(* Functoria *)

module DNS_client = Dns_client_mirage.Make (Mirage_random_stdlib) (Time) (Mclock) (Pclock) (Tcpip_stack_socket.V4V6)
module Happy_eyeballs = Happy_eyeballs_mirage.Make (Time) (Mclock) (Tcpip_stack_socket.V4V6) (DNS_client)
module Mimic_happy_eyeballs = Mimic_happy_eyeballs.Make (Tcpip_stack_socket.V4V6) (DNS_client) (Happy_eyeballs)
module HTTP_server = Paf_mirage.Make (Tcpip_stack_socket.V4V6.TCP)
module HTTP_client = Http_mirage_client.Make (Pclock) (Tcpip_stack_socket.V4V6.TCP) (Mimic_happy_eyeballs)

let http_1_1_error_handler ?notify (ipaddr, port) ?request:_ error respond =
  let contents = match error with
    | `Bad_gateway -> Fmt.str "Bad gateway (%a:%d)" Ipaddr.pp ipaddr port
    | `Bad_request -> Fmt.str "Bad request (%a:%d)" Ipaddr.pp ipaddr port
    | `Exn exn -> Fmt.str "Exception %S (%a:%d)" (Printexc.to_string exn) Ipaddr.pp ipaddr port
    | `Internal_server_error -> Fmt.str "Internal server error (%a:%d)" Ipaddr.pp ipaddr port in
  let open Httpaf in
  Option.iter (fun push -> push (Some ((ipaddr, port), error))) notify ;
  let headers = Headers.of_list
    [ "content-type", "text/plain"
    ; "content-length", string_of_int (String.length contents)
    ; "connection", "close" ] in
  let body = respond headers in
  Body.write_string body contents ;
  Body.close_writer body

let alpn_error_handler
  : type reqd headers request response ro wo.
    ?notify:(((Ipaddr.t * int) * Alpn.server_error) option -> unit) ->
    (Ipaddr.t * int) -> (reqd, headers, request, response, ro, wo) Alpn.protocol ->
    ?request:request -> Alpn.server_error -> (headers -> wo) -> unit
  = fun ?notify (ipaddr, port) protocol ?request:_ error respond ->
    let contents = match error with
      | `Bad_gateway -> Fmt.str "Bad gateway (%a:%d)" Ipaddr.pp ipaddr port
      | `Bad_request -> Fmt.str "Bad request (%a:%d)" Ipaddr.pp ipaddr port
      | `Exn exn -> Fmt.str "Exception %S (%a:%d)" (Printexc.to_string exn) Ipaddr.pp ipaddr port
      | `Internal_server_error -> Fmt.str "Internal server error (%a:%d)" Ipaddr.pp ipaddr port in
    Option.iter (fun push -> push (Some ((ipaddr, port), error))) notify ;
    let headers =
      [ "content-type", "text/plain"
      ; "content-length", string_of_int (String.length contents) ] in
    match protocol with
    | Alpn.HTTP_1_1 _ ->
      let open Httpaf in
      let headers = Headers.of_list (("connection", "close") :: headers) in
      let body = respond headers in
      Body.write_string body contents ;
      Body.close_writer body
    | Alpn.H2 _ ->
      let open H2 in
      let headers = Headers.of_list headers in
      let body = respond headers in
      H2.Body.Writer.write_string body contents ;
      H2.Body.Writer.close body

type alpn_handler =
   { handler : 'reqd 'headers 'request 'response 'ro 'wo.
     'reqd -> ('reqd, 'headers, 'request, 'response, 'ro, 'wo) Alpn.protocol -> unit }
[@@unboxed]

let server ?error ?stop stack = function
  | `HTTP_1_1 (port, handler) ->
    let open Lwt.Syntax in
    let+ http_server = HTTP_server.init ~port stack in
    let http_service = HTTP_server.http_service ~error_handler:(http_1_1_error_handler ?notify:error)
      (fun _flow (_ipaddr, _port) -> handler) in
    HTTP_server.serve ?stop http_service http_server
  | `ALPN (tls, port, handler) ->
    let open Lwt.Syntax in
    let alpn_handler =
      { Alpn.error= (fun edn protocol ?request v respond -> alpn_error_handler ?notify:error edn protocol ?request v respond)
      ; Alpn.request= (fun _flow (_ipaddr, _port) reqd protocol -> handler.handler reqd protocol) } in
    let+ http_server = HTTP_server.init ~port stack in
    let alpn_service = HTTP_server.alpn_service ~tls alpn_handler in
    HTTP_server.serve ?stop alpn_service http_server

