const WebSocket = require('ws');
const { spawn } = require('child_process');
const path = require('path');

const PORT = 8000;
const AAC_FILE_PATH = path.join(__dirname, 'audio.aac');

// 创建 WebSocket 服务器
const wss = new WebSocket.Server({ port: PORT }, () => {
  console.log(`WebSocket server started on port ${PORT}`);
});

function sendAudioStream(ws, filePath) {
  const ffmpeg = spawn('ffmpeg', [
    '-i', filePath,        // 输入文件
    '-f', 'adts',          // 输出格式
    '-acodec', 'copy',     // 复制编码
    '-vn',                 // 不输出视频
    '-'                    // 输出到标准输出
  ]);

  //  const sampleRate = 44100; // 采样率
  const sampleRate = 16000; // 采样率
  // const frameDuration = frameSize / sampleRate; // 每帧的持续时间，单位为毫秒
  
  const frameSize = 4096; //frameSize fixed 1024=>4096    // AAC 帧大小
  let buffer = Buffer.alloc(0);
  let frameTime = 0;
  ffmpeg.stdout.on('data', (chunk) => {
    buffer = Buffer.concat([buffer, chunk]);
    while (buffer.length >= frameSize) {
       const frame = buffer.slice(0, frameSize);
      buffer = buffer.slice(frameSize);
    //   setTimeout(() => {
    //     if (ws.readyState === WebSocket.OPEN) {
          ws.send(frame);
    //     }
    //   }, frameTime);
    //   frameTime += frameDuration;
    }
  });

  ffmpeg.stderr.on('data', (data) => {
    console.error(`ffmpeg error: ${data}`);
  });

  ffmpeg.on('close', (code) => {
    console.log(`ffmpeg process exited with code ${code}`);
    if (ws.readyState === WebSocket.OPEN) {
      sendAudioStream(ws, filePath); // 重启 ffmpeg 以实现循环推流
    }
  });

  ws.on('close', () => {
    ffmpeg.kill();
  });
}

wss.on('connection', (ws) => {
  console.log('Client connected');
  sendAudioStream(ws, AAC_FILE_PATH);
  
  ws.on('close', () => {
    console.log('Client disconnected');
  });
});

wss.on('error', (err) => {
  console.error('WebSocket server error:', err);
});