Create methods to create a Stripe customer and subscribe to a plan

go.mod

@@ -3,13 +3,11 @@ module myapp
 go 1.22.5
 
 require (
+	github.com/alexedwards/scs/v2 v2.8.0
 	github.com/go-chi/chi/v5 v5.1.0
 	github.com/go-chi/cors v1.2.1
 	github.com/go-sql-driver/mysql v1.8.1
 	github.com/stripe/stripe-go/v79 v79.6.0
 )
 
-require (
+require filippo.io/edwards25519 v1.1.0 // indirect
-	filippo.io/edwards25519 v1.1.0 // indirect
-	github.com/alexedwards/scs/v2 v2.8.0 // indirect
-)

internal/cards/cards.go

@@ -2,8 +2,10 @@ package cards
 
 import (
 	"github.com/stripe/stripe-go/v79"
+	"github.com/stripe/stripe-go/v79/customer"
 	"github.com/stripe/stripe-go/v79/paymentintent"
 	"github.com/stripe/stripe-go/v79/paymentmethod"
+	"github.com/stripe/stripe-go/v79/subscription"
 )
 
 type Card struct {
@@ -71,6 +73,51 @@ func (c *Card) RetrievePaymentIntent(id string) (*stripe.PaymentIntent, error) {
 	return pi, nil
 }
 
+func (c *Card) SubscribeToPlan(
+	cust *stripe.Customer,
+	plan, email, last4, cardType string,
+) (string, error) {
+	stripeCustomerID := cust.ID
+	items := []*stripe.SubscriptionItemsParams{
+		{Plan: stripe.String(plan)},
+	}
+
+	params := &stripe.SubscriptionParams{
+		Customer: stripe.String(stripeCustomerID),
+		Items:    items,
+	}
+
+	params.AddMetadata("last_four", last4)
+	params.AddMetadata("card_type", cardType)
+	params.AddExpand("latest_invoice.payment_intent")
+	subscription, err := subscription.New(params)
+	if err != nil {
+		return "", err
+	}
+	return subscription.ID, nil
+}
+
+func (c *Card) CreateCustomer(pm, email string) (*stripe.Customer, string, error) {
+	stripe.Key = c.Secret
+	customerParams := &stripe.CustomerParams{
+		PaymentMethod: stripe.String(pm),
+		Email:         stripe.String(email),
+		InvoiceSettings: &stripe.CustomerInvoiceSettingsParams{
+			DefaultPaymentMethod: stripe.String(pm),
+		},
+	}
+
+	cust, err := customer.New(customerParams)
+	if err != nil {
+		msg := ""
+		if stripeErr, ok := err.(*stripe.Error); ok {
+			msg = cardErrorMessage(stripeErr.Code)
+		}
+		return nil, msg, err
+	}
+	return cust, "", nil
+}
+
 func cardErrorMessage(code stripe.ErrorCode) string {
 	msg := ""