// 16-bit PCM mono WAV encoder.

export function encodeWav(samples: Float32Array, fs: number, peak = 0.99): Blob {
  let max = 0;
  for (let k = 0; k < samples.length; k++) max = Math.max(max, Math.abs(samples[k]));
  const gain = max > 0 ? peak / max : 0;
  const buf = new ArrayBuffer(44 + samples.length * 2);
  const v = new DataView(buf);
  const str = (o: number, s: string) => { for (let k = 0; k < s.length; k++) v.setUint8(o + k, s.charCodeAt(k)); };
  str(0, "RIFF");
  v.setUint32(4, 36 + samples.length * 2, true);
  str(8, "WAVE");
  str(12, "fmt ");
  v.setUint32(16, 16, true);
  v.setUint16(20, 1, true);
  v.setUint16(22, 1, true);
  v.setUint32(24, fs, true);
  v.setUint32(28, fs * 2, true);
  v.setUint16(32, 2, true);
  v.setUint16(34, 16, true);
  str(36, "data");
  v.setUint32(40, samples.length * 2, true);
  for (let k = 0; k < samples.length; k++) {
    const s = Math.max(-1, Math.min(1, samples[k] * gain));
    v.setInt16(44 + 2 * k, Math.round(s * 32767), true);
  }
  return new Blob([buf], { type: "audio/wav" });
}