open Lwt.Infix
open Lwt.Syntax

let successful = ref 0
let failed = ref 0

(* middleware *)
let count_requests inner_handler request =
  try%lwt
    inner_handler request >>= fun response ->
    successful := !successful + 1;
    Lwt.return response
  with exn ->
    failed := !failed + 1;
    raise exn

let () =
  Dream.run @@ Dream.logger @@ count_requests
  @@ Dream.router
       [
         Dream.get "/" (fun _ -> Dream.html "Hello, world!");
         Dream.get "/error" (fun _ -> failwith "failed on purpose");
         Dream.get "/count" (fun _ ->
             Dream.html
               (Printf.sprintf "%3i successful requests<br>%3i failed requests"
                  !successful !failed));
         Dream.get "/echo/:word" (fun request ->
             Dream.html (Dream.param request "word"));
         Dream.post "/echo" (fun request ->
             let* body = Dream.body request in
             Dream.respond
               ~headers:[ ("Content-Type", "application/octet-stream") ]
               body);
       ]