index.js

'use strict';

let os = require('os');

let port = (process.env.APPLICATION_PORT) ? process.env.APPLICATION_PORT : 8080;

let fileServer = new(require('node-static').Server)();
let app = require('http').createServer(function(req, res) {
  fileServer.serve(req, res);
}).listen(port);

let io = require('socket.io')(app);

io.on('connection', function(socket) {

  // convenience function to log server messages on the client
  function log() {
    let array = ['Message from server:'];
    array.push.apply(array, arguments);
    socket.emit('log', array);
  }

  function RoomParticipants(room) {
    return io.sockets.adapter.rooms[room] ? io.sockets.adapter.rooms[room].length : 0
  }

  socket.on('message', function(data, room) {
    log('Client said: ', data);
    // for a real app, would be room-only (not broadcast)

    io.sockets.in(room).emit('message', data);
  });

  socket.on('ID of presenter', function(room, presenterID) {
    io.sockets.in(room).emit('ID of presenter', presenterID);
  });

  socket.on('create or join', function(room) {
    log('Received request to create or join room ' + room);

    console.log("Number of all currently connected sockets: ",Object.keys(io.sockets.sockets).length);

    log('Room ' + room + ' now has ' + RoomParticipants(room) + ' client(s)');

    if (RoomParticipants(room) === 0) {
      log('Client ID ' + socket.id + ' created room ' + room);
      socket.join(room).emit('created', room, socket.id);
      console.log("Number participants for room ", room,": ", RoomParticipants(room));
    } else if (RoomParticipants(room) < 10) {
      log('Client ID ' + socket.id + ' joined room ' + room);
      io.sockets.in(room).emit('join', room, socket.id);
      socket.join(room).emit('joined', room, socket.id);
      io.sockets.in(room).emit('ready');
      console.log("Number participants for room ", room,": ", RoomParticipants(room));
    } else { // if room is full
      socket.emit('full', room);
    }
  });

  socket.on('ipaddr', function() {
    let ifaces = os.networkInterfaces();
    for (let dev in ifaces) {
      ifaces[dev].forEach(function(details) {
        if (details.family === 'IPv4' && details.address !== '127.0.0.1') {
          socket.emit('ipaddr', details.address);
        }
      });
    }
  });

});