import { describe, expect, it } from 'vitest';
import {
  MAIN_PHRASE_BARS,
  MUSIC_BAR_SECONDS,
  INTRO_IN_END_SECONDS,
  SOUNDTRACK_SAMPLE_RATE,
  mainPhraseOffsetSeconds,
  nextSafeBarTime,
  resolveInitialPlayback,
} from '@/audio/soundtrack-transport';

describe('soundtrack transport decisions', () => {
  it('starts at the intro only on Start and otherwise chooses the matching main phrase', () => {
    expect(resolveInitialPlayback({
      atStart: true,
      bias: 'open',
      entryPhrase: 0,
      intensity: 0,
    })).toEqual({ kind: 'intro' });

    expect(resolveInitialPlayback({
      atStart: false,
      bias: 'shadow',
      entryPhrase: 3,
      intensity: 0.5,
    })).toEqual({ kind: 'main', offsetSeconds: mainPhraseOffsetSeconds(3) });

    expect(mainPhraseOffsetSeconds(Number.NaN)).toBe(0);
    const finalPhraseSample = Math.round(
      7 * MAIN_PHRASE_BARS * MUSIC_BAR_SECONDS * SOUNDTRACK_SAMPLE_RATE,
    );
    expect(mainPhraseOffsetSeconds(99)).toBe(finalPhraseSample / SOUNDTRACK_SAMPLE_RATE);
  });

  it('coalesces an exit onto the next bar with enough time for a clean crossfade', () => {
    const anchorTime = 1;
    const now = anchorTime + MUSIC_BAR_SECONDS * 2 + 0.1;
    const transitionTime = nextSafeBarTime(now, anchorTime, 0.25);

    expect(transitionTime).toBeCloseTo(anchorTime + MUSIC_BAR_SECONDS * 3, 8);
    expect(transitionTime).toBeGreaterThanOrEqual(now + 0.25);
    expect(nextSafeBarTime(anchorTime, anchorTime, 0)).toBe(anchorTime);

    const earliestIntroExit = nextSafeBarTime(
      anchorTime + INTRO_IN_END_SECONDS - 0.35,
      anchorTime,
      0.35,
    );
    expect(earliestIntroExit).toBeCloseTo(anchorTime + MUSIC_BAR_SECONDS * 2, 8);
  });
});