munch

-module(munch@internal@hmac).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch, inline]).
-define(FILEPATH, "src/munch/internal/hmac.gleam").
-export([new/3]).

-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/munch/internal/hmac.gleam", 44).
?DOC(false).
-spec xor_each_byte(bitstring(), integer(), list(bitstring())) -> bitstring().
xor_each_byte(Bytes, Mask, Accumulator) ->
    case Bytes of
        <<Byte:8, Rest/bitstring>> ->
            xor_each_byte(
                Rest,
                Mask,
                [<<(munch@internal@bitwise:'xor'(Byte, Mask)):8>> | Accumulator]
            );

        _ ->
            _pipe = Accumulator,
            _pipe@1 = lists:reverse(_pipe),
            gleam_stdlib:bit_array_concat(_pipe@1)
    end.

-file("src/munch/internal/hmac.gleam", 36).
?DOC(false).
-spec masked_key_block(bitstring(), integer(), integer()) -> bitstring().
masked_key_block(Key, Mask, Block_size) ->
    Zero_bits = (Block_size - erlang:byte_size(Key)) * 8,
    Key_block = <<Key/bitstring, 0:(erlang:max(0, Zero_bits))>>,
    xor_each_byte(Key_block, Mask, []).

-file("src/munch/internal/hmac.gleam", 10).
?DOC(false).
-spec new(fun(() -> munch@internal@hash:hash()), integer(), bitstring()) -> munch@internal@hash:hash().
new(Hash, Block_size, Key) ->
    Key@1 = gleam_stdlib:bit_array_pad_to_bytes(Key),
    Key@2 = case erlang:byte_size(Key@1) > Block_size of
        true ->
            _pipe = Hash(),
            _pipe@1 = munch@internal@hash:update(_pipe, Key@1),
            munch@internal@hash:finish(_pipe@1);

        false ->
            Key@1
    end,
    Inner = masked_key_block(Key@2, 16#36, Block_size),
    Outer = masked_key_block(Key@2, 16#5C, Block_size),
    State = begin
        _pipe@2 = Hash(),
        munch@internal@hash:update(_pipe@2, Inner)
    end,
    Finish = fun(State@1) ->
        Inner_digest = munch@internal@hash:finish(State@1),
        _pipe@3 = Hash(),
        _pipe@4 = munch@internal@hash:update(_pipe@3, Outer),
        _pipe@5 = munch@internal@hash:update(_pipe@4, Inner_digest),
        munch@internal@hash:finish(_pipe@5)
    end,
    munch@internal@hash:from(State, fun munch@internal@hash:update/2, Finish).