%% -*- mode: erlang; tab-width: 4; indent-tabs-mode: 1; st-rulers: [70] -*-
%% vim: ts=4 sw=4 ft=erlang noet
%%%-------------------------------------------------------------------
%%% @author Andrew Bennett <potatosaladx@gmail.com>
%%% @copyright 2014-2022, Andrew Bennett
%%% @doc
%%%
%%% @end
%%% Created :  23 Jul 2015 by Andrew Bennett <potatosaladx@gmail.com>
%%%-------------------------------------------------------------------
-module(jose_jwe_alg_dir).
-behaviour(jose_jwe).
-behaviour(jose_jwe_alg).

-include("jose_jwk.hrl").

%% jose_jwe callbacks
-export([from_map/1]).
-export([to_map/2]).
%% jose_jwe_alg callbacks
-export([generate_key/3]).
-export([key_decrypt/3]).
-export([key_encrypt/3]).
-export([next_cek/3]).
%% API

%% Types
-type alg() :: dir.

-export_type([alg/0]).

%%====================================================================
%% jose_jwe callbacks
%%====================================================================

from_map(F = #{ <<"alg">> := <<"dir">> }) ->
	{dir, maps:remove(<<"alg">>, F)}.

to_map(dir, F) ->
	F#{ <<"alg">> => <<"dir">> }.

%%====================================================================
%% jose_jwe_alg callbacks
%%====================================================================

generate_key(_Fields, {ENCModule, ENC}, dir) ->
	jose_jwe_alg:generate_key({oct, (ENCModule:bits(ENC) div 8)}, <<"dir">>, ENCModule:algorithm(ENC)).

key_decrypt(Key, _EncryptedKey, dir) when is_binary(Key) ->
	Key;
key_decrypt(#jose_jwk{kty={KTYModule, KTY}}, _EncryptedKey, dir) ->
	KTYModule:derive_key(KTY).

key_encrypt(_Key, _DecryptedKey, dir) ->
	{<<>>, dir}.

next_cek(Key, {_ENCModule, _ENC}, dir) when is_binary(Key) ->
	{Key, dir};
next_cek(#jose_jwk{kty={KTYModule, KTY}}, {ENCModule, ENC}, dir) ->
	next_cek(KTYModule:derive_key(KTY), {ENCModule, ENC}, dir).

%%====================================================================
%% API functions
%%====================================================================

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