add spa handler

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

handler.go

@@ -199,8 +199,7 @@ func (h *Server) HTTPHandlerFunc(handler interface{}) (http.HandlerFunc, error)
 
 		cf, err := h.newCodec(ct)
 		if err != nil {
-			w.WriteHeader(http.StatusBadRequest)
-			_, _ = w.Write([]byte(err.Error()))
+			w.WriteHeader(http.StatusUnsupportedMediaType)
 			return
 		}
 
@@ -312,7 +311,7 @@ func (h *Server) HTTPHandlerFunc(handler interface{}) (http.HandlerFunc, error)
 		}
 		if nct := w.Header().Get(metadata.HeaderContentType); nct != ct {
 			if cf, err = h.newCodec(nct); err != nil {
-				h.errorHandler(ctx, nil, w, r, err, http.StatusBadRequest)
+				h.errorHandler(ctx, nil, w, r, err, http.StatusInternalServerError)
 				return
 			}
 		}
@@ -679,7 +678,7 @@ func (h *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}
 	if nct := w.Header().Get(metadata.HeaderContentType); nct != ct {
 		if cf, err = h.newCodec(nct); err != nil {
-			h.errorHandler(ctx, nil, w, r, err, http.StatusBadRequest)
+			h.errorHandler(ctx, nil, w, r, err, http.StatusInternalServerError)
 			return
 		}
 	}

handler/spa/spa.go

@@ -0,0 +1,19 @@
+package spa
+
+import (
+	"io/fs"
+	"net/http"
+	"strings"
+)
+
+// Handler serve files from dir and redirect to index if file not exists
+var Handler = func(prefix string, dir fs.FS) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		f := http.StripPrefix(prefix, http.FileServer(http.FS(dir)))
+		if _, err := fs.Stat(dir, strings.TrimPrefix(r.RequestURI, prefix)); err != nil {
+			r.RequestURI = prefix
+			r.URL.Path = prefix
+		}
+		f.ServeHTTP(w, r)
+	}
+}