%%% Copyright (c) 2015, NORDUnet A/S.
%%% See LICENSE for licensing information.

-module(tlv).

-export([encode/2, decode/1]).

-spec encode(binary(), binary()) -> binary().
encode(Type, Value) ->
    4 = byte_size(Type),           % FIXME: make Type a 4 octet binary
    Len = byte_size(Value) + 8,
    <<Len:32, Type/binary, Value/binary>>.

-spec decode(binary()) -> {binary(), binary(), binary()}.
decode(Data) ->
    <<TotalLength:32, Rest1/binary>> = Data,
    Length = TotalLength - 8,
    <<Type:4/binary-unit:8, Rest2/binary>> = Rest1,
    <<Value:Length/binary-unit:8, Rest3/binary>> = Rest2,
    {Type, Value, Rest3}.

%%%%%%%%%%%%%%%%%%%%

-include_lib("eunit/include/eunit.hrl").
-define(TESTDATA1, {<<"DATA">>, <<"some data">>}).
-define(TESTDATA2, {<<"DAT2">>, <<"some other data">>}).

the_test_() ->
    {setup,
     fun() -> [?TESTDATA1, ?TESTDATA2] end,
     fun(_) -> ok end,
     fun(TestVectors) ->
             [?_assertEqual({T, V, <<>>}, decode(encode(T, V))) ||
                 {T, V} <- TestVectors] end}.