import 'package:flutter_test/flutter_test.dart';
import 'package:just_audio/just_audio.dart' show PlayerState, ProcessingState;
import 'package:pluriwave/servicios/servicio_audio.dart';

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

/// eq-estado-unico — the equalizer's on/off flag gets a SINGLE owner.
///
/// Reported bug: «alguna emisora parece que esta con la ecualizacion activada
/// (suena muy alto) pero con el boton desactivado», and «pulsando sobre el
/// boton de ecualizar en Android Auto tampoco activaba ni desactivaba».
///
/// The flag used to live in three independent copies — the handler's
/// hardcoded `_ecualizadorActivo = true`, `EstadoEcualizador._activo`, and
/// SharedPreferences — and the persisted value only ever reached the handler
/// through `EstadoEcualizador.cargarPersistido()`, which a headless Android
/// Auto engine (no Activity, no Provider tree, no `EstadoRadio._init`) never
/// runs. So in the car the handler played with the equalizer forced ON while
/// disk and the phone UI both said OFF.
///
/// NOTE on testability: the long-standing comment in `servicio_audio.dart`
/// claiming `PluriWaveAudioHandler` "cannot be instantiated in a unit test
/// (a real just_audio.AudioPlayer needs platform MethodChannels)" is WRONG
/// as of just_audio 0.9.46 — `AudioPlayer`'s constructor resolves its
/// platform lazily and never becomes active without a `setUrl`, so the
/// handler constructs fine here and every EQ path that does not touch the
/// native effect is directly exercisable. That is what the dispatch tests
/// below rely on; only the native `setEnabled`/`setGain` calls stay out of
/// reach (they sit behind `_eqDisponible`, which is `false` off-device).
void main() {
  TestWidgetsFlutterBinding.ensureInitialized();

  final crearHandler = registrarHandlersLiberables();

  group('estadoEqInicial (A — seed the handler from disk on every engine)', () {
    test('adopts the persisted value when there is one', () {
      expect(estadoEqInicial(persistido: false), isFalse);
      expect(estadoEqInicial(persistido: true), isTrue);
    });

    test('defaults to ON only when nothing was ever persisted', () {
      expect(
        estadoEqInicial(persistido: null),
        isTrue,
        reason: 'a first install keeps the historical default (EQ on)',
      );
    });
  });

  group('registrarHandler (A — seeding)', () {
    test('consults the injected read port exactly once and seeds the handler '
        'with the persisted value', () async {
      final handler = crearHandler();
      var lecturas = 0;

      registrarHandler(
        handler,
        leerEqActivoPersistido: () async {
          lecturas++;
          return false;
        },
      );
      await Future<void>.delayed(Duration.zero);

      expect(lecturas, 1, reason: 'exactly one disk read per engine start');
      expect(
        handler.ecualizadorActivo,
        isFalse,
        reason: 'the handler must adopt what the phone UI persisted',
      );
    });

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

      registrarHandler(
        handler,
        leerEqActivoPersistido: () async => throw StateError('sin disco'),
      );
      await Future<void>.delayed(Duration.zero);

      expect(handler.ecualizadorActivo, isTrue);
    });

    test('without a read port the handler is left untouched (widget tests, '
        'fakes)', () async {
      final handler = crearHandler();
      await handler.setEcualizadorActivo(false);

      registrarHandler(handler);
      await Future<void>.delayed(Duration.zero);

      expect(handler.ecualizadorActivo, isFalse);
    });
  });

  /// A, CONSTRUCTION-WINDOW half. `_eqActivoPersistido` (the module-level
  /// cache behind `_ecualizadorActivo = estadoEqInicial(persistido: ...)`)
  /// had zero coverage on BOTH sides: replacing that initialiser with the old
  /// hardcoded `= true` left the suite green, and so did deleting the
  /// `_eqActivoPersistido = activo` write in `_aplicarEcualizadorActivo`.
  ///
  /// The window it closes is real: `AudioService.init` builds the handler
  /// through its `builder` callback and only AFTER that future resolves does
  /// `main.dart` reach `registrarHandler`. A car tap landing inside that
  /// window would otherwise hit a handler whose flag had never seen disk.
  group('A (construction window) — a handler built after a disk read', () {
    test('a handler constructed AFTER a read port has already answered '
        'starts from the persisted value, not from a hardcoded default',
        () async {
      // One engine does the read `registrarHandler` performs in main.dart.
      final primero = crearHandler();

