var app = require('http').createServer(handler),
io = require('socket.io').listen(app),
fs = require('fs'),
url = require('url'),
SerialPort = require('serialport').SerialPort,
// initialize serialport using the /dev/cu.usbmodem1411 serial port
// remember to change this string if your arduino is using a different serial port
// To know your device on linux just execute this command line bellow
// dmesg | tail | grep tty
// Most important! To discover your device on the linux just execute on terminal this command line bellow
// dmesg | tail | grep tty
// In my case show: [30514.044931] cdc_acm 3-1.4:1.0: ttyACM0: USB ACM device

sp = new SerialPort('/dev/ttyACM0', {
baudRate: 9600
}),
// this var will contain the message string dispatched by arduino
arduinoMessage = '',
/**

• helper function to load any app file required by client.html

• @param { String } pathname: path of the file requested to the nodejs server

• @param { Object } res: http://nodejs.org/api/http.html#http_class_http_serverresponse
  */
  readFile = function(pathname, res) {
  // an empty path returns client.html
  if (pathname === '/')
  pathname = '../client.html';

  fs.readFile('../client/' + pathname, function(err, data) {
  if (err) {
  console.log(err);
  res.writeHead(500);
  return res.end('Error loading client.html');
  }
  res.writeHead(200);
  res.end(data);
  });
  },
  /**
  *

• This function is used as proxy to print the arduino messages into the nodejs console and on the page

• @param { Buffer } buffer: buffer data sent via serialport

• @param { Object } socket: it's the socket.io instance managing the connections with the client.html page
  *
  */
  sendMessage = function(buffer, socket) {
  // concatenating the string buffers sent via usb port
  arduinoMessage += buffer.toString();

  // detecting the end of the string
  if (arduinoMessage.indexOf('\r') >= 0) {
  // log the message into the terminal
  // console.log(arduinoMessage);
  // send the message to the client
  socket.volatile.emit('notification', arduinoMessage);
  // reset the output string to an empty value
  arduinoMessage = '';
  }
  };

// creating a new websocket
io.sockets.on('connection', function(socket) {
// listen all the serial port messages sent from arduino and passing them to the proxy function sendMessage
sp.on('data', function(data) {
sendMessage(data, socket);
});
// listen all the websocket "lightStatus" messages coming from the client.html page
socket.on('lightStatus', function(lightStatus) {
sp.write(lightStatus + '\r', function() {
// log the light status into the terminal
console.log('the light should be: ' + lightStatus);
});
});
});

// just some debug listeners
sp.on('close', function(err) {
console.log('Port closed!');
});

sp.on('error', function(err) {
console.error('error', err);
});

sp.on('open', function() {
console.log('Port opened!');
});

// L3T'S R0CK!!!
// creating the server ( localhost:8000 )
app.listen(8000);
// server handler
function handler(req, res) {
readFile(url.parse(req.url).pathname, res);
}