% Copyright (C) 2014-2019 Olivier Boudeville
%
% This file is part of the Ceylan-Myriad library.
%
% This library is free software: you can redistribute it and/or modify
% it under the terms of the GNU Lesser General Public License or
% the GNU General Public License, as they are published by the Free Software
% Foundation, either version 3 of these Licenses, or (at your option)
% any later version.
% You can also redistribute it and/or modify it under the terms of the
% Mozilla Public License, version 1.1 or later.
%
% This library is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
% GNU Lesser General Public License and the GNU General Public License
% for more details.
%
% You should have received a copy of the GNU Lesser General Public
% License, of the GNU General Public License and of the Mozilla Public License
% along with this library.
% If not, see <http://www.gnu.org/licenses/> and
% <http://www.mozilla.org/MPL/>.
%
% Author: Olivier Boudeville [olivier (dot) boudeville (at) esperide (dot) com]


% Unit tests for the cipher_utils toolbox.
%
% See the cipher_utils.erl tested module.
%
-module(cipher_utils_test).


% For run/0 export and al:
-include("test_facilities.hrl").


-spec run() -> no_return().
run() ->

	test_facilities:start( ?MODULE ),

	%TransformList = [ id ],
	%TransformList = [ id, id ],
	%TransformList = [ { offset, 117 } ],

	%TransformList = [ { compress, zip } ],
	%TransformList = [ { compress, bzip2 } ],
	%TransformList = [ { compress, xz } ],

	%TransformList = [ { insert_random, _Seed={ 4, 48, 25 },
	%				  _Range=10 } ],

	%TransformList = [ delta_combine ],

	%TransformList = [ { shuffle, _Seed={ 140, 98, 250 }, _Length=7 } ],

	%TransformList = [ { 'xor', _XOR="A string can be used as well" } ],

	MyMealyTable = cipher_utils:generate_mealy_table( _StateCount=500 ),

	%TransformList = [ { mealy, _InitialState=2, MyMealyTable } ],

	% A rather complete key (compression is better be done among the first):
	TransformList = [
					  delta_combine,
					  { compress, xz },
					  { offset, 41 },
					  { insert_random, _FirstInsertSeed={ 412, 1418, 2565 },
						_FirstRange=10 },
					  { shuffle, _ShuffleSeed={ 140, 98, 250 }, _Length=79 },
					  { 'xor', "All human beings are born free and equal "
						"in dignity and rights." },
					  delta_combine,
					  { mealy, _InitialMealyState=50, MyMealyTable },
					  { insert_random, _SecondInsertSeed={ 432, 4118, 255 },
						_SecondRange=11 },
					  delta_combine
					],

	KeyFilename = "my-test-key-file.cipher",


	test_facilities:display( "Generating a key from specified transform list, "
							 "to be stored in file '~s'.", [ KeyFilename ] ),

	case file_utils:is_existing_file( KeyFilename ) of

		true ->
			% Otherwise generation will halt on error:
			test_facilities:display( "(removing previously existing "
									 "key file '~s')~n", [ KeyFilename ] ),
			file_utils:remove_file( KeyFilename );

		false ->
			ok

	end,

	cipher_utils:generate_key( KeyFilename, TransformList ),

	SourceFilename = "my-content-file",

	% Add some content:
	file_utils:copy_file( "GNUmakefile", SourceFilename ),

	OriginalContent = file_utils:read_whole( SourceFilename ),

	EncryptedFilename = SourceFilename ++ ".encrypted",


	test_facilities:display( "Encrypting '~s' into '~s', using key file '~s'.",
					 [ SourceFilename, EncryptedFilename, KeyFilename ] ),

	cipher_utils:encrypt( SourceFilename, EncryptedFilename, KeyFilename ),


	DecryptedFilename = SourceFilename ++ ".decrypted",

	test_facilities:display( "Decrypting '~s' into '~s', using the same key.",
							 [ EncryptedFilename, DecryptedFilename ] ),

	cipher_utils:decrypt( EncryptedFilename, DecryptedFilename, KeyFilename ),

	FinalContent = file_utils:read_whole( DecryptedFilename ),

	case OriginalContent =:= FinalContent of

		true ->
			test_facilities:display( "Original file and decrypted one match." );

		false ->
			throw( decrypted_content_differs )

	end,

	file_utils:remove_files( [ KeyFilename, EncryptedFilename,
							   DecryptedFilename, SourceFilename ] ),

	test_facilities:stop().