basic net/http compatible middleware

middleware.go

func main() {
	r := chi.Router()
	r.Use(Basic())
	r.Use(Static("/static", "server2/static"))
	http.ListenAndServe(":3000", r)
}

type Middleware func(next http.Handler) http.Handler

func Basic() Middleware {
	return func(next http.Handler) http.Handler {
		fn := func(w http.ResponseWriter, r *http.Request) {
			next.ServeHTTP(w, r)
		}
		return http.HandlerFunc(fn)
	}
}

// Static serves static files
//
// pattern - string displayed on the URL (ie. "/static" in "localhost:8080/static")
// dir - string where the file is located relative to go.mod
//
//	r.Use(Static("/static", "server2/static"))
func Static(pattern, dir string) Middleware {
	fs := http.FileServer(http.Dir(dir))
	h := http.StripPrefix(pattern+"/", fs)
	return func(next http.Handler) http.Handler {
		fn := func(w http.ResponseWriter, r *http.Request) {
			_, after, ok1 := strings.Cut(r.URL.Path, "/")
			before, _, ok2 := strings.Cut(after, "/")
			rPath := "/" + before
			if !ok1 || !ok2 || pattern != rPath {
				next.ServeHTTP(w, r)
				return
			}
			h.ServeHTTP(w, r)
		}
		return http.HandlerFunc(fn)
	}
}