open Lwt.Infix

(* a list associating user nicknames to the output channels that write to their connections *)
(* Once we fix the other functions this should change to []*)
let sessions = ref [("",Lwt_io.null)]
exception Quit

(* replace Lwt.return below with code that uses Lwt_list.iter_p to
  print sender: msg on each output channel (excluding the sender's)*)
let rec send_all sender msg = Lwt.return ()

(* remove a session from the list of sessions: important so we don't try to
   write to a closed connection *)
let remove_session nn =
  sessions := List.remove_assoc nn !sessions;
  send_all nn "<left chat>" >>= fun () ->
  Lwt.return ()

(* Modify to handle the "Quit" case separately, closing the channels before removing the session *)
let handle_error e nn inp outp = remove_session nn

(* modify sessions to remove (nn,outp) association, add (new_nn,outp) association.
   also notify other participants of new nickname *)
let change_nn nn outp new_nn = Lwt.return ()

(*  + obtain initial nick(name),
    + add (nick,outp) to !sessions, and
    + announce join to other users *)
let handle_login nr (inp,outp) =
Lwt_io.printl "Enter initial nick:" >>= fun () -> Lwt.return ();;

(* modify handle_input below to detect /q, /n, and /l commands *)
let handle_input nr outp l = send_all !nr l

let chat_server _ (inp,outp) =
  let nick = ref "" in
  (* replace () below with call to handle_login *)
  let _ =  handle_login nick (inp,outp) in
  let rec main_loop () =
	  Lwt_io.read_line inp >>= handle_input nick outp >>= main_loop in
  Lwt.catch main_loop (fun e -> handle_error e !nick inp outp)