'use strict';

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

const LOCAL_PORT = 1935;
const REMOTE_PORT = 1936;
const REMOTE_ADDR = '127.0.0.1';

/**
 * 头长度(Byte)
 */
const HEAD_LEN = 4;

/**
 * 标识长度(Byte)
 */
const IDENTIFIER_LEN = 2;

/**
 * 目标媒体服务器标识
 * 10:9999 -> 16:270f
 * 支持2字节对应最大十进制32767
 */
const MEDIA_SERVER_IDENTIFIER = 9999;

const proxy = net.createServer(function (socket) {
    const targetSocket = net.createConnection({
        host: REMOTE_ADDR,
        port: REMOTE_PORT,
    }, function () {
        console.log('Proxy connected to target server');
    });

    socket.on('data', function (data) {
        // 写入标识
        const identifierBuf = Buffer.alloc(IDENTIFIER_LEN);
        identifierBuf.writeInt16BE(MEDIA_SERVER_IDENTIFIER, 0);
        // 写入包头
        const headBuf = Buffer.alloc(HEAD_LEN);
        headBuf.writeUInt32BE(data.byteLength + IDENTIFIER_LEN, 0);
        // 发送包头
        targetSocket.write(headBuf);
        // 发送标识
        targetSocket.write(identifierBuf);
        // 发送包内容
        targetSocket.write(data);
        // console.log(data.toString('hex'));
    });

    socket.on('close', function () {
        targetSocket.end();
        console.log('client disconnected');
    });

    socket.on('error', function (error) {
        console.log(`error:客户端异常断开: ${error}`);
    });

    targetSocket.on('data', function (chunk) {
        socket.write(chunk);
    });

    targetSocket.on('close', function () {
        socket.end();
    });
});

proxy.on('error', function (err) {
    throw err;
});

proxy.listen(LOCAL_PORT, function () {
    console.log('Zone1 proxy listening on ' + LOCAL_PORT);
});