B2B-88: add starter kit structure and elements

packages/billing/stripe/src/services/create-stripe-checkout.ts

@@ -0,0 +1,136 @@
+import type { Stripe } from 'stripe';
+import { z } from 'zod';
+
+import type { CreateBillingCheckoutSchema } from '@kit/billing/schema';
+
+/**
+ * @description If set to true, users can start a trial without entering their credit card details
+ */
+const enableTrialWithoutCreditCard =
+  process.env.STRIPE_ENABLE_TRIAL_WITHOUT_CC === 'true';
+
+/**
+ * @name createStripeCheckout
+ * @description Creates a Stripe Checkout session, and returns an Object
+ * containing the session, which you can use to redirect the user to the
+ * checkout page
+ */
+export async function createStripeCheckout(
+  stripe: Stripe,
+  params: z.infer<typeof CreateBillingCheckoutSchema>,
+) {
+  // in MakerKit, a subscription belongs to an organization,
+  // rather than to a user
+  // if you wish to change it, use the current user ID instead
+  const clientReferenceId = params.accountId;
+
+  // we pass an optional customer ID, so we do not duplicate the Stripe
+  // customers if an organization subscribes multiple times
+  const customer = params.customerId ?? undefined;
+
+  // docs: https://stripe.com/docs/billing/subscriptions/build-subscription
+  const mode: Stripe.Checkout.SessionCreateParams.Mode =
+    params.plan.paymentType === 'recurring' ? 'subscription' : 'payment';
+
+  const isSubscription = mode === 'subscription';
+
+  let trialDays: number | null | undefined = params.plan.trialDays;
+
+  // if the customer already exists, we do not set a trial period
+  if (customer) {
+    trialDays = undefined;
+  }
+
+  const trialSettings =
+    trialDays && enableTrialWithoutCreditCard
+      ? {
+          trial_settings: {
+            end_behavior: {
+              missing_payment_method: 'cancel' as const,
+            },
+          },
+        }
+      : {};
+
+  // this should only be set if the mode is 'subscription'
+  const subscriptionData:
+    | Stripe.Checkout.SessionCreateParams.SubscriptionData
+    | undefined = isSubscription
+    ? {
+        trial_period_days: trialDays,
+        metadata: {
+          accountId: params.accountId,
+          ...(params.metadata ?? {}),
+        },
+        ...trialSettings,
+      }
+    : {};
+
+  const urls = getUrls({
+    returnUrl: params.returnUrl,
+  });
+
+  // we use the embedded mode, so the user does not leave the page
+  const uiMode = 'embedded';
+
+  const customerData = customer
+    ? {
+        customer,
+      }
+    : {
+        customer_email: params.customerEmail,
+      };
+
+  const customerCreation =
+    isSubscription || customer
+      ? ({} as Record<string, string>)
+      : { customer_creation: 'always' };
+
+  const lineItems = params.plan.lineItems.map((item) => {
+    if (item.type === 'metered') {
+      return {
+        price: item.id,
+      };
+    }
+
+    // if we pass a custom quantity for the item ID
+    // we use that - otherwise we set it to 1 by default
+    const quantity =
+      params.variantQuantities.find((variant) => {
+        return variant.variantId === item.id;
+      })?.quantity ?? 1;
+
+    return {
+      price: item.id,
+      quantity,
+    };
+  });
+
+  const paymentCollectionMethod =
+    enableTrialWithoutCreditCard && params.plan.trialDays
+      ? {
+          payment_method_collection: 'if_required' as const,
+        }
+      : {};
+
+  return stripe.checkout.sessions.create({
+    mode,
+    allow_promotion_codes: params.enableDiscountField,
+    ui_mode: uiMode,
+    line_items: lineItems,
+    client_reference_id: clientReferenceId,
+    subscription_data: subscriptionData,
+    ...customerCreation,
+    ...customerData,
+    ...urls,
+    ...paymentCollectionMethod,
+  });
+}
+
+function getUrls(params: { returnUrl: string }) {
+  const returnUrl = `${params.returnUrl}?session_id={CHECKOUT_SESSION_ID}`;
+
+  return {
+    return_url: returnUrl,
+  };
+}