src/lib/audio-recorder.ts

// src/lib/audio-recorder.ts

import EventEmitter from 'eventemitter3';
import { audioContext } from './utils';
import VolMeterWorket from './worklets/vol-meter';

export class AudioRecorder extends EventEmitter {
  public recording = false;
  private mediaStream: MediaStream | null = null;
  private audioContext: AudioContext | null = null;
  private processor: ScriptProcessorNode | null = null;
  private source: MediaStreamAudioSourceNode | null = null;
  private volMeter: AudioWorkletNode | null = null;

  constructor() {
    super();
  }

  private async init() {
    if (!this.audioContext) {
      this.audioContext = await audioContext({ id: 'audio-in' });
    }
    if (!this.mediaStream) {
      try {
        this.mediaStream = await navigator.mediaDevices.getUserMedia({
          audio: {
            sampleRate: 16000,
            channelCount: 1,
            echoCancellation: true,
            noiseSuppression: true,
          },
          video: false,
        });
      } catch (err) {
        console.error('Error getting media stream:', err);
        this.emit('error', err);
        return;
      }
    }
  }

  public async start() {
    if (this.recording) {
      return;
    }
    
    await this.init();

    if (!this.audioContext || !this.mediaStream) {
        console.error("AudioContext or MediaStream not available.");
        return;
    }

    this.recording = true;
    this.source = this.audioContext.createMediaStreamSource(this.mediaStream);
    this.processor = this.audioContext.createScriptProcessor(1024, 1, 1);
    
    this.processor.onaudioprocess = (e) => {
      if (!this.recording) return;
      const inputData = e.inputBuffer.getChannelData(0);
      const pcm16 = this.floatTo16BitPCM(inputData);
      const base64 = this.pcm16ToBase64(pcm16);
      this.emit('data', base64);
    };

    // --- بخش کلیدی: اضافه کردن Volume Meter ---
    try {
        await this.audioContext.audioWorklet.addModule(VolMeterWorket);
        this.volMeter = new AudioWorkletNode(this.audioContext, 'vumeter');
        this.volMeter.port.onmessage = (event) => {
            if(event.data.volume) {
                // ارسال رویداد جدید به همراه حجم صدا
                this.emit('volume', event.data.volume);
            }
        };
        this.source.connect(this.volMeter);
    } catch(err) {
        console.error("Error adding AudioWorklet module", err);
    }
    // ------------------------------------------

    this.source.connect(this.processor);
    this.processor.connect(this.audioContext.destination);
    
    this.emit('start');
  }

  public stop() {
    if (!this.recording) {
      return;
    }
    this.recording = false;
    this.emit('stop');
    
    this.source?.disconnect();
    this.processor?.disconnect();
    this.volMeter?.disconnect();

    this.source = null;
    this.processor = null;
    this.volMeter = null;
  }
  
  // توابع کمکی برای تبدیل فرمت صدا
  private floatTo16BitPCM(input: Float32Array): Int16Array {
    const output = new Int16Array(input.length);
    for (let i = 0; i < input.length; i++) {
      const s = Math.max(-1, Math.min(1, input[i]));
      output[i] = s < 0 ? s * 0x8000 : s * 0x7FFF;
    }
    return output;
  }

  private pcm16ToBase64(pcm16: Int16Array): string {
    const buffer = pcm16.buffer;
    const bytes = new Uint8Array(buffer);
    let binary = '';
    for (let i = 0; i < bytes.byteLength; i++) {
      binary += String.fromCharCode(bytes[i]);
    }
    return btoa(binary);
  }
}