test.ml

let rec start_heartbeat_loop conn interval =
    let open Websocket_lwt_unix in
    let open Websocket in
    match !recv_hb_ack with
    | true  -> let () = (recv_hb_ack := false) in
               let%lwt () = Lwt_io.printf "Sleeping for %f seconds!\n" interval in
               let%lwt () = Lwt_unix.sleep interval in
               let (json_resp : Yojson.Safe.t) = match !last_seq with
               | Some n -> `Assoc [ ("op", `Int 1); ("d", `Int n) ]
               | None -> `Assoc [ ("op", `Int 1); ("d", `Null) ] in
               let content = Yojson.Safe.pretty_to_string json_resp in
               let%lwt () = write conn (Frame.create ~content ()) in
               let%lwt () = Lwt_io.printf "Sending heartbeat...\n" in
               start_heartbeat_loop conn interval
    | false -> write conn (Frame.create ~opcode:Close ())

let handle_ws_message conn msg token =
    let open Yojson.Safe in
    let%lwt () = Lwt_io.printf "> %s\n" msg in
    let msg_json = from_string msg in
    let opcode = msg_json |> Util.member "op" |> Util.to_int in
    match opcode with
    | 10 -> let interval_ms = msg_json |> Util.member "d" |> Util.member "heartbeat_interval" |> Util.to_int in
            let interval_sec = (float_of_int interval_ms) /. 1000. in
            start_heartbeat_loop conn interval_sec
    |  _ -> Lwt_io.printf "Unsupported opcode found!\n"