let stack ipaddr =
  let open Lwt.Syntax in
  let* tcpv4v6 = Tcpip_stack_socket.V4V6.TCP.connect ~ipv4_only:false ~ipv6_only:false
    ipaddr None in
  let* udpv4v6 = Tcpip_stack_socket.V4V6.UDP.connect ~ipv4_only:false ~ipv6_only:false
    ipaddr None in
  Tcpip_stack_socket.V4V6.connect udpv4v6 tcpv4v6

let test01 =
  Alcotest_lwt.test_case "Simple Hello World! (GET)" `Quick @@ fun _sw () ->
  let open Lwt.Syntax in
  let stop = Lwt_switch.create () in
  let handler reqd =
    let open Httpaf in
    let contents = "Hello World!" in
    let headers = Headers.of_list
      [ "content-type", "text/plain"
      ; "content-length", string_of_int (String.length contents)
      ; "connection", "close" ] in
    let response = Response.create ~headers `OK in
    Reqd.respond_with_string reqd response contents in
  let* stack = stack Ipaddr.V4.Prefix.loopback in
  let happy_eyeballs = Happy_eyeballs.create stack in
  let* ctx = Mimic_happy_eyeballs.connect happy_eyeballs in
  let* t = HTTP_client.connect ctx in
  let* `Initialized _thread = server ~stop (Tcpip_stack_socket.V4V6.tcp stack)
    (`HTTP_1_1 (8080, handler)) in
  let* result = Http_mirage_client.request t "http://localhost:8080/"
    (fun _response buf str -> Buffer.add_string buf str ; Lwt.return buf)
    (Buffer.create 0x100) in
  match result with
  | Error err ->
    let* () = Lwt_switch.turn_off stop in
    let* () = Tcpip_stack_socket.V4V6.disconnect stack in
    Alcotest.failf "Client error: %a" Mimic.pp_error err
  | Ok (_response, buf) ->
    let* () = Lwt_switch.turn_off stop in
    let* () = Tcpip_stack_socket.V4V6.disconnect stack in
    let body = Buffer.contents buf in
    Alcotest.(check string) "body" "Hello World!" body ;
    Lwt.return_unit

let random_string ~len =
  let res = Bytes.create len in
  for i = 0 to len - 1 do
    Bytes.set res i (Char.chr (Random.bits () land 0xff))
  done ; Bytes.unsafe_to_string res

let test02 =
  Alcotest_lwt.test_case "Repeat (POST)" `Quick @@ fun _sw () ->
  let open Lwt.Syntax in
  let stop = Lwt_switch.create () in
  let handler reqd =
    let open Httpaf in
    let { Request.meth; _ } = Reqd.request reqd in
    if meth <> `POST then invalid_arg "Invalid HTTP method" ;
    let headers = Headers.of_list
      [ "content-type", "text/plain" ] in
    let response = Response.create ~headers `OK in
    let src = Reqd.request_body reqd in
    let dst = Reqd.respond_with_streaming reqd response in
    let rec on_eof () =
      Body.close_reader src ;
      Body.close_writer dst
    and on_read buf ~off ~len =
      Body.write_bigstring dst ~off ~len buf ;
      Body.schedule_read src ~on_eof ~on_read in
    Body.schedule_read src ~on_eof ~on_read in
  let* stack = stack Ipaddr.V4.Prefix.loopback in
  let happy_eyeballs = Happy_eyeballs.create stack in
  let* ctx = Mimic_happy_eyeballs.connect happy_eyeballs in
  let* t = HTTP_client.connect ctx in
  let* `Initialized _thread = server ~stop (Tcpip_stack_socket.V4V6.tcp stack)
    (`HTTP_1_1 (8080, handler)) in
  let str = random_string ~len:0x1000 in
  let* result = Http_mirage_client.request ~meth:`POST ~body:str t "http://localhost:8080/"
    (fun _response buf str -> Buffer.add_string buf str ; Lwt.return buf)
    (Buffer.create 0x1000) in
  match result with
  | Error err ->
    let* () = Lwt_switch.turn_off stop in
    let* () = Tcpip_stack_socket.V4V6.disconnect stack in
    Alcotest.failf "Client error: %a" Mimic.pp_error err
  | Ok (_response, buf) ->
    let* () = Lwt_switch.turn_off stop in
    let* () = Tcpip_stack_socket.V4V6.disconnect stack in
    let body = Buffer.contents buf in
    Alcotest.(check string) "body" str body ;
    Lwt.return_unit
 
 let () = Alcotest_lwt.run "http-mirage-client"
     [ "http/1.1", [ test01; test02 ] ]
   |> Lwt_main.run