import { test, expect } from "bun:test";
import { mkdtemp, rm } from "node:fs/promises";
import { tmpdir } from "node:os";
import { join } from "node:path";
import { buildSong, loadSongDir } from "../../src/bench/dataset.ts";

test("buildSong writes all artefacts; loadSongDir reads them; stems sum to mix; idempotent", async () => {
  const root = await mkdtemp(join(tmpdir(), "stsheets-ds-"));
  try {
    const dir = await buildSong("t1a", 1, root);
    const files = ["song.json", "truth.gp", "mix.wav", "mix.mp3"];
    for (const f of files) expect(await Bun.file(join(dir, f)).exists()).toBe(true);
    const { song, truth, mix, stems } = await loadSongDir(dir);
    for (const t of song.tracks) expect(await Bun.file(join(dir, "stems", `${t.name}.wav`)).exists()).toBe(true);
    expect(truth.tracks[0]!.notes.length).toBe(song.tracks[0]!.notes.length);
    expect(mix.channels.length).toBe(2);

    // Oracle stems are the exact mix contributions: they sum to the mix (PCM16 rounding only).
    expect(stems.size).toBe(song.tracks.length);
    let maxDiff = 0;
    for (let c = 0; c < mix.channels.length; c++) {
      const m = mix.channels[c]!;
      for (let i = 0; i < m.length; i++) {
        let s = 0;
        for (const a of stems.values()) s += a.channels[c]![i] ?? 0;
        maxDiff = Math.max(maxDiff, Math.abs(s - m[i]!));
      }
    }
    expect(maxDiff).toBeLessThan(2e-3);

    const before = (await Bun.file(join(dir, "mix.mp3")).stat()).mtimeMs;
    expect(await buildSong("t1a", 1, root)).toBe(dir);
    expect((await Bun.file(join(dir, "mix.mp3")).stat()).mtimeMs).toBe(before);
  } finally {
    await rm(root, { recursive: true, force: true });
  }
}, 120_000);

test("multi-track t1b: stems on disk sum to mix.wav", async () => {
  const root = await mkdtemp(join(tmpdir(), "stsheets-ds-"));
  try {
    const dir = await buildSong("t1b", 1, root);
    expect(dir).toBe(join(root, "t1b", "1"));
    const { song, mix, stems } = await loadSongDir(dir);
    expect(song.tracks.length).toBeGreaterThan(1);
    expect(stems.size).toBe(song.tracks.length);
    let maxDiff = 0;
    for (let c = 0; c < mix.channels.length; c++) for (let i = 0; i < mix.channels[c]!.length; i++) {
      let s = 0;
      for (const a of stems.values()) s += a.channels[c]![i] ?? 0;
      maxDiff = Math.max(maxDiff, Math.abs(s - mix.channels[c]![i]!));
    }
    expect(maxDiff).toBeLessThan(2e-3);
  } finally {
    await rm(root, { recursive: true, force: true });
  }
}, 120_000);