ShareIt/app.js

var app = require('express')();
var server = require('http').Server(app);
var io = require('socket.io')(server);
var fs = require('fs');

var port = process.env.PORT;

var sockets = [];
var Files = {};

app.get('/', function (req, res) {
  res.sendFile(__dirname + '/public/index.html');
});

io.on('connection', (socket) => {
  sockets.push(socket);
  socket.on('disconnect', (data) => {
    console.log("Socket disconnect");
    var index = sockets.indexOf(socket);
    if (index > -1) {
		sockets.splice(index, 1);
	}
  });

  addEvents(socket);
});


server.listen(800);


function addEvents(socket){
	socket.on("wannafile", function(data){
		var name = data.name;
		console.log("File incoming");
		console.log(data);

		if(!name)return;
		if(!Files[name]){
			Files[name] = {
				position : 0,
				total : data.size,
				Data : ""
			}
		}
		var Name = name;
		var entry = Files[name];
		try{
            var Stat = fs.statSync('Temp/' +  Name);
            if(Stat.isFile())
            {
                Files[Name]['position'] = Stat.size;
            }
        }
        catch(er){} //It's a New File
        fs.open("Temp/" + Name, "a", 0755, function(err, fd){
            if(err)
            {
                console.log(err);
            }
            else
            {
                Files[Name]['Handler'] = fd; //We store the file handler so we can write to it later
				socket.emit(name, {position: Files[name].position, total: Files[name].total});
            }
        });
	});
	socket.on("upload", function(data){
		var Name = data.name;
        Files[Name].position += data['data'].length;
        Files[Name]['Data'] += data['data'];
        if(Files[Name]['position'] == Files[Name]['total']) //If File is Fully Uploaded
        {
            fs.write(Files[Name]['Handler'], Files[Name]['Data'], null, 'Binary', function(err, Writen){
            	console.log("File is finished!");
				socket.emit(Name, { position : Files[Name].position, total : Files[Name].total});
            });
        }
        else if(Files[Name]['Data'].length > 10485760){ //If the Data Buffer reaches 10MB
			console.log("Buffer is full!");
            fs.write(Files[Name]['Handler'], Files[Name]['Data'], null, 'Binary', function(err, Writen){
                Files[Name]['Data'] = ""; //Reset The Buffer
                socket.emit(Name, { position : Files[Name].position, total : Files[Name].total});
            });
        }
        else
        {
			socket.emit(Name, { position : Files[Name].position, total : Files[Name].total});
        }
	});
}