Lofi_Generator/lib/audio/audioEngine.ts

import * as Tone from 'tone';
import { DrumMachine } from './drumMachine';
import { ChordEngine } from './chordEngine';
import { AmbientLayer } from './ambientLayer';
import {
  EngineState,
  AudioEngineCallbacks,
  LayerName,
  MeterLevels,
  LoopRegion,
} from '@/types/audio';

class AudioEngine {
  private static instance: AudioEngine | null = null;

  private drumMachine: DrumMachine | null = null;
  private chordEngine: ChordEngine | null = null;
  private ambientLayer: AmbientLayer | null = null;

  private masterGain: Tone.Gain | null = null;
  private masterCompressor: Tone.Compressor | null = null;
  private masterLimiter: Tone.Limiter | null = null;
  private masterReverb: Tone.Reverb | null = null;

  // Meters for level detection
  private drumMeter: Tone.Meter | null = null;
  private chordMeter: Tone.Meter | null = null;
  private ambientMeter: Tone.Meter | null = null;
  private masterMeter: Tone.Meter | null = null;

  // Panners for stereo positioning
  private drumPanner: Tone.Panner | null = null;
  private chordPanner: Tone.Panner | null = null;
  private ambientPanner: Tone.Panner | null = null;

  // Solo state tracking
  private soloState: Record<LayerName, boolean> = {
    drums: false,
    chords: false,
    ambient: false,
  };

  // Pre-solo volume states for restoration
  private preSoloMuted: Record<LayerName, boolean> | null = null;

  // Timeline state
  private durationBars: number = 16;
  private loopRegion: LoopRegion = { start: 0, end: 16, enabled: false };
  private meterAnimationId: number | null = null;
  private barTrackerId: number | null = null;

  private callbacks: AudioEngineCallbacks = {};

  private state: EngineState = {
    isPlaying: false,
    isInitialized: false,
    bpm: 78,
    swing: 0.12,
    currentStep: 0,
    volumes: {
      master: 0.8,
      drums: 0.8,
      chords: 0.6,
      ambient: 0.4,
    },
    muted: {
      drums: false,
      chords: false,
      ambient: false,
    },
  };

  private constructor() {}

  static getInstance(): AudioEngine {
    if (!AudioEngine.instance) {
      AudioEngine.instance = new AudioEngine();
    }
    return AudioEngine.instance;
  }

  async initialize(): Promise<void> {
    if (this.state.isInitialized) return;

    // Start Tone.js audio context (requires user gesture)
    await Tone.start();

    // Set up transport
    Tone.getTransport().bpm.value = this.state.bpm;
    Tone.getTransport().swing = this.state.swing;
    Tone.getTransport().swingSubdivision = '16n';

    // Create meters
    this.drumMeter = new Tone.Meter({ smoothing: 0.8 });
    this.chordMeter = new Tone.Meter({ smoothing: 0.8 });
    this.ambientMeter = new Tone.Meter({ smoothing: 0.8 });
    this.masterMeter = new Tone.Meter({ smoothing: 0.8 });

    // Create panners
    this.drumPanner = new Tone.Panner(0);
    this.chordPanner = new Tone.Panner(0);
    this.ambientPanner = new Tone.Panner(0);

    // Master chain
    this.masterGain = new Tone.Gain(this.state.volumes.master);
    this.masterCompressor = new Tone.Compressor({
      threshold: -20,
      ratio: 4,
      attack: 0.003,
      release: 0.25,
    });
    this.masterLimiter = new Tone.Limiter(-1);
    this.masterReverb = new Tone.Reverb({
      decay: 2,
      wet: 0.15,
    });

    // Chain: gain -> reverb -> compressor -> limiter -> meter -> destination
    this.masterGain.connect(this.masterReverb);
    this.masterReverb.connect(this.masterCompressor);
    this.masterCompressor.connect(this.masterLimiter);
    this.masterLimiter.connect(this.masterMeter);
    this.masterMeter.toDestination();

    // Initialize layers with panners and meters in chain
    this.drumMachine = new DrumMachine(this.drumPanner);
    this.chordEngine = new ChordEngine(this.chordPanner);
    this.ambientLayer = new AmbientLayer(this.ambientPanner);

    // Connect panners -> meters -> master
    this.drumPanner.connect(this.drumMeter);
    this.drumMeter.connect(this.masterGain);

    this.chordPanner.connect(this.chordMeter);
    this.chordMeter.connect(this.masterGain);

    this.ambientPanner.connect(this.ambientMeter);
    this.ambientMeter.connect(this.masterGain);

    // Create sequences
    this.drumMachine.createSequence((step) => {
      this.state.currentStep = step;
      this.callbacks.onStepChange?.(step);
    });
    this.chordEngine.createSequence();

