// WebAudio synth of the AIM "buddy in / buddy out" door sounds. The real AIM
// samples are copyrighted, so these are originals built to evoke them: a wooden
// door CREAK (swept band-pass noise with stick-slip amplitude wobble) plus a
// low thunk/latch. Open = creak rising + soft settle; close = creak falling
// into a heavier slam. All generated on the fly — no audio files.

let ctx = null;
let master = null;
let noiseBuf = null;
let enabled = true;

export function setEnabled(on) { enabled = on; }
export function isEnabled() { return enabled; }

function ensure() {
  if (ctx) return ctx;
  const AC = window.AudioContext || window.webkitAudioContext;
  if (!AC) return null;
  ctx = new AC();
  master = ctx.createGain();
  master.gain.value = 0.9;
  master.connect(ctx.destination);
  // 1s of white noise to feed the creak filter.
  const len = ctx.sampleRate;
  noiseBuf = ctx.createBuffer(1, len, ctx.sampleRate);
  const d = noiseBuf.getChannelData(0);
  for (let i = 0; i < len; i++) d[i] = Math.random() * 2 - 1;
  return ctx;
}

// Must be called from a user gesture (the handle submit) to satisfy autoplay.
export function unlock() {
  ensure();
  if (ctx && ctx.state === 'suspended') ctx.resume();
}

// A creak: band-pass-filtered noise whose center frequency sweeps f0->f1, with a
// sawtooth LFO chewing the amplitude to give the dry stick-slip "rrrr" texture.
function creak(t0, dur, f0, f1, peak, lfoHz) {
  const src = ctx.createBufferSource();
  src.buffer = noiseBuf;
  src.loop = true;

  const bp = ctx.createBiquadFilter();
  bp.type = 'bandpass';
  bp.Q.value = 7;
  bp.frequency.setValueAtTime(f0, t0);
  bp.frequency.exponentialRampToValueAtTime(f1, t0 + dur);

  const env = ctx.createGain();
  env.gain.setValueAtTime(0.0001, t0);
  env.gain.exponentialRampToValueAtTime(peak, t0 + 0.035);
  env.gain.exponentialRampToValueAtTime(0.0001, t0 + dur);

  // stick-slip tremolo: LFO (-depth..+depth) summed onto a base gain.
  const trem = ctx.createGain();
  trem.gain.value = 0.55;
  const lfo = ctx.createOscillator();
  lfo.type = 'sawtooth';
  lfo.frequency.setValueAtTime(lfoHz, t0);
  lfo.frequency.linearRampToValueAtTime(lfoHz * 0.6, t0 + dur);
  const lfoDepth = ctx.createGain();
  lfoDepth.gain.value = 0.5;
  lfo.connect(lfoDepth).connect(trem.gain);

  src.connect(bp).connect(env).connect(trem).connect(master);
  src.start(t0); src.stop(t0 + dur + 0.05);
  lfo.start(t0); lfo.stop(t0 + dur + 0.05);
}

// A wooden thunk/latch: short pitched triangle blip that drops in pitch.
function thunk(t0, freq, dur, peak) {
  const o = ctx.createOscillator();
  o.type = 'triangle';
  o.frequency.setValueAtTime(freq * 1.5, t0);
  o.frequency.exponentialRampToValueAtTime(freq, t0 + dur);
  const g = ctx.createGain();
  g.gain.setValueAtTime(0.0001, t0);
  g.gain.exponentialRampToValueAtTime(peak, t0 + 0.008);
  g.gain.exponentialRampToValueAtTime(0.0001, t0 + dur);
  o.connect(g).connect(master);
  o.start(t0); o.stop(t0 + dur + 0.02);
}

// Door swings OPEN: a latch tick, a creak that rises, a soft settle.
export function doorOpen() {
  if (!enabled || !ensure()) return;
  const t = ctx.currentTime;
  thunk(t, 520, 0.04, 0.18);          // latch lifts
  creak(t + 0.02, 0.34, 300, 760, 0.5, 28); // hinge creak, rising
  thunk(t + 0.34, 130, 0.13, 0.3);    // door settles open
}

// Door clicks SHUT: a faster falling creak into a heavier low slam + latch.
export function doorClose() {
  if (!enabled || !ensure()) return;
  const t = ctx.currentTime;
  creak(t, 0.24, 720, 300, 0.45, 40); // hinge creak, falling
  thunk(t + 0.22, 95, 0.17, 0.55);    // the slam
  thunk(t + 0.33, 780, 0.04, 0.2);    // latch clicks
}