module S = Tiny_httpd
module S_eio = Tiny_httpd_eio

let now_ = Unix.gettimeofday
let ( let@ ) = ( @@ )

(* util: a little middleware collecting statistics *)
let middleware_stat () : S.Middleware.t * (unit -> string) =
  let n_req = ref 0 in
  let total_time_ = ref 0. in
  let parse_time_ = ref 0. in
  let build_time_ = ref 0. in
  let write_time_ = ref 0. in

  let m h req ~resp =
    incr n_req;
    let t1 = S.Request.start_time req in
    let t2 = now_ () in
    h req ~resp:(fun response ->
        let t3 = now_ () in
        resp response;
        let t4 = now_ () in
        total_time_ := !total_time_ +. (t4 -. t1);
        parse_time_ := !parse_time_ +. (t2 -. t1);
        build_time_ := !build_time_ +. (t3 -. t2);
        write_time_ := !write_time_ +. (t4 -. t3))
  and get_stat () =
    Printf.sprintf
      "%d requests (average response time: %.3fms = %.3fms + %.3fms + %.3fms)"
      !n_req
      (!total_time_ /. float !n_req *. 1e3)
      (!parse_time_ /. float !n_req *. 1e3)
      (!build_time_ /. float !n_req *. 1e3)
      (!write_time_ /. float !n_req *. 1e3)
  in
  m, get_stat

let () =
  let port_ = ref 8080 in
  let j = ref 32 in
  Arg.parse
    (Arg.align
       [
         "--port", Arg.Set_int port_, " set port";
         "-p", Arg.Set_int port_, " set port";
         "--debug", Arg.Unit (fun () -> S._enable_debug true), " enable debug";
         "-j", Arg.Set_int j, " maximum number of connections";
       ])
    (fun _ -> raise (Arg.Bad ""))
    "echo [option]*";

  (* use eio *)
  let@ stdenv = Eio_main.run in
  let@ sw = Eio.Switch.run in

  (* create server *)
  let server : S.t =
    S_eio.create ~port:!port_ ~max_connections:!j ~stdenv ~sw ()
  in

  (* TODO: re-enable
     Tiny_httpd_camlzip.setup ~compress_above:1024 ~buf_size:(16 * 1024) server; *)
  let m_stats, get_stats = middleware_stat () in
  S.add_middleware server ~stage:(`Stage 1) m_stats;

  (* say hello *)
  S.add_route_handler ~meth:`GET server
    S.Route.(exact "hello" @/ string @/ return)
    (fun name _req -> S.Response.make_string (Ok ("hello " ^ name ^ "!\n")));

  (* compressed file access *)
  S.add_route_handler ~meth:`GET server
    S.Route.(exact "zcat" @/ string_urlencoded @/ return)
    (fun path _req ->
      let ic = open_in path in
      let str = S.Byte_stream.of_chan ic in
      let mime_type =
        try
          let p = Unix.open_process_in (Printf.sprintf "file -i -b %S" path) in
          try
            let s = [ "Content-Type", String.trim (input_line p) ] in
            ignore @@ Unix.close_process_in p;
            s
          with _ ->
            ignore @@ Unix.close_process_in p;
            []
        with _ -> []
      in
      S.Response.make_stream ~headers:mime_type (Ok str));

  (* echo request *)
  S.add_route_handler server
    S.Route.(exact "echo" @/ return)
    (fun req ->
      let q =
        S.Request.query req
        |> List.map (fun (k, v) -> Printf.sprintf "%S = %S" k v)
        |> String.concat ";"
      in
      S.Response.make_string
        (Ok (Format.asprintf "echo:@ %a@ (query: %s)@." S.Request.pp req q)));

  (* file upload *)
  S.add_route_handler_stream ~meth:`PUT server
    S.Route.(exact "upload" @/ string @/ return)
    (fun path req ->
      S._debug (fun k ->
          k "start upload %S, headers:\n%s\n\n%!" path
            (Format.asprintf "%a" S.Headers.pp (S.Request.headers req)));
      try
        let oc = open_out @@ "/tmp/" ^ path in
        S.Byte_stream.to_chan oc req.S.Request.body;
        flush oc;
        S.Response.make_string (Ok "uploaded file")
      with e ->
        S.Response.fail ~code:500 "couldn't upload file: %s"
          (Printexc.to_string e));

  (* stats *)
  S.add_route_handler server
    S.Route.(exact "stats" @/ return)
    (fun _req ->
      let stats = get_stats () in
      S.Response.make_string @@ Ok stats);

  (* main page *)
  S.add_route_handler server
    S.Route.(return)
    (fun _req ->
      let open Tiny_httpd_html in
      let h =
        html []
          [
            head [] [ title [] [ txt "index of echo" ] ];
            body []
              [
                h3 [] [ txt "welcome!" ];
                p [] [ b [] [ txt "endpoints are:" ] ];
                ul []
                  [
                    li [] [ pre [] [ txt "/hello/:name (GET)" ] ];
                    li []
                      [
                        pre []
                          [
                            a [ A.href "/echo/" ] [ txt "echo" ];
                            txt " echo back query";
                          ];
                      ];
                    li []
                      [ pre [] [ txt "/upload/:path (PUT) to upload a file" ] ];
                    li []
                      [
                        pre []
                          [
                            txt
                              "/zcat/:path (GET) to download a file (deflate \
                               transfer-encoding)";
                          ];
                      ];
                    li []
                      [
                        pre []
                          [
                            a [ A.href "/stats/" ] [ txt "/stats/" ];
                            txt " (GET) to access statistics";
                          ];
                      ];
                    li []
                      [
                        pre []
                          [
                            a [ A.href "/vfs/" ] [ txt "/vfs" ];
                            txt " (GET) to access a VFS embedded in the binary";
                          ];
                      ];
                  ];
              ];
          ]
      in
      let s = to_string_top h in
      S.Response.make_string ~headers:[ "content-type", "text/html" ] @@ Ok s);

  Printf.printf "listening on http://%s:%d\n%!" (S.addr server) (S.port server);
  match S.run server with
  | Ok () -> ()
  | Error e -> raise e