/*
 * Compilation Copyright (c) 1995-2019 by Wei Dai.  All rights reserved.
 *	This copyright applies only to this software distribution package
 *	as a compilation, and does not imply a copyright on any particular
 *	file in the package.
 * 
 *	Boost Software License - Version 1.0 - August 17th, 2003
 *
 *	Permission is hereby granted, free of charge, to any person or organization
 *	obtaining a copy of the software and accompanying documentation covered by
 *	this license (the "Software") to use, reproduce, display, distribute,
 *	execute, and transmit the Software, and to prepare derivative works of the
 *	Software, and to permit third-parties to whom the Software is furnished to
 *	do so, all subject to the following:
 * 
 *	The copyright notices in the Software and this entire statement, including
 *	the above license grant, this restriction and the following disclaimer,
 *	must be included in all copies of the Software, in whole or in part, and
 *	all derivative works of the Software, unless such copies or derivative
 *	works are solely in the form of machine-executable object code generated by
 *	a source language processor.
 *
 *	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, TITLE AND NON-INFRINGEMENT. IN NO EVENT
 *	SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
 *	FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
 *	ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 *	DEALINGS IN THE SOFTWARE.
 */

// basecode.h - originally written and placed in the public domain by Wei Dai

/// \file
/// \brief Base classes for working with encoders and decoders.

#ifndef CRYPTOPP_BASECODE_H
#define CRYPTOPP_BASECODE_H

#include "cryptlib.h"
#include "filters.h"
#include "algparam.h"
#include "argnames.h"

NAMESPACE_BEGIN(CryptoPP)

/// \brief Encoder for bases that are a power of 2
class CRYPTOPP_DLL BaseN_Encoder : public Unflushable<Filter>
{
public:
	/// \brief Construct a BaseN_Encoder
	/// \param attachment a BufferedTransformation to attach to this object
	BaseN_Encoder(BufferedTransformation *attachment=NULLPTR)
		: m_alphabet(NULLPTR), m_padding(0), m_bitsPerChar(0)
		, m_outputBlockSize(0), m_bytePos(0), m_bitPos(0)
			{Detach(attachment);}

	/// \brief Construct a BaseN_Encoder
	/// \param alphabet table of ASCII characters to use as the alphabet
	/// \param log2base the log<sub>2</sub>base
	/// \param attachment a BufferedTransformation to attach to this object
	/// \param padding the character to use as padding
	/// \pre log2base must be between 1 and 7 inclusive
	/// \throws InvalidArgument if log2base is not between 1 and 7
	BaseN_Encoder(const byte *alphabet, int log2base, BufferedTransformation *attachment=NULLPTR, int padding=-1)
		: m_alphabet(NULLPTR), m_padding(0), m_bitsPerChar(0)
		, m_outputBlockSize(0), m_bytePos(0), m_bitPos(0)
	{
		Detach(attachment);
		IsolatedInitialize(MakeParameters(Name::EncodingLookupArray(), alphabet)
			(Name::Log2Base(), log2base)
			(Name::Pad(), padding != -1)
			(Name::PaddingByte(), byte(padding)));
	}

	void IsolatedInitialize(const NameValuePairs &parameters);
	size_t Put2(const byte *begin, size_t length, int messageEnd, bool blocking);

private:
	const byte *m_alphabet;
	int m_padding, m_bitsPerChar, m_outputBlockSize;
	int m_bytePos, m_bitPos;
	SecByteBlock m_outBuf;
};

/// \brief Decoder for bases that are a power of 2
class CRYPTOPP_DLL BaseN_Decoder : public Unflushable<Filter>
{
public:
	/// \brief Construct a BaseN_Decoder
	/// \param attachment a BufferedTransformation to attach to this object
	/// \details padding is set to -1, which means use default padding. If not
	///   required, then the value must be set via IsolatedInitialize().
	BaseN_Decoder(BufferedTransformation *attachment=NULLPTR)
		: m_lookup(NULLPTR), m_bitsPerChar(0)
		, m_outputBlockSize(0), m_bytePos(0), m_bitPos(0)
			{Detach(attachment);}

	/// \brief Construct a BaseN_Decoder
	/// \param lookup table of values
	/// \param log2base the log<sub>2</sub>base
	/// \param attachment a BufferedTransformation to attach to this object
	/// \details log2base is the exponent (like 5 in 2<sup>5</sup>), and not
	///   the number of elements (like 32).
	/// \details padding is set to -1, which means use default padding. If not
	///   required, then the value must be set via IsolatedInitialize().
	BaseN_Decoder(const int *lookup, int log2base, BufferedTransformation *attachment=NULLPTR)
		: m_lookup(NULLPTR), m_bitsPerChar(0)
		, m_outputBlockSize(0), m_bytePos(0), m_bitPos(0)
	{
		Detach(attachment);
		IsolatedInitialize(MakeParameters(Name::DecodingLookupArray(), lookup)(Name::Log2Base(), log2base));
	}

	void IsolatedInitialize(const NameValuePairs &parameters);
	size_t Put2(const byte *begin, size_t length, int messageEnd, bool blocking);

	/// \brief Initializes BaseN lookup array
	/// \param lookup table of values
	/// \param alphabet table of ASCII characters
	/// \param base the base for the encoder
	/// \param caseInsensitive flag indicating whether the alphabet is case sensitivie
	/// \pre COUNTOF(lookup) == 256
	/// \pre COUNTOF(alphabet) == base
	/// \details Internally, the function sets the first 256 elements in the lookup table to
	///  their value from the alphabet array or -1. base is the number of element (like 32),
	///  and not an exponent (like 5 in 2<sup>5</sup>)
	static void CRYPTOPP_API InitializeDecodingLookupArray(int *lookup, const byte *alphabet, unsigned int base, bool caseInsensitive);

private:
	const int *m_lookup;
	int m_bitsPerChar, m_outputBlockSize;
	int m_bytePos, m_bitPos;
	SecByteBlock m_outBuf;
};

/// \brief Filter that breaks input stream into groups of fixed size
class CRYPTOPP_DLL Grouper : public Bufferless<Filter>
{
public:
	/// \brief Construct a Grouper
	/// \param attachment a BufferedTransformation to attach to this object
	Grouper(BufferedTransformation *attachment=NULLPTR)
		: m_groupSize(0), m_counter(0) {Detach(attachment);}

	/// \brief Construct a Grouper
	/// \param groupSize the size of the grouping
	/// \param separator the separator to use between groups
	/// \param terminator the terminator appeand after processing
	/// \param attachment a BufferedTransformation to attach to this object
	Grouper(int groupSize, const std::string &separator, const std::string &terminator, BufferedTransformation *attachment=NULLPTR)
		: m_groupSize(0), m_counter(0)
	{
		Detach(attachment);
		IsolatedInitialize(MakeParameters(Name::GroupSize(), groupSize)
			(Name::Separator(), ConstByteArrayParameter(separator))
			(Name::Terminator(), ConstByteArrayParameter(terminator)));
	}

	void IsolatedInitialize(const NameValuePairs &parameters);
	size_t Put2(const byte *begin, size_t length, int messageEnd, bool blocking);

private:
	SecByteBlock m_separator, m_terminator;
	size_t m_groupSize, m_counter;
};

NAMESPACE_END

#endif
