Wrap http.ResponseWriter with proxying another interfaces

http_response_writer.go

func wrapResponseWriter(w http.ResponseWriter, codeHook func(int)) http.ResponseWriter {
	rw := &rw{w: w, codeHook: codeHook}
	hj, hasHijack := w.(http.Hijacker)
	fl, hasFlusher := w.(http.Flusher)
	rf, hasReadFrom := w.(io.ReaderFrom)

	switch {
	case hasHijack && hasFlusher && hasReadFrom:
		return struct {
			http.ResponseWriter
			http.Hijacker
			http.Flusher
			io.ReaderFrom
		}{rw, hj, fl, rf}
	case hasHijack && hasFlusher:
		return struct {
			http.ResponseWriter
			http.Hijacker
			http.Flusher
		}{rw, hj, fl}
	case hasHijack && hasReadFrom:
		return struct {
			http.ResponseWriter
			http.Hijacker
			io.ReaderFrom
		}{rw, hj, rf}
	case hasFlusher && hasReadFrom:
		return struct {
			http.ResponseWriter
			http.Flusher
			io.ReaderFrom
		}{rw, fl, rf}
	case hasHijack:
		return struct {
			http.ResponseWriter
			http.Hijacker
		}{rw, hj}
	case hasFlusher:
		return struct {
			http.ResponseWriter
			http.Flusher
		}{rw, fl}
	case hasReadFrom:
		return struct {
			http.ResponseWriter
			io.ReaderFrom
		}{rw, rf}
	default:
		return struct {
			http.ResponseWriter
		}{rw}
	}
}

type rw struct {
	w        http.ResponseWriter
	codeHook func(int)
}

func (w *rw) Header() http.Header {
	return w.w.Header()
}

func (w *rw) WriteHeader(code int) {
	w.codeHook(code)
	w.w.WriteHeader(code)
}

func (w *rw) Write(b []byte) (int, error) {
	return w.w.Write(b)
}