promotions

cmd/cart/main.go

@@ -149,8 +149,11 @@ func main() {
 			// any matched actions (e.g. the Volymrabatt volume discount), which adjust
 			// TotalPrice/TotalDiscount on top of line items and vouchers.
 			promotionCtx := promotions.NewContextFromCart(g, promotions.WithNow(time.Now()))
-			_, actions := promotionService.EvaluateAll(promotionStore.Snapshot(), promotionCtx)
-			promotions.ApplyActions(g, actions)
+			results, _ := promotionService.EvaluateAll(promotionStore.Snapshot(), promotionCtx)
+			// ApplyResults applies qualifying actions in priority order and records
+			// every effect — both applied discounts and pending "spend X more for ..."
+			// nudges with their progress — in g.AppliedPromotions.
+			promotionService.ApplyResults(g, results, promotionCtx)
 			g.Version++
 			return nil
 		}),
@@ -275,6 +278,11 @@ func main() {
 	mux.Handle("/mcp", promotionMCP.Handler())
 	mux.Handle("/mcp/", promotionMCP.Handler())
 
+	// Stateless promotion evaluation: POST a (possibly partial) eval context and
+	// get back the resulting totals plus the applied/pending effect breakdown,
+	// without creating or mutating a real cart.
+	mux.HandleFunc("POST /promotions/evaluate", newPromotionEvaluateHandler(promotionStore, promotionService))
+
 	// only for local
 	mux.HandleFunc("GET /add/remote/{host}", func(w http.ResponseWriter, r *http.Request) {
 		pool.AddRemote(r.PathValue("host"))

cmd/cart/promotions_evaluate.go

@@ -0,0 +1,29 @@
+package main
+
+import (
+	"encoding/json"
+	"errors"
+	"io"
+	"net/http"
+
+	"git.k6n.net/mats/go-cart-actor/pkg/promotions"
+)
+
+// newPromotionEvaluateHandler serves POST /promotions/evaluate: it takes a
+// (possibly partial) evaluation context and returns the totals plus the
+// applied/pending promotion effects, without creating or mutating a real cart.
+// An empty body is treated as an empty context (evaluates against no items).
+func newPromotionEvaluateHandler(store *promotions.Store, svc *promotions.PromotionService) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		var req promotions.EvaluateRequest
+		if err := json.NewDecoder(r.Body).Decode(&req); err != nil && !errors.Is(err, io.EOF) {
+			http.Error(w, "invalid JSON body: "+err.Error(), http.StatusBadRequest)
+			return
+		}
+		resp := svc.Evaluate(store.Snapshot(), req)
+		w.Header().Set("Content-Type", "application/json")
+		if err := json.NewEncoder(w).Encode(resp); err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+		}
+	}
+}