const net = require('node:net');

const LOCAL_PORT = 1936;
const REMOTE_PORT = 1935;
const REMOTE_ADDR = '39.101.185.102';
/**
 * 包头是4字节无符号整数，表示数据包长度
 */
const HEADER_LENGTH = 4;

const routeTable = {
  '01020304': { host: '39.101.185.102', port: 1935 },
}

function bootstrap() {
  const proxy = net.createServer();

  proxy.on('connection', (clientSocket) => {
    console.log('Client connected');
    let num = 0;
    let buf = Buffer.alloc(0);
    let framelen = 0;

    // 创建一个新的连接到目标服务器
    const targetSocket = net.createConnection({
      host: REMOTE_ADDR,
      port: REMOTE_PORT,
    }, () => {
      console.log('Proxy connected to target server');
    });

    // 将接收到的数据转发到目标服务器
    clientSocket.on('data', chunk => {
      console.log('接收原始报文:', chunk.toString('hex'));
      buf = Buffer.concat([buf, chunk]);
      console.log('buffer length', buf.length);
      let origin; 
      const chunklen = chunk.length;
      if (chunklen < HEADER_LENGTH) return;
      framelen = framelen || buf.readUInt32BE(0);
      if (chunklen - HEADER_LENGTH === framelen) {
        origin = buf.subarray(HEADER_LENGTH, chunklen);
        buf = Buffer.alloc(0);
        framelen = 0;
      } else if (chunklen - HEADER_LENGTH > framelen) {
        origin = buf.subarray(HEADER_LENGTH, chunklen);
        buf = buf.subarray(chunklen);
        if (buf.length >= HEADER_LENGTH) {
          framelen = buf.readUInt32BE(0);
        } else {
          framelen = 0;
        }
      }
      console.log('数据帧长度:', framelen);
      if (origin) {
        num += 1;
        targetSocket.write(origin);
        console.log('第'+num+'段报文', origin.toString('hex'));
      }
    });

    // 将目标服务器的响应数据转发回客户端
    targetSocket.on('data', chunk => {
      clientSocket.write(chunk);
    });

    // 处理代理与目标服务器的关闭事件
    clientSocket.on('close', () => {
      targetSocket.end();
    });
    targetSocket.on('close', () => {
      clientSocket.end();
    });
  });

  // 监听本地端口
  proxy.listen(LOCAL_PORT, () => {
    console.log('Zone2 proxy server is listening on port ' + LOCAL_PORT);
  });
}
bootstrap();