PROCITY/web/js/world/audio.js

// PROCITY Lane B — audio.js  (round 11, the audio round)
// The street-side WebAudio engine. ONE AudioContext, unlocked on the first user gesture (the
// pointer-lock click is the natural anchor). Looping beds crossfade off systems that already exist —
// day/night segment, weather, tram proximity, player footsteps — plus shop-door music **spill** and
// interaction SFX. Interior beds belong to Lane F (it calls playInterior/stopInterior with Lane C's
// room.audio contract); this engine just ducks the street while inside.
//
// HOUSE AUDIO LAW (obeyed throughout):
//   1. Silent-and-happy: missing/blocked/failed audio → silence, never an error or console warning.
//   2. Nothing plays before the first gesture; ?mute=1 forces silence; ?noassets=1 → zero fetches.
//   3. Deterministic flavour: what a shop spills is a pure function of its type (seeded upstream).
//   4. ≤25 MB, lazy-loaded; the per-frame update() path allocates nothing (only ramps gains).
//
// Self-contained: reads live state off window.PROCITY and self-ticks via rAF, so the shell only has
// to createAudioEngine(PROCITY) once. Exposes window.PROCITY.audio for Lane F's smokes.

const BASE = 'assets/';

// shop type → street-spill music key (manifest.music). Only these types leak a bed to the footpath;
// others are interior room-tone only. Matches manifest.music[*].types.
const SPILL_MUSIC = { record: 'record-shop', milkbar: 'milkbar', video: 'video-synth', arcade: 'arcade', dept: 'arcade', general: 'milkbar' };

export function createAudioEngine(PROCITY, { noassets = false, mute = false } = {}) {
  const params = new URLSearchParams(location.search);
  const forcedMute = mute || (params.get('mute') != null && params.get('mute') !== '0');
  const NOASSETS = noassets || PROCITY.noassets || (params.get('noassets') != null && params.get('noassets') !== '0');
  const AC = window.AudioContext || window.webkitAudioContext;

  const state = { ready: false, muted: !!forcedMute, unsupported: !AC, loaded: 0, mode: 'silent', nearestSpill: null };

  // Silent surface — still satisfies the public API so F's smokes pass with zero sound.
  if (!AC || forcedMute) {
    state.mode = forcedMute ? 'muted' : 'unsupported';
    return {
      state, get ready() { return false; }, get muted() { return true; },
      setMasterGain() {}, mute() { state.muted = true; }, unmute() {},
      playSfx() {}, footstep() {}, playInterior() {}, stopInterior() {},
      update() {}, dispose() {},
    };
  }

  let ctx, master, buses;
  try {
    ctx = new AC();
    master = ctx.createGain(); master.gain.value = 0.9; master.connect(ctx.destination);
    buses = { ambience: mk(0.5), music: mk(0.7), sfx: mk(0.95), tram: mk(0.7) };
    for (const b of Object.values(buses)) b.connect(master);
  } catch { state.mode = 'ctx-failed'; return { state, get ready() { return false; }, get muted() { return true; }, setMasterGain() {}, mute() {}, unmute() {}, playSfx() {}, footstep() {}, playInterior() {}, stopInterior() {}, update() {}, dispose() {} }; }
  state.mode = 'live';
  function mk(v) { const g = ctx.createGain(); g.gain.value = v; return g; }
  function ramp(param, to, sec) {
    const t = ctx.currentTime;
    param.cancelScheduledValues(t); param.setValueAtTime(param.value, t);
    param.linearRampToValueAtTime(to, t + Math.max(0.02, sec));
  }

