server.js

var http = require("http");
var https = require("https");
var util = require("util");
var cheerio = require("cheerio");
var express = require("express");
var app = express();

app.set('view engine', 'ejs');

//from snipplr
function elapsedTime (createdAt)
{
    var ageInSeconds = (new Date().getTime() - new Date(createdAt).getTime()) / 1000;
    var s = function(n) { return n == 1 ? '' : 's' };
    if (ageInSeconds < 0) {
        return 'just now';
    }
    if (ageInSeconds < 60) {
        var n = ageInSeconds;
        return n + ' second' + s(n) + ' ago';
    }
    if (ageInSeconds < 60 * 60) {
        var n = Math.floor(ageInSeconds/60);
        return n + ' minute' + s(n) + ' ago';
    }
    if (ageInSeconds < 60 * 60 * 24) {
        var n = Math.floor(ageInSeconds/60/60);
        return n + ' hour' + s(n) + ' ago';
    }
    if (ageInSeconds < 60 * 60 * 24 * 7) {
        var n = Math.floor(ageInSeconds/60/60/24);
        return n + ' day' + s(n) + ' ago';
    }
    if (ageInSeconds < 60 * 60 * 24 * 31) {
        var n = Math.floor(ageInSeconds/60/60/24/7);
        return n + ' week' + s(n) + ' ago';
    }
    if (ageInSeconds < 60 * 60 * 24 * 365) {
        var n = Math.floor(ageInSeconds/60/60/24/31);
        return n + ' month' + s(n) + ' ago';
    }
    var n = Math.floor(ageInSeconds/60/60/24/365);
    return n + ' year' + s(n) + ' ago';
}

require("./helper.js")();

MongoClient.connect(mongourl, function(err, db)
{
	if (err)
	{
		 throw err;
	}

	var datacollection = db.collection("data");
	var lastupdatecollection = db.collection("lastupdate");
	var checklist = db.collection("checklist");

	var processor = require("./process.js");

	app.get('/',function(req,res) {
		res.send("Try <a href='/contest/OCT18B/all'>OCT18B</a>");
	})

	app.get('/add/:contest', function(req,res) {
		var cid = req.params.contest;
		checklist.findOneAndReplace(
			{
				contest: cid,
				 parse:['all']
			},
			{
				contest: cid,
				parse:['all']
			},
			{
				upsert: true
			},
			function(err,result) {
				if(result) {
					processor(true);
					res.redirect('/contest/'+cid+'/all');
				} else {
					res.render("error", {message: "Couldnot add to checklist"});
				}
			})
	})

	app.get('/contest/:contestid/:type', function(req, res)
	{
		processor();
		checklist.findOne({contest: req.params.contestid},function(err,obj) {
			if(err) {
				return;
			}
			if(obj) {
				lastupdatecollection.findOne({contest: req.params.contestid}, function (err, dateobj)
				{
					if (err)
						throw err;

					if (dateobj)
					{
						datacollection.find({contest: req.params.contestid, type: req.params.type}).sort({rank: 1}).toArray((err, result) => {
							if (err)
								throw err;

							for (var i in result)
							{
								result[i].change = result[i].rating - result[i].previous;
							}

							var typename = req.params.type[0].toUpperCase() + req.params.type.slice(1);

							res.render('rating', {elapsed: elapsedTime(dateobj.date), contest: req.params.contestid, type: req.params.type, typename: typename, result: result});
						});
					}
					else
					{
						res.status(404);
						res.render("error", {message: "We are currently calculating ratings for this contest!"});
					}
				});
			}
			else {
				res.status(404);
				var link = req.protocol + "://" + req.get('host') + "/add/" + req.params.contestid
				res.render("error", {
					message: "No contest predictions found for such contest! Click the button to add contest.",
					link: link});
			}
		});
	});

	app.use(function(req, res)
	{
		processor();
		res.status(500);
		res.render("error", {message: "Invalid link!"});
	});

	app.listen(8080);

	console.log('Listening on http://127.0.0.1:8080');
	
	processor();
	
});