index.js

var express = require('express');
var https = require('https');
var moment = require('moment-timezone');
var nodeCache = require('node-cache');
var util = require('util');
var zlib = require('zlib');

var config = require('./config.json');
var userAgent = util.format('xmlstats-exnode/%s (%s)', config.version, config.user_agent_contact);
var authorization = util.format('Bearer %s', config.access_token);

var shortDate = 'YYYYMMDD';
var longDate = 'dddd, MMMM D, YYYY';

// instruct cache to keep items for 10 minutes
var cache = new nodeCache({ stdTTL: 600 });

var app = express();
app.set('view engine', 'jade');
app.use(express.static(__dirname + '/css'));
app.use(express.static(__dirname + '/'));
app.locals.moment = require('moment-timezone');

// See https://erikberg.com/api/endpoints#requrl Request URL Convention
// for an explanation
var xmlstatsUrl = {
    host: 'erikberg.com',
    sport: undefined,
    endpoint: 'events',
    id: undefined,
    format: 'json',
    params: {
      sport: 'mlb',
      date: ''
    }
};

// This web app responds to requests to "GET /" and "GET /yyyyMMdd"
// and returns 404 for everything else. The default is to return
// data for the current date. Otherwise, it checks for an 'id' parameter
// that contains a valid date in yyyyMMdd format and returns data for that
// date.
app.get('/:id?', function (req, res) {
  xmlstatsUrl.params.date = moment().format(shortDate);
  console.log(req.params)
  if (req.params.id) {
    if (moment(req.params.id, shortDate, true).isValid()) {
      xmlstatsUrl.params.date = formatDate(req.params.id, shortDate);
    } else {
      res.status(404).render('error', { code: 404, reason: 'Invalid date.' });
      return;
    }
  }

  var url = buildUrl(xmlstatsUrl);

  httpGet(url, function (statusCode, contentType, data) {
    if (statusCode !== 200) {
      console.warn('Server did not return a "200 OK" response! ' +
          'Got "%s" instead.', statusCode);
      // If error response is of type 'application/json', it will be an
      // XmlstatsError see https://erikberg.com/api/objects/xmlstats-error
      var reason = (contentType === 'application/json')
          ? data.error.description
          : data;
      res.status(statusCode).render('error', { code: statusCode, reason: reason });
      return;
    }
    // Store good response in cache
    cache.set(url, data);
    var titleDate = formatDate(data.events_date, longDate);
    res.render('index', { header: titleDate, events: data });
  });
});

function httpGet(url, callback) {
  var data = cache.get(url);
  if (data) {
    callback(200, 'application/json', data);
    return;
  }

  var options = {
    hostname: xmlstatsUrl.host,
    path: url,
    headers: {
      'Accept-Encoding': 'gzip',
      Authorization: authorization,
      'User-Agent': userAgent
    }
  };

  var req = https.get(options, function(res) {
    var content;
    var data = [];

    if (res.headers['content-encoding'] === 'gzip') {
      var gzip = zlib.createGunzip();
      res.pipe(gzip);
      content = gzip;
    } else {
      content = res;
    }

    content.on('data', function (chunk) {
      data.push(chunk);
    });

    content.on('end', function() {
      var json = JSON.parse(Buffer.concat(data));
      callback(res.statusCode, res.headers['content-type'], json);
    });
  });

  req.on('error', function (err) {
    callback(500, 'text/plain', 'Unable to contact server: ' + err.message);
    console.error('Unable to contact server: %s', err.message);
  });
}

function formatDate(date, fmt) {
  return moment.tz(date, config.time_zone).format(fmt);
}

// See https://erikberg.com/api/endpoints#requrl Request URL Convention
// for an explanation
function buildUrl(opts) {
  var ary = [opts.sport, opts.endpoint, opts.id];

  var path = ary.filter(function (element) {
    return element !== undefined;
  }).join('/');
  var url = util.format('https://%s/%s.%s', opts.host, path, opts.format);

  // check for parameters and create parameter string
  if (opts.params) {
    var paramList = [];
    for (var key in opts.params) {
      if (opts.params.hasOwnProperty(key)) {
        paramList.push(util.format('%s=%s',
            encodeURIComponent(key), encodeURIComponent(opts.params[key])));
      }
    }
    var paramString = paramList.join('&');
    if (paramList.length > 0) {
      url += '?' + paramString;
    }
  }
  return url;
}

app.listen(8000);