import { useEffect, useMemo, useRef, useState } from "react";
import { encodeWav, prepareAudio, toAudioBuffer } from "@plate-dyn/core";

export interface AudioPlayerProps {
  /** Pressure signal [Pa] */
  p: Float64Array;
  fs: number;
  /** Peak level of the export and the playback [dBFS]; default -1 */
  normalizeDbfs?: number;
  label?: string;
  /** Base name for the exported .wav file (no extension) */
  filename?: string;
}

/**
 * Plays the radiated-pressure estimate once, exactly as long as it is, and
 * offers the same clip as a 24-bit mono WAV download, peak-normalized as the
 * reference simulators write theirs. The displayed peak in pascals is not
 * normalized.
 */
export function AudioPlayer({
  p,
  fs,
  normalizeDbfs = -1,
  label,
  filename = "plate-sound",
}: AudioPlayerProps) {
  const prep = useMemo(
    () => prepareAudio(p, fs, 10 ** (normalizeDbfs / 20)),
    [p, fs, normalizeDbfs],
  );
  const ctxRef = useRef<AudioContext | null>(null);
  const srcRef = useRef<AudioBufferSourceNode | null>(null);
  const [playing, setPlaying] = useState(false);
  useEffect(() => () => stop(), []);

  const stop = () => {
    srcRef.current?.stop();
    srcRef.current = null;
    setPlaying(false);
  };
  const play = () => {
    if (!ctxRef.current) ctxRef.current = new AudioContext();
    const ctx = ctxRef.current;
    void ctx.resume();
    stop();
    const src = ctx.createBufferSource();
    src.buffer = toAudioBuffer(ctx, prep);
    src.connect(ctx.destination);
    src.start();
    src.onended = () => setPlaying(false);
    srcRef.current = src;
    setPlaying(true);
  };
  const download = () => {
    const blob = new Blob([encodeWav(prep.samples, Math.round(prep.fs), 24) as BlobPart], {
      type: "audio/wav",
    });
    const url = URL.createObjectURL(blob);
    const a = document.createElement("a");
    a.href = url;
    a.download = `${filename}.wav`;
    a.click();
    setTimeout(() => URL.revokeObjectURL(url), 0);
  };

  return (
    <div className="pl-row pl-small">
      <button className="pl-btn" onClick={playing ? stop : play} disabled={p.length < 2}>
        {playing ? "Stop" : `Play${label ? ` ${label}` : ""}`}
      </button>
      <button
        className="pl-btn"
        onClick={download}
        disabled={p.length < 2}
        title="Download as a 24-bit mono WAV file at the simulation's sample rate"
      >
        Save .wav
      </button>
      <span className="pl-muted">
        {prep.durationS.toFixed(2)} s at {fs} Hz, peak {prep.peakPa.toExponential(2)} Pa; normalized
        to {normalizeDbfs} dBFS for playback and export
      </span>
    </div>
  );
}