// Deterministic node-side tests: MIDI round trip, tempo math, editing
// ops, DSP determinism, and mixing rules. Run with: npm test

import assert from 'node:assert/strict';
import { TempoMap } from '../src/midi/time.ts';
import { parseMidi } from '../src/midi/parse.ts';
import { writeMidi } from '../src/midi/write.ts';
import { quantizeNotes, transposeNotes } from '../src/midi/ops.ts';
import { drumNote, epianoNote, leadNote, pluckNote } from '../src/instruments/dsp.ts';
import { builtinInstruments } from '../src/instruments/builtins.ts';
import { audibleTracks, encodeWavMono16, mixTracks, trackRenderKey } from '../src/audio/render.ts';
import type { Note, Song, Track } from '../src/types.ts';

let failed = 0;
let passed = 0;
function test(name: string, fn: () => void) {
  try {
    fn();
    passed++;
    console.log(`ok - ${name}`);
  } catch (err) {
    failed++;
    console.error(`FAIL - ${name}`);
    console.error(err);
  }
}

function close(a: number, b: number, tol = 1e-9) {
  assert.ok(Math.abs(a - b) <= tol, `${a} !~ ${b}`);
}

function hash(buf: Float32Array): number {
  let h = 0x811c9dc5;
  for (let i = 0; i < buf.length; i++) {
    h ^= Math.round(buf[i] * 1e6) & 0xffff;
    h = Math.imul(h, 0x01000193);
  }
  return h >>> 0;
}

function mkNote(tick: number, duration: number, pitch: number, velocity: number, id: string): Note {
  return { id, tick, duration, pitch, velocity };
}

function mkTrack(id: string, instrumentId: string, notes: Note[], extra: Partial<Track> = {}): Track {
  return { id, name: id, instrumentId, volume: 1, mute: false, solo: false, notes, ...extra };
}

// --- tempo map ---

test('tempo map: constant 120 bpm', () => {
  const tm = new TempoMap(480, [{ tick: 0, usPerQuarter: 500000 }]);
  close(tm.tickToSec(480), 0.5);
  close(tm.tickToSec(1920), 2);
  close(tm.secToTick(1), 960);
  close(tm.bpmAt(0), 120);
});

test('tempo map: tempo change mid-song', () => {
  const tm = new TempoMap(480, [
    { tick: 0, usPerQuarter: 500000 },
    { tick: 960, usPerQuarter: 250000 },
  ]);
  close(tm.tickToSec(960), 1);
  close(tm.tickToSec(1920), 1.5);
  close(tm.secToTick(1.25), 1440);
  close(tm.bpmAt(1000), 240);
});

test('tempo map: bar.beat display in 4/4 and 3/4', () => {
  const tm44 = new TempoMap(480, [], [{ tick: 0, numerator: 4, denominator: 4 }]);
  assert.deepEqual(tm44.barBeatAt(0), { bar: 1, beat: 1 });
  assert.deepEqual(tm44.barBeatAt(480 * 5), { bar: 2, beat: 2 });
  const tm34 = new TempoMap(480, [], [{ tick: 0, numerator: 3, denominator: 4 }]);
  assert.deepEqual(tm34.barBeatAt(480 * 3), { bar: 2, beat: 1 });
});

test('tempo map: grid lines mark bars', () => {
  const tm = new TempoMap(480, [], [{ tick: 0, numerator: 4, denominator: 4 }]);
  const lines = tm.gridLines(0, 1920);
  assert.equal(lines.length, 4);
  assert.deepEqual(lines[0], { tick: 0, isBar: true });
  assert.deepEqual(lines[1], { tick: 480, isBar: false });
});

