Add getCustomerDefaultPaymentMethod method

Author: Definence

src/helpers/stripe_helpers.ts

@@ -22,6 +22,37 @@ export interface StripePaymentMethod {
   };
 }
 
+export interface StripeDefaultPaymentMethod {
+  id: string;
+  type: 'card' | 'us_bank_account';
+  object?: string;
+  card?: StripeCard;
+  us_bank_account?: StripeUSBankAccount;
+}
+
+export interface StripeCustomer {
+  data: {
+    invoice_settings?: {
+      default_payment_method?: StripeDefaultPaymentMethod;
+    };
+    sources?: {
+      data: Array<StripeCard & { id?: string; object?: string }>;
+    };
+  };
+}
+
+export interface CustomerDefaultPaymentMethod {
+  isPaymentMethod: boolean;
+  label: string;
+  last4: string;
+  expMonth?: number;
+  expYear?: number;
+  bankName?: string;
+  brand?: string;
+  id: string;
+  object: string;
+}
+
 export class StripeHelpers {
   /**
    * Returns a formatted card brand label. Abbreviates "American Express" to "Amex".
@@ -74,4 +105,77 @@ export class StripeHelpers {
     }
     return 'Unknown Card';
   }
+
+  /**
+   * Extracts the default payment method from a Stripe customer object
+   * @param stripeCustomer - A stripe customer object as returned by the API
+   * @param useFallback - Whether to return a dummy card if no card is found
+   * @returns Payment method information or null
+   */
+  static getCustomerDefaultPaymentMethod(
+    stripeCustomer: StripeCustomer | null,
+    useFallback = false
+  ): CustomerDefaultPaymentMethod | null {
+    if (!stripeCustomer || !stripeCustomer.data) return null;
+
+    const defaultPaymentMethod = stripeCustomer.data.invoice_settings?.default_payment_method;
+
+    if (defaultPaymentMethod?.type === 'card' && defaultPaymentMethod.card) {
+      const { card } = defaultPaymentMethod;
+      return {
+        isPaymentMethod: true,
+        label: StripeHelpers.getCardLabel(card),
+        last4: card.last4 || '',
+        expMonth: card.exp_month,
+        expYear: card.exp_year,
+        brand: card.brand,
+        id: defaultPaymentMethod.id,
+        object: defaultPaymentMethod.object || 'payment_method',
+      };
+    } else if (
+      defaultPaymentMethod?.type === 'us_bank_account' &&
+      defaultPaymentMethod.us_bank_account
+    ) {
+      const { us_bank_account } = defaultPaymentMethod;
+      return {
+        isPaymentMethod: true,
+        label: StripeHelpers.getUSBankAccountLabel(us_bank_account),
+        last4: us_bank_account.last4,
+        bankName: us_bank_account.bank_name,
+        id: defaultPaymentMethod.id,
+        object: defaultPaymentMethod.object || 'payment_method',
+      };
+    }
+
+    const defaultSource = stripeCustomer.data.sources?.data?.[0];
+
+    if (defaultSource && 'last4' in defaultSource && 'exp_month' in defaultSource) {
+      const card = defaultSource as StripeCard & { id?: string; object?: string };
+      return {
+        isPaymentMethod: false,
+        label: StripeHelpers.getCardLabel(card),
+        last4: card.last4 || '',
+        expMonth: card.exp_month,
+        expYear: card.exp_year,
+        brand: card.brand,
+        id: card.id || '',
+        object: card.object || 'card',
+      };
+    }
+
+    if (useFallback) {
+      return {
+        isPaymentMethod: false,
+        label: 'Unknown Card',
+        last4: 'XXXX',
+        expMonth: 0,
+        expYear: 0,
+        brand: 'Unknown',
+        id: 'N/A',
+        object: 'card',
+      };
+    }
+
+    return null;
+  }
 }