open Swim.Types

external env_cast : 'a -> 'b = "%identity"

let hex_of_cstruct cs =
  let len = Cstruct.length cs in
  let buf = Buffer.create (len * 2) in
  for i = 0 to len - 1 do
    Buffer.add_string buf (Printf.sprintf "%02x" (Cstruct.get_uint8 cs i))
  done;
  Buffer.contents buf

let () =
  Eio_main.run @@ fun env ->
  let env = env_cast env in
  Eio.Switch.run @@ fun sw ->
  let net = env#net in
  let sock =
    Swim.Transport.create_udp_socket net ~sw ~addr:"\127\000\000\001" ~port:7947
  in

  Printf.printf "Bound to 127.0.0.1:7947\n%!";

  (* Create and send a ping to Go memberlist *)
  let self =
    make_node_info
      ~id:(node_id_of_string "ocaml-node")
      ~addr:(`Udp (Eio.Net.Ipaddr.of_raw "\127\000\000\001", 7947))
      ~meta:""
  in
  let target_id = node_id_of_string "go-node" in
  let ping = Ping { seq = 1; target = target_id; sender = self } in

  let packet = { cluster = ""; primary = ping; piggyback = [] } in
  let send_buf = Cstruct.create 1500 in
  match Swim.Codec.encode_packet packet ~buf:send_buf with
  | Error _ -> Printf.eprintf "Encode failed\n"
  | Ok len ->
      let encoded = Cstruct.sub send_buf 0 len in
      Printf.printf "Sending ping (%d bytes): %s\n%!" len
        (hex_of_cstruct encoded);

      let dst = `Udp (Eio.Net.Ipaddr.of_raw "\127\000\000\001", 7946) in
      Eio.Net.send sock ~dst [ encoded ];
      Printf.printf "Sent! Waiting for ack...\n%!";

      (* Wait for response *)
      let recv_buf = Cstruct.create 1500 in
      for i = 1 to 5 do
        Printf.printf "Waiting for packet %d (with 2s timeout)...\n%!" i;
        Eio.Fiber.fork ~sw (fun () ->
            let src, n = Eio.Net.recv sock recv_buf in
            let received = Cstruct.sub recv_buf 0 n in
            Printf.printf "Received %d bytes from %s\n%!" n
              (match src with
              | `Udp (ip, port) ->
                  Printf.sprintf "%s:%d"
                    (Fmt.to_to_string Eio.Net.Ipaddr.pp ip)
                    port
              | _ -> "unknown");
            Printf.printf "Hex: %s\n%!" (hex_of_cstruct received);
            Printf.printf "First byte (msg type): %d\n%!"
              (Cstruct.get_uint8 received 0));
        Eio.Time.sleep env#clock 2.0
      done