glimiter

-module(glimiter).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch]).

-export([new_limiter/2, limit_guard/4]).
-export_type([limiter/0]).

-opaque limiter() :: {limiter,
        gleam@dict:dict(binary(), list(birl:time())),
        integer(),
        birl@duration:duration()}.

-spec new_limiter(integer(), birl@duration:duration()) -> limiter().
new_limiter(Count, Size) ->
    {limiter, gleam@dict:new(), Count, Size}.

-spec add(limiter(), binary()) -> gleam@dict:dict(binary(), list(birl:time())).
add(Limiter, Key) ->
    Now = birl:now(),
    case gleam@dict:get(erlang:element(2, Limiter), Key) of
        {ok, Timestamps} ->
            gleam@dict:insert(
                erlang:element(2, Limiter),
                Key,
                [Now | Timestamps]
            );

        {error, _} ->
            gleam@dict:insert(erlang:element(2, Limiter), Key, [Now])
    end.

-spec filter_prev_window(limiter(), binary()) -> gleam@dict:dict(binary(), list(birl:time())).
filter_prev_window(Limiter, Key) ->
    _assert_subject = gleam@dict:get(erlang:element(2, Limiter), Key),
    {ok, Times} = case _assert_subject of
        {ok, _} -> _assert_subject;
        _assert_fail ->
            erlang:error(#{gleam_error => let_assert,
                        message => <<"Assertion pattern match failed"/utf8>>,
                        value => _assert_fail,
                        module => <<"glimiter"/utf8>>,
                        function => <<"filter_prev_window"/utf8>>,
                        line => 47})
    end,
    Now = birl:now(),
    New_times = gleam@list:filter(
        Times,
        fun(Time) ->
            End_time = birl:add(Time, erlang:element(4, Limiter)),
            case birl:compare(Now, End_time) of
                lt ->
                    true;

                eq ->
                    true;

                _ ->
                    false
            end
        end
    ),
    gleam@dict:insert(erlang:element(2, Limiter), Key, New_times).

-spec limit_guard(limiter(), binary(), HFM, fun((limiter()) -> HFM)) -> HFM.
limit_guard(Limiter, Key, Consequence, Alternetive) ->
    Limiter@1 = {limiter,
        add(Limiter, Key),
        erlang:element(3, Limiter),
        erlang:element(4, Limiter)},
    Limiter@2 = {limiter,
        filter_prev_window(Limiter@1, Key),
        erlang:element(3, Limiter@1),
        erlang:element(4, Limiter@1)},
    _assert_subject = gleam@dict:get(erlang:element(2, Limiter@2), Key),
    {ok, Times} = case _assert_subject of
        {ok, _} -> _assert_subject;
        _assert_fail ->
            erlang:error(#{gleam_error => let_assert,
                        message => <<"Assertion pattern match failed"/utf8>>,
                        value => _assert_fail,
                        module => <<"glimiter"/utf8>>,
                        function => <<"limit_guard"/utf8>>,
                        line => 25})
    end,
    case erlang:length(Times) < erlang:element(3, Limiter@2) of
        true ->
            Alternetive(Limiter@2);

        false ->
            Consequence
    end.