silvrgit/lib/fx.js

const http = require('http');
const LimitedArray = require('limitedarray');
const trend = require('trend');
const logger = require('log4js').getLogger('fx');
const delay = (60000 * 30);
let fxCache = {};
let history = new LimitedArray(48); // one days worth in 5 minute chunks

function getFx() {
  logger.info('FX request');
  function fxQuery(callback) {
    let options = {
      host: 'openexchangerates.org',
                  //  port: 80,
      path: '/api/latest.json?app_id=0eb932cee3bc40259f824d4b4c96c7d2',
                  // method: 'GET',
      headers: { }
    };

    http.request(options).on('response', response => {
      let data = '';
      response.on('data', chunk => {
        data += chunk;
      });
      response.on('end', () => {
        logger.info('Data done...');
        callback(JSON.parse(data));
      });
      response.on('error', e => {
        logger.error(e);
      });
    }).end();
  }

  fxQuery(a => {
    logger.info('Got FX data. Storing it');
    fxCache = a;

    history.push(a.rates.GBP);
    fxCache.history = history.get();
    fxCache.trend = trend(fxCache.history, {avgPoints: 12});

  });
}

function updateFX() {
  logger.warn('updateBitcoin');
  getFx();
  const now = new Date();
  const mod = delay - (now.getTime() % delay);

  let fxUpdateFn = () => {
    updateFX();
  };
  setTimeout(fxUpdateFn.bind(this), mod + 10);
}

updateFX();

exports.doFx = (req, res) => {
  logger.info('FX request');
  res.setHeader('Content-Type', 'application/json');
  res.end(JSON.stringify(fxCache));

};