    // Start meter animation loop
    this.startMeterLoop();

    // Start bar tracking
    this.startBarTracking();

    this.state.isInitialized = true;
    this.notifyStateChange();
  }

  setCallbacks(callbacks: AudioEngineCallbacks): void {
    this.callbacks = callbacks;
  }

  private notifyStateChange(): void {
    this.callbacks.onStateChange?.({ ...this.state });
  }

  async play(): Promise<void> {
    if (!this.state.isInitialized) {
      await this.initialize();
    }

    this.ambientLayer?.start();
    Tone.getTransport().start();
    this.state.isPlaying = true;
    this.notifyStateChange();
  }

  pause(): void {
    Tone.getTransport().pause();
    this.ambientLayer?.stop();
    this.state.isPlaying = false;
    this.notifyStateChange();
  }

  stop(): void {
    Tone.getTransport().stop();
    this.ambientLayer?.stop();
    this.state.isPlaying = false;
    this.state.currentStep = 0;
    this.notifyStateChange();
  }

  generateNewBeat(): void {
    this.drumMachine?.randomize();
    this.chordEngine?.randomize();
    this.notifyStateChange();
  }

  setBpm(bpm: number): void {
    this.state.bpm = Math.max(60, Math.min(100, bpm));
    Tone.getTransport().bpm.value = this.state.bpm;
    this.notifyStateChange();
  }

  setSwing(swing: number): void {
    this.state.swing = Math.max(0, Math.min(0.5, swing));
    Tone.getTransport().swing = this.state.swing;
    this.notifyStateChange();
  }

  setMasterVolume(volume: number): void {
    this.state.volumes.master = Math.max(0, Math.min(1, volume));
    this.masterGain?.gain.rampTo(this.state.volumes.master, 0.1);
    this.notifyStateChange();
  }

  setLayerVolume(layer: LayerName, volume: number): void {
    const normalizedVolume = Math.max(0, Math.min(1, volume));
    this.state.volumes[layer] = normalizedVolume;

    switch (layer) {
      case 'drums':
        this.drumMachine?.setVolume(normalizedVolume);
        break;
      case 'chords':
        this.chordEngine?.setVolume(normalizedVolume);
        break;
      case 'ambient':
        this.ambientLayer?.setVolume(normalizedVolume);
        break;
    }

    this.notifyStateChange();
  }

  toggleMute(layer: LayerName): void {
    this.state.muted[layer] = !this.state.muted[layer];

    switch (layer) {
      case 'drums':
        this.drumMachine?.mute(this.state.muted[layer]);
        break;
      case 'chords':
        this.chordEngine?.mute(this.state.muted[layer]);
        break;
      case 'ambient':
        this.ambientLayer?.mute(this.state.muted[layer]);
        break;
    }

    this.notifyStateChange();
  }

  setMuted(layer: LayerName, muted: boolean): void {
    this.state.muted[layer] = muted;

    switch (layer) {
      case 'drums':
        this.drumMachine?.mute(muted);
        break;
      case 'chords':
        this.chordEngine?.mute(muted);
        break;
      case 'ambient':
        this.ambientLayer?.mute(muted);
        break;
    }

    this.notifyStateChange();
  }

  getState(): EngineState {
    return { ...this.state };
  }

  // Meter methods
  private startMeterLoop(): void {
    const updateMeters = () => {
      if (this.state.isPlaying && this.callbacks.onMeterUpdate) {
        this.callbacks.onMeterUpdate(this.getMeterLevels());
      }
      this.meterAnimationId = requestAnimationFrame(updateMeters);
    };
    this.meterAnimationId = requestAnimationFrame(updateMeters);
  }

  private stopMeterLoop(): void {
    if (this.meterAnimationId !== null) {
      cancelAnimationFrame(this.meterAnimationId);
      this.meterAnimationId = null;
    }
  }

  getMeterLevels(): MeterLevels {
    const normalize = (val: number | number[]): number => {
      const v = typeof val === 'number' ? val : val[0] ?? -Infinity;
      const db = Math.max(-60, Math.min(0, v));
      return (db + 60) / 60;
    };

    return {
      drums: normalize(this.drumMeter?.getValue() ?? -Infinity),
      chords: normalize(this.chordMeter?.getValue() ?? -Infinity),
      ambient: normalize(this.ambientMeter?.getValue() ?? -Infinity),
      master: normalize(this.masterMeter?.getValue() ?? -Infinity),
    };
  }

