foursquare.js

const request = require('request');

var foursquareUserToken = process.env["FOURSQUARE_USER_TOKEN"];
var foursquareConfig = {
  'secrets' : {
    'clientId' : process.env["FOURSQUARE_CLIENT_ID"],
    'clientSecret' : process.env["FOURSQUARE_CLIENT_SECRET"],
    'redirectUrl' : process.env["FOURSQUARE_REDIRECT_URI"]
  }
};
var foursquareApi = require('node-foursquare')(foursquareConfig);

var response = {
    message: "(none)"
};

exports.postToSlack = function(response, callback) {

    if (!response.report) {
        callback(response);
        return;
    }

    const url = process.env["SLACK_WEBHOOK_URL"];
    if (!url) {
        callback(response)
        return
    }

    request.post(
      {
        headers : { 'Content-type' : 'application/json' },
        url,
        form : {payload: JSON.stringify({text: response.merchant+': '+response.message})}
      },
      (error, res, body) => callback(response)
    );
};

exports.checkTransaction = function(body, callback) {

    var type = body.type;

    if (type != "transaction.created") {
        callback({"message":"Unsupported event type:" + type, report: false});
        return;
    }

    var tx = body.data;

    var myAccountId = process.env["MONZO_ACCOUNT_ID"];
    if (!myAccountId || (tx.account_id !== myAccountId)) {
        callback({"message": "Monzo Account ID does not match", report: true});
        return;
    }

    var merchant = tx.merchant;

    if (merchant.online) {
        callback({"message":"Unsupported transaction: online", report: false});
        return;
    }

    response.merchant = merchant.name

    // First we need a foursquare id
    if (merchant.metadata.foursquare_id) {

        console.log('getDetails for ' + merchant.metadata.foursquare_id);

        foursquareApi.Venues.getDetails(merchant.metadata.foursquare_id, {}, foursquareUserToken, function(error, fsqVenue) {

            console.log("Transaction detected at: " + merchant.name);

            /*
            // Foursquare response contains this block:
            beenHere: {
                count: 20,
                unconfirmedCount: 0,
                marked: true,
                lastVisitedAt: 1476107751,
                lastCheckinExpiredAt: 1476118551
            }
            */

            var beenHere = fsqVenue.venue.beenHere;

            // check been here before BUT not today / lastCheckinExpired
            if (beenHere.count > 0) {

                today = new Date();
                today.setHours(0);
                today.setMinutes(0);
                today.setSeconds(0);

                // check the tx time is today
                var txTime = new Date(Date.parse(tx.created));

                if (txTime.getTime() >= today.getTime()) {

                    var lastVisit = new Date(beenHere.lastVisitedAt * 1000);

                    if (lastVisit.getTime() < today.getTime()) {

                        // attempt checkin
                        foursquareApi.Checkins.add(merchant.metadata.foursquare_id, {}, foursquareUserToken, function(error, checkinResponse) {

                            if (error) {
                                response.message = "Error posting to Swarm";
                                response.error = error;
                                response.report = true;
                                callback(response);
                            } else {
                                response.message = "Checked-in 👍";
                                response.report = true;
                                callback(response);
                            }

                        });

                    } else {
                        response.message = 'Already checked in here today, abort!';
                        response.report = false;
                        callback(response);
                    }
                } else {
                    response.message = 'Transaction was not for today, abort!';
                    response.report = false;
                    callback(response);
                }

            } else {
                response.message = 'No previous checkins here, abort!';
                response.report = false;
                callback(response);
            }

        });

    } else {
        response.message = 'No foursquare ID available, abort!';
        response.report = false;
        callback(response);
    }

};