handle checkout resume

main.go

@@ -199,6 +199,9 @@ func main() {
 		w.Write([]byte("ok"))
 	})
 	mux.HandleFunc("/checkout", func(w http.ResponseWriter, r *http.Request) {
+		orderId := r.URL.Query().Get("order_id")
+		order := &CheckoutOrder{}
+		if orderId == "" {
 			cookie, err := r.Cookie("cartid")
 			if err != nil {
 				w.WriteHeader(http.StatusBadRequest)
@@ -224,13 +227,21 @@ func main() {
 				w.WriteHeader(http.StatusInternalServerError)
 				w.Write([]byte(err.Error()))
 			}
-		order := CheckoutOrder{}
 			err = json.Unmarshal(reply.Payload, &order)
 			if err != nil {
 				w.WriteHeader(http.StatusInternalServerError)
 				w.Write([]byte(err.Error()))
 				return
 			}
+		} else {
+			prevOrder, err := KlarnaInstance.GetOrder(orderId)
+			if err != nil {
+				w.WriteHeader(http.StatusBadRequest)
+				w.Write([]byte(err.Error()))
+				return
+			}
+			order = prevOrder
+		}
 		w.Header().Set("Content-Type", "text/html; charset=utf-8")
 		w.WriteHeader(http.StatusOK)
 		w.Write([]byte(fmt.Sprintf(tpl, order.HTMLSnippet)))