kdleam

-module(kdleam@bignum).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch, inline]).
-define(FILEPATH, "src/kdleam/bignum.gleam").
-export([base_to_decimal/2]).

-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).

-file("src/kdleam/bignum.gleam", 77).
?DOC(false).
-spec mul_add_loop(list(integer()), integer(), integer(), list(integer())) -> list(integer()).
mul_add_loop(Digits, Factor, Carry, Acc) ->
    case Digits of
        [] ->
            case Carry of
                0 ->
                    lists:reverse(Acc);

                _ ->
                    mul_add_loop([], Factor, Carry div 10, [Carry rem 10 | Acc])
            end;

        [D | Rest] ->
            Value = (D * Factor) + Carry,
            Digit = Value rem 10,
            Next_carry = Value div 10,
            mul_add_loop(Rest, Factor, Next_carry, [Digit | Acc])
    end.

-file("src/kdleam/bignum.gleam", 73).
?DOC(false).
-spec mul_add(list(integer()), integer(), integer()) -> list(integer()).
mul_add(Digits, Factor, Addend) ->
    mul_add_loop(Digits, Factor, Addend, []).

-file("src/kdleam/bignum.gleam", 98).
?DOC(false).
-spec strip_leading_zeros(list(integer())) -> list(integer()).
strip_leading_zeros(Digits) ->
    case Digits of
        [0, Next | Rest] ->
            strip_leading_zeros([Next | Rest]);

        _ ->
            Digits
    end.

-file("src/kdleam/bignum.gleam", 62).
?DOC(false).
-spec convert_loop(list(integer()), integer(), list(integer())) -> list(integer()).
convert_loop(Source_digits, Source_base, Acc) ->
    case Source_digits of
        [] ->
            strip_leading_zeros(lists:reverse(Acc));

        [D | Rest] ->
            convert_loop(Rest, Source_base, mul_add(Acc, Source_base, D))
    end.

-file("src/kdleam/bignum.gleam", 58).
?DOC(false).
-spec convert(list(integer()), integer()) -> list(integer()).
convert(Source_digits, Source_base) ->
    convert_loop(Source_digits, Source_base, [0]).

-file("src/kdleam/bignum.gleam", 105).
?DOC(false).
-spec digits_to_string(list(integer())) -> binary().
digits_to_string(Digits) ->
    case Digits of
        [] ->
            <<"0"/utf8>>;

        _ ->
            _pipe = Digits,
            _pipe@1 = gleam@list:map(_pipe, fun erlang:integer_to_binary/1),
            gleam@string:join(_pipe@1, <<""/utf8>>)
    end.

-file("src/kdleam/bignum.gleam", 36).
?DOC(false).
-spec digit_value(binary()) -> {ok, integer()} | {error, nil}.
digit_value(G) ->
    case G of
        <<"0"/utf8>> ->
            {ok, 0};

        <<"1"/utf8>> ->
            {ok, 1};

        <<"2"/utf8>> ->
            {ok, 2};

        <<"3"/utf8>> ->
            {ok, 3};

        <<"4"/utf8>> ->
            {ok, 4};

        <<"5"/utf8>> ->
            {ok, 5};

        <<"6"/utf8>> ->
            {ok, 6};

        <<"7"/utf8>> ->
            {ok, 7};

        <<"8"/utf8>> ->
            {ok, 8};

        <<"9"/utf8>> ->
            {ok, 9};

        <<"a"/utf8>> ->
            {ok, 10};

        <<"A"/utf8>> ->
            {ok, 10};

        <<"b"/utf8>> ->
            {ok, 11};

        <<"B"/utf8>> ->
            {ok, 11};

        <<"c"/utf8>> ->
            {ok, 12};

        <<"C"/utf8>> ->
            {ok, 12};

        <<"d"/utf8>> ->
            {ok, 13};

        <<"D"/utf8>> ->
            {ok, 13};

        <<"e"/utf8>> ->
            {ok, 14};

        <<"E"/utf8>> ->
            {ok, 14};

        <<"f"/utf8>> ->
            {ok, 15};

        <<"F"/utf8>> ->
            {ok, 15};

        _ ->
            {error, nil}
    end.

-file("src/kdleam/bignum.gleam", 17).
?DOC(false).
-spec decode_digits(list(binary()), integer(), list(integer())) -> {ok,
        list(integer())} |
    {error, nil}.
decode_digits(Graphemes, Base, Acc) ->
    case Graphemes of
        [] ->
            {ok, lists:reverse(Acc)};

        [G | Rest] ->
            case digit_value(G) of
                {error, _} ->
                    {error, nil};

                {ok, V} ->
                    case V < Base of
                        false ->
                            {error, nil};

                        true ->
                            decode_digits(Rest, Base, [V | Acc])
                    end
            end
    end.

-file("src/kdleam/bignum.gleam", 6).
?DOC(false).
-spec base_to_decimal(binary(), integer()) -> {ok, binary()} | {error, nil}.
base_to_decimal(Digits, Base) ->
    case gleam@string:to_graphemes(Digits) of
        [] ->
            {error, nil};

        Graphemes ->
            case decode_digits(Graphemes, Base, []) of
                {error, _} ->
                    {error, nil};

                {ok, Values} ->
                    {ok, digits_to_string(convert(Values, Base))}
            end
    end.