-module(ids@ulid).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch]).

-export([monotonic_generate/1, monotonic_from_timestamp/2, decode/1, from_parts/2, from_timestamp/1, generate/0, start/0]).
-export_type([message/0, state/0]).

-opaque message() :: {generate,
        gleam@erlang@process:subject({ok, binary()} | {error, binary()})} |
    {generate_from_timestamp,
        integer(),
        gleam@erlang@process:subject({ok, binary()} | {error, binary()})}.

-opaque state() :: {state, integer(), bitstring()}.

-spec monotonic_generate(gleam@erlang@process:subject(message())) -> {ok,
        binary()} |
    {error, binary()}.
monotonic_generate(Channel) ->
    gleam@otp@actor:call(Channel, fun(Field@0) -> {generate, Field@0} end, 1000).

-spec monotonic_from_timestamp(
    gleam@erlang@process:subject(message()),
    integer()
) -> {ok, binary()} | {error, binary()}.
monotonic_from_timestamp(Channel, Timestamp) ->
    gleam@otp@actor:call(
        Channel,
        fun(Subject) -> {generate_from_timestamp, Timestamp, Subject} end,
        1000
    ).

-spec encode_bytes(bitstring()) -> binary().
encode_bytes(Binary) ->
    case Binary of
        <<Index:5/unsigned, Rest/bitstring>> ->
            _pipe = <<"0123456789ABCDEFGHJKMNPQRSTVWXYZ"/utf8>>,
            _pipe@1 = gleam@string:to_graphemes(_pipe),
            _pipe@2 = gleam@list:at(_pipe@1, Index),
            _pipe@3 = gleam@result:unwrap(_pipe@2, <<"0"/utf8>>),
            gleam@string:append(_pipe@3, encode_bytes(Rest));

        _ ->
            <<""/utf8>>
    end.

-spec encode_base32(bitstring()) -> binary().
encode_base32(Bytes) ->
    To_pad = begin
        _pipe = Bytes,
        _pipe@1 = erlang:bit_size(_pipe),
        _pipe@2 = gleam@int:modulo(_pipe@1, 5),
        _pipe@3 = gleam@result:unwrap(_pipe@2, 5),
        _pipe@4 = gleam@int:subtract(_pipe@3, 5),
        _pipe@5 = gleam@int:absolute_value(_pipe@4),
        _pipe@6 = gleam@int:modulo(_pipe@5, 5),
        gleam@result:unwrap(_pipe@6, 0)
    end,
    encode_bytes(<<0:(lists:max([(To_pad), 0])), Bytes/bitstring>>).

-spec decode_base32(binary()) -> {ok, bitstring()} | {error, nil}.
decode_base32(Binary) ->
    Crockford_with_index = begin
        _pipe = <<"0123456789ABCDEFGHJKMNPQRSTVWXYZ"/utf8>>,
        _pipe@1 = gleam@string:to_graphemes(_pipe),
        gleam@list:index_map(_pipe@1, fun(X, I) -> {X, I} end)
    end,
    Bits = begin
        _pipe@2 = Binary,
        _pipe@3 = gleam@string:to_graphemes(_pipe@2),
        gleam@list:fold(
            _pipe@3,
            <<>>,
            fun(Acc, C) ->
                Index = begin
                    _pipe@4 = Crockford_with_index,
                    _pipe@5 = gleam@list:key_find(_pipe@4, C),
                    gleam@result:unwrap(_pipe@5, 0)
                end,
                <<Acc/bitstring, Index:5>>
            end
        )
    end,
    Padding = begin
        _pipe@6 = Bits,
        _pipe@7 = erlang:bit_size(_pipe@6),
        _pipe@8 = gleam@int:modulo(_pipe@7, 8),
        gleam@result:unwrap(_pipe@8, 0)
    end,
    case Bits of
        <<0:Padding, Res/bitstring>> ->
            {ok, Res};

        _ ->
            {error, nil}
    end.

