-module(glimit@rate_limiter).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch]).

-export([new/2, shutdown/1, hit/1, has_full_bucket/1, set_now/2]).
-export_type([state/0, message/0]).

-type state() :: {state,
        integer(),
        integer(),
        integer(),
        gleam@option:option(integer()),
        gleam@option:option(integer())}.

-type message() :: shutdown |
    {hit, gleam@erlang@process:subject({ok, nil} | {error, nil})} |
    {has_full_bucket, gleam@erlang@process:subject(boolean())} |
    {set_now, integer()}.

-spec refill_bucket(state()) -> state().
refill_bucket(State) ->
    Now@1 = case erlang:element(6, State) of
        none ->
            glimit@utils:now();

        {some, Now} ->
            Now
    end,
    Time_diff = case erlang:element(5, State) of
        none ->
            0;

        {some, Last_update} ->
            Now@1 - Last_update
    end,
    Token_count = begin
        _pipe = erlang:element(4, State) + (erlang:element(3, State) * Time_diff),
        _pipe@1 = gleam@int:min(_pipe, erlang:element(2, State)),
        gleam@int:max(_pipe@1, 0)
    end,
    erlang:setelement(
        5,
        erlang:setelement(4, State, Token_count),
        {some, Now@1}
    ).

-spec remove_token(state()) -> state().
remove_token(State) ->
    erlang:setelement(4, State, erlang:element(4, State) - 1).

-spec handle_message(message(), state()) -> gleam@otp@actor:next(message(), state()).
handle_message(Message, State) ->
    case Message of
        shutdown ->
            {stop, normal};

        {hit, Client} ->
            State@1 = refill_bucket(State),
            {Result, State@2} = case erlang:element(4, State@1) of
                0 ->
                    {{error, nil}, State@1};

                _ ->
                    {{ok, nil}, remove_token(State@1)}
            end,
            gleam@otp@actor:send(Client, Result),
            gleam@otp@actor:continue(State@2);

        {has_full_bucket, Client@1} ->
            State@3 = refill_bucket(State),
            Result@1 = erlang:element(4, State@3) =:= erlang:element(2, State@3),
            gleam@otp@actor:send(Client@1, Result@1),
            gleam@otp@actor:continue(State@3);

        {set_now, Now} ->
            gleam@otp@actor:continue(erlang:setelement(6, State, {some, Now}))
    end.

-spec new(integer(), integer()) -> {ok, gleam@erlang@process:subject(message())} |
    {error, nil}.
new(Max_token_count, Token_rate) ->
    State = {state, Max_token_count, Token_rate, Max_token_count, none, none},
    _pipe = gleam@otp@actor:start(State, fun handle_message/2),
    gleam@result:nil_error(_pipe).

-spec shutdown(gleam@erlang@process:subject(message())) -> nil.
shutdown(Rate_limiter) ->
    gleam@otp@actor:send(Rate_limiter, shutdown).

-spec hit(gleam@erlang@process:subject(message())) -> {ok, nil} | {error, nil}.
hit(Rate_limiter) ->
    gleam@otp@actor:call(Rate_limiter, fun(Field@0) -> {hit, Field@0} end, 10).

-spec has_full_bucket(gleam@erlang@process:subject(message())) -> boolean().
has_full_bucket(Rate_limiter) ->
    gleam@otp@actor:call(
        Rate_limiter,
        fun(Field@0) -> {has_full_bucket, Field@0} end,
        10
    ).

-spec set_now(gleam@erlang@process:subject(message()), integer()) -> nil.
set_now(Rate_limiter, Now) ->
    gleam@otp@actor:send(Rate_limiter, {set_now, Now}).