badge endpoint

pkg/inventory/badge.go

@@ -0,0 +1,51 @@
+package inventory
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+)
+
+// StockReader abstracts the inventory getter for badge rendering.
+type StockReader interface {
+	GetInventory(ctx context.Context, sku SKU, locationID LocationID) (int64, error)
+}
+
+// BadgeHandler returns an http.HandlerFunc that renders an HTML stock badge fragment.
+func BadgeHandler(reader StockReader) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		sku := r.URL.Query().Get("sku")
+		if sku == "" {
+			http.Error(w, "missing sku parameter", http.StatusBadRequest)
+			return
+		}
+
+		locationID := LocationID(r.URL.Query().Get("location_id"))
+		if locationID == "" {
+			locationID = "default"
+		}
+
+		w.Header().Set("Content-Type", "text/html; charset=utf-8")
+		w.Header().Set("Cache-Control", "private, max-age=5")
+
+		qty, err := reader.GetInventory(r.Context(), SKU(sku), locationID)
+		if err != nil {
+			w.WriteHeader(http.StatusOK)
+			w.Write([]byte(`<span class="stock-badge stock-unknown" data-sku="` + sku + `">Availability unavailable</span>`))
+			return
+		}
+
+		var htmlSnippet string
+		switch {
+		case qty > 10:
+			htmlSnippet = fmt.Sprintf(`<span class="stock-badge stock-in-stock" data-sku="%s">✓ In stock</span>`, sku)
+		case qty > 0:
+			htmlSnippet = fmt.Sprintf(`<span class="stock-badge stock-low-stock" data-sku="%s">⚡ Only %d left!</span>`, sku, qty)
+		default:
+			htmlSnippet = fmt.Sprintf(`<span class="stock-badge stock-out-of-stock" data-sku="%s">✕ Out of stock</span>`, sku)
+		}
+
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte(htmlSnippet))
+	}
+}