silvrgit/lib/fx.js

const http = require('http');
const LimitedArray = require('limitedarray');
const trend = require('trend');
const logger = require('log4js').getLogger('fx');
const delay = 2764800; // 32 days divided by 1000
let fxCache = {};
const history = new LimitedArray(48); // one days worth in 5 minute chunks

function getFx() {
  logger.info('FX request');
  function fxQuery(callback) {
    const 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;

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

function updateFX() {
  logger.warn('updateBitcoin');

  const now = new Date();

  if (now.getTime() > 1505696400000) 
    getFx();
  
  const mod = delay - (now.getTime() % delay);

  const 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));
};