update customer

internal/ucp/customer.go

@@ -2,9 +2,12 @@ package ucp
 
 import (
 	"context"
+	"crypto/sha256"
+	"encoding/hex"
 	"encoding/json"
 	"fmt"
 	"net/http"
+	"time"
 
 	"git.k6n.net/mats/go-cart-actor/pkg/profile"
 	messages "git.k6n.net/mats/go-cart-actor/proto/profile"
@@ -24,7 +27,52 @@ func NewCustomerServer(applier ProfileApplier) *CustomerServer {
 // UCP Customer endpoints
 // ---------------------------------------------------------------------------
 
-// handleGetCustomer handles GET /customers/{id}.
+// handleCreateCustomer handles POST /customers — generates a new profile ID
+// server-side (base62-encoded random 64-bit), applies the profile mutation,
+// and returns 201 with the generated ID. Unlike PUT /customers/{id}, the
+// caller does not choose the identifier.
+func (s *CustomerServer) handleCreateCustomer(w http.ResponseWriter, r *http.Request) {
+	var req CustomerUpdateRequest
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid request body: "+err.Error())
+		return
+	}
+
+	rawId, err := profile.NewProfileId()
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, "failed to generate id")
+		return
+	}
+	id := uint64(rawId)
+
+	msg := &messages.SetProfile{
+		Name:      req.Name,
+		Email:     req.Email,
+		Phone:     req.Phone,
+		Language:  req.Language,
+		Currency:  req.Currency,
+		AvatarUrl: req.AvatarUrl,
+	}
+
+	if _, err := s.applier.Apply(r.Context(), id, msg); err != nil {
+		writeError(w, http.StatusInternalServerError, "failed to create customer: "+err.Error())
+		return
+	}
+
+	g, err := s.applier.Get(r.Context(), id)
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, "failed to read customer: "+err.Error())
+		return
+	}
+
+	writeJSON(w, http.StatusCreated, customerGrainToResponse(rawId.String(), g))
+}
+
+// handleGetCustomer handles GET /customers/{id} with ETag-based conditional
+// GET support. When the client sends If-None-Match matching the current ETag,
+// a 304 Not Modified is returned with no body — the caller reuses their cached
+// response. The ETag is derived from the grain's lastChange timestamp and
+// customer data hash, so it changes on any mutation.
 func (s *CustomerServer) handleGetCustomer(w http.ResponseWriter, r *http.Request) {
 	id, ok := parseCustomerID(r)
 	if !ok {
@@ -38,6 +86,19 @@ func (s *CustomerServer) handleGetCustomer(w http.ResponseWriter, r *http.Reques
 		return
 	}
 
+	etag := computeCustomerETag(r.PathValue("id"), g)
+
+	if match := r.Header.Get("If-None-Match"); match != "" {
+		if match == etag || match == "*" {
+			w.Header().Set("ETag", etag)
+			w.Header().Set("Vary", "Accept-Encoding")
+			w.WriteHeader(http.StatusNotModified)
+			return
+		}
+	}
+
+	w.Header().Set("ETag", etag)
+	w.Header().Set("Vary", "Accept-Encoding")
 	writeJSON(w, http.StatusOK, customerGrainToResponse(r.PathValue("id"), g))
 }
 
@@ -317,6 +378,15 @@ func containsNotFound(errStr string) bool {
 	return false
 }
 
+// computeCustomerETag returns a strong ETag for the customer's current state,
+// derived from the grain's lastChange timestamp and a hash of the ID + change
+// time. Any mutation (profile update, address change, linking) advances
+// lastChange, so the ETag changes when data changes.
+func computeCustomerETag(id string, g *profile.ProfileGrain) string {
+	h := sha256.Sum256([]byte(id + "\x00" + g.GetLastChange().Format(time.RFC3339Nano)))
+	return `"` + hex.EncodeToString(h[:16]) + `"`
+}
+
 // customerGrainToResponse converts a ProfileGrain to a CustomerResponse.
 func customerGrainToResponse(id string, g *profile.ProfileGrain) CustomerResponse {
 	resp := CustomerResponse{