import 'package:flutter_test/flutter_test.dart';
import 'package:pluriwave/servicios/servicio_audio.dart';

/// EQ audio-focus re-apply — pure decision predicate truth table.
///
/// Covers spec "EQ Audio-Focus Re-Apply Specification": whenever
/// `androidAudioSessionIdStream` emits a new native session id mid-playback
/// (audio-focus ducking by another app), the equalizer must be re-attached
/// and the current preset's gains re-pushed, gated on EQ availability so it
/// never races `_recrearPlayer()`'s teardown/rebuild.
///
/// [PluriWaveAudioHandler] cannot be instantiated in unit tests — its
/// constructor builds a real `just_audio.AudioPlayer` that requires platform
/// MethodChannels (confirmed by `servicio_audio_source_switch_test.dart`, "We
/// cannot instantiate the handler in unit tests"). The only unit-testable
/// surface is the pure, side-effect-free static predicate
/// `debeReaplicarEcualizador`, extracted per the design's "Interfaces /
/// Contracts" section. Listener wiring and the actual native re-attach are
/// covered by manual on-device QA (spec's Testability Matrix), not here.
void main() {
  group('debeReaplicarEcualizador (EQ audio-focus re-apply predicate)', () {
    test('rotation while playing returns true', () {
      // Spec: Requirement "Session Id Rotation Triggers EQ Re-Apply" /
      // Scenario "Session id rotates while playing".
      expect(
        PluriWaveAudioHandler.debeReaplicarEcualizador(
          sessionId: 2,
          ultimaSessionIdEq: 1,
          eqDisponible: true,
        ),
        isTrue,
        reason: 'a genuine id rotation with EQ available must re-apply',
      );
    });

    test('same id re-emitted returns false', () {
      // Spec: Scenario "Same id re-emitted produces no redundant re-apply".
      expect(
        PluriWaveAudioHandler.debeReaplicarEcualizador(
          sessionId: 1,
          ultimaSessionIdEq: 1,
          eqDisponible: true,
        ),
        isFalse,
        reason: 'a duplicate emission of the already-processed id is a no-op',
      );
    });

    test('first activation / matching guard returns false', () {
      // Spec: Scenario "First legitimate activation is not double-applied".
      // Same shape as the duplicate-id case above, kept as a distinct named
      // case per design's testing table to document intent: this represents
      // the id emitted right after a station switch already set the guard
      // (via _activarEcualizador() at the station-switch call site), not
      // just an arbitrary repeated emission.
      expect(
        PluriWaveAudioHandler.debeReaplicarEcualizador(
          sessionId: 1,
          ultimaSessionIdEq: 1,
          eqDisponible: true,
        ),
        isFalse,
        reason:
            'the first post-station-switch emission must not double-apply '
            'on top of the station-switch path\'s own _activarEcualizador()',
      );
    });

    test('null id returns false', () {
      // Spec: Requirement "Session Id Rotation Triggers EQ Re-Apply"
      // (non-null precondition).
      expect(
        PluriWaveAudioHandler.debeReaplicarEcualizador(
          sessionId: null,
          ultimaSessionIdEq: 1,
          eqDisponible: true,
        ),
        isFalse,
        reason: 'a null session id must never trigger a re-apply',
      );
    });

    test('teardown gate returns false', () {
      // Spec: Requirement "Re-Apply Is Gated On EQ Availability" / Scenario
      // "Rotation during player teardown is safely skipped".
      expect(
        PluriWaveAudioHandler.debeReaplicarEcualizador(
          sessionId: 9,
          ultimaSessionIdEq: 1,
          eqDisponible: false,
        ),
        isFalse,
        reason:
            'while _eqDisponible is false (mid _recrearPlayer teardown), '
            're-apply must be skipped entirely to avoid racing the rebuild',
      );
    });
  });
}