Add Lemon Squeezy Billing System

packages/billing/lemon-squeezy/src/services/create-lemon-squeezy-checkout.ts

@@ -0,0 +1,82 @@
+import {
+  NewCheckout,
+  createCheckout,
+  getCustomer,
+} from '@lemonsqueezy/lemonsqueezy.js';
+import { z } from 'zod';
+
+import { CreateBillingCheckoutSchema } from '@kit/billing/schema';
+
+import { getLemonSqueezyEnv } from '../schema/lemon-squeezy-server-env.schema';
+import { initializeLemonSqueezyClient } from './lemon-squeezy-sdk';
+
+/**
+ * Creates a checkout for a Lemon Squeezy product.
+ *
+ * @param {object} params - The parameters for creating the checkout.
+ * @return {Promise<object>} - A promise that resolves to the created Lemon Squeezy checkout.
+ * @throws {Error} - If no line items are found in the subscription.
+ */
+export async function createLemonSqueezyCheckout(
+  params: z.infer<typeof CreateBillingCheckoutSchema>,
+) {
+  await initializeLemonSqueezyClient();
+
+  const lineItem = params.plan.lineItems[0];
+
+  if (!lineItem) {
+    throw new Error('No line items found in subscription');
+  }
+
+  const env = getLemonSqueezyEnv();
+  const storeId = env.storeId;
+  const variantId = lineItem.id;
+
+  const urls = getUrls({
+    returnUrl: params.returnUrl,
+  });
+
+  const customer = params.customerId
+    ? await getCustomer(params.customerId)
+    : null;
+
+  let customerEmail = params.customerEmail;
+
+  // if we can find an existing customer using the ID,
+  // we use the email from the customer object so that we can
+  // link the previous subscription to this one
+  // otherwise it will create a new customer if another email is provided (ex. a different team member)
+  if (customer?.data) {
+    customerEmail = customer.data.data.attributes.email;
+  }
+
+  const newCheckout: NewCheckout = {
+    checkoutOptions: {
+      embed: true,
+      media: true,
+      logo: true,
+    },
+    checkoutData: {
+      email: customerEmail,
+      custom: {
+        account_id: params.accountId,
+      },
+    },
+    productOptions: {
+      redirectUrl: urls.return_url,
+    },
+    expiresAt: null,
+    preview: true,
+    testMode: process.env.NODE_ENV !== 'production',
+  };
+
+  return createCheckout(storeId, variantId, newCheckout);
+}
+
+function getUrls(params: { returnUrl: string }) {
+  const returnUrl = `${params.returnUrl}?session_id={CHECKOUT_SESSION_ID}`;
+
+  return {
+    return_url: returnUrl,
+  };
+}