'use strict'

const net = require('net')

let server = null
let sockets = []

// cleans the input of carriage return, newline
const cleanInput = data => data.toString().replace(/(\r\n|\n|\r)/gm, '')

// executed when data is received from a socket
const receiveData = (socket, data) => {
  const cleanData = cleanInput(data)
  if (cleanData === "@quit") {
    socket.end('Goodbye!\n')
  } else {
    for (let i = 0; i < sockets.length; i++) {
      if (sockets[i] !== socket) {
        sockets[i].write(data)
      }
    }
  }
}

// executed when a socket ends
const closeSocket = socket => {
   const i = sockets.indexOf(socket)
   if (i != -1) sockets.splice(i, 1)
}

// callback method executed when a new TCP socket is opened
const newSocket = socket => {
   sockets.push(socket)
   socket.write('Welcome to the Telnet server!\n')
   socket.on('data', data => receiveData(socket, data))
   socket.on('end', () => closeSocket(socket))
}

// create a new server
module.exports = (port) => { 
  if (server === null) server = net.createServer(newSocket).listen(port)
  return server
}