handle dynamic json data and examples for subscription details

pkg/cart/mutation_upsert_subscriptiondetails.go

@@ -0,0 +1,57 @@
+package cart
+
+import (
+	"encoding/json"
+	"fmt"
+
+	messages "git.tornberg.me/go-cart-actor/pkg/messages"
+)
+
+func UpsertSubscriptionDetails(g *CartGrain, m *messages.UpsertSubscriptionDetails) error {
+	if m == nil {
+		return nil
+	}
+
+	// Create new subscription details when Id is nil.
+	if m.Id == nil {
+		// Validate JSON if provided.
+		var meta json.RawMessage
+		if m.Data != nil && len(m.Data.Value) > 0 {
+			if !json.Valid(m.Data.Value) {
+				return fmt.Errorf("subscription details invalid json")
+			}
+			meta = json.RawMessage(m.Data.Value)
+		}
+
+		id := MustNewCartId().String()
+		g.SubscriptionDetails[id] = &SubscriptionDetails{
+			Id:           id,
+			OfferingCode: m.OfferingCode,
+			SigningType:  m.SigningType,
+			Meta:         meta,
+		}
+		return nil
+	}
+
+	// Update existing entry.
+	existing, ok := g.SubscriptionDetails[*m.Id]
+	if !ok {
+		return fmt.Errorf("subscription details not found")
+	}
+	if m.OfferingCode != "" {
+		existing.OfferingCode = m.OfferingCode
+	}
+	if m.SigningType != "" {
+		existing.SigningType = m.SigningType
+	}
+	if m.Data != nil {
+		// Only validate & assign if there is content; empty -> leave as-is.
+		if len(m.Data.Value) > 0 {
+			if !json.Valid(m.Data.Value) {
+				return fmt.Errorf("subscription details invalid json")
+			}
+			existing.Meta = m.Data.Value
+		}
+	}
+	return nil
+}