  // Panner methods
  setPan(layer: LayerName, value: number): void {
    const normalizedPan = Math.max(-1, Math.min(1, value));

    switch (layer) {
      case 'drums':
        this.drumPanner?.pan.rampTo(normalizedPan, 0.1);
        break;
      case 'chords':
        this.chordPanner?.pan.rampTo(normalizedPan, 0.1);
        break;
      case 'ambient':
        this.ambientPanner?.pan.rampTo(normalizedPan, 0.1);
        break;
    }
  }

  getPan(layer: LayerName): number {
    switch (layer) {
      case 'drums':
        return this.drumPanner?.pan.value ?? 0;
      case 'chords':
        return this.chordPanner?.pan.value ?? 0;
      case 'ambient':
        return this.ambientPanner?.pan.value ?? 0;
    }
  }

  // Solo methods
  setSolo(layer: LayerName, enabled: boolean): void {
    const hadAnySolo = Object.values(this.soloState).some(Boolean);
    this.soloState[layer] = enabled;
    const hasAnySolo = Object.values(this.soloState).some(Boolean);

    if (!hadAnySolo && hasAnySolo) {
      this.preSoloMuted = { ...this.state.muted };
    }

    if (hasAnySolo) {
      const layers: LayerName[] = ['drums', 'chords', 'ambient'];
      layers.forEach((l) => {
        const shouldMute = !this.soloState[l];
        this.setMuted(l, shouldMute);
      });
    } else if (hadAnySolo && !hasAnySolo && this.preSoloMuted) {
      const layers: LayerName[] = ['drums', 'chords', 'ambient'];
      layers.forEach((l) => {
        this.setMuted(l, this.preSoloMuted![l]);
      });
      this.preSoloMuted = null;
    }
  }

  getSoloState(): Record<LayerName, boolean> {
    return { ...this.soloState };
  }

  // Timeline methods
  private startBarTracking(): void {
    if (this.barTrackerId !== null) {
      Tone.getTransport().clear(this.barTrackerId);
    }

    this.barTrackerId = Tone.getTransport().scheduleRepeat((time) => {
      const position = Tone.getTransport().position;
      const [bars, beats] = String(position).split(':').map(Number);
      Tone.getDraw().schedule(() => {
        this.callbacks.onBarChange?.(bars, beats);
      }, time);
    }, '4n');
  }

  seek(bar: number, beat: number = 0): void {
    const position = `${bar}:${beat}:0`;
    Tone.getTransport().position = position;
    this.callbacks.onBarChange?.(bar, beat);
  }

  setDuration(bars: number): void {
    this.durationBars = Math.max(4, Math.min(128, bars));
  }

  getDuration(): number {
    return this.durationBars;
  }

  setLoopRegion(start: number, end: number, enabled: boolean): void {
    this.loopRegion = { start, end, enabled };

    if (enabled) {
      Tone.getTransport().setLoopPoints(`${start}:0:0`, `${end}:0:0`);
      Tone.getTransport().loop = true;
    } else {
      Tone.getTransport().loop = false;
    }
  }

  getLoopRegion(): LoopRegion {
    return { ...this.loopRegion };
  }

  getPlaybackPosition(): { bar: number; beat: number; sixteenth: number } {
    const position = String(Tone.getTransport().position);
    const [bars, beats, sixteenths] = position.split(':').map(Number);
    return { bar: bars || 0, beat: beats || 0, sixteenth: sixteenths || 0 };
  }

  // Pattern access methods
  getDrumMachine(): DrumMachine | null {
    return this.drumMachine;
  }

  getChordEngine(): ChordEngine | null {
    return this.chordEngine;
  }

  dispose(): void {
    this.stop();
    this.stopMeterLoop();

    if (this.barTrackerId !== null) {
      Tone.getTransport().clear(this.barTrackerId);
      this.barTrackerId = null;
    }

    this.drumMachine?.dispose();
    this.chordEngine?.dispose();
    this.ambientLayer?.dispose();
    this.masterGain?.dispose();
    this.masterCompressor?.dispose();
    this.masterLimiter?.dispose();
    this.masterReverb?.dispose();

    // Dispose new components
    this.drumMeter?.dispose();
    this.chordMeter?.dispose();
    this.ambientMeter?.dispose();
    this.masterMeter?.dispose();
    this.drumPanner?.dispose();
    this.chordPanner?.dispose();
    this.ambientPanner?.dispose();

    this.drumMachine = null;
    this.chordEngine = null;
    this.ambientLayer = null;
    this.masterGain = null;
    this.masterCompressor = null;
    this.masterLimiter = null;
    this.masterReverb = null;
    this.drumMeter = null;
    this.chordMeter = null;
    this.ambientMeter = null;
    this.masterMeter = null;
    this.drumPanner = null;
    this.chordPanner = null;
    this.ambientPanner = null;

    this.state.isInitialized = false;
    this.state.isPlaying = false;
    AudioEngine.instance = null;
  }
}

export const audioEngine = AudioEngine.getInstance();
export default audioEngine;