reaktor/src/engine/audioEngine.js

/**
 * audioEngine.js — Bridge between node graph state and Tone.js audio graph
 * Creates, connects, and destroys Tone.js nodes as the user edits the patch
 */
import * as Tone from 'tone';
import { state } from './state.js';
import { getModuleDef } from './moduleRegistry.js';

// Map moduleId → { node: Tone.js node, inputs: {portName: node/param}, outputs: {portName: node} }
const audioNodes = {};

// Active keyboard state
const keyboardState = { frequency: 440, gate: false };

// ==================== Global Master Clock ====================
// Single clock with integer tick counter. All sequencers/piano rolls
// derive their step positions from this shared tick count.
// Using integers avoids floating-point drift entirely.
export const MASTER_TICK_RATE = 120; // Hz — 6x headroom for 300 BPM sixteenths (20 Hz). Lower = less main thread pressure.
let _masterClock = null;
const _tickListeners = new Map(); // id → callback(audioTime, ticks)

export function subscribeTick(id, callback) {
  _tickListeners.set(id, callback);
}

export function unsubscribeTick(id) {
  _tickListeners.delete(id);
}

function startMasterClock() {
  if (_masterClock) return;
  let _startTime = 0;
  let _started = false;
  _masterClock = new Tone.Clock((time) => {
    if (!_started) { _startTime = time; _started = true; }
    // Derive ticks from precise AudioContext.currentTime, not a counter.
    // Counters fall behind when callbacks are delayed (GC, UI, tab throttle).
    // The time parameter is always accurate regardless of callback jitter.
    const ticks = Math.round((time - _startTime) * MASTER_TICK_RATE);
    for (const cb of _tickListeners.values()) {
      cb(time, ticks);
    }
  }, MASTER_TICK_RATE);
  _masterClock.start();
}

function stopMasterClock() {
  if (_masterClock) {
    try { _masterClock.stop(); } catch {}
    try { _masterClock.dispose(); } catch {}
    _masterClock = null;
  }
  _tickListeners.clear();
}

// ==================== Node creation ====================

function createNode(mod) {
  const def = getModuleDef(mod.type);
  if (!def) return null;

  const p = { ...Object.fromEntries(Object.entries(def.params).map(([k, v]) => [k, v.default])), ...mod.params };

