open Lwt.Syntax
open Shared

let handle_client request client =
  match Dream.session "user_id" request with
  | None -> Dream.log "User does not exists" |> Lwt.return
  | Some user_id ->
    (* TODO catch marshal failure *)
    let state =
      match User.get_state user_id with
      | Error _e -> assert false
      | Ok state -> state
    in
    let state_msg = Network.Full_state state in

    (* send user island state *)
    let* () =
      Dream.send ~text_or_binary:`Text client (Network.marshal state_msg)
    in

    let rec loop () =
      match%lwt Dream.receive client with
      | None -> Dream.close_websocket client
      | Some s ->
        let state =
          match User.get_state user_id with
          | Error _e -> assert false
          | Ok state -> state
        in
        let (Network.Action_msg action : Network.client_message) =
          Network.unmarshal s
        in
        let res =
          match State.check_action state action with
          | Error _e as error -> error
          | Ok action' ->
            (* update server state *)
            let state = State.perform_action state action' in
            User.set_state user_id state;
            Ok action'
        in
        let* () =
          Dream.send client (Network.marshal (Network.Update_result res))
        in
        loop ()
    in
    loop ()