scheduler-user-reminder.js

// heroku scheduler script for email reminders for the users who hasn't updated the status last 7 days
// heroku scheduler runs every day 

var MongoClient = require('mongodb').MongoClient;
var ObjectId = require('mongodb').ObjectId;

const sgClient = require('@sendgrid/mail');
sgClient.setApiKey(process.env.SENDGRID_API_KEY); 
var sender = process.env.SENDGRID_EMAIL;

MongoClient.connect(process.env.MONGO_URL).then(function (db) {
    console.log("CONNECTED TO DB");
    checkUsersStatus(db);

}).catch(err => {
    console.error("An error occurred reading the database.");
    console.error(err);
});

function checkUsersStatus(db) {

    // get all users 
    // for each user check status date greater than 7 days
    let counter = 0;

    var checkDate = new Date();
    var pastDate = checkDate.getDate() - 7;
    checkDate.setDate(pastDate);

    let collection = db.collection('users');
    let statusCollection = db.collection('status');
    let allUsersCount = 0
    let emails = [];

    collection.find().count().then(function (count) {
        console.log("Total users count :", count);

        allUsersCount = count;

        const cursor = collection.find();
        cursor.forEach(function (user) {

            statusCollection.find({
                user: ObjectId(new ObjectId(user._id)),
                date: {
                    "$gte": checkDate
                }
            }).count().then(function (count) {

                if (count === 0) {
                    console.log("user has not updated status", user.email);
                    emails.push(user.email);
                    isDone();
                } else {
                    isDone();
                }

            });
        }, function (err) {

        });

    });


    function isDone() {
        counter += 1;
        //console.log("isDONE", allUsersCount, counter)
        if (allUsersCount === counter) {
            sendEmail(emails);
        }
    }

}

sendEmail = (toEmails) => {
    console.log("emails", toEmails)
    // TEST
    toEmails= ["eertugrul@thorntontomasetti.com", "lkunjukutty@thorntontomasetti.com"];
    const mailOptions = {
        to: toEmails,
        from: sender,
        subject: "Please report your status",
        text: "This is a friendly reminder that you haven't reported your status last 7 days, please sign in the Healthy Reentry app and submit your status."
    };

    sgClient.sendMultiple(mailOptions, function (err) {
        console.log("err?", err)
        if (err)
            return;
        else
            console.log('sent');


    });

}