-spec decode(binary()) -> {ok, {integer(), bitstring()}} | {error, binary()}.
decode(Ulid) ->
    case decode_base32(Ulid) of
        {ok, <<Timestamp:48/unsigned, Randomness:80/bitstring>>} ->
            {ok, {Timestamp, Randomness}};

        _ ->
            {error,
                <<"Error: Decoding failed. Is a valid ULID being supplied?"/utf8>>}
    end.

-spec from_parts(integer(), bitstring()) -> {ok, binary()} | {error, binary()}.
from_parts(Timestamp, Randomness) ->
    case {Timestamp, Randomness} of
        {Time, <<Rand:80/bitstring>>} when Time =< 281474976710655 ->
            _pipe = <<Timestamp:48, Rand/bitstring>>,
            _pipe@1 = encode_base32(_pipe),
            {ok, _pipe@1};

        _ ->
            Error = gleam@string:concat(
                [<<"Error: The timestamp is too large or randomness isn't 80 bits. Please use an Unix timestamp smaller than "/utf8>>,
                    gleam@int:to_string(281474976710655),
                    <<"."/utf8>>]
            ),
            {error, Error}
    end.

-spec from_timestamp(integer()) -> {ok, binary()} | {error, binary()}.
from_timestamp(Timestamp) ->
    from_parts(Timestamp, crypto:strong_rand_bytes(10)).

-spec generate() -> binary().
generate() ->
    Timestamp = os:system_time(millisecond),
    case from_timestamp(Timestamp) of
        {ok, Ulid} ->
            Ulid;

        _ ->
            erlang:error(#{gleam_error => panic,
                    message => <<"Error: Couldn't generate ULID."/utf8>>,
                    module => <<"ids/ulid"/utf8>>,
                    function => <<"generate"/utf8>>,
                    line => 89})
    end.

-spec generate_response_ulid(
    integer(),
    gleam@erlang@process:subject({ok, binary()} | {error, binary()}),
    state()
) -> gleam@otp@actor:next(message(), state()).
generate_response_ulid(Timestamp, Reply, State) ->
    case erlang:element(2, State) =:= Timestamp of
        true ->
            Randomness = begin
                _pipe = erlang:element(3, State),
                _pipe@1 = binary:decode_unsigned(_pipe),
                _pipe@2 = gleam@int:add(_pipe@1, 1),
                binary:encode_unsigned(_pipe@2)
            end,
            case from_parts(Timestamp, Randomness) of
                {ok, Ulid} ->
                    gleam@otp@actor:send(Reply, {ok, Ulid});

                _ ->
                    gleam@otp@actor:send(
                        Reply,
                        {error, <<"Error: Couldn't generate ULID."/utf8>>}
                    )
            end,
            gleam@otp@actor:continue({state, Timestamp, Randomness});

        false ->
            Randomness@1 = crypto:strong_rand_bytes(10),
            case from_parts(Timestamp, Randomness@1) of
                {ok, Ulid@1} ->
                    gleam@otp@actor:send(Reply, {ok, Ulid@1});

                _ ->
                    gleam@otp@actor:send(
                        Reply,
                        {error, <<"Error: Couldn't generate ULID."/utf8>>}
                    )
            end,
            gleam@otp@actor:continue({state, Timestamp, Randomness@1})
    end.

-spec handle_msg(message(), state()) -> gleam@otp@actor:next(message(), state()).
handle_msg(Msg, State) ->
    case Msg of
        {generate, Reply} ->
            _pipe = os:system_time(millisecond),
            generate_response_ulid(_pipe, Reply, State);

        {generate_from_timestamp, Timestamp, Reply@1} ->
            _pipe@1 = Timestamp,
            generate_response_ulid(_pipe@1, Reply@1, State)
    end.

-spec start() -> {ok, gleam@erlang@process:subject(message())} |
    {error, gleam@otp@actor:start_error()}.
start() ->
    gleam@otp@actor:start({state, 0, <<>>}, fun handle_msg/2).