glimit

-module(glimit@rate_limiter).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch, inline]).
-define(FILEPATH, "src/glimit/rate_limiter.gleam").
-export([new/3, hit/2, get_count/1, remove/2, sweep/1, set_now/2]).
-export_type([hit_error/0, state/1, message/1]).

-if(?OTP_RELEASE >= 27).
-define(MODULEDOC(Str), -moduledoc(Str)).
-define(DOC(Str), -doc(Str)).
-else.
-define(MODULEDOC(Str), -compile([])).
-define(DOC(Str), -compile([])).
-endif.

?MODULEDOC(false).

-type hit_error() :: rate_limited | unavailable.

-type state(FOD) :: {state,
        fun((FOD) -> integer()),
        fun((FOD) -> integer()),
        gleam@dict:dict(FOD, glimit@bucket:bucket_state()),
        gleam@option:option(integer()),
        gleam@option:option(integer()),
        gleam@erlang@process:subject(message(FOD)),
        gleam@option:option(integer())}.

-type message(FOE) :: {hit,
        FOE,
        gleam@erlang@process:subject({ok, nil} | {error, hit_error()})} |
    {get_count, gleam@erlang@process:subject(integer())} |
    {remove, FOE, gleam@erlang@process:subject(nil)} |
    sweep |
    {sweep_sync, gleam@erlang@process:subject(nil)} |
    {set_now, integer(), gleam@erlang@process:subject(nil)}.

-file("src/glimit/rate_limiter.gleam", 75).
?DOC(false).
-spec get_now(state(any())) -> integer().
get_now(State) ->
    case erlang:element(8, State) of
        {some, Now} ->
            Now;

        none ->
            glimit@utils:now()
    end.

-file("src/glimit/rate_limiter.gleam", 82).
?DOC(false).
-spec ensure_bucket(state(FOK), FOK) -> {ok,
        {glimit@bucket:bucket_state(), state(FOK)}} |
    {error, nil}.
ensure_bucket(State, Identifier) ->
    case gleam_stdlib:map_get(erlang:element(4, State), Identifier) of
        {ok, B} ->
            {ok, {B, State}};

        {error, _} ->
            gleam@result:'try'(
                glimit_ffi:rescue(
                    fun() -> (erlang:element(2, State))(Identifier) end
                ),
                fun(Max) ->
                    gleam@result:'try'(
                        glimit_ffi:rescue(
                            fun() -> (erlang:element(3, State))(Identifier) end
                        ),
                        fun(Rate) -> case glimit@bucket:new(Max, Rate) of
                                {ok, B@1} ->
                                    Buckets = gleam@dict:insert(
                                        erlang:element(4, State),
                                        Identifier,
                                        B@1
                                    ),
                                    {ok,
                                        {B@1,
                                            {state,
                                                erlang:element(2, State),
                                                erlang:element(3, State),
                                                Buckets,
                                                erlang:element(5, State),
                                                erlang:element(6, State),
                                                erlang:element(7, State),
                                                erlang:element(8, State)}}};

                                {error, _} ->
                                    {error, nil}
                            end end
                    )
                end
            )
    end.

-file("src/glimit/rate_limiter.gleam", 116).
?DOC(false).
-spec is_idle(
    glimit@bucket:bucket_state(),
    integer(),
    gleam@option:option(integer())
) -> boolean().
is_idle(B, Now, Max_idle_ms) ->
    case Max_idle_ms of
        none ->
            false;

        {some, Threshold} ->
            case erlang:element(5, B) of
                none ->
                    true;

                {some, Last_update} ->
                    (Now - Last_update) > Threshold
            end
    end.

-file("src/glimit/rate_limiter.gleam", 106).
?DOC(false).
-spec do_sweep(state(FOP)) -> state(FOP).
do_sweep(State) ->
    Now = get_now(State),
    Buckets = begin
        _pipe = erlang:element(4, State),
        gleam@dict:filter(
            _pipe,
            fun(_, B) ->
                not glimit@bucket:is_full(B, Now) andalso not is_idle(
                    B,
                    Now,
                    erlang:element(6, State)
                )
            end
        )
    end,
    {state,
        erlang:element(2, State),
        erlang:element(3, State),
        Buckets,
        erlang:element(5, State),
        erlang:element(6, State),
        erlang:element(7, State),
        erlang:element(8, State)}.

-file("src/glimit/rate_limiter.gleam", 128).
?DOC(false).
-spec schedule_sweep(state(any())) -> nil.
schedule_sweep(State) ->
    case erlang:element(5, State) of
        {some, Ms} ->
            _ = gleam@erlang@process:send_after(
                erlang:element(7, State),
                Ms,
                sweep
            ),
            nil;

        none ->
            nil
    end.

