-module(glats@handler).
-compile([no_auto_import, nowarn_unused_vars]).

-export([handle_subscription/3]).
-export_type([state/0]).

-type state() :: {subscription_state,
        gleam@erlang@process:subject(glats@connection:command()),
        fun((glats@message:message(), gleam@erlang@process:subject(glats@connection:command())) -> {ok,
                nil} |
            {error, binary()})}.

-spec map_message(gleam@dynamic:dynamic()) -> glats@message:message().
map_message(Msg) ->
    _pipe = Msg,
    _pipe@1 = 'Elixir.Glats':convert_msg(_pipe),
    gleam@result:unwrap(
        _pipe@1,
        {message, <<"error"/utf8>>, gleam@map:new(), none, <<"body"/utf8>>}
    ).

-spec handle_subscription(
    gleam@erlang@process:subject(glats@connection:command()),
    binary(),
    fun((glats@message:message(), gleam@erlang@process:subject(glats@connection:command())) -> {ok,
            nil} |
        {error, binary()})
) -> {ok, gleam@erlang@process:subject(glats@message:message())} |
    {error, gleam@otp@actor:start_error()}.
handle_subscription(Conn, Subject, Handler) ->
    gleam@otp@actor:start_spec(
        {spec,
            fun() ->
                Receiver = gleam@erlang@process:new_subject(),
                Selector = begin
                    _pipe = gleam_erlang_ffi:new_selector(),
                    gleam@erlang@process:selecting_anything(
                        _pipe,
                        fun map_message/1
                    )
                end,
                case glats@connection:subscribe(Conn, Receiver, Subject) of
                    {ok, _} ->
                        {ready, {subscription_state, Conn, Handler}, Selector};

                    {error, Err} ->
                        {failed, Err}
                end
            end,
            10000,
            fun(Msg, State) ->
                case (erlang:element(3, State))(Msg, erlang:element(2, State)) of
                    {ok, _} ->
                        {continue, State};

                    {error, _} ->
                        {stop, {abnormal, <<"handler returned error!"/utf8>>}}
                end
            end}
    ).