import 'dart:async';
import 'dart:ui' show Locale;

import 'package:audio_service/audio_service.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:just_audio/just_audio.dart';
import 'package:pluriwave/l10n/gen/app_localizations.dart';
import 'package:pluriwave/servicios/servicio_audio.dart';

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

/// Android for Cars App Quality Guidelines — transport state machine.
///
/// Google Play returned "Approved with Issues" against version code 157:
/// «clicking on stop button makes the entire app useless». These tests drive
/// the REAL [PluriWaveAudioHandler] against a scripted [AudioPlayer] double
/// (installed through [PluriWaveAudioHandler.fabricaReproductorPrueba]) so
/// the published `playbackState` sequence — the only thing Android Auto ever
/// sees — can be asserted end to end.
void main() {
  TestWidgetsFlutterBinding.ensureInitialized();

  final crearHandler = registrarHandlersLiberables();

  late _GuionReproductor guion;

  setUp(() {
    guion = _GuionReproductor();
    PluriWaveAudioHandler.fabricaReproductorPrueba =
        (pipeline, carga) => _ReproductorFalso(guion, pipeline, carga);
  });

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

  group('stop() durante cambios de fuente en vuelo (P0 — botón Stop)', () {
    test(
      'dos cambios encolados y un stop: el ultimo estado publicado es idle, '
      'nunca vuelve a loading',
      () async {
        final handler = crearHandler();
        final publicados = <AudioProcessingState>[];
        final sub = handler.playbackState.listen(
          (estado) => publicados.add(estado.processingState),
        );

        unawaited(
          handler
              .playMediaItem(const MediaItem(id: 'https://a', title: 'A'))
              .catchError((_) {}),
        );
        unawaited(
          handler
              .playMediaItem(const MediaItem(id: 'https://b', title: 'B'))
              .catchError((_) {}),
        );

        await handler.stop();
        // Drain both queued source changes: they must discover the stale
        // revision WITHOUT ever publishing again.
        await pumpEventQueue();
        await sub.cancel();

        expect(
          publicados.last,
          AudioProcessingState.idle,
          reason:
              'a stale queued source change must never rewrite `loading` over '
              'the `idle` that stop() published — that is what leaves Android '
              'Auto spinning forever on a dead session. Secuencia: $publicados',
        );
      },
    );
  });

  group('pause() durante un cambio de fuente en vuelo (P0 — botón Pausa)', () {
    test('la emisora NO arranca: _player.play() nunca se invoca', () async {
      guion.completerSetUrl = Completer<Duration?>();
      final handler = crearHandler();

      unawaited(
        handler
            .playMediaItem(const MediaItem(id: 'https://a', title: 'A'))
            .catchError((_) {}),
      );
      await pumpEventQueue();
      expect(
        guion.llamadasSetUrl,
        1,
        reason: 'precondicion: el cambio de fuente esta en vuelo',
      );

      await handler.pause();
      guion.completerSetUrl!.complete(null);
      await pumpEventQueue();

      expect(
        guion.llamadasPlay,
        0,
        reason:
            'the user pressed Pause while the station was loading — the load '
            'finishing afterwards must never start playback behind their back',
      );
    });

    test(
      'y el coche no se queda en el spinner: el estado publicado sale de '
      'loading',
      () async {
        guion.completerSetUrl = Completer<Duration?>();
        final handler = crearHandler();

        unawaited(
          handler
              .playMediaItem(const MediaItem(id: 'https://a', title: 'A'))
              .catchError((_) {}),
        );
        await pumpEventQueue();

        await handler.pause();
        guion.completerSetUrl!.complete(null);
        await pumpEventQueue();

        expect(
          handler.playbackState.value.processingState,
          isNot(AudioProcessingState.loading),
          reason:
              'withholding the play() must not leave the car showing the '
              'spinner the load started with — nothing else will publish, '
              'because the player never transitions',
        );
        expect(handler.playbackState.value.playing, isFalse);
      },
    );
  });

  group('Suelo de estado terminal (P0 — nunca un spinner eterno)', () {
    setUp(() {
      PluriWaveAudioHandler.vigilanciaTransitoria = const Duration(
        milliseconds: 60,
      );
    });

    tearDown(() {
      PluriWaveAudioHandler.vigilanciaTransitoria =
          PluriWaveAudioHandler.vigilanciaTransitoriaPorDefecto;
    });

    test(
      'un buffering publicado SIN carga viva cae a un estado terminal dentro '
      'de la ventana',
      () async {
        final handler = crearHandler();