  switch (mod.type) {
    case 'oscillator': {
      const osc = new Tone.Oscillator({ type: p.waveform, frequency: p.frequency, detune: p.detune });
      osc.start();
      // Modulation scaler for freq input: LFO (-1..1) × scale → added to osc.frequency
      // Scale = half the current frequency so modulation is musically meaningful
      const freqMod = new Tone.Gain(p.frequency * 0.5);
      freqMod.connect(osc.frequency);
      return {
        node: osc,
        _freqMod: freqMod,
        inputs: { freq: freqMod, detune: osc.detune },
        outputs: { out: osc },
        dispose: () => { osc.stop(); freqMod.disconnect(); freqMod.dispose(); osc.dispose(); },
      };
    }
    case 'lfo': {
      const lfo = new Tone.LFO({ type: p.waveform, frequency: p.frequency, amplitude: p.amplitude, min: -1, max: 1 });
      lfo.start();
      return {
        node: lfo,
        inputs: {},
        outputs: { out: lfo },
        dispose: () => { lfo.stop(); lfo.dispose(); },
      };
    }
    case 'noise': {
      const noise = new Tone.Noise(p.type);
      noise.start();
      return {
        node: noise,
        inputs: {},
        outputs: { out: noise },
        dispose: () => { noise.stop(); noise.dispose(); },
      };
    }
    case 'filter': {
      const filter = new Tone.Filter({ type: p.type, frequency: p.frequency, Q: p.Q });
      // Modulation scaler for cutoff input: LFO (-1..1) × scale → added to filter.frequency
      // Scale = cutoff value so full LFO sweep covers 0 to 2× the cutoff
      const cutoffMod = new Tone.Gain(p.frequency);
      cutoffMod.connect(filter.frequency);
      return {
        node: filter,
        _cutoffMod: cutoffMod,
        inputs: { in: filter, cutoff: cutoffMod },
        outputs: { out: filter },
        dispose: () => { cutoffMod.disconnect(); cutoffMod.dispose(); filter.dispose(); },
      };
    }
    case 'envelope': {
      const env = new Tone.Envelope({ attack: p.attack, decay: p.decay, sustain: p.sustain, release: p.release });
      // Connect env to a signal so it can be used as modulation source
      const sig = new Tone.Signal(0);
      env.connect(sig);
      return {
        node: env,
        _sig: sig,
        inputs: { gate: null }, // Gate is handled via triggerAttack/Release
        outputs: { out: sig },
        dispose: () => { env.dispose(); sig.dispose(); },
      };
    }
    case 'vca': {
      const gain = new Tone.Gain(p.gain);
      // CV modulation scaler: envelope (0-1) × gain param → added to gain.gain
      const cvMod = new Tone.Gain(p.gain);
      cvMod.connect(gain.gain);
      return {
        node: gain,
        _cvMod: cvMod,
        inputs: { in: gain, cv: cvMod },
        outputs: { out: gain },
        dispose: () => { cvMod.disconnect(); cvMod.dispose(); gain.dispose(); },
      };
    }
    case 'delay': {
      const delay = new Tone.FeedbackDelay({ delayTime: p.delayTime, feedback: p.feedback, wet: p.wet });
      return {
        node: delay,
        inputs: { in: delay },
        outputs: { out: delay },
        dispose: () => delay.dispose(),
      };
    }
    case 'reverb': {
      const reverb = new Tone.Reverb({ decay: p.decay, wet: p.wet });
      return {
        node: reverb,
        inputs: { in: reverb },
        outputs: { out: reverb },
        dispose: () => reverb.dispose(),
      };
    }
    case 'distortion': {
      const dist = new Tone.Distortion({ distortion: p.distortion, wet: p.wet });
      return {
        node: dist,
        inputs: { in: dist },
        outputs: { out: dist },
        dispose: () => dist.dispose(),
      };
    }
    case 'mixer': {
      const master = new Tone.Gain(1);
      const ch1 = new Tone.Gain(p.gain1);
      const ch2 = new Tone.Gain(p.gain2);
      const ch3 = new Tone.Gain(p.gain3);
      const ch4 = new Tone.Gain(p.gain4);
      ch1.connect(master); ch2.connect(master); ch3.connect(master); ch4.connect(master);
      return {
        node: master,
        _channels: [ch1, ch2, ch3, ch4],
        inputs: { in1: ch1, in2: ch2, in3: ch3, in4: ch4 },
        outputs: { out: master },
        dispose: () => { [ch1, ch2, ch3, ch4, master].forEach(n => n.dispose()); },
      };
    }
    case 'scope': {
      const analyser = new Tone.Analyser('waveform', 2048);
      return {
        node: analyser,
        inputs: { in: analyser },
        outputs: {},
        analyser,
        dispose: () => analyser.dispose(),
      };
    }
    case 'cv2gate': {
      // Converts a continuous CV signal to gate on/off based on threshold.
      // Uses an analyser to read the CV value and triggers connected envelopes.
      const analyser = new Tone.Analyser('waveform', 32);
      const gateSig = new Tone.Signal(0);
      return {
        node: analyser,
        _gateSig: gateSig,
        _gateState: false,
        inputs: { in: analyser },
        outputs: { gate: gateSig },
        dispose: () => { analyser.dispose(); gateSig.dispose(); },
      };
    }
    case 'output': {
      // True stereo output: separate left/right channels → merge → master gain → destination
      const leftGain = new Tone.Gain(1);
      const rightGain = new Tone.Gain(1);
      const merge = new Tone.Merge();
      const master = new Tone.Gain(Tone.dbToGain(p.volume));
      leftGain.connect(merge, 0, 0);
      rightGain.connect(merge, 0, 1);
      merge.connect(master);
      master.toDestination();
      return {
        node: master,
        _merge: merge,
        _leftGain: leftGain,
        _rightGain: rightGain,
        inputs: { left: leftGain, right: rightGain },
        outputs: {},
        dispose: () => {
          leftGain.disconnect(); leftGain.dispose();
          rightGain.disconnect(); rightGain.dispose();
          merge.disconnect(); merge.dispose();
          master.disconnect(); master.dispose();
        },
      };
    }
    case 'keyboard':
    case 'drumpad': {
      const freqSig = new Tone.Signal(440);
      const gateSig = new Tone.Signal(0);
      return {
        node: null,
        inputs: {},
        outputs: { freq: freqSig, gate: gateSig },
        _freqSig: freqSig,
        _gateSig: gateSig,
        dispose: () => { freqSig.dispose(); gateSig.dispose(); },
      };
    }
    case 'sequencer': {
      const freqSig = new Tone.Signal(440);
      const gateSig = new Tone.Signal(0);
      // Sequencer loop managed externally by SequencerWidget
      return {
        node: null,
        inputs: {},
        outputs: { freq: freqSig, gate: gateSig },
        _freqSig: freqSig,
        _gateSig: gateSig,
        _seq: null, // Tone.Sequence set by widget
        dispose: () => {
          freqSig.dispose(); gateSig.dispose();
        },
      };
    }
    case 'pianoroll': {
      const freqSig = new Tone.Signal(440);
      const gateSig = new Tone.Signal(0);
      return {
        node: null,
        inputs: {},
        outputs: { freq: freqSig, gate: gateSig },
        _freqSig: freqSig,
        _gateSig: gateSig,
        _part: null, // Tone.Part set by widget
        dispose: () => {
          freqSig.dispose(); gateSig.dispose();
        },
      };
    }
    default:
      return null;
  }
}

