// Solution of MQTTHandsOnNodeJSClient, part of http://tmb.gr/mqtt
// Licensed https://tamberg.mit-license.org/

// Terminal 1: $ node bot2.js 
// Terminal 2: $ mqtt pub -t 'chats/tamberg' -h 'test.mosquitto.org' -m 'nice'

// Terminal 1: (Output)
// nice
// not nice

var mqtt = require('mqtt');
var client = mqtt.connect('mqtt://test.mosquitto.org/');

client.on('connect', function () {
  client.subscribe('chats/tamberg');
});

client.on('message', function (topic, message) {
  console.log(message.toString());
  var prefix = 'not ';
  if (message.indexOf(prefix) != 0) {
    client.publish('chats/tamberg', prefix + message);
  }
});