// This header file contains bodies of functions.

#ifndef __ZLIBHELPER_H__
#define __ZLIBHELPER_H__

#include <ascript.h>
#include <zlib.h>

namespace AScript {
namespace ZLib {

//-----------------------------------------------------------------------------
// GZHeader
// see RFC 1952 (GZIP file format specification version 4.3) for specification
//-----------------------------------------------------------------------------
