add more payment related shit

pkg/cart/mutation_payment_started.go

@@ -0,0 +1,86 @@
+package cart
+
+import (
+	"fmt"
+	"strings"
+	"time"
+
+	messages "git.k6n.net/go-cart-actor/pkg/messages"
+)
+
+// PaymentStarted registers the beginning of a payment attempt for a cart.
+// It either upserts the payment entry (based on paymentId) or creates a new one,
+// marks the cart as having an in-progress payment, and recalculates the PaidInFull flag.
+func PaymentStarted(grain *CartGrain, msg *messages.PaymentStarted) error {
+	if msg == nil {
+		return fmt.Errorf("PaymentStarted: nil payload")
+	}
+	paymentID := strings.TrimSpace(msg.PaymentId)
+	if paymentID == "" {
+		return fmt.Errorf("PaymentStarted: missing paymentId")
+	}
+	if msg.Amount < 0 {
+		return fmt.Errorf("PaymentStarted: amount cannot be negative")
+	}
+
+	currency := strings.TrimSpace(msg.Currency)
+	provider := strings.TrimSpace(msg.Provider)
+	method := copyOptionalString(msg.Method)
+
+	startedAt := time.Now().UTC()
+	if msg.StartedAt != nil {
+		startedAt = msg.StartedAt.AsTime()
+	}
+
+	payment, found := grain.FindPayment(paymentID)
+
+	if found {
+		if payment.Status != PaymentStatusPending {
+			return fmt.Errorf("PaymentStarted: payment already started")
+		}
+		if payment.PaymentId != paymentID {
+			payment.PaymentId = paymentID
+		}
+		payment.Status = PaymentStatusPending
+		payment.Amount = msg.Amount
+		if currency != "" {
+			payment.Currency = currency
+		}
+		if provider != "" {
+			payment.Provider = provider
+		}
+		if method != nil {
+			payment.Method = method
+		}
+		payment.StartedAt = &startedAt
+		payment.CompletedAt = nil
+		payment.ProcessorReference = nil
+	} else {
+		grain.Payments = append(grain.Payments, &CartPayment{
+			PaymentId: paymentID,
+			Status:    PaymentStatusPending,
+			Amount:    msg.Amount,
+			Currency:  currency,
+			Provider:  provider,
+			Method:    method,
+			StartedAt: &startedAt,
+		})
+	}
+
+	grain.PaymentInProgress = true
+	grain.PaymentStatus = PaymentStatusPending
+
+	return nil
+}
+
+func copyOptionalString(src *string) *string {
+	if src == nil {
+		return nil
+	}
+	trimmed := strings.TrimSpace(*src)
+	if trimmed == "" {
+		return nil
+	}
+	dst := trimmed
+	return &dst
+}