1 files changed, 24 insertions, 0 deletions
diff --git a/lib/portal/portal_ws.ml b/lib/portal/portal_ws.ml
new file mode 100644
index 0000000..f2c0cf5
--- /dev/null
+++ b/lib/portal/portal_ws.ml
@@ -0,0 +1,24 @@
+open Lwt.Syntax
+
+open Js_of_ocaml
+let jss = Js.string
+let sjs = Js.to_string
+
+let lwt_ws (url : string) =
+  (** [lwt_ws url] returns a stream and a push function for the websocket at [url].
+      Pushing [None] closes the websocket.
+      If the websocket is closed server-side, it's up to the caller's to close the push stream. *)
+  let open Lwt_stream in
+  let handle ws incoming () =
+    let+ _ = iter (fun msg -> ws##send (jss msg)) incoming
+    in (ws##close)
+  in let stream, message = create () (* websocket -> user *)
+     and incoming, push = create () (* user -> websocket *)
+     in let (ws : WebSockets.webSocket Js.t) = new%js WebSockets.webSocket (jss url)
+        in ws##.onmessage :=
+             Dom.handler (fun x -> Some (sjs x##.data) |> message; Js._false);
+           ws##.onopen :=
+             Dom.handler (fun _ -> Lwt.async @@ handle ws incoming; Js._false);
+           ws##.onclose :=
+             Dom.handler (fun _ -> message None; Js._true);
+           stream, push