// --- MIDI round trip ---

function sortedNotes(t: Track): [number, number, number, number][] {
  return t.notes
    .map((n) => [n.tick, n.duration, n.pitch, n.velocity] as [number, number, number, number])
    .sort((a, b) => a[0] - b[0] || a[2] - b[2]);
}

test('MIDI write/parse round trip preserves notes, tempo, and drums', () => {
  const song: Song = {
    ppq: 480,
    tempo: [
      { tick: 0, usPerQuarter: 500000 },
      { tick: 1920, usPerQuarter: 400000 },
    ],
    timeSig: [{ tick: 0, numerator: 3, denominator: 4 }],
    tracks: [
      mkTrack('melody', 'pluck', [
        mkNote(0, 480, 60, 100, 'a'),
        mkNote(480, 240, 64, 90, 'b'),
        mkNote(100000, 960, 72, 127, 'c'), // multi-byte delta times
        mkNote(480, 240, 67, 1, 'd'), // chord + min velocity
      ]),
      mkTrack('kit', 'drumkit', [
        mkNote(0, 120, 36, 110, 'e'),
        mkNote(480, 120, 38, 80, 'f'),
      ]),
    ],
  };
  const bytes = writeMidi(song);
  const back = parseMidi(bytes);
  assert.equal(back.ppq, 480);
  assert.equal(back.tracks.length, 2);
  assert.deepEqual(sortedNotes(back.tracks[0]), sortedNotes(song.tracks[0]));
  assert.deepEqual(sortedNotes(back.tracks[1]), sortedNotes(song.tracks[1]));
  assert.equal(back.tracks[0].name, 'melody');
  assert.equal(back.tracks[1].instrumentId, 'drumkit'); // came back on channel 10
  assert.equal(back.tracks[0].instrumentId, 'pluck');
  assert.deepEqual(back.tempo, song.tempo);
  assert.equal(back.timeSig[0].numerator, 3);
  assert.equal(back.timeSig[0].denominator, 4);
});

test('parse splits a multi-channel track by channel', () => {
  const song: Song = {
    ppq: 480,
    tempo: [{ tick: 0, usPerQuarter: 500000 }],
    timeSig: [{ tick: 0, numerator: 4, denominator: 4 }],
    tracks: [
      mkTrack('a', 'pluck', [mkNote(0, 480, 60, 100, 'a')]),
      mkTrack('b', 'drumkit', [mkNote(0, 120, 42, 100, 'b')]),
    ],
  };
  // write produces separate MTrks; merging them into one channel-mixed
  // stream is what a format 0 file would look like, so parse the format 1
  // bytes and just confirm channels landed apart.
  const back = parseMidi(writeMidi(song));
  assert.equal(back.tracks.length, 2);
  assert.equal(back.tracks[1].instrumentId, 'drumkit');
});

// --- editing ops ---

test('quantize rounds note starts to the grid', () => {
  const notes = [mkNote(130, 100, 60, 100, 'a'), mkNote(59, 100, 61, 100, 'b')];
  const q = quantizeNotes(notes, 120);
  assert.equal(q[0].tick, 120);
  assert.equal(q[1].tick, 0); // 59 rounds down to the grid origin
  const onlyA = quantizeNotes(notes, 120, new Set(['a']));
  assert.equal(onlyA[0].tick, 120);
  assert.equal(onlyA[1].tick, 59);
});

test('transpose clamps to the MIDI range', () => {
  const notes = [mkNote(0, 100, 126, 100, 'a')];
  assert.equal(transposeNotes(notes, 12)[0].pitch, 127);
  assert.equal(transposeNotes(notes, -300)[0].pitch, 0);
});

