even more refactoring

mutation_set_pickup_point.go

@@ -0,0 +1,56 @@
+package main
+
+import (
+	"fmt"
+
+	messages "git.tornberg.me/go-cart-actor/proto"
+)
+
+// mutation_set_pickup_point.go
+//
+// Registers the SetPickupPoint mutation using the generic mutation registry.
+//
+// Semantics (mirrors original switch-based implementation):
+//   - Locate the delivery with Id == payload.DeliveryId
+//   - Set (or overwrite) its PickupPoint with the provided data
+//   - Does NOT alter pricing or taxes (so no totals recalculation required)
+//
+// Validation / Error Handling:
+//   - If payload is nil -> error
+//   - If DeliveryId not found -> error
+//
+// Concurrency:
+//   - Relies on the existing expectation that higher-level mutation routing
+//     serializes Apply() calls per grain; if stricter guarantees are needed,
+//     a delivery-level lock could be introduced later.
+//
+// Future Extensions:
+//   - Validate pickup point fields (country code, zip format, etc.)
+//   - Track history / audit of pickup point changes
+//   - Trigger delivery price adjustments (which would then require WithTotals()).
+func init() {
+	RegisterMutation[messages.SetPickupPoint](
+		"SetPickupPoint",
+		func(g *CartGrain, m *messages.SetPickupPoint) error {
+			if m == nil {
+				return fmt.Errorf("SetPickupPoint: nil payload")
+			}
+
+			for _, d := range g.Deliveries {
+				if d.Id == int(m.DeliveryId) {
+					d.PickupPoint = &messages.PickupPoint{
+						Id:      m.Id,
+						Name:    m.Name,
+						Address: m.Address,
+						City:    m.City,
+						Zip:     m.Zip,
+						Country: m.Country,
+					}
+					return nil
+				}
+			}
+			return fmt.Errorf("SetPickupPoint: delivery id %d not found", m.DeliveryId)
+		},
+		// No WithTotals(): pickup point does not change pricing / tax.
+	)
+}