feat(stripe): add booking_id metadata to payment links

Refactored payment link creation to ensure booking_id is set in both the
PaymentLink and PaymentIntent metadata. Extracted parameter building
logic
into a helper for improved testability. Added a unit test to verify
metadata propagation.

internal/driver/stripe/client.go

@@ -125,18 +125,37 @@ type CreatePaymentLinkParams struct {
 
 // CreatePaymentLink creates a payment link for the provided booking metadata and amount.
 func (c *Client) CreatePaymentLink(ctx context.Context, params CreatePaymentLinkParams) (string, error) {
+	linkParams, err := buildPaymentLinkCreateParams(params)
+	if err != nil {
+		return "", err
+	}
+
+	linkParams.Context = ctx
+
+	pl, err := c.api.V1PaymentLinks.Create(ctx, linkParams)
+	if err != nil {
+		return "", fmt.Errorf("failed to create payment link: %w", err)
+	}
+
+	return pl.URL, nil
+}
+
+func buildPaymentLinkCreateParams(params CreatePaymentLinkParams) (*stripe.PaymentLinkCreateParams, error) {
 	if params.Amount <= 0 {
-		return "", errors.New("amount must be greater than zero")
+		return nil, errors.New("amount must be greater than zero")
 	}
 	currency := strings.ToLower(strings.TrimSpace(params.Currency))
 	if currency == "" {
-		return "", errors.New("currency is required")
+		return nil, errors.New("currency is required")
 	}
 	if params.BookingID == 0 {
-		return "", errors.New("booking id is required")
+		return nil, errors.New("booking id is required")
 	}
 
 	amountCents := int64(math.Round(params.Amount * 100))
+	metadata := map[string]string{
+		"booking_id": strconv.FormatUint(uint64(params.BookingID), 10),
+	}
 
 	linkParams := &stripe.PaymentLinkCreateParams{
 		LineItems: []*stripe.PaymentLinkCreateLineItemParams{
@@ -151,8 +170,9 @@ func (c *Client) CreatePaymentLink(ctx context.Context, params CreatePaymentLink
 				Quantity: stripe.Int64(1),
 			},
 		},
-		Metadata: map[string]string{
-			"booking_id": strconv.FormatUint(uint64(params.BookingID), 10),
+		Metadata: metadata,
+		PaymentIntentData: &stripe.PaymentLinkCreatePaymentIntentDataParams{
+			Metadata: metadata,
 		},
 	}
 
@@ -164,14 +184,7 @@ func (c *Client) CreatePaymentLink(ctx context.Context, params CreatePaymentLink
 		linkParams.PaymentMethodTypes = stripe.StringSlice(params.PaymentMethodTypes)
 	}
 
-	linkParams.Context = ctx
-
-	pl, err := c.api.V1PaymentLinks.Create(ctx, linkParams)
-	if err != nil {
-		return "", fmt.Errorf("failed to create payment link: %w", err)
-	}
-
-	return pl.URL, nil
+	return linkParams, nil
 }
 
 func deriveMethod(pi *stripe.PaymentIntent) string {

internal/driver/stripe/client_test.go

@@ -0,0 +1,28 @@
+package stripe
+
+import "testing"
+
+func TestBuildPaymentLinkCreateParamsSetsBookingMetadataOnPaymentIntent(t *testing.T) {
+	params, err := buildPaymentLinkCreateParams(CreatePaymentLinkParams{
+		Amount:             120.50,
+		Currency:           "EUR",
+		BookingID:          42,
+		Description:        "Villa booking",
+		PaymentMethodTypes: []string{"card"},
+	})
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if params.Metadata["booking_id"] != "42" {
+		t.Fatalf("payment link metadata missing booking id: %+v", params.Metadata)
+	}
+
+	if params.PaymentIntentData == nil {
+		t.Fatal("payment intent data should not be nil")
+	}
+
+	if params.PaymentIntentData.Metadata["booking_id"] != "42" {
+		t.Fatalf("payment intent metadata missing booking id: %+v", params.PaymentIntentData.Metadata)
+	}
+}