        handler.manejarEstadoPlayer(
          PlayerState(false, ProcessingState.buffering),
        );
        expect(
          handler.playbackState.value.processingState,
          AudioProcessingState.buffering,
          reason: 'precondicion: el coche esta viendo el spinner',
        );

        await Future<void>.delayed(const Duration(milliseconds: 250));

        expect(
          handler.playbackState.value.processingState,
          isIn(const [
            AudioProcessingState.ready,
            AudioProcessingState.idle,
            AudioProcessingState.error,
          ]),
          reason:
              'the only exits from loading/buffering are player events that '
              '.distinct() can swallow — without a floor the car spins '
              'forever over a session nobody is driving',
        );
      },
    );

    test('una carga LEGITIMA en vuelo no se interrumpe', () async {
      guion.completerSetUrl = Completer<Duration?>();
      final handler = crearHandler();

      unawaited(
        handler
            .playMediaItem(const MediaItem(id: 'https://a', title: 'A'))
            .catchError((_) {}),
      );
      await pumpEventQueue();

      await Future<void>.delayed(const Duration(milliseconds: 250));

      expect(
        handler.playbackState.value.processingState,
        AudioProcessingState.loading,
        reason:
            'the watchdog is a floor for a STALLED state machine, not a cap '
            'on how long a slow station may take to open',
      );
    });

    test(
      'un mount estancado NO cae en un idle mudo: publica un motivo legible '
      '(hallazgo 3)',
      () async {
        final handler = crearHandler();

        // Exact shape of a stalled icecast mount: the socket opens, `setUrl`
        // returns inside the timeout (so no TimeoutException and no
        // PlayerException — `_esErrorDeRed` never fires and the reconnect
        // machine is never entered), and then no data ever arrives. State
        // sits at buffering with `_cambiosEnVuelo` already back to 0.
        handler.manejarEstadoPlayer(
          PlayerState(false, ProcessingState.buffering),
        );

        await Future<void>.delayed(const Duration(milliseconds: 250));

        final estado = handler.playbackState.value;
        expect(
          estado.processingState,
          AudioProcessingState.error,
          reason:
              'a bare `idle` routes straight into `AudioService._stop()` '
              '(audio_service.dart:1131-1135), so the driver got silence, a '
              'dead session and no explanation. `error` keeps the session '
              'alive and carries a message',
        );
        expect(
          estado.errorMessage,
          isNotNull,
          reason:
              'the floor must say something the driver can read and act on',
        );
      },
    );

    test(
      'un rebuffer normal a mitad de emision NO se convierte en error '
      '(regresion: el suelo miraba solo processingState)',
      () async {
        final handler = crearHandler();

        // Established playback: the stream delivered audio and ExoPlayer
        // reached `ready` while playing. This is what separates a re-buffer
        // from a mount that never produced a byte.
        handler.manejarEstadoPlayer(PlayerState(true, ProcessingState.ready));
        // Ordinary mid-stream re-buffer: `bufferForPlaybackAfterRebuffer` is
        // 5 s, so a tunnel or an LTE handover routinely holds this state for
        // longer than the floor's window. ExoPlayer raised no error, so
        // `_intentarReconexion` never ran and `reintentoPendiente` is false;
        // `_cambiosEnVuelo` is already 0 because the non-blocking
        // `_iniciarPlaySinBloquear` returned long ago.
        handler.manejarEstadoPlayer(
          PlayerState(true, ProcessingState.buffering),
        );
        expect(
          handler.playbackState.value.processingState,
          AudioProcessingState.buffering,
          reason: 'precondicion: el reproductor esta rellenando el buffer',
        );

        await Future<void>.delayed(const Duration(milliseconds: 250));

        final estado = handler.playbackState.value;
        expect(
          estado.processingState,
          isNot(AudioProcessingState.error),
          reason:
              'a self-recovering re-buffer over live audio must never be '
              'converted into a hard STATE_ERROR: the driver is in a tunnel, '
              'not on a dead mount, and `_errorTerminal` latches so nothing '
              'the player emits afterwards could undo it',
        );
        expect(
          estado.playing,
          isTrue,
          reason:
              'the player still owns the timeline — publishing `playing: '
              'false` over it desynchronises the head unit transport row',
        );
        expect(
          estado.errorMessage,
          isNull,
          reason: 'nothing failed, so there is nothing to tell the driver',
        );
      },
    );

    test(
      'un mount que NUNCA entrego audio sigue cayendo al suelo aunque el '
      'reproductor diga playing: true',
      () async {
        final handler = crearHandler();

