Status Board Foursquare Server written in pure node.js

statusboard.js

/**
 * Status Board Foursquare Server
 */
var http = require('http');
var https = require('https');
var querystring = require('querystring');
var util = require('util');

/**
 * Configuration for the server
 */
var PORT = process.env.PORT;
var TOKEN = process.env.FOURSQUARE_TOKEN;
var IDS = process.env.FOURSQUARE_IDS.split(',').reduce(function(a, e) {
  a[e] = true;
  return a;
}, {});
var HEADER = [process.env.HEADER];

/**
 * Time Constants
 */
var MINUTE = 1000 * 60;
var HOUR = 60 * MINUTE;
var DAY = 24 * HOUR;
var WEEK = 7 * DAY;
var YEAR = 52 * WEEK;

/**
 * Foursquare reqeust params
 *
 * @constant
 * @type {Object}
 */
var FOURSQUARE = {
  hostname: 'api.foursquare.com',
  path: '/v2/checkins/recent?' + querystring.stringify({
    oauth_token: TOKEN
  })
};

/**
 * Gets the checkins from foursquare
 *
 * @param {Function} callback Called with the response directly
 */
var getCheckins = function(callback) {
  https.get(FOURSQUARE, function(res) {
    var buffer = '';

    res.on('data', function(chunk) {
      buffer += chunk;
    });

    res.on('end', function() {
      try {
        var data = JSON.parse(buffer);
        callback(null, data);
      } catch (err) {
        callback(err);
      }
    });
  }).on('error', function(err) {
    callback(err);
  });
};

/**
 * Checks if a checkin is from a friend
 *
 * @param  {Checkin}  checkin The checkin
 * @return {Boolean}          Whether or not it is from a friend
 */
var isFriend = function(checkin) {
  return IDS[checkin.user.id];
};

/**
 * Returns the initial of a name
 *
 * @param  {String} name The name
 * @return {String}      The first letter capitalized
 */
var initialOf = function(name) {
  return name[0].toUpperCase();
};

/**
 * Converts a delta into a delta string
 *
 * @param  {Number} delta    The time delta
 * @param  {Number} constant The time constant
 * @param  {String} suffix   The time suffix
 * @return {String}          The delta time string
 */
var toDeltaString = function(delta, constant, suffix) {
  return '' + Math.floor(delta / constant) + suffix;
};

/**
 * Gets the detla time string
 *
 * @param  {Number} time The timestampe from foursquare
 * @return {String}      The string representation
 */
var getDelta = function(time) {
  var delta = Date.now() - (time * 1000);

  if (delta > YEAR) {
    return toDeltaString(delta, YEAR, 'y');
  }

  if (delta > WEEK) {
    return toDeltaString(delta, WEEK, 'w');
  }

  if (delta > DAY) {
    return toDeltaString(delta, DAY, 'd');
  }

  if (delta > HOUR) {
    return toDeltaString(delta, HOUR, 'h');
  }

  if (delta > MINUTE) {
    return toDeltaString(delta, MINUTE, 'm');
  }

  return 'now';
};

/**
 * Converts a checkin into a row
 *
 * @param  {Checkin} checkin The checkin
 * @return {String}          The string representation
 */
var toRow = function(checkin) {
  var user = checkin.user;
  var name = initialOf(user.firstName) + initialOf(user.lastName);
  var venue = checkin.venue.name;
  var time = getDelta(checkin.createdAt);

  return util.format('"%s","%s (%s)"', name, venue, time);
};

/**
 * Handles requests to the server
 * 
 * @param {Request}  req
 * @param {Response} res
 */
var handleRequest = function(req, res) {
  getCheckins(function(err, checkins) {
    if (err) {
      console.error(err);
      res.status = 500;
      return res.end();
    }

    var rows = checkins.response.recent.filter(isFriend).map(toRow);
    var data = HEADER.concat(rows).join('\n');

    res.status = 200;
    res.setHeader('Content-Type', 'text/plain');
    res.end(data);
  });
};

var server = http.createServer(handleRequest);
server.listen(PORT);