(defn- limited-stream [is max-size]
  (proxy [LimitedInputStream]
      [is max-size]
    (raiseError [max count]
      (throw (ex-info "Request too large."
                      {:max max
                       :count count
                       :type :request-too-large})))))

(defn wrap-request-size-limit [h max-size request-too-large-fn]
  (fn [r]
    (let [content-length (Long/valueOf (get-in r [:headers "content-length"] "0"))
          body (:body r)]
      (cond (< max-size content-length)
            (request-too-large-fn r max-size content-length)

            (instance? java.io.InputStream body)
            (try
              (h (assoc r :body (limited-stream body max-size)))
              (catch Exception e
                (let [d (ex-data e)]
                  (if (= (:type d) :request-too-large)
                    (request-too-large-fn r (:max d) (:count d))
                    (throw e)))))

            :default
            (h r)))))