      // Pin the module cache to the OPPOSITE value first. Without this the
      // test passes for the wrong reason: whatever ran before may already
      // have left the cache on `false`, so deleting the disk→cache write in
      // `_sembrarEcualizadorDesdeDisco` would still leave this green. Seeding
      // does NOT write the cache (`_aplicarEcualizadorActivo` returns before
      // it when `persistir: false`), so after this pin that write is the only
      // path that can bring the cache back down to `false`.
      await primero.setEcualizadorActivo(true);

      registrarHandler(primero, leerEqActivoPersistido: () async => false);
      await Future<void>.delayed(Duration.zero);
      expect(primero.ecualizadorActivo, isFalse);

      // Now the construction window: a handler built by `AudioService.init`'s
      // builder, with no port of its own yet.
      final segundo = crearHandler();

      expect(
        segundo.ecualizadorActivo,
        isFalse,
        reason:
            'a car tap landing before registrarHandler must not find the '
            'equalizer forced on while disk says off',
      );
    });

    test('the cache follows what the handler itself writes, in both '
        'directions', () async {
      final handler = crearHandler();
      registrarHandler(handler);

      await handler.setEcualizadorActivo(false);
      expect(
        crearHandler().ecualizadorActivo,
        isFalse,
        reason:
            'the write side of the cache: a toggle must be visible to the '
            'next handler built on this engine',
      );

      await handler.setEcualizadorActivo(true);
      expect(crearHandler().ecualizadorActivo, isTrue);
    });
  });

  group('B — the handler persists its OWN toggle', () {
    test('an eq toggle writes through the injected port even with no '
        'EstadoEcualizador in play', () async {
      final handler = crearHandler();
      final escrituras = <bool>[];

      registrarHandler(
        handler,
        guardarEqActivoPersistido: (activo) async => escrituras.add(activo),
      );

      await handler.setEcualizadorActivo(false);
      await handler.setEcualizadorActivo(true);

      expect(
        escrituras,
        [false, true],
        reason:
            'a car/notification toggle must survive a process restart '
            'without any UI object existing',
      );
    });

    test('seeding from disk does NOT write back to disk', () async {
      final handler = crearHandler();
      final escrituras = <bool>[];

      registrarHandler(
        handler,
        leerEqActivoPersistido: () async => false,
        guardarEqActivoPersistido: (activo) async => escrituras.add(activo),
      );
      await Future<void>.delayed(Duration.zero);

      expect(handler.ecualizadorActivo, isFalse);
      expect(escrituras, isEmpty);
    });

    test('a failing write port never breaks the toggle', () async {
      final handler = crearHandler();

      registrarHandler(
        handler,
        guardarEqActivoPersistido: (_) async => throw StateError('disco lleno'),
      );

      await handler.setEcualizadorActivo(false);

      expect(handler.ecualizadorActivo, isFalse);
    });
  });

  group('decidirToggleEq (C — the customAction decision)', () {
    test('flips the current value', () {
      expect(
        decidirToggleEq(activoActual: true, eqDisponible: true).nuevoActivo,
        isFalse,
      );
      expect(
        decidirToggleEq(activoActual: false, eqDisponible: true).nuevoActivo,
        isTrue,
      );
    });

    test('a native call is required only when the effect is attached', () {
      expect(
        decidirToggleEq(
          activoActual: true,
          eqDisponible: true,
        ).requiereLlamadaNativa,
        isTrue,
      );
      expect(
        decidirToggleEq(
          activoActual: true,
          eqDisponible: false,
        ).requiereLlamadaNativa,
        isFalse,
        reason:
            'with no native Equalizer effect the flag still flips, but '
            'nothing is pushed to the platform',
      );
    });

