-module(docs@utils@timer).
-compile([no_auto_import, nowarn_unused_vars]).

-export([timer/2, interval/2]).
-export_type([timer_msg/0]).

-type timer_msg() :: cancel |
    {timeout, fun(() -> nil)} |
    {interval,
        gleam@erlang@process:subject(timer_msg()),
        integer(),
        fun(() -> nil)}.

-spec handle_timer_message(timer_msg(), integer()) -> gleam@otp@actor:next(integer()).
handle_timer_message(Msg, State) ->
    case Msg of
        cancel ->
            {stop, normal};

        {timeout, Cb} ->
            Cb(),
            {stop, normal};

        {interval, Actor, Interval_ms, Cb@1} ->
            Cb@1(),
            gleam@erlang@process:send_after(
                Actor,
                Interval_ms,
                {interval, Actor, Interval_ms, Cb@1}
            ),
            {continue, State}
    end.

-spec timer(integer(), fun(() -> nil)) -> gleam@erlang@process:timer().
timer(Interval_ms, Callback) ->
    _assert_subject = gleam@otp@actor:start(
        Interval_ms,
        fun handle_timer_message/2
    ),
    {ok, Actor} = case _assert_subject of
        {ok, _} -> _assert_subject;
        _assert_fail ->
            erlang:error(#{gleam_error => assert,
                        message => <<"Assertion pattern match failed"/utf8>>,
                        value => _assert_fail,
                        module => <<"docs/utils/timer"/utf8>>,
                        function => <<"timer"/utf8>>,
                        line => 34})
    end,
    gleam@erlang@process:send_after(Actor, Interval_ms, {timeout, Callback}).

-spec interval(integer(), fun(() -> nil)) -> fun(() -> nil).
interval(Interval_ms, Callback) ->
    _assert_subject = gleam@otp@actor:start(
        Interval_ms,
        fun handle_timer_message/2
    ),
    {ok, Actor} = case _assert_subject of
        {ok, _} -> _assert_subject;
        _assert_fail ->
            erlang:error(#{gleam_error => assert,
                        message => <<"Assertion pattern match failed"/utf8>>,
                        value => _assert_fail,
                        module => <<"docs/utils/timer"/utf8>>,
                        function => <<"interval"/utf8>>,
                        line => 41})
    end,
    gleam@erlang@process:send_after(
        Actor,
        Interval_ms,
        {interval, Actor, Interval_ms, Callback}
    ),
    fun() -> gleam@otp@actor:send(Actor, cancel) end.