// ==================== Public API ====================

export function ensureNode(moduleId) {
  if (audioNodes[moduleId]) return audioNodes[moduleId];
  const mod = state.modules.find(m => m.id === moduleId);
  if (!mod) return null;
  const node = createNode(mod);
  if (node) audioNodes[moduleId] = node;
  return node;
}

export function getAudioNode(moduleId) {
  return audioNodes[moduleId] || null;
}

export function destroyNode(moduleId) {
  const entry = audioNodes[moduleId];
  if (!entry) return;
  try { entry.dispose(); } catch (e) { console.warn('dispose error', e); }
  delete audioNodes[moduleId];
}

export function connectWire(conn) {
  const fromEntry = ensureNode(conn.from.moduleId);
  const toEntry = ensureNode(conn.to.moduleId);
  if (!fromEntry || !toEntry) return;

  // Skip audio-graph connection for keyboard/sequencer/pianoroll freq → oscillator freq.
  // These signals carry absolute Hz values that would be mangled by the oscillator's
  // frequency-modulation Gain scaler. Instead, triggerKeyboard / setSequencerSignals
  // set the oscillator frequency directly when notes are played.
  const fromMod = state.modules.find(m => m.id === conn.from.moduleId);
  const toMod = state.modules.find(m => m.id === conn.to.moduleId);
  if (fromMod && ['keyboard', 'drumpad', 'sequencer', 'pianoroll'].includes(fromMod.type) &&
      conn.from.port === 'freq' && toMod?.type === 'oscillator' && conn.to.port === 'freq') {
    return; // handled imperatively in triggerKeyboard / setSequencerSignals
  }

  const output = fromEntry.outputs[conn.from.port];
  const input = toEntry.inputs[conn.to.port];
  if (!output || input === undefined || input === null) return;

  try {
    if (typeof output.connect === 'function') {
      output.connect(input);
    }
  } catch (e) {
    console.warn('connect error', e);
  }
}

export function disconnectWire(conn) {
  const fromEntry = audioNodes[conn.from.moduleId];
  const toEntry = audioNodes[conn.to.moduleId];
  if (!fromEntry || !toEntry) return;

  const output = fromEntry.outputs[conn.from.port];
  const input = toEntry.inputs[conn.to.port];
  if (!output || !input) return;

  try {
    if (typeof output.disconnect === 'function') {
      output.disconnect(input);
    }
  } catch (e) {
    // Tone.js may throw if not connected
  }
}

export function updateParam(moduleId, paramName, value) {
  const entry = audioNodes[moduleId];
  const mod = state.modules.find(m => m.id === moduleId);
  if (!entry || !mod) return;

  const def = getModuleDef(mod.type);
  if (!def) return;

