/**
 * Turn a pressure signal into something Web Audio can play. Peak normalization
 * is a playback convenience (the absolute level of the Rayleigh estimate is not
 * calibrated anyway) and is reported so the interface can say so.
 */
export interface AudioPrep {
  samples: Float32Array;
  fs: number;
  /** Peak of the original signal [Pa] */
  peakPa: number;
  /** Gain applied so the peak sits at `target` */
  gain: number;
  durationS: number;
}

export function prepareAudio(p: Float64Array, fs: number, target = 0.8): AudioPrep {
  let peak = 0;
  for (let i = 0; i < p.length; i++) {
    const a = Math.abs(p[i]);
    if (a > peak) peak = a;
  }
  const gain = peak > 0 ? target / peak : 1;
  const samples = new Float32Array(p.length);
  for (let i = 0; i < p.length; i++) samples[i] = Number.isFinite(p[i]) ? p[i] * gain : 0;
  return { samples, fs, peakPa: peak, gain, durationS: p.length / fs };
}

export function toAudioBuffer(ctx: BaseAudioContext, prep: AudioPrep): AudioBuffer {
  const n = Math.max(1, prep.samples.length);
  const buf = ctx.createBuffer(1, n, prep.fs);
  const data = (prep.samples.length ? prep.samples : new Float32Array(1)) as Float32Array<ArrayBuffer>;
  buf.copyToChannel(data, 0);
  return buf;
}