/*
 * This file is a part of Tito - a cryptography library
 * and is distributed under the 2-Clause BSD licence.
 * Author: Tomasz Sowa <t.sowa@ttmath.org>
 */

/* 
 * Copyright (c) 2012-2022, Tomasz Sowa
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 */

#ifndef headerfile_tito_base64
#define headerfile_tito_base64

#include <string>


namespace Tito
{


class Base64
{
public:

	Base64();

	/*
	 * padding character
	 * default '=';
	 */
	void SetPadding(char c);

	/*
	 * if false then allow the strings passed to Decode(...) methods to now have the trailing padding characters ('=')
	 * default: true
	 */
	void RequirePaddingOnDecodedStrings(bool require);

	void Encode(const char * in, size_t len,	std::string & out);
	void Encode(const char * in,				std::string & out);
	void Encode(const std::string & in,			std::string & out);

	bool Decode(const char * in, size_t len,	std::string & out);
	bool Decode(const char * in,				std::string & out);
	bool Decode(const std::string & in,			std::string & out);

	bool Decode(const wchar_t * in, size_t len, std::string & out);
	bool Decode(const wchar_t * in, 			std::string & out);
	bool Decode(const std::wstring & in, 		std::string & out);


private:

	static const char * tabbase64;
	size_t tabbase64_len;
	char padding;
	unsigned int not_existing;
	bool require_padding_on_decoded_strings;

	void Convert3to4Pieces(const char * s, size_t len, unsigned int * tab4);
	void ConvertFrom4to3Pieces(const unsigned int * tab4, unsigned int * tab3);
	bool CharFromBase64(unsigned int from, unsigned int & to);
	void Save4PiecesToString(std::string & s, const unsigned int * tab4);

	template<typename CharType>
	bool Make4pieces(const CharType * s, size_t len, unsigned int * tab4);

	template<typename StringType>
	void Save3PiecesToString(const unsigned int * tab3, StringType & s);

	template<typename CharType, typename StringType>
	bool DecodeRaw(const CharType * in, size_t len, StringType & out);

};


template<typename CharType>
bool Base64::Make4pieces(const CharType * s, size_t len, unsigned int * tab4)
{
	for(size_t i=0 ; i<4 ; ++i)
	{
		if( i >= len || s[i] == padding )
			tab4[i] = not_existing;
		else
		if( !CharFromBase64(static_cast<unsigned int>(s[i]), tab4[i]) )
			return false;
	}

return true;
}


template<typename StringType>
void Base64::Save3PiecesToString(const unsigned int * tab3, StringType & s)
{
	for(int i=0 ; i<3 ; ++i)
	{
		if( tab3[i] != not_existing )
			s += tab3[i];
	}
}


template<typename CharType, typename StringType>
bool Base64::DecodeRaw(const CharType * in, size_t len, StringType & out)
{
unsigned int tab3[3];
unsigned int tab4[4];

	out.clear();
	size_t new_size = len - len/3 + 3;
	out.reserve(new_size);

	if( require_padding_on_decoded_strings && len % 4 != 0 )
		return false;

	while( len > 0 )
	{
		if( !Make4pieces(in, len, tab4) )
			return false;

		ConvertFrom4to3Pieces(tab4, tab3);
		Save3PiecesToString(tab3, out);

		in += 4;
		len = (len >= 4) ? len - 4 : 0;
	}

return true;
}






} // namespace Tito



#endif