        // `just_audio`'s `playing` is the play-when-ready intent flag: it
        // flips to true the moment `play()` is called, whether or not a
        // single byte ever arrives. So the stalled icecast mount the floor
        // exists for reports `playing: true` too — `playing` alone can never
        // be the discriminator.
        handler.manejarEstadoPlayer(
          PlayerState(true, ProcessingState.buffering),
        );

        await Future<void>.delayed(const Duration(milliseconds: 250));

        final estado = handler.playbackState.value;
        expect(
          estado.processingState,
          AudioProcessingState.error,
          reason:
              'no `ready` was ever reached on this run, so nothing is '
              're-buffering: the driver is staring at a spinner and the floor '
              'is the only exit',
        );
        expect(estado.errorMessage, isNotNull);
      },
    );

    test(
      'la ventana del suelo respeta el presupuesto de diez segundos hasta el '
      'primer mensaje',
      () {
        expect(
          PluriWaveAudioHandler.vigilanciaTransitoriaPorDefecto,
          lessThanOrEqualTo(const Duration(seconds: 10)),
          reason:
              'the floor is the ONLY exit for a stalled mount, so its window '
              'IS the time-to-first-message for that failure mode; twenty '
              "seconds was double the code's own cited budget",
        );
      },
    );
  });

  group('Error terminal de reproduccion: la sesion sobrevive (hallazgo 2)', () {
    test(
      'el ultimo estado publicado es error CON mensaje, y no lo sigue un idle',
      () async {
        // A non-network failure: `_esErrorDeRed` is false, so this goes
        // straight down the terminal path instead of the reconnect machine.
        guion.errorSetUrl = Exception('mount muerto');
        final handler = crearHandler();
        final publicados = <AudioProcessingState>[];
        final sub = handler.playbackState.listen(
          (estado) => publicados.add(estado.processingState),
        );

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

        // What `_player.stop()` really does: just_audio.dart:1016-1025
        // switches to the idle dummy platform, so `playerStateStream` emits a
        // distinct (playing:false, idle). The double cannot do that on its
        // own, so the test drives the exact event the real player would.
        guion.ultimoReproductor!.emitir(
          PlayerState(false, ProcessingState.idle),
        );
        await pumpEventQueue();
        await sub.cancel();

        final estado = handler.playbackState.value;
        expect(
          estado.processingState,
          AudioProcessingState.error,
          reason:
              'forwarding that idle makes audio_service call '
              'AudioService._stop() -> deactivateMediaSession() + stopSelf(), '
              'so PluriWave dropped off the Android Auto playback surface a '
              'single event-loop turn after showing the error',
        );
        expect(estado.errorMessage, isNotNull);
        expect(
          publicados.last,
          isNot(AudioProcessingState.idle),
          reason: 'secuencia publicada: $publicados',
        );
        expect(
          handler.mediaItem.value,
          isNotNull,
          reason:
              'Android Auto drops a session with no metadata to show, so '
              'nulling the media item on the error path makes the app vanish '
              'from the car pane even when the state itself survives — the '
              'station that failed has to keep its name on screen',
        );
      },
    );

    test(
      'un stop() del usuario DESPUES del error sigue produciendo un idle real '
      '(la sesion tiene que poder morir cuando el conductor lo pide)',
      () async {
        guion.errorSetUrl = Exception('mount muerto');
        final handler = crearHandler();

        await handler
            .playMediaItem(const MediaItem(id: 'https://a', title: 'A'))
            .catchError((_) {});
        await pumpEventQueue();
        expect(
          handler.playbackState.value.processingState,
          AudioProcessingState.error,
          reason: 'precondicion',
        );

        await handler.stop();
        await pumpEventQueue();

        expect(
          handler.playbackState.value.processingState,
          AudioProcessingState.idle,
          reason:
              'suppressing the error-driven idle must NEVER make the Stop '
              'button unkillable — that is the original citation',
        );
      },
    );
  });

  group('Presupuesto de tiempo hasta el primer mensaje (<= 10 s)', () {
    tearDown(() {
      PluriWaveAudioHandler.timeoutCambioFuente =
          PluriWaveAudioHandler.timeoutCambioFuentePorDefecto;
    });

    test('el timeout por defecto deja el primer mensaje dentro de 10 s', () {
      expect(
        PluriWaveAudioHandler.timeoutCambioFuentePorDefecto,
        lessThanOrEqualTo(const Duration(seconds: 10)),
        reason:
            'Android for Cars App Quality Guidelines allow ten seconds before '
            'the driver must be told something; the first attempt alone used '
            'to burn twelve',
      );
    });

