Automatic Subscription Renewal / Cancellation Service via Receipt Validation

iap-manager.js

const moment = require('moment');
var appleReceiptVerify = require('node-apple-receipt-verify')

// initialise receipt verify instance
appleReceiptVerify.config({
  secret: process.env.APPLE_APP_STORE_SECRET,
  environment: [process.env.APPLE_APP_STORE_ENVIRONMENT],
  excludeOldTransactions: true,
  ignoreExpired: true,
});

// define service interval to 1 hour
const interval = 60 * 60 * 1000; 

module.exports = {

  // service logic - main function of service
  renewOrCancelSubscriptions: async function (client) {
    try {
      const db = client.db('my-app-db');

      // get accounts past renewal date
      const accounts = await db
        .collection('users')
        .find({
          'plan.nextRenewal': {
            $lte: moment().unix()
          }
        })
        .toArray();

      if (accounts.length === 0) {
        return;
      }

      // for each over-due account
      for (let account of accounts) {
        const expiryTimestamp = account.plan.expiryTimestamp;

        // get latest transaction from receipt
        const receipt = await db
          .collection('iap-receipts')
          .find({
            verified: true,
            user_id: account._id,
          })
          .sort({
            timestamp: -1
          })
          .toArray();

        try {

          // get latest subscription receipt
          const record = receipt[0];

          // re-verify receipt to get the latest subscription status
          const purchases = await appleReceiptVerify.validate({
            receipt: record.receipt
          });

          // no active transactions (cancelled or expired subscription)
          if(purchases.length === 0) {
            
            // change to free tier and remove plan metadata from user record
            await db
              .collection('users')
              .updateOne({
                _id: account._id
              }, {
                $unset: {
                  'plan.expiryTimestamp': true,
                },
                $set: {
                  'plan.planId': 'free'
                }
              });
          }

          // active purchases returned with latest expiry timestamp
          if (purchases.length !== 0) {
            
            // get the latest purchase from receipt verification
            const latestPurchase = purchases[0];

            // reformat the expiration date as a unix timestamp
            let latestExpiryTimestamp = latestPurchase.expirationDate;
            let productId = latestPurchase.productId;
            latestExpiryTimestamp = Math.round(latestExpiryTimestamp / 1000);

            // update renewal date if more than current one
            if (latestExpiryTimestamp > expiryTimestamp) {
              await db
                .collection('users')
                .updateOne({
                  _id: account._id
                }, {
                  $set: {
                    'plan.planId': productId,
                    'plan.nextRenewal': latestExpiryTimestamp
                  }
                });
            }
          }
        } catch (e) {
          console.log(e);
        }
      }
    } catch (e) {
      console.log(e);
    }
  },

  // define service loop and initiate service
  init: async function (client) {
    module.exports.renewOrCancelSubscriptions(client);

    setInterval(async function () {
      module.exports.renewOrCancelSubscriptions(client);
    }, interval)
  }
};