    test('the flag still flips with no native effect — the car button must '
        'never look inert', () {
      expect(
        decidirToggleEq(activoActual: false, eqDisponible: false).nuevoActivo,
        isTrue,
      );
    });
  });

  group('customAction dispatch (C — zero coverage before this)', () {
    test('the accionEqToggle literal routes through decidirToggleEq', () async {
      final handler = crearHandler();
      registrarHandler(handler);
      await handler.setEcualizadorActivo(true);

      await handler.customAction(accionEqToggle);
      expect(handler.ecualizadorActivo, isFalse);

      await handler.customAction(accionEqToggle);
      expect(handler.ecualizadorActivo, isTrue);
    });

    test('a car toggle persists through the same write port as a phone '
        'toggle', () async {
      final handler = crearHandler();
      final escrituras = <bool>[];
      registrarHandler(
        handler,
        guardarEqActivoPersistido: (activo) async => escrituras.add(activo),
      );
      // Explicit starting state. A fresh handler seeds `_ecualizadorActivo`
      // from the module-level `_eqActivoPersistido` cache, which any earlier
      // test in this file leaves at whatever it last wrote. This assertion
      // is about what the TOGGLE does, not about what the previous test
      // happened to leave behind — without these two lines, simply
      // reordering the tests silently flips the expectation to `[true]`.
      await handler.setEcualizadorActivo(true);
      escrituras.clear();

      await handler.customAction(accionEqToggle);

      expect(escrituras, [false]);
    });

    test('an unknown custom action is a silent no-op', () async {
      final handler = crearHandler();
      registrarHandler(handler);
      final antes = handler.ecualizadorActivo;

      await handler.customAction('accion.inexistente');

      expect(handler.ecualizadorActivo, antes);
    });
  });

  group('debeReasertarEcualizadorNativo (D — re-assert on activation)', () {
    test('an idle -> active transition with the effect attached re-asserts', () {
      expect(
        PluriWaveAudioHandler.debeReasertarEcualizadorNativo(
          estado: ProcessingState.ready,
          reproductorActivoAntes: false,
          eqDisponible: true,
        ),
        isTrue,
        reason:
            "just_audio's AudioEffect.setEnabled only reaches the platform "
            'while the player is active, so a toggle made while stopped '
            'never landed natively',
      );
    });

    test('staying active does not re-assert on every event', () {
      expect(
        PluriWaveAudioHandler.debeReasertarEcualizadorNativo(
          estado: ProcessingState.ready,
          reproductorActivoAntes: true,
          eqDisponible: true,
        ),
        isFalse,
      );
    });

    test('going idle does not re-assert', () {
      expect(
        PluriWaveAudioHandler.debeReasertarEcualizadorNativo(
          estado: ProcessingState.idle,
          reproductorActivoAntes: true,
          eqDisponible: true,
        ),
        isFalse,
      );
    });

    test('no attached effect never re-asserts', () {
      expect(
        PluriWaveAudioHandler.debeReasertarEcualizadorNativo(
          estado: ProcessingState.ready,
          reproductorActivoAntes: false,
          eqDisponible: false,
        ),
        isFalse,
      );
    });

    test('buffering/loading/completed already count as active', () {
      for (final estado in [
        ProcessingState.loading,
        ProcessingState.buffering,
        ProcessingState.completed,
      ]) {
        expect(
          PluriWaveAudioHandler.debeReasertarEcualizadorNativo(
            estado: estado,
            reproductorActivoAntes: false,
            eqDisponible: true,
          ),
          isTrue,
          reason:
              '$estado is a non-idle state, i.e. the platform player is '
              'attached and accepts effect calls',
        );
      }
    });
  });

