// Mono 16-bit PCM WAV encoder.

/** Encodes the signal as a 16-bit PCM mono WAV file; samples are clamped to [-1, 1]. */
export function encodeWav(samples: Float32Array, fs: number): Blob {
  const n = samples.length;
  const dataBytes = n * 2;
  const buf = new ArrayBuffer(44 + dataBytes);
  const v = new DataView(buf);
  const ascii = (offset: number, s: string): void => {
    for (let k = 0; k < s.length; k++) v.setUint8(offset + k, s.charCodeAt(k));
  };
  const rate = Math.round(fs);
  ascii(0, "RIFF");
  v.setUint32(4, 36 + dataBytes, true);
  ascii(8, "WAVE");
  ascii(12, "fmt ");
  v.setUint32(16, 16, true); // fmt chunk size
  v.setUint16(20, 1, true); // PCM
  v.setUint16(22, 1, true); // channels
  v.setUint32(24, rate, true);
  v.setUint32(28, rate * 2, true); // byte rate
  v.setUint16(32, 2, true); // block align
  v.setUint16(34, 16, true); // bits per sample
  ascii(36, "data");
  v.setUint32(40, dataBytes, true);
  for (let k = 0; k < n; k++) {
    const x = samples[k];
    const s = x > 1 ? 1 : x < -1 ? -1 : x !== x ? 0 : x;
    v.setInt16(44 + 2 * k, Math.round(s * 32767), true);
  }
  return new Blob([buf], { type: "audio/wav" });
}