/**
 * The level meters of the Song tab (#359): the dB scale, how a level and its peak rise and fall, and
 * the clip lamp that stays lit.
 */
import { describe, expect, it } from 'vitest';
import {
  gainToDb,
  hushMeter,
  METER_FALL,
  meterClipped,
  meterShare,
  meterZone,
  PEAK_HOLD,
  peakText,
  QUIET_METER,
  QUIET_SIDE,
  stepMeter,
  stepSide,
} from '../../src/editor/song/meterView';

describe('meter scale', () => {
  it('runs from -48 to +6 dBFS, full scale at 0 dB', () => {
    expect(gainToDb(1)).toBe(0);
    expect(gainToDb(0.5)).toBeCloseTo(-6.02, 2);
    expect(gainToDb(0)).toBe(-Infinity);
    expect(meterShare(-48)).toBe(0);
    expect(meterShare(-Infinity)).toBe(0);
    expect(meterShare(6)).toBe(1);
    expect(meterShare(0)).toBeCloseTo(48 / 54, 6);
  });

  it('is green, yellow from -6 dB and red past 0 dB', () => {
    expect(meterZone(-6.1)).toBe('ok');
    expect(meterZone(-6)).toBe('warm');
    expect(meterZone(0)).toBe('warm');
    expect(meterZone(0.1)).toBe('hot');
  });

  it('writes a peak to a tenth of a dB', () => {
    expect(peakText(-Infinity)).toBe('-inf');
    expect(peakText(-3.24)).toBe('-3.2');
    expect(peakText(1.46)).toBe('+1.5');
    expect(peakText(-0.01)).toBe('0.0');
  });
});

describe('a side of a meter', () => {
  it('jumps up at once and falls back slowly', () => {
    const up = stepSide(QUIET_SIDE, 1, 0, 0.016);
    expect(up.level).toBe(0);
    const later = stepSide(up, 0, 0.5, 0.5);
    expect(later.level).toBeCloseTo(-METER_FALL * 0.5, 6);
    const louder = stepSide(later, 0.5, 0.516, 0.016);
    expect(louder.level).toBeCloseTo(-6.02, 2);
  });

  it('holds its peak, then lets it fall', () => {
    const hit = stepSide(QUIET_SIDE, 1, 10, 0.016);
    const held = stepSide(hit, 0.01, 10 + PEAK_HOLD - 0.1, 0.016);
    expect(held.peak).toBe(0);
    const falling = stepSide(held, 0.01, 10 + PEAK_HOLD + 0.1, 0.2);
    expect(falling.peak).toBeCloseTo(-METER_FALL * 0.2, 6);
    const gone = stepSide(falling, 0, 20, 3);
    expect(gone.peak).toBe(-Infinity);
    expect(gone.level).toBe(-Infinity);
  });

  it('lights the clip lamp past full scale and keeps it lit', () => {
    expect(stepSide(QUIET_SIDE, 1, 0, 0).clipped).toBe(false);
    const clipped = stepSide(QUIET_SIDE, 1.01, 0, 0);
    expect(clipped.clipped).toBe(true);
    expect(stepSide(clipped, 0, 30, 30).clipped).toBe(true);
  });

  it('keeps the two sides apart: a sound panned hard clips one side only', () => {
    const meter = stepMeter(QUIET_METER, [2, 0], 0, 0);
    expect(meter[0].clipped).toBe(true);
    expect(meter[1].clipped).toBe(false);
    expect(meter[0].level).toBeCloseTo(6.02, 2);
    expect(meter[1].level).toBe(-Infinity);
    expect(meterClipped(meter)).toBe(true);
  });

  it('goes dark when nothing plays, its clip lamp still lit', () => {
    const hushed = hushMeter(stepMeter(QUIET_METER, [2, 0.5], 0, 0));
    expect(hushed.map((side) => [side.level, side.peak])).toEqual([
      [-Infinity, -Infinity],
      [-Infinity, -Infinity],
    ]);
    expect(hushed.map((side) => side.clipped)).toEqual([true, false]);
  });
});