  switch (mod.type) {
    case 'oscillator':
      if (paramName === 'waveform') entry.node.type = value;
      else if (paramName === 'frequency') {
        entry.node.frequency.value = value;
        // Update mod scaler proportionally
        if (entry._freqMod) entry._freqMod.gain.value = value * 0.5;
      }
      else if (paramName === 'detune') entry.node.detune.value = value;
      break;
    case 'lfo':
      if (paramName === 'waveform') entry.node.type = value;
      else if (paramName === 'frequency') entry.node.frequency.value = value;
      else if (paramName === 'amplitude') entry.node.amplitude.value = value;
      break;
    case 'noise':
      if (paramName === 'type') entry.node.type = value;
      break;
    case 'filter':
      if (paramName === 'type') entry.node.type = value;
      else if (paramName === 'frequency') {
        entry.node.frequency.value = value;
        // Update mod scaler proportionally
        if (entry._cutoffMod) entry._cutoffMod.gain.value = value;
      }
      else if (paramName === 'Q') entry.node.Q.value = value;
      break;
    case 'envelope':
      if (paramName === 'attack') entry.node.attack = value;
      else if (paramName === 'decay') entry.node.decay = value;
      else if (paramName === 'sustain') entry.node.sustain = value;
      else if (paramName === 'release') entry.node.release = value;
      break;
    case 'vca':
      if (paramName === 'gain') {
        const hasCV = state.connections.some(c => c.to.moduleId === moduleId && c.to.port === 'cv');
        if (!hasCV) entry.node.gain.value = value;
        if (entry._cvMod) entry._cvMod.gain.value = value;
      }
      break;
    case 'delay':
      if (paramName === 'delayTime') entry.node.delayTime.value = value;
      else if (paramName === 'feedback') entry.node.feedback.value = value;
      else if (paramName === 'wet') entry.node.wet.value = value;
      break;
    case 'reverb':
      if (paramName === 'decay') entry.node.decay = value;
      else if (paramName === 'wet') entry.node.wet.value = value;
      break;
    case 'distortion':
      if (paramName === 'distortion') entry.node.distortion = value;
      else if (paramName === 'wet') entry.node.wet.value = value;
      break;
    case 'mixer':
      if (paramName.startsWith('gain')) {
        const idx = parseInt(paramName.replace('gain', '')) - 1;
        if (entry._channels && entry._channels[idx]) entry._channels[idx].gain.value = value;
      }
      break;
    case 'output':
      if (paramName === 'volume') entry.node.gain.value = Tone.dbToGain(value);
      break;
    case 'keyboard':
    case 'drumpad':
    case 'cv2gate':
    case 'sequencer':
    case 'pianoroll':
      // All params stored in state, managed by widgets
      break;
  }
}

// Cache connection lookups for hot-path audio scheduling
// Rebuilt only when connections actually change (dirty flag, no computation on hit)
let _connCacheDirty = true;
const _connByModulePort = new Map(); // "moduleId-portName" → [connections]

export function invalidateConnectionCache() {
  _connCacheDirty = true;
}

function getConnectionsFrom(moduleId, portName) {
  if (_connCacheDirty) {
    _connByModulePort.clear();
    for (const conn of state.connections) {
      const key = `${conn.from.moduleId}-${conn.from.port}`;
      if (!_connByModulePort.has(key)) _connByModulePort.set(key, []);
      _connByModulePort.get(key).push(conn);
    }
    _connCacheDirty = false;
  }
  return _connByModulePort.get(`${moduleId}-${portName}`) || [];
}

export function setSequencerSignals(moduleId, freq, gate) {
  const entry = audioNodes[moduleId];
  if (!entry) return;
  if (entry._freqSig) entry._freqSig.value = freq;
  if (entry._gateSig) entry._gateSig.value = gate ? 1 : 0;

  // Set connected oscillator frequencies directly
  for (const conn of getConnectionsFrom(moduleId, 'freq')) {
    const oscEntry = audioNodes[conn.to.moduleId];
    if (oscEntry?.node?.frequency) {
      oscEntry.node.frequency.value = freq;
    }
  }

