Watch for discounts on Steam games!

steamSaleWatch.js

'use strict';

// npm install cheerio colors moment optimist

// builtins
var http   = require('http'),
// 3rd party
    cheerio = require('cheerio'),
    colors  = require('colors/safe'),
    moment  = require('moment'),
    argv    = require('optimist')
              .usage('\nWatch steam sale items.\n\nUsage: $0')
              .demand(['g', 'i', 'p'])
              .default({g: 730, i: 60, p: 50})
              .describe({'b':'check a bundle, not an individual game',
                         'g':'a game / bundle id',
                         'i':'an interval in seconds',
                         'p':'a target discount percentage',
                         'q':'quiet - only alert when percentage drops below target'})
              .argv;

// globals
var checkInterval = (parseInt(argv.i) * 1000),
    condition = '';

//
// main
//

console.log('\nchecking item ' + colors.yellow(argv.g) + ' every ' + argv.i + ' seconds.\n');

checkItem(argv.g);

setInterval(function() { checkItem(argv.g) }, checkInterval);

//
// functions
//
function checkItem(itemId) {

  var type = 'app';

  if (argv.b) {
    var type = 'sub';
  }

  var html = '',
      options = {
        headers: {
          'user-agent':'Mozilla/5.0 (Windows NT 6.3; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2049.0 Safari/537.36'
        },
        hostname: 'store.steampowered.com',
        path: '/' + type + '/' + itemId
      };

  var req = http.request(options, function (res) {
    if (res.statusCode == '500' ) {
      console.log('item does not exist');
      return;
    };

    if (res.statusCode != '200') {
      console.log('bad http response, is steam store down?');
      return;
    };

    res.on('data', function (chunk) {

      html += chunk;

    }).on('end', function () {
      // now that we've finished reading the page
      var $ = cheerio.load(html),
          itemName = '',
          discountPercent = '';

      if (argv.b) {
        itemName = $('.pageheader').html(),
        discountPercent = $('div.game_purchase_action:nth-child(4) > div:nth-child(1) > div:nth-child(1)').html();
      } else {
        itemName = $('.apphub_AppName').html(),
        discountPercent = $('div.game_purchase_action:nth-child(5) > div:nth-child(1) > div:nth-child(1) > div:nth-child(1)').html();
      }

      if (!discountPercent) {
        console.log(colors.red(itemName + ' is not currently on sale'));
      } else {
        if (Math.abs(parseInt(discountPercent)) > argv.p) {
          console.log(colors.green(itemName + ' currently on sale at ' + discountPercent + ' retail!!!'));
        } else {
          if (!argv.q) {
            console.log(colors.yellow(itemName) + ' currently on sale at ' + discountPercent + ' retail');
          }
        }
      }
    });
  });

  req.on('error', function (err) {
    console.log('error: ' + err.message);
  });

  req.write('\n');

  req.end();
}