  // ── manifest.audio (self-fetched once; honours ?noassets) ──
  // Retries a few times: the single-threaded dev server can drop a fetch during the boot burst, and a
  // one-shot failure would otherwise mute the town for the whole session. state.manifest is a diag.
  let AUDIO = null;
  const manifestReady = (async () => {
    if (NOASSETS) { state.manifest = 'skipped-noassets'; return null; }
    if (PROCITY.manifest?.audio) { AUDIO = PROCITY.manifest.audio; state.manifest = 'ok'; return AUDIO; }
    for (let attempt = 0; attempt < 3 && !AUDIO; attempt++) {
      try {
        const r = await fetch(BASE + 'manifest.json', { cache: 'force-cache' });
        if (r.ok) { AUDIO = (await r.json()).audio || null; }
      } catch { /* transient — back off and retry */ }
      if (!AUDIO) await new Promise((res) => setTimeout(res, 150 * (attempt + 1)));
    }
    state.manifest = AUDIO ? 'ok' : 'null-audio';   // silent-and-happy either way
    return AUDIO;
  })();

  // ── lazy buffer cache ──
  const buffers = new Map(); // key → AudioBuffer | 'loading' | 'failed'
  async function load(key, entry) {
    if (NOASSETS || !entry) return null;
    const cached = buffers.get(key);
    if (cached) return (cached === 'loading' || cached === 'failed') ? null : cached;
    buffers.set(key, 'loading');
    for (const url of [entry.file, entry.fallback]) {
      if (!url) continue;
      try {
        const res = await fetch(BASE + url);
        if (!res.ok) continue;
        const buf = await ctx.decodeAudioData(await res.arrayBuffer());
        buffers.set(key, buf); state.loaded++;
        return buf;
      } catch { /* try the fallback, else fall through to silence */ }
    }
    buffers.set(key, 'failed');   // house law: a missing file is silence, not an error
    return null;
  }

  // ── layers ──
  // persistent bed: one looping source started once, gain-ramped (day/night/rain never change key).
  // swap bed: source is replaced when its key changes (spill / interior music+tone).
  function layer(bus) { const g = ctx.createGain(); g.gain.value = 0; g.connect(bus); return { g, src: null, key: null, starting: false }; }
  const L = {
    day: layer(buses.ambience), night: layer(buses.ambience), rain: layer(buses.ambience),
    spill: layer(buses.music), tram: layer(buses.tram),
    iMusic: layer(buses.music), iTone: layer(buses.ambience),
  };
  state.layers = L;

  async function persistBed(l, key, entry, target, fade = 1.4) {
    if (key && !l.src && !l.starting) {
      l.starting = true;
      const buf = await load(key, entry);
      if (buf) { const s = ctx.createBufferSource(); s.buffer = buf; s.loop = true; s.connect(l.g); s.start(); l.src = s; l.key = key; }
      l.starting = false;
    }
    ramp(l.g.gain, l.src ? target : 0, fade);
  }
  async function swapBed(l, key, entry, target, fade = 0.8) {
    if (l.key !== key) {
      if (l.src) { const old = l.src; l.src = null; try { old.stop(ctx.currentTime + 0.35); } catch {} }
      l.key = key;
      if (key && entry) {
        l.starting = true;
        const buf = await load('bed:' + key, entry);
        if (buf && l.key === key) { const s = ctx.createBufferSource(); s.buffer = buf; s.loop = true; s.connect(l.g); s.start(); l.src = s; }
        l.starting = false;
      }
    }
    ramp(l.g.gain, (l.key && l.src) ? target : 0, fade);
  }

  // ── one-shot SFX ──
  async function playSfx(key, { gain = 1 } = {}) {
    if (state.muted || NOASSETS || !state.ready) return;
    await manifestReady;
    const entry = AUDIO?.sfx?.[key]; if (!entry) return;
    const buf = await load('sfx:' + key, entry); if (!buf) return;
    fire(buf, (entry.gain ?? 0.7) * gain, buses.sfx);
  }
  async function footstep(surface = 'pavement') {
    if (state.muted || NOASSETS || !state.ready) return;
    await manifestReady;
    const arr = AUDIO?.sfx?.footstep?.[surface] || AUDIO?.sfx?.footstep?.pavement;
    if (!arr || !arr.length) return;
    const i = Math.floor(Math.random() * arr.length);   // transient variant — determinism law is about shop content, not step timing
    const buf = await load(`step:${surface}:${i}`, arr[i]); if (!buf) return;
    fire(buf, 0.5 + Math.random() * 0.15, buses.sfx);
  }
  function fire(buf, gain, bus) {
    const src = ctx.createBufferSource(); src.buffer = buf;
    const vg = ctx.createGain(); vg.gain.value = gain;
    src.connect(vg); vg.connect(bus); src.start();
    src.onended = () => { try { src.disconnect(); vg.disconnect(); } catch {} };
  }

