import test from "node:test";
import assert from "node:assert/strict";
import { Stft, fft } from "../src/analysis/spectrogram.ts";
import { encodeWav, scaleForPlayback } from "../src/audio/player.ts";

test("FFT of a sine peaks at the right bin", () => {
  const n = 1024, re = new Float32Array(n), im = new Float32Array(n);
  for (let i = 0; i < n; i++) re[i] = Math.sin((2 * Math.PI * 64 * i) / n);
  fft(re, im);
  let best = 0;
  for (let b = 1; b < n / 2; b++) if (Math.hypot(re[b], im[b]) > Math.hypot(re[best], im[best])) best = b;
  assert.equal(best, 64);
  assert.ok(Math.abs(Math.hypot(re[64], im[64]) - n / 2) < 1e-2);
});

test("incremental STFT tracks a chirp's centroid", () => {
  const fs = 44100, st = new Stft(fs, 1024, 256);
  const sig = new Float32Array(fs);
  for (let i = 0; i < fs; i++) { const t = i / fs; sig[i] = Math.sin(2 * Math.PI * (500 * t + 2000 * t * t)); }
  let cols = 0;
  for (let s = 0; s < fs; s += 1000) cols += st.push(sig.subarray(s, Math.min(fs, s + 1000)));
  assert.equal(cols, st.columns.length);
  assert.ok(cols > 150);
  const early = st.centroid[5], late = st.centroid[cols - 5];
  assert.ok(early > 400 && early < 1200 && late > 3500 && late < 5500, `${early} ${late}`);
});

test("WAV encoding and playback scaling", () => {
  const p = new Float32Array([0, 2, -4, 1]);
  const s = scaleForPlayback(p, true);
  assert.ok(Math.abs(Math.max(...Array.from(s).map(Math.abs)) - 0.9) < 1e-6);
  const blob = encodeWav(s, 44100);
  assert.equal(blob.size, 44 + 8);
});