  // Trigger connected envelopes
  for (const conn of getConnectionsFrom(moduleId, 'gate')) {
    const envEntry = audioNodes[conn.to.moduleId];
    if (envEntry && envEntry.node instanceof Tone.Envelope) {
      if (gate) envEntry.node.triggerAttack();
      else envEntry.node.triggerRelease();
    }
  }
}

export function triggerKeyboard(moduleId, freq, gate) {
  const entry = audioNodes[moduleId];
  if (!entry) return;
  if (entry._freqSig) entry._freqSig.value = freq;
  if (entry._gateSig) entry._gateSig.value = gate ? 1 : 0;

  // Set connected oscillator frequencies directly
  for (const conn of getConnectionsFrom(moduleId, 'freq')) {
    const oscEntry = audioNodes[conn.to.moduleId];
    if (oscEntry?.node?.frequency) {
      oscEntry.node.frequency.value = freq;
    }
  }

  // Trigger connected envelopes
  for (const conn of getConnectionsFrom(moduleId, 'gate')) {
    const envEntry = audioNodes[conn.to.moduleId];
    if (envEntry && envEntry.node instanceof Tone.Envelope) {
      if (gate) envEntry.node.triggerAttack();
      else envEntry.node.triggerRelease();
    }
  }
}

export async function startAudio() {
  await Tone.start();
  state.isRunning = true;
  startMasterClock();

  // Rebuild entire audio graph
  rebuildGraph();
}

export function stopAudio() {
  stopMasterClock();

  // Stop and reset Transport
  try {
    Tone.getTransport().stop();
    Tone.getTransport().cancel();
    Tone.getTransport().position = 0;
  } catch (e) {}

  // Destroy all nodes
  for (const id of Object.keys(audioNodes)) {
    destroyNode(parseInt(id));
  }
  state.isRunning = false;
}

export function rebuildGraph() {
  // Destroy all existing nodes
  for (const id of Object.keys(audioNodes)) {
    destroyNode(parseInt(id));
  }

  // Create nodes for all modules
  for (const mod of state.modules) {
    ensureNode(mod.id);
  }

  // Create all connections
  for (const conn of state.connections) {
    connectWire(conn);
  }

  // Zero base gain on VCAs with active CV connection.
  // When envelope controls VCA, base gain must be 0 so silence is possible.
  for (const mod of state.modules) {
    if (mod.type !== 'vca') continue;
    const hasCV = state.connections.some(c => c.to.moduleId === mod.id && c.to.port === 'cv');
    const entry = audioNodes[mod.id];
    if (entry && hasCV) entry.node.gain.value = 0;
  }

  // Auto-trigger envelopes that have no gate connection (free-running mode).
  // This allows noise/ambient patches to work without a keyboard/sequencer.
  for (const mod of state.modules) {
    if (mod.type !== 'envelope') continue;
    const hasGateInput = state.connections.some(
      c => c.to.moduleId === mod.id && c.to.port === 'gate'
    );
    if (!hasGateInput) {
      const entry = audioNodes[mod.id];
      if (entry && entry.node && typeof entry.node.triggerAttack === 'function') {
        entry.node.triggerAttack();
      }
    }
  }

  // Register CV→Gate modules on master clock for threshold detection
  for (const mod of state.modules) {
    if (mod.type !== 'cv2gate') continue;
    const entry = audioNodes[mod.id];
    if (!entry) continue;
    subscribeTick(`cv2gate-${mod.id}`, () => {
      const data = entry.node.getValue();
      const sample = typeof data === 'number' ? data : (data?.[0] ?? 0);
      const threshold = mod.params?.threshold ?? 0.5;
      const gateOn = sample > threshold;
      if (gateOn !== entry._gateState) {
        entry._gateState = gateOn;
        entry._gateSig.value = gateOn ? 1 : 0;
        // Trigger/release connected envelopes
        for (const conn of getConnectionsFrom(mod.id, 'gate')) {
          const envEntry = audioNodes[conn.to.moduleId];
          if (envEntry && envEntry.node instanceof Tone.Envelope) {
            if (gateOn) envEntry.node.triggerAttack();
            else envEntry.node.triggerRelease();
          }
        }
      }
    });
  }
}

export function getAnalyserData(moduleId) {
  const entry = audioNodes[moduleId];
  if (!entry || !entry.analyser) return null;
  return entry.analyser.getValue();
}