Extract middleware into function

handler.go

@@ -112,12 +112,13 @@ func NewHandler(config Config) (*Handler, error) {
 		dataStore:       config.DataStore,
 		basePath:        base,
 		isBasePathAbs:   uri.IsAbs(),
-		routeHandler:    mux,
 		locks:           make(map[string]bool),
 		CompleteUploads: make(chan FileInfo),
 		logger:          logger,
 	}
 
+	handler.routeHandler = handler.TusMiddleware(mux)
+
 	mux.Post("", http.HandlerFunc(handler.postFile))
 	mux.Head(":id", http.HandlerFunc(handler.headFile))
 	mux.Get(":id", http.HandlerFunc(handler.getFile))
@@ -129,6 +130,11 @@ func NewHandler(config Config) (*Handler, error) {
 
 // Implement the http.Handler interface.
 func (handler *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	handler.routeHandler.ServeHTTP(w, r)
+}
+
+func (handler *Handler) TusMiddleware(h http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		// Allow overriding the HTTP method. The reason for this is
 		// that some libraries/environments to not support PATCH and
 		// DELETE requests, e.g. Flash in a browser and parts of Java
@@ -181,7 +187,8 @@ func (handler *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		}
 
 		// Proceed with routing the request
-	handler.routeHandler.ServeHTTP(w, r)
+		h.ServeHTTP(w, r)
+	})
 }
 
 // Create a new file upload using the datastore after validating the length