var SERVER_PORT = 61590;
var CLIENT_PORT = 61600;
var HOST = '192.168.1.20';

var dgram = require('dgram');
var server = dgram.createSocket('udp4');
var client = dgram.createSocket('udp4');

let value1 = 0;
let value2 = 0;
let value3 = 0;

server.on('listening', function () {
  var address = server.address();
  console.log('UDP Server listening on ' + address.address + ":" + address.port);
});

function sendData() {
  var message = new Buffer(`${value1},${value2},${value3}`);

  client.send(message, 0, message.length, CLIENT_PORT, HOST, function(err, bytes) {
    if (err) {
      throw err;
    }
    else {
      console.log(`UDP message sent to ${HOST}:${CLIENT_PORT} - ${message}`);
    }
  });
}

server.on('message', function (message, remote) {
  console.log(remote.address + ':' + remote.port +' - ' + message);
  let arr = message.toString().split(",");
  value1 = arr.length > 0 ? arr[0] : 0;
  value2 = arr.length > 1 ? arr[1] : 0;
  value3 = arr.length > 2 ? arr[2] : 0;
  sendData();
});

server.bind(SERVER_PORT);