Refactor billing data loading and schema configuration

This update enhances the capability of the billing system to handle different types of billing modes (subscription-based or one-time payments) and introduces an environment variable for configuring the preferred billing mode. It also refactors the data fetching process in the `loadPersonalAccountBillingPageData` and `loadTeamAccountBillingPageData` to retrieve the proper data depending on the chosen billing mode. Detailed documentation was added in README.md to guide the configuration of the billing schema.

apps/web/app/(dashboard)/home/[account]/_lib/server/team-account-billing-page.loader.ts

@@ -2,25 +2,105 @@ import 'server-only';
 
 import { cache } from 'react';
 
+import { SupabaseClient } from '@supabase/supabase-js';
+
+import { z } from 'zod';
+
 import { getSupabaseServerComponentClient } from '@kit/supabase/server-component-client';
 
+import { Database } from '~/lib/database.types';
+
+/**
+ * The variable BILLING_MODE represents the billing mode for a service. It can
+ * have either the value 'subscription' or 'one-time'. If not provided, the default
+ * value is 'subscription'. The value can be overridden by the environment variable
+ * BILLING_MODE.
+ *
+ * If the value is 'subscription', we fetch the subscription data for the user.
+ * If the value is 'one-time', we fetch the orders data for the user.
+ * if none of these suits your needs, please override the below function.
+ */
+const BILLING_MODE = z
+  .enum(['subscription', 'one-time'])
+  .default('subscription')
+  .parse(process.env.BILLING_MODE);
+
 export const loadTeamAccountBillingPage = cache((accountId: string) => {
   const client = getSupabaseServerComponentClient();
 
-  // TODO: improve these queries to only load the necessary data
-  const subscription = client
+  const data =
+    BILLING_MODE === 'subscription'
+      ? getSubscriptionData(client, accountId)
+      : getOrdersData(client, accountId);
+
+  const customerId = getBillingCustomerId(client, accountId);
+
+  return Promise.all([data, customerId]);
+});
+
+/**
+ * Get the subscription data for the given user.
+ * @param client
+ * @param accountId
+ */
+function getSubscriptionData(
+  client: SupabaseClient<Database>,
+  accountId: string,
+) {
+  return client
     .from('subscriptions')
     .select('*, items: subscription_items !inner (*)')
     .eq('account_id', accountId)
     .maybeSingle()
-    .then(({ data }) => data);
+    .then((response) => {
+      if (response.error) {
+        throw response.error;
+      }
 
-  const customerId = client
+      return response.data;
+    });
+}
+
+/**
+ * Get the orders data for the given user.
+ * @param client
+ * @param accountId
+ */
+function getOrdersData(client: SupabaseClient<Database>, accountId: string) {
+  return client
+    .from('orders')
+    .select('*, items: order_items !inner (*)')
+    .eq('account_id', accountId)
+    .maybeSingle()
+    .then((response) => {
+      if (response.error) {
+        throw response.error;
+      }
+
+      return response.data;
+    });
+}
+
+/**
+ * Get the billing customer ID for the given user.
+ * If the user does not have a billing customer ID, it will return null.
+ * @param client
+ * @param accountId
+ */
+function getBillingCustomerId(
+  client: SupabaseClient<Database>,
+  accountId: string,
+) {
+  return client
     .from('billing_customers')
     .select('customer_id')
     .eq('account_id', accountId)
     .maybeSingle()
-    .then(({ data }) => data?.customer_id);
+    .then((response) => {
+      if (response.error) {
+        throw response.error;
+      }
 
-  return Promise.all([subscription, customerId]);
-});
+      return response.data?.customer_id;
+    });
+}