Added migration to backfill offer ids in subscriptions (#14511)

refs https://github.com/TryGhost/Team/issues/1520

- Sets the `offer_id` in the `members_stripe_customers_subscriptions` table based on the `offer_redemptions` that have the same tier and cadence
- We currently use the same subscription <-> offer linking when viewing a member
- The MySQL query is quite optimized in a single UPDATE query, but in SQLite we'll need to run (maximum) one UPDATE query for every offer (not per subscription).
- Best to merge this migration in 4.x (not in 5.0) because it is better (less error prone) to run this migration before starting to fill the offer_id field for updated migrations instead of after (https://github.com/TryGhost/Ghost/pull/14488)
- We need the SQLite migration for sites that will only migrate to MySQL at 5.0

core/server/data/migrations/versions/4.45/2022-04-19-12-23-backfill-subscriptions-offers.js

@@ -0,0 +1,60 @@
+const logging = require('@tryghost/logging');
+const DatabaseInfo = require('@tryghost/database-info');
+
+const {createTransactionalMigration} = require('../../utils');
+
+module.exports = createTransactionalMigration(
+    async function up(knex) {
+        logging.info('Backfilling "offer_id" column in "members_stripe_customers_subscriptions" by matching tier and cadence');
+
+        const subquery = `
+            SELECT
+                members_stripe_customers_subscriptions.id as subscription_id,
+                offer_redemptions.offer_id as offer_id
+            FROM
+                members_stripe_customers_subscriptions
+                JOIN offer_redemptions ON offer_redemptions.subscription_id = members_stripe_customers_subscriptions.id
+                JOIN offers ON offers.id = offer_redemptions.offer_id
+                JOIN stripe_prices ON members_stripe_customers_subscriptions.stripe_price_id = stripe_prices.stripe_price_id
+                JOIN stripe_products ON stripe_prices.stripe_product_id = stripe_products.stripe_product_id
+            WHERE
+                offers.product_id = stripe_products.product_id
+                AND offers.interval = stripe_prices.interval
+                AND members_stripe_customers_subscriptions.offer_id is null
+        `;
+
+        if (DatabaseInfo.isSQLite(knex)) {
+            // Less optimized for SQLite
+            const result = await knex.raw(subquery);
+            const updatedRows = result.length;
+            const subscriptionsToUpdate = result;
+
+            logging.info(`Setting the offer_id for ${updatedRows} members_stripe_customers_subscriptions`);
+
+            // eslint-disable-next-line no-restricted-syntax
+            for (const u of subscriptionsToUpdate) { 
+                // eslint-disable-next-line no-restricted-syntax
+                await knex('members_stripe_customers_subscriptions')
+                    .update('offer_id', u.offer_id)
+                    .where('id', u.subscription_id); 
+            }
+        } else {
+            // Single update query
+            const query = `
+                UPDATE 
+                    members_stripe_customers_subscriptions,
+                    (${subquery}) as c
+                SET members_stripe_customers_subscriptions.offer_id = c.offer_id
+                WHERE c.subscription_id = members_stripe_customers_subscriptions.id
+            `;
+
+            const result = await knex.raw(query);
+            const updatedRows = result[0].affectedRows;
+
+            logging.info(`Updated ${updatedRows} members_stripe_customers_subscriptions with an offer_id`);
+        }
+    },
+    async function down() {
+        // We risk losing data if we would reset offer_id here
+    }
+);