    test(
      'una fuente que nunca responde publica un mensaje visible al agotar el '
      'primer intento',
      () async {
        PluriWaveAudioHandler.timeoutCambioFuente = const Duration(
          milliseconds: 100,
        );
        guion.setUrlCuelga = true;
        final handler = crearHandler();

        unawaited(
          handler
              .playMediaItem(const MediaItem(id: 'https://muerta', title: 'X'))
              .catchError((_) {}),
        );
        await Future<void>.delayed(const Duration(milliseconds: 300));

        expect(
          handler.playbackState.value.errorMessage,
          isNotNull,
          reason:
              'the backoff used to publish `buffering` with errorMessage: '
              'null, so the car showed a silent spinner for the whole ~100 s '
              'reconnect window',
        );
        expect(
          handler.playbackState.value.processingState,
          AudioProcessingState.buffering,
          reason: 'still retrying — the message rides ON TOP of the retry',
        );
      },
    );

    test('los reintentos siguen DETRAS del mensaje', () async {
      PluriWaveAudioHandler.timeoutCambioFuente = const Duration(
        milliseconds: 100,
      );
      guion.setUrlCuelga = true;
      final handler = crearHandler();

      unawaited(
        handler
            .playMediaItem(const MediaItem(id: 'https://muerta', title: 'X'))
            .catchError((_) {}),
      );
      // First backoff delay is 1 s (ControladorReconexion default).
      await Future<void>.delayed(const Duration(milliseconds: 1300));

      expect(
        guion.llamadasSetUrl,
        greaterThanOrEqualTo(2),
        reason: 'the reconnect machine keeps working after the first message',
      );
      expect(
        handler.playbackState.value.errorMessage,
        isNotNull,
        reason:
            'and the message survives the retry: re-entering `_cambiarFuente` '
            'must not blank the car screen back to a silent spinner',
      );
    });
  });

  /// A handler nobody released goes on running: its terminal-state floor
  /// timer, its `ControladorReconexion` backoff (1/2/4/8/16 s, which easily
  /// outlives the test that armed it) and whatever is still queued on
  /// `_colaCambioFuente`. When one of those finally performs a source change
  /// it calls `_crearPlayer()`, which reads the CURRENT static
  /// `fabricaReproductorPrueba` — so it builds a double bound to a LATER
  /// test's script and increments that test's counters for work it never
  /// asked for. A suite that passes under those conditions passes by luck.
  group('Liberacion del handler: nada sobrevive al test que lo creo', () {
    tearDown(() {
      PluriWaveAudioHandler.timeoutCambioFuente =
          PluriWaveAudioHandler.timeoutCambioFuentePorDefecto;
    });

    test(
      'un handler liberado NO vuelve a construir un reproductor contra la '
      'fabrica del test siguiente',
      () async {
        PluriWaveAudioHandler.timeoutCambioFuente = const Duration(
          milliseconds: 60,
        );
        guion.setUrlCuelga = true;
        final handler = crearHandler();

        unawaited(
          handler
              .playMediaItem(const MediaItem(id: 'https://muerta', title: 'X'))
              .catchError((_) {}),
        );
        // Long enough for the source-change timeout to fire and the reconnect
        // machine to arm its first backoff retry (1 s).
        await Future<void>.delayed(const Duration(milliseconds: 200));
        expect(
          guion.llamadasSetUrl,
          1,
          reason: 'precondicion: hay un reintento armado detras',
        );

        await handler.liberar();

        // Exactly what the framework does between tests: a brand-new script
        // and a factory bound to it. Nothing from the previous test may
        // reach this.
        final guionSiguiente = _GuionReproductor();
        PluriWaveAudioHandler.fabricaReproductorPrueba = (pipeline, carga) =>
            _ReproductorFalso(guionSiguiente, pipeline, carga);

        await Future<void>.delayed(const Duration(milliseconds: 1400));

        expect(
          guionSiguiente.llamadasSetUrl,
          0,
          reason:
              'the leaked backoff retry re-enters `_cambiarFuente`, which '
              'calls `_crearPlayer()` and therefore reads whatever factory is '
              'installed NOW — attributing a dead handler s work to the test '
              'that happens to be running',
        );
        expect(
          guionSiguiente.ultimoReproductor,
          isNull,
          reason: 'no player at all may be built against the new script',
        );
      },
    );

    test('liberar() es idempotente', () async {
      final handler = crearHandler();

      await handler.liberar();
      await handler.liberar();
    });
  });

  group('Idioma de la superficie del coche (motor sin Activity)', () {
    tearDown(() {
      PluriWaveAudioHandler.lectorLocalePlataforma =
          PluriWaveAudioHandler.lectorLocalePlataformaPorDefecto;
    });

