open Lwt.Syntax

exception ClosedStream
exception InvalidStanza of string

let get stream =
  (** [get stream] returns a promise containing an element of [stream].

      If [stream] is closed, it throws a ClosedStream Lwt exception. *)
  let* stanza = Lwt_stream.get stream
  in match stanza with
     | Some stanza -> Lwt.return stanza
     | None -> Lwt.fail ClosedStream

let start domain : Portal.t Lwt.t =
  (** [start domain] is a promise containing a Portal (stream * push) connected to the XMPP server [domain].

      Currently, it doesn't handle anything except the initial [<open/>] stanza. *)
  let* stream, _push = Portal.connect domain
  in let push = function
       | None -> _push (Some Portal.stanza_close);
                 _push None;
       | anything -> _push anything
     in Some (Portal.stanza_open domain) |> push;
        (* TODO: check this is a good stanza *)
        let+ _ = get stream
        in stream, push