-file("src/glimit/rate_limiter.gleam", 138).
?DOC(false).
-spec handle_message(state(FOV), message(FOV)) -> gleam@otp@actor:next(state(FOV), message(FOV)).
handle_message(State, Message) ->
    case Message of
        {hit, Identifier, Client} ->
            case ensure_bucket(State, Identifier) of
                {ok, {B, State@1}} ->
                    Now = get_now(State@1),
                    {Result, B@1} = glimit@bucket:hit(B, Now),
                    Buckets = gleam@dict:insert(
                        erlang:element(4, State@1),
                        Identifier,
                        B@1
                    ),
                    State@2 = {state,
                        erlang:element(2, State@1),
                        erlang:element(3, State@1),
                        Buckets,
                        erlang:element(5, State@1),
                        erlang:element(6, State@1),
                        erlang:element(7, State@1),
                        erlang:element(8, State@1)},
                    case Result of
                        {ok, nil} ->
                            gleam@otp@actor:send(Client, {ok, nil});

                        {error, nil} ->
                            gleam@otp@actor:send(Client, {error, rate_limited})
                    end,
                    gleam@otp@actor:continue(State@2);

                {error, _} ->
                    gleam@otp@actor:send(Client, {error, unavailable}),
                    gleam@otp@actor:continue(State)
            end;

        {get_count, Client@1} ->
            gleam@otp@actor:send(Client@1, maps:size(erlang:element(4, State))),
            gleam@otp@actor:continue(State);

        {remove, Identifier@1, Client@2} ->
            Buckets@1 = gleam@dict:delete(
                erlang:element(4, State),
                Identifier@1
            ),
            State@3 = {state,
                erlang:element(2, State),
                erlang:element(3, State),
                Buckets@1,
                erlang:element(5, State),
                erlang:element(6, State),
                erlang:element(7, State),
                erlang:element(8, State)},
            gleam@otp@actor:send(Client@2, nil),
            gleam@otp@actor:continue(State@3);

        sweep ->
            State@4 = do_sweep(State),
            schedule_sweep(State@4),
            gleam@otp@actor:continue(State@4);

        {sweep_sync, Client@3} ->
            State@5 = do_sweep(State),
            gleam@otp@actor:send(Client@3, nil),
            gleam@otp@actor:continue(State@5);

        {set_now, Now@1, Client@4} ->
            gleam@otp@actor:send(Client@4, nil),
            gleam@otp@actor:continue(
                {state,
                    erlang:element(2, State),
                    erlang:element(3, State),
                    erlang:element(4, State),
                    erlang:element(5, State),
                    erlang:element(6, State),
                    erlang:element(7, State),
                    {some, Now@1}}
            )
    end.

-file("src/glimit/rate_limiter.gleam", 196).
?DOC(false).
-spec new(
    fun((FPC) -> integer()),
    fun((FPC) -> integer()),
    gleam@option:option(integer())
) -> {ok, gleam@erlang@process:subject(message(FPC))} | {error, nil}.
new(Per_second, Burst_limit, Max_idle_ms) ->
    Sweep_interval_ms = {some, 10000},
    _pipe@1 = gleam@otp@actor:new_with_initialiser(
        1000,
        fun(Self_subject) ->
            State = {state,
                Burst_limit,
                Per_second,
                maps:new(),
                Sweep_interval_ms,
                Max_idle_ms,
                Self_subject,
                none},
            schedule_sweep(State),
            {ok,
                begin
                    _pipe = gleam@otp@actor:initialised(State),
                    gleam@otp@actor:returning(_pipe, Self_subject)
                end}
        end
    ),
    _pipe@2 = gleam@otp@actor:on_message(_pipe@1, fun handle_message/2),
    _pipe@3 = gleam@otp@actor:start(_pipe@2),
    _pipe@4 = gleam@result:map(
        _pipe@3,
        fun(Started) -> erlang:element(3, Started) end
    ),
    gleam@result:map_error(_pipe@4, fun(_) -> nil end).

-file("src/glimit/rate_limiter.gleam", 230).
?DOC(false).
-spec hit(gleam@erlang@process:subject(message(FPH)), FPH) -> {ok, nil} |
    {error, hit_error()}.
hit(Rate_limiter, Identifier) ->
    case glimit@utils:safe_call(
        Rate_limiter,
        fun(_capture) -> {hit, Identifier, _capture} end,
        1000
    ) of
        {ok, {ok, nil}} ->
            {ok, nil};

        {ok, {error, Err}} ->
            {error, Err};

        {error, nil} ->
            {error, unavailable}
    end.

-file("src/glimit/rate_limiter.gleam", 243).
?DOC(false).
-spec get_count(gleam@erlang@process:subject(message(any()))) -> integer().
get_count(Rate_limiter) ->
    _pipe = glimit@utils:safe_call(
        Rate_limiter,
        fun(Field@0) -> {get_count, Field@0} end,
        1000
    ),
    gleam@result:unwrap(_pipe, 0).

-file("src/glimit/rate_limiter.gleam", 250).
?DOC(false).
-spec remove(gleam@erlang@process:subject(message(FPN)), FPN) -> {ok, nil} |
    {error, nil}.
remove(Rate_limiter, Identifier) ->
    glimit@utils:safe_call(
        Rate_limiter,
        fun(_capture) -> {remove, Identifier, _capture} end,
        1000
    ).

-file("src/glimit/rate_limiter.gleam", 260).
?DOC(false).
-spec sweep(gleam@erlang@process:subject(message(any()))) -> {ok, nil} |
    {error, nil}.
sweep(Rate_limiter) ->
    glimit@utils:safe_call(
        Rate_limiter,
        fun(Field@0) -> {sweep_sync, Field@0} end,
        1000
    ).

-file("src/glimit/rate_limiter.gleam", 267).
?DOC(false).
-spec set_now(gleam@erlang@process:subject(message(any())), integer()) -> nil.
set_now(Rate_limiter, Now) ->
    _ = glimit@utils:safe_call(
        Rate_limiter,
        fun(_capture) -> {set_now, Now, _capture} end,
        1000
    ),
    nil.