    /// Drives a NON-network failure through the real source-change path so the
    /// terminal error message published to the car can be read back.
    Future<String?> mensajeDeError(PluriWaveAudioHandler handler) async {
      guion.errorSetUrl = Exception('boom');
      await handler
          .playMediaItem(const MediaItem(id: 'https://a', title: 'A'))
          .catchError((_) {});
      await pumpEventQueue();
      return handler.playbackState.value.errorMessage;
    }

    test(
      'sin configurarLocalizaciones, los mensajes salen en el locale de la '
      'plataforma, no en es',
      () async {
        PluriWaveAudioHandler.lectorLocalePlataforma = () =>
            const Locale('en');
        final handler = crearHandler();

        final mensaje = await mensajeDeError(handler);

        expect(
          mensaje,
          lookupAppLocalizations(const Locale('en')).audioErrorUnexpectedPlayback,
          reason:
              '`configurarLocalizaciones` only ever runs from '
              '`mini_reproductor.dart` didChangeDependencies. The headless '
              'Android Auto engine has no Activity and no widget tree, so it '
              'never ran there and every car message came out in Spanish',
        );
        expect(
          mensaje,
          isNot(
            lookupAppLocalizations(
              const Locale('es'),
            ).audioErrorUnexpectedPlayback,
          ),
        );
      },
    );

    test('un locale de plataforma no soportado conserva el respaldo es', () async {
      PluriWaveAudioHandler.lectorLocalePlataforma = () => const Locale('sw');
      final handler = crearHandler();

      expect(
        await mensajeDeError(handler),
        lookupAppLocalizations(const Locale('es')).audioErrorUnexpectedPlayback,
        reason: 'the existing fallback must survive an unresolvable locale',
      );
    });

    test('configurarLocalizaciones sigue teniendo prioridad', () async {
      PluriWaveAudioHandler.lectorLocalePlataforma = () => const Locale('en');
      final handler = crearHandler();
      handler.configurarLocalizaciones(
        lookupAppLocalizations(const Locale('fr')),
      );

      expect(
        await mensajeDeError(handler),
        lookupAppLocalizations(const Locale('fr')).audioErrorUnexpectedPlayback,
        reason: 'the phone UI still owns the locale once a widget tree exists',
      );
    });
  });
}

/// Shared script/observation record for every [_ReproductorFalso] the handler
/// builds (it rebuilds its player on every source change, so counters cannot
/// live on the instance).
class _GuionReproductor {
  int llamadasPlay = 0;
  int llamadasSetUrl = 0;
  final urlsSolicitadas = <String>[];

  /// When set, `setUrl` completes with this error instead of succeeding.
  Object? errorSetUrl;

  /// When true, `setUrl` never completes (simulates a dead stream that only
  /// the source-change timeout can end).
  bool setUrlCuelga = false;

  /// When set, `setUrl` returns this completer's future, so a test can hold a
  /// source change mid-flight and release it after acting on the handler.
  Completer<Duration?>? completerSetUrl;

  /// The handler rebuilds its player on every source change, so a test that
  /// needs to drive a player event has to reach the LATEST instance.
  _ReproductorFalso? ultimoReproductor;
}

/// A [AudioPlayer] whose platform-touching methods are replaced by the script
/// above. Everything else (the rx subjects the constructor wires up) is the
/// real thing, so the handler's stream plumbing is exercised unchanged.
class _ReproductorFalso extends AudioPlayer {
  _ReproductorFalso(
    this._guion,
    AudioPipeline pipeline,
    AudioLoadConfiguration carga,
  ) : super(audioPipeline: pipeline, audioLoadConfiguration: carga) {
    _guion.ultimoReproductor = this;
  }

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

  /// Drives the exact `playerStateStream` event the real player would emit.
  void emitir(PlayerState estado) {
    if (!_estados.isClosed) _estados.add(estado);
  }

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

  @override
  Future<Duration?> setUrl(
    String url, {
    Map<String, String>? headers,
    Duration? initialPosition,
    bool preload = true,
    dynamic tag,
  }) {
    _guion.llamadasSetUrl++;
    _guion.urlsSolicitadas.add(url);
    if (_guion.setUrlCuelga) return Completer<Duration?>().future;
    final pendiente = _guion.completerSetUrl;
    if (pendiente != null) return pendiente.future;
    final error = _guion.errorSetUrl;
    if (error != null) return Future<Duration?>.error(error);
    return Future<Duration?>.value(null);
  }

  @override
  Future<void> play() async {
    _guion.llamadasPlay++;
  }

  @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();
  }
}