%% MIT License

%% Copyright (c) 2019, Sergei Semichev <chessvegas@chessvegas.com>

%% Permission is hereby granted, free of charge, to any person obtaining a copy
%% of this software and associated documentation files (the "Software"), to deal
%% in the Software without restriction, including without limitation the rights
%% to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
%% copies of the Software, and to permit persons to whom the Software is
%% furnished to do so, subject to the following conditions:

%% The above copyright notice and this permission notice shall be included in all
%% copies or substantial portions of the Software.

%% THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
%% IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
%% FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
%% AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
%% LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
%% OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
%% SOFTWARE.

-module(uef_crypt).

-export([md5_hex/1]).

-ifdef(TEST).
-include_lib("eunit/include/eunit.hrl").
-endif.

%%%------------------------------------------------------------------------------
%%%   API
%%%------------------------------------------------------------------------------

%% md5_hex/1
-spec md5_hex(IoData :: iodata()) -> Binary :: binary().
%% @doc
%% Returns binary Binary in hexadecimal form of md5 hash of the argument IoData
%% @end
md5_hex(IoData) ->
	hstr(erlang:md5(IoData)).


%%%------------------------------------------------------------------------------
%%%   Internal functions
%%%------------------------------------------------------------------------------

%% hstr/1
-spec hstr(binary()) -> binary().
hstr(B) when is_binary(B) ->
	T = {$0,$1,$2,$3,$4,$5,$6,$7,$8,$9,$a,$b,$c,$d,$e,$f},
	<< <<(element(X bsr 4 + 1, T)), (element(X band 16#0F + 1, T))>>
	|| <<X:8>> <= B >>.


%%%------------------------------------------------------------------------------
%%%   Tests
%%%------------------------------------------------------------------------------

-ifdef(TEST).

md5_hex_test_() ->
	% Check with https://www.md5hashgenerator.com/
	[
	?_assertEqual(<<"e2fc714c4727ee9395f324cd2e7f331f">>, md5_hex(<<"abcd">>)),
	?_assertEqual(<<"e2fc714c4727ee9395f324cd2e7f331f">>, md5_hex("abcd")),
	?_assertEqual(<<"e2fc714c4727ee9395f324cd2e7f331f">>, md5_hex(["a", "bcd"])),
	?_assertEqual(<<"e2fc714c4727ee9395f324cd2e7f331f">>, md5_hex(["a", "b", ["c", ["d"]]])),
	?_assertEqual(<<"6cd3556deb0da54bca060b4c39479839">>, md5_hex(<<"Hello, world!">>)),
	?_assertEqual(<<"aa3ad0839299f15e1e407d0d1a62f507">>, md5_hex(<<"кто здесь?"/utf8>>)),
	?_assertEqual(<<"56bf18da956bee82e008090e3d95ad7c">>, md5_hex(<<"誰在這裡"/utf8>>))
	].

-endif. % end of tests