Webtask.io little hack

daily-exchange.js

/**
 * This script can be automatically triggered with IFTTT Stocks trigger and should 
 * be called with the following query string params:
 *
 * inputCurrency={{InputCurrency}}
 * outputCurrency={{OutputCurrency}}
 * exchangeRate={{ExchangeRate}}
 * infoUrl={{InfoUrl}}
 * checkTime={{CheckTime}}
 * 
 * And it will create a document in a mongoDB as per ctx.data.MONGO_URL
 * connection string.
 *
 * To create a webtask with it make sure you provide a secret as follows:
 * </pre>
 * $ wt create --secret MONGO_URL=mongodb://... daily-exchange.js
 * https://....run.webtask.io/exchange-analytic
 * </pre>
 * Keep in mind that you will need this URL to configure the IFTTT hook. 
 * 
 * @link https://auth0.com/blog/if-this-then-node-dot-js-extending-ifttt-with-webtask-dot-io/
 * @link https://ifttt.com/applets/50581531d For a working IFTTT trigger if Stock then Maker
 */
var MongoClient = require('mongodb').MongoClient;

/**
 * creates a doc in a mongoDB "exchange" collection for given Currencies and ratio.
 *
 * @param {db object} db Mongo db associated to ctx.data.MONGO_URL
 * @param {object} data contains all necessary info for the doc creation.
 */
var persist = function (db, data) {
  console.log(data);
  db.collection('exchange').insertOne(
    {
      "inputCurrency" : data.inputCurrency,
      "outputCurrency" : data.outputCurrency,
      "exchangeRate" : parseFloat(data.exchangeRate),
      "infoUrl" : data.infoUrl,
      "checkTime" : data.checkTime,
      "timestamp" : Date.parse(data.checkTime.split(' at ')[0] + ' (en-US)')
    },
    {"forceServerObjectId": true}
  ).then(r => console.log(r));
};

var cbRunner = function (err, cb, main) {
  if (err) {
    console.log("cbRunner error received");
    return cb(err);
  }
  main();
  return cb(null, "Success!");
};

module.exports = function (ctx, done) {
  return MongoClient.connect(
    ctx.data.MONGO_URL,
    (err, db) => cbRunner(err, done, () => persist(db, ctx.data))
  );
};

exchange-analytic.js

/**
 * This is an endpoint that can take useful insigths in gathered data.
 * Currently it shows last week and last month revenue for a given Currency pair.
 * Note that you must create one IFTTT hook for each Currency pair you want to keep updated.
 * Currently it shows the calculated values as a JSON:
 * 
 * {"weekRevenue":-0.058565..,"monthRevenue":-0.07215..}
 * The revnue is relative to one, with the current formula, a value of 1 means 100% revenue.  
 * 
 * This endpoint can be triggereg manually with the browser or curl, or by a REST client. 
 */
var MongoClient = require('mongodb').MongoClient;

var revenue = function (db, inputCurrency, outputCurrency) {
  var now = new Date();
  var today = new Date(now.getFullYear(), now.getMonth(), now.getDate(), 0, 0, 0);
  var lastWeek = new Date(now.getFullYear(), now.getMonth(), now.getDate() - 7, 0, 0, 0);
  var lastMonth = new Date(now.getFullYear(), now.getMonth() - 1, now.getDate(), 0, 0, 0);

  var docsArr = fetchDocs(db, today, lastWeek, lastMonth, inputCurrency, outputCurrency);

  return docsArr.then(function(docs) {
    var weekRevenue, monthRevenue;
    if (docs[0] && docs[1]) {
      weekRevenue = (docs[0].exchangeRate / docs[1].exchangeRate) - 1;
    }
    if (docs[0] && docs[2]) {
      monthRevenue = (docs[0].exchangeRate / docs[2].exchangeRate) - 1;
    }
    var out = {
      "weekRevenue": weekRevenue,
      "monthRevenue": monthRevenue
    };
      console.log(docsArr);
    console.log(out);
    return out;
  });
};

function fetchDocs (db, today, lastWeek, lastMonth, inputCurrency, outputCurrency){
  var query = {
    "$or" : [
      {"timestamp" : {$eq: Date.parse(today)}},
      {"timestamp" : {$eq: Date.parse(lastWeek)}},
      {"timestamp" : {$eq: Date.parse(lastMonth)}}
      ],
      "inputCurrency" : {"$eq": inputCurrency},
      "outputCurrency" : {"$eq": outputCurrency}
    };

  console.log(query, today,  Date.parse(today),  Date.parse(lastWeek),  Date.parse(lastMonth));
  return db.collection('exchange').find(query)
  .sort({"timestamp": -1})
  .toArray();
}

var cbRunner = function (err, cb, main) {
  if (err) {
    console.log("cbRunner error received");
    return cb(err);
  }
  main().then(out => cb(null, out));
};

module.exports = function (ctx, done) {
  return MongoClient.connect(
    ctx.data.MONGO_URL,
    (err, db) => cbRunner(err, done, () => revenue(db, ctx.data.inputCurrency, ctx.data.outputCurrency))
  );
};