  /// D, WIRING half. Everything above this group tests the pure
  /// [PluriWaveAudioHandler.debeReasertarEcualizadorNativo] predicate and
  /// nothing else: deleting the `playerStateStream` listener's whole re-assert
  /// block — the `if (debeReasertar...) unawaited(_reasertarEcualizadorNativo())`
  /// call, the `_reproductorActivo = proc != ProcessingState.idle` edge
  /// tracking — left the suite green. That is the SAME producer-only hole that
  /// let a dead Android Auto EQ button ship, so it gets closed here rather than
  /// re-tested at the predicate.
  ///
  /// [PluriWaveAudioHandler.manejarEstadoPlayer] IS the listener body — the
  /// same method `playerStateStream.listen` is subscribed to — so these
  /// drive the real handler through real player-state transitions.
  group('D (wiring) — the playerState idle -> active edge', () {
    PlayerState estado(ProcessingState proc, {bool playing = false}) =>
        PlayerState(playing, proc);

    test('the first non-idle event re-asserts the native effect exactly '
        'once, and staying active never re-asserts again', () async {
      final handler = crearHandler();
      registrarHandler(handler);
      handler.simularEcualizadorDisponible(true);

      expect(handler.reasercionesEcualizador, 0);

      handler.manejarEstadoPlayer(estado(ProcessingState.loading));
      expect(
        handler.reasercionesEcualizador,
        1,
        reason:
            "just_audio's AudioEffect.setEnabled is a no-op while the "
            'platform player is detached, so a toggle made while stopped '
            'only lands on this edge',
      );

      handler.manejarEstadoPlayer(estado(ProcessingState.buffering));
      handler.manejarEstadoPlayer(estado(ProcessingState.ready, playing: true));
      handler.manejarEstadoPlayer(estado(ProcessingState.completed));
      expect(
        handler.reasercionesEcualizador,
        1,
        reason:
            'the player emits many events while active; re-asserting on '
            'each one would be a native call storm',
      );
    });

    test('going idle re-arms the edge, so stop + play re-asserts again — '
        'this is the `_reproductorActivo = proc != idle` line', () async {
      final handler = crearHandler();
      registrarHandler(handler);
      handler.simularEcualizadorDisponible(true);

      handler.manejarEstadoPlayer(estado(ProcessingState.ready, playing: true));
      expect(handler.reasercionesEcualizador, 1);

      handler.manejarEstadoPlayer(estado(ProcessingState.idle));
      expect(
        handler.reasercionesEcualizador,
        1,
        reason: 'going idle itself never re-asserts',
      );

      handler.manejarEstadoPlayer(estado(ProcessingState.ready, playing: true));
      expect(
        handler.reasercionesEcualizador,
        2,
        reason:
            'without the edge-tracking assignment the flag would stay true '
            'and the toggle made while stopped would never land natively',
      );
    });

    test('with no native effect attached nothing is ever re-asserted', () async {
      final handler = crearHandler();
      registrarHandler(handler);
      // `_eqDisponible` is false off-device, which is also the real
      // "device has no Equalizer effect" case.

      handler.manejarEstadoPlayer(estado(ProcessingState.ready, playing: true));
      handler.manejarEstadoPlayer(estado(ProcessingState.idle));
      handler.manejarEstadoPlayer(estado(ProcessingState.ready, playing: true));

      expect(handler.reasercionesEcualizador, 0);
    });
  });

  group('F — the EQ re-push must not rewind the car progress bar', () {
    test('the EQ controls re-push refreshes updatePosition from the '
        'player', () async {
      final handler = crearHandler();
      registrarHandler(handler);
      handler.playbackState.add(
        handler.playbackState.value.copyWith(
          updatePosition: const Duration(minutes: 3),
        ),
      );

      await handler.setEcualizadorActivo(false);

      expect(
        handler.playbackState.value.updatePosition,
        handler.posicionActual,
        reason:
            'copyWith stamps a fresh updateTime but keeps the OLD '
            'updatePosition, so an EQ tap told the car "you are at 3:00, as '
            'of right now" and the bar snapped backwards',
      );
    });
  });
}