  // ── interior beds (Lane F calls these with Lane C's room.audio = {musicKey, toneKey}) ──
  async function playInterior(spec) {
    if (state.muted || NOASSETS || !spec) return;
    await manifestReady;
    const mEntry = spec.musicKey && AUDIO?.music?.[spec.musicKey];
    const tEntry = spec.toneKey && AUDIO?.ambience?.[spec.toneKey];
    swapBed(L.iMusic, spec.musicKey || null, mEntry || null, mEntry?.gain ?? 0.5, 1.0);
    swapBed(L.iTone, spec.toneKey || null, tEntry || null, tEntry?.gain ?? 0.35, 1.0);
  }
  function stopInterior() { ramp(L.iMusic.g.gain, 0, 0.7); ramp(L.iTone.g.gain, 0, 0.7); }

  // ── unlock on first gesture (autoplay policy) ──
  function unlock() {
    if (state.ready || state.muted) return;
    ctx.resume().then(() => { state.ready = true; }).catch(() => {});
    window.removeEventListener('pointerdown', unlock, true);
    window.removeEventListener('keydown', unlock, true);
  }
  window.addEventListener('pointerdown', unlock, true);
  window.addEventListener('keydown', unlock, true);

  // ── enterShop → doorbell + door SFX (dispatched by the shell on a door click) ──
  const onEnter = () => { playSfx('door-open'); playSfx('doorbell', { gain: 0.9 }); };
  window.addEventListener('procity:enterShop', onEnter);

  // ── per-frame update (self-ticked; allocates nothing) ──
  const shopType = new Map();
  (PROCITY.plan?.shops || []).forEach((s) => shopType.set(s.id, s.type));
  const shopById = new Map();
  (PROCITY.plan?.shops || []).forEach((s) => shopById.set(s.id, s));
  const _cam = { x: 0, z: 0 };
  const v = { lx: null, lz: null, stepAcc: 0, spillT: 0, tramX: null, tramZ: null, tramRang: false };
  const STRIDE = 0.72, SPILL_R = 9, TRAM_R = 55, TRAM_BELL_R = 22;

  function update(dt) {
    if (!state.ready || state.muted) return;
    const P = PROCITY;
    const mode = P.mode || 'street';
    const street = mode === 'street';
    const cam = P.camera?.position; if (!cam) return;
    _cam.x = cam.x; _cam.z = cam.z;
    const clk = P.lighting?.getClock?.();
    const night = !!(clk && clk.night);

    // ── ambience day/night beds (street only; ducked to 0 in interior/map) ──
    const amb = AUDIO?.ambience;
    persistBed(L.day, 'street-day', amb?.['street-day'], street && !night ? (amb?.['street-day']?.gain ?? 0.5) : 0);
    persistBed(L.night, 'street-night', amb?.['street-night'], street && night ? (amb?.['street-night']?.gain ?? 0.5) : 0);

    // ── rain layer (gain follows weather intensity; only when it's actually raining) ──
    const w = P.weather || { state: 'clear', intensity: 0 };
    const rainT = (street && w.state === 'rain') ? (amb?.rain?.gain ?? 0.45) * Math.max(0.15, w.intensity) : 0;
    persistBed(L.rain, 'rain', amb?.rain, rainT);

    // ── footsteps (player movement on the street, while pointer-locked) ──
    if (street && P.player?.isLocked && v.lx != null) {
      const d = Math.hypot(_cam.x - v.lx, _cam.z - v.lz);
      if (d > 0.0005) {
        v.stepAcc += d;
        const stride = P.player.isRunning ? STRIDE * 1.15 : STRIDE;
        if (v.stepAcc >= stride) { v.stepAcc = 0; footstep('pavement'); }
      }
    } else { v.stepAcc = 0; }
    v.lx = _cam.x; v.lz = _cam.z;

