feat(#31): Add ability to record the stripe customer id in the customers table when a purchase is made

src/lib/utils/supabase/admin.ts

@@ -110,6 +110,31 @@ const createCustomerInStripe = async (uuid: string, email: string) => {
 	return newCustomer.id;
 };
 
+const getStripeCustomerId = async (email: string, uuid: string) => {
+	const { data: existingSupabaseCustomer, error: queryError } = await supabaseAdmin
+		.from('customers')
+		.select('*')
+		.eq('id', uuid)
+		.maybeSingle();
+
+	if (queryError) {
+		throw new Error(`Supabase customer lookup failed: ${queryError.message}`);
+	}
+
+	let stripeCustomerId: string | undefined;
+	if (existingSupabaseCustomer?.stripe_customer_id) {
+		const existingStripeCustomer = await stripeClient.customers.retrieve(
+			existingSupabaseCustomer.stripe_customer_id
+		);
+		stripeCustomerId = existingStripeCustomer.id;
+	} else {
+		const stripeCustomers = await stripeClient.customers.list({ email: email });
+		stripeCustomerId = stripeCustomers.data.length > 0 ? stripeCustomers.data[0].id : undefined;
+	}
+
+	return stripeCustomerId;
+};
+
 const createOrRetrieveCustomer = async ({ email, uuid }: { email: string; uuid: string }) => {
 	// Check if the customer already exists in Supabase
 	const { data: existingSupabaseCustomer, error: queryError } = await supabaseAdmin
@@ -453,5 +478,7 @@ export {
 	addCredits,
 	deductCredits,
 	getUserCredits,
-	getActiveProductsWithPrices
+	getActiveProductsWithPrices,
+	upsertCustomerToSupabase,
+	getStripeCustomerId
 };

src/routes/api/checkout/+server.ts

@@ -1,5 +1,7 @@
 import { type RequestHandler, redirect } from '@sveltejs/kit';
 import { stripe as stripeClient } from '$lib/utils/stripe';
+import { getStripeCustomerId } from '$lib/utils/supabase/admin';
+import type Stripe from 'stripe';
 
 // Create a checkout session
 export const POST: RequestHandler = async ({ request, cookies, locals: { safeGetSession } }) => {
@@ -26,9 +28,16 @@ export const POST: RequestHandler = async ({ request, cookies, locals: { safeGet
 		quantity: item.quantity
 	}));
 
-	const checkoutSession = await stripeClient.checkout.sessions.create({
-		customer_creation: 'always',
-		customer_email: userEmail,
+	let stripeCustomerId = null;
+
+	// Get the existing Stripe customer ID from Supabase, if it exists
+	try {
+		stripeCustomerId = await getStripeCustomerId(userEmail!, userId);
+	} catch (error) {
+		console.error('Error fetching Stripe customer ID:', error);
+	}
+
+	const stripeCheckoutSessionObject = {
 		line_items: lineItems,
 		mode: 'payment',
 		success_url: `${request.headers.get('origin')}/checkout/success`,
@@ -36,7 +45,18 @@ export const POST: RequestHandler = async ({ request, cookies, locals: { safeGet
 		metadata: {
 			userId: userId
 		}
-	});
+	} as Stripe.Checkout.SessionCreateParams;
+
+	if (stripeCustomerId) {
+		// If the user has a Stripe customer ID, attach it to the checkout session
+		stripeCheckoutSessionObject.customer = stripeCustomerId;
+	} else {
+		// If the user doesn't have a Stripe customer ID, create a new customer
+		stripeCheckoutSessionObject.customer_creation = 'always';
+		stripeCheckoutSessionObject.customer_email = userEmail;
+	}
+
+	const checkoutSession = await stripeClient.checkout.sessions.create(stripeCheckoutSessionObject);
 
 	// Store the checkout session.id for access from the frontend
 	cookies.set('checkout_session_id', checkoutSession.id, { path: '/' });

src/routes/api/checkout/create-customer/+server.ts

@@ -0,0 +1,16 @@
+import { json } from '@sveltejs/kit';
+import type { RequestHandler } from './$types';
+import { upsertCustomerToSupabase } from '$lib/utils/supabase/admin';
+
+export const GET: RequestHandler = async ({ url, locals: { safeGetSession } }) => {
+	const stripeCustomerId = url.searchParams.get('stripeCustomerId');
+	const { session } = await safeGetSession();
+
+	if (!session || !stripeCustomerId) {
+		return json({ error: 'Unauthorized' }, { status: 401 });
+	}
+
+	await upsertCustomerToSupabase(session?.user.id, stripeCustomerId);
+
+	return json({ message: 'Customer created' });
+};

src/routes/checkout/success/+page.ts

@@ -2,8 +2,8 @@ import type { PageLoad } from './$types';
 import { redirect } from '@sveltejs/kit';
 import Stripe from 'stripe';
 
-export const load: PageLoad = async ({fetch}) => {
-  const response = await fetch('/api/checkout/status');
+export const load: PageLoad = async ({ fetch }) => {
+	const response = await fetch('/api/checkout/status');
 	if (!response.ok) {
 		console.error('Failed to fetch checkout status');
 		return;
@@ -18,10 +18,19 @@ export const load: PageLoad = async ({fetch}) => {
 		throw redirect(303, '/checkout/cancelled');
 	}
 
+	// Save the stripe customer id in the customers table
+	const stripeCustomerId = checkoutSession.customer as string;
+	console.log('stripeCustomerId', stripeCustomerId);
+	const createCustomerResponse = await fetch(
+		'/api/checkout/create-customer?stripeCustomerId=' + stripeCustomerId
+	);
+	if (!createCustomerResponse.ok) {
+		console.error('Failed to create customer');
+	}
+
 	return {
 		checkoutSession,
 		lineItems,
 		paymentStatus
 	};
 };
-