.simularEcualizadorDisponible(true);

      await handler.playMediaItem(
        const MediaItem(id: 'https://a', title: 'A'),
      );
      await pumpEventQueue();

      expect(
        handler.ecualizadorDisponible,
        isTrue,
        reason:
            'this is the flag every native EQ path is gated on; false here '
            'is exactly the reported «does nothing»',
      );
    });
  });

  group('D — a failed native call is traced and never lies', () {
    test('a throwing setEnabled is traced instead of swallowed', () async {
      PluriWaveAudioHandler.fabricaEcualizadorPrueba =
          () => _EcualizadorQueFalla();
      final handler = crearHandler();
      registrarHandler(handler);
      handler.simularEcualizadorDisponible(true);

      await handler.setEcualizadorActivo(true);

      expect(
        handler.fallosNativosEcualizador,
        greaterThan(0),
        reason:
            'the silent `catch (_) {}` made a dead native equalizer '
            'indistinguishable from a working one in a car logcat',
      );
    });

    test('a failed on/off call leaves the published state honest instead of '
        'claiming a state the audio does not have', () async {
      PluriWaveAudioHandler.fabricaEcualizadorPrueba =
          () => _EcualizadorQueFalla();
      final handler = crearHandler();
      registrarHandler(handler);
      handler.simularEcualizadorDisponible(true);
      await handler.sembrarEcualizadorActivo(false);

      await handler.setEcualizadorActivo(true);

      expect(
        handler.ecualizadorActivo,
        isFalse,
        reason:
            'the native effect refused, so the car icon must not read "on" '
            'over audio that is not equalized',
      );
    });

    test('a failed on/off call is not persisted', () async {
      PluriWaveAudioHandler.fabricaEcualizadorPrueba =
          () => _EcualizadorQueFalla();
      final handler = crearHandler();
      final escrituras = <bool>[];
      registrarHandler(
        handler,
        guardarEqActivoPersistido: (activo) async => escrituras.add(activo),
      );
      handler.simularEcualizadorDisponible(true);
      await handler.sembrarEcualizadorActivo(false);

      await handler.setEcualizadorActivo(true);

      expect(
        escrituras,
        isEmpty,
        reason:
            'persisting a state the device rejected would resurrect it on '
            'the next engine start',
      );
    });
  });
}

/// An `AndroidEqualizer` whose `setEnabled` always throws, standing in for a
/// device whose native `Equalizer` effect refuses the call. Nothing else is
/// overridden, so the rest of the handler runs unchanged.
class _EcualizadorQueFalla extends AndroidEqualizer {
  @override
  Future<void> setEnabled(bool enabled) async {
    throw StateError('el efecto nativo rechazo la llamada');
  }
}

/// Minimal script/observation record shared by every [_ReproductorFalsoEq]
/// the handler builds (it rebuilds its player on every source change).
class _GuionReproductorEq {
  int llamadasSetUrl = 0;
  _ReproductorFalsoEq? ultimoReproductor;
}

/// An [AudioPlayer] whose platform-touching methods are replaced, so a real
/// station change can be driven under `flutter test`. Mirrors the double in
/// `servicio_audio_transporte_test.dart`.
class _ReproductorFalsoEq extends AudioPlayer {
  _ReproductorFalsoEq(
    this._guion,
    AudioPipeline pipeline,
    AudioLoadConfiguration carga,
  ) : super(audioPipeline: pipeline, audioLoadConfiguration: carga) {
    _guion.ultimoReproductor = this;
  }

  final _GuionReproductorEq _guion;
  final _estados = StreamController<PlayerState>.broadcast();

  @override
  Stream<PlayerState> get playerStateStream => _estados.stream;

  @override
  Future<Duration?> setUrl(
    String url, {
    Map<String, String>? headers,
    Duration? initialPosition,
    bool preload = true,
    dynamic tag,
  }) async {
    _guion.llamadasSetUrl++;
    return null;
  }

  @override
  Future<void> play() async {}

  @override
  Future<void> pause() async {}

  @override
  Future<void> stop() async {}

  @override
  Future<void> setVolume(double volume) async {}

  @override
  Future<void> dispose() async {
    await _estados.close();
  }
}