    // ── shop-door music spill (throttled scan of nearby live doors) ──
    v.spillT -= dt;
    if (street && v.spillT <= 0) {
      v.spillT = 0.2;
      let bestKey = null, bestGain = 0, bestId = null;
      const doorMeshes = P.chunks?.getDoorMeshes?.() || [];
      for (let m = 0; m < doorMeshes.length; m++) {
        const rects = doorMeshes[m].userData?.doorRects; if (!rects) continue;
        for (let i = 0; i < rects.length; i++) {
          const r = rects[i];
          const dist = Math.hypot(r.x - _cam.x, r.z - _cam.z);
          if (dist > SPILL_R) continue;
          const key = SPILL_MUSIC[shopType.get(r.shopId)]; if (!key) continue;
          const shop = shopById.get(r.shopId);
          if (P.isOpen && shop && !P.isOpen(shop)) continue;   // only open shops spill (Lane F §3.5 hours)
          const g = (AUDIO?.music?.[key]?.gain ?? 0.5) * 0.5 * ((SPILL_R - dist) / SPILL_R);
          if (g > bestGain) { bestGain = g; bestKey = key; bestId = r.shopId; }
        }
      }
      state.nearestSpill = bestId;
      swapBed(L.spill, bestKey, bestKey ? AUDIO?.music?.[bestKey] : null, bestGain, 0.6);
    } else if (!street && L.spill.key) {
      ramp(L.spill.g.gain, 0, 0.4);
    }

    // ── tram rumble (distance-gain) + bell (rings once as it settles at a stop nearby) ──
    const tramG = P.scene?.getObjectByName?.('tram');
    if (street && tramG) {
      const p = tramG.position, dist = Math.hypot(p.x - _cam.x, p.z - _cam.z);
      const rumbleT = dist < TRAM_R ? (AUDIO?.sfx?.['tram-rumble']?.gain ?? 0.5) * ((TRAM_R - dist) / TRAM_R) : 0;
      persistBed(L.tram, 'tram-rumble', AUDIO?.sfx?.['tram-rumble'], rumbleT, 0.5);
      // bell: near + (nearly) stationary (dwelling at a stop) → one ring per dwell
      const moved = v.tramX == null ? 1 : Math.hypot(p.x - v.tramX, p.z - v.tramZ);
      if (dist < TRAM_BELL_R && moved < 0.02) { if (!v.tramRang) { playSfx('tram-bell'); v.tramRang = true; } }
      else if (moved > 0.1) v.tramRang = false;
      v.tramX = p.x; v.tramZ = p.z;
    } else if (L.tram.key) { ramp(L.tram.g.gain, 0, 0.5); }
  }

  // self-tick
  let raf = 0, lastT = 0;
  function tick(now) { raf = requestAnimationFrame(tick); const dt = lastT ? Math.min((now - lastT) / 1000, 0.1) : 0.016; lastT = now; try { update(dt); } catch {} }
  raf = requestAnimationFrame(tick);

  // ── public surface ──
  function dispose() {
    cancelAnimationFrame(raf);
    window.removeEventListener('pointerdown', unlock, true);
    window.removeEventListener('keydown', unlock, true);
    window.removeEventListener('procity:enterShop', onEnter);
    try { ctx.close(); } catch {}
  }
  return {
    state,
    get ready() { return state.ready; },
    get muted() { return state.muted; },
    setMasterGain(v2) { ramp(master.gain, Math.max(0, Math.min(1, v2)), 0.1); },
    mute() { state.muted = true; ramp(master.gain, 0, 0.15); },
    unmute() { state.muted = false; ramp(master.gain, 0.9, 0.2); },
    playSfx, footstep, playInterior, stopInterior, update, dispose,
  };
}