defmodule Distr do
   def init(_type, req, []) do
     {:ok, req, :no_state}
   end

   def terminate(reason, request, state) do
     :ok
   end

   def handle(req, state) do
     {url, _} = :cowboy_req.url(req)
     {code, body, headers} = case HTTPoison.request (:get, next_url(url)) do
       {:ok, resp} -> {resp.status_code, resp.body, resp.headers}
       {:error, _} -> {500, "<h1>500 - Internal Server Error</h1>", []}
     end
     {:ok, reply} = :cowboy_req.reply(code, headers, body, req)
     {:ok, reply, state}
   end

   def next_url(url) do
     purl = URI.parse(url)
     "#{purl.scheme}://#{next_host()}#{purl.path}"
   end

   def next_host() do
     :random.seed(:os.timestamp)
     [next|_] = Enum.shuffle(["127.0.0.3", "127.0.0.4"])
     next
   end
 end