chore: import upstream snapshot with attribution

apps/sim/lib/billing/stripe-payment-method.ts

@@ -0,0 +1,75 @@
+import { createLogger } from '@sim/logger'
+import { getErrorMessage } from '@sim/utils/errors'
+import type Stripe from 'stripe'
+
+const logger = createLogger('StripePaymentMethod')
+
+/**
+ * Extract the payment-method id from any of the shapes Stripe returns
+ * for a `default_payment_method` field (id string, full object, null,
+ * or undefined).
+ */
+function getPaymentMethodId(
+  pm: string | Stripe.PaymentMethod | null | undefined
+): string | undefined {
+  return typeof pm === 'string' ? pm : pm?.id
+}
+
+/**
+ * Extract the customer id from any of the shapes Stripe returns for a
+ * `customer` field (id string, full `Customer`, or `DeletedCustomer`).
+ */
+export function getCustomerId(
+  customer: string | Stripe.Customer | Stripe.DeletedCustomer | null | undefined
+): string | undefined {
+  if (!customer) return undefined
+  return typeof customer === 'string' ? customer : customer.id
+}
+
+/**
+ * Resolve a subscription's default payment method with fallback to the
+ * customer's invoice-settings PM. Used for ad-hoc invoices that are
+ * not directly linked to the subscription (overage, credits, threshold
+ * billing) so Stripe can auto-collect on finalize.
+ *
+ * Returns both the resolved PM id and the subscription's collection
+ * method so callers can pass it through to `invoices.create` without a
+ * second subscription retrieve. On any Stripe error the returned
+ * `collectionMethod` is `null` — callers should treat that as
+ * "unknown" and handle accordingly rather than assuming a default.
+ */
+export async function resolveDefaultPaymentMethod(
+  stripe: Stripe,
+  stripeSubscriptionId: string,
+  customerId: string
+): Promise<{
+  paymentMethodId: string | undefined
+  collectionMethod: 'charge_automatically' | 'send_invoice' | null
+}> {
+  let collectionMethod: 'charge_automatically' | 'send_invoice' | null = null
+  let paymentMethodId: string | undefined
+
+  try {
+    const sub = await stripe.subscriptions.retrieve(stripeSubscriptionId)
+    collectionMethod =
+      sub.collection_method === 'send_invoice' ? 'send_invoice' : 'charge_automatically'
+    paymentMethodId = getPaymentMethodId(sub.default_payment_method)
+
+    if (!paymentMethodId && collectionMethod === 'charge_automatically') {
+      const customer = await stripe.customers.retrieve(customerId)
+      if (customer && !('deleted' in customer)) {
+        paymentMethodId = getPaymentMethodId(
+          (customer as Stripe.Customer).invoice_settings?.default_payment_method
+        )
+      }
+    }
+  } catch (error) {
+    logger.warn('Failed to resolve default payment method', {
+      stripeSubscriptionId,
+      customerId,
+      error: getErrorMessage(error),
+    })
+  }
+
+  return { paymentMethodId, collectionMethod }
+}