// --- DSP ---

test('DSP is deterministic and finite', () => {
  for (const [name, fn] of [
    ['pluck', pluckNote],
    ['epiano', epianoNote],
    ['lead', leadNote],
    ['drum', drumNote],
  ] as const) {
    const a = fn(44100, name === 'drum' ? 38 : 60, 0.8, 0.4);
    const b = fn(44100, name === 'drum' ? 38 : 60, 0.8, 0.4);
    assert.equal(hash(a), hash(b), `${name} not deterministic`);
    assert.ok(a.length > 1000, `${name} too short`);
    let peak = 0;
    for (let i = 0; i < a.length; i++) {
      assert.ok(Number.isFinite(a[i]), `${name} produced non-finite sample`);
      peak = Math.max(peak, Math.abs(a[i]));
    }
    assert.ok(peak > 0.01, `${name} is silent`);
    assert.ok(peak <= 1.5, `${name} peak too hot: ${peak}`);
  }
});

test('builtin instrument render places notes at the right time', () => {
  const pluck = builtinInstruments.find((i) => i.id === 'pluck')!;
  const sr = 44100;
  const out = pluck.render({
    notes: [{ timeSec: 1, durationSec: 0.25, pitch: 69, velocity: 0.8 }],
    sampleRate: sr,
    lengthSamples: sr * 3,
  }) as Float32Array;
  assert.equal(out.length, sr * 3);
  let before = 0;
  for (let i = 0; i < sr - 10; i++) before = Math.max(before, Math.abs(out[i]));
  let after = 0;
  for (let i = sr; i < sr * 2; i++) after = Math.max(after, Math.abs(out[i]));
  assert.equal(before, 0);
  assert.ok(after > 0.01);
});

// --- mixing ---

test('mute and solo select audible tracks', () => {
  const a = mkTrack('a', 'pluck', []);
  const b = mkTrack('b', 'pluck', [], { mute: true });
  const c = mkTrack('c', 'pluck', []);
  assert.deepEqual([...audibleTracks([a, b, c])].sort(), ['a', 'c']);
  const cSolo = { ...c, solo: true };
  assert.deepEqual([...audibleTracks([a, b, cSolo])], ['c']);
});

test('mixTracks applies volume and excludes muted tracks', () => {
  const a = mkTrack('a', 'pluck', [], { volume: 0.5 });
  const b = mkTrack('b', 'pluck', [], { mute: true });
  const buffers = new Map<string, Float32Array>([
    ['a', new Float32Array([0.4, 0.4])],
    ['b', new Float32Array([0.9, 0.9])],
  ]);
  const mix = mixTracks([a, b], buffers);
  close(mix[0], 0.2, 1e-6);
});

test('trackRenderKey changes when the notes change', () => {
  const song: Song = {
    ppq: 480,
    tempo: [{ tick: 0, usPerQuarter: 500000 }],
    timeSig: [{ tick: 0, numerator: 4, denominator: 4 }],
    tracks: [],
  };
  const t1 = mkTrack('a', 'pluck', [mkNote(0, 480, 60, 100, 'a')]);
  const t2 = mkTrack('a', 'pluck', [mkNote(0, 480, 61, 100, 'a')]);
  const t3 = mkTrack('a', 'epiano', [mkNote(0, 480, 60, 100, 'a')]);
  assert.equal(trackRenderKey(song, t1), trackRenderKey(song, mkTrack('a', 'pluck', [mkNote(0, 480, 60, 100, 'zzz')])));
  assert.notEqual(trackRenderKey(song, t1), trackRenderKey(song, t2));
  assert.notEqual(trackRenderKey(song, t1), trackRenderKey(song, t3));
});

test('WAV encoding writes a well-formed header', () => {
  const wav = encodeWavMono16(new Float32Array([0, 0.5, -0.5, 2]), 44100);
  assert.equal(wav.length, 44 + 8);
  assert.equal(String.fromCharCode(...wav.subarray(0, 4)), 'RIFF');
  assert.equal(String.fromCharCode(...wav.subarray(8, 12)), 'WAVE');
  const dv = new DataView(wav.buffer);
  assert.equal(dv.getUint32(24, true), 44100);
  assert.equal(dv.getInt16(44 + 6, true), 32767); // clipped to full scale
});

console.log(`\n${passed} passed, ${failed} failed`);
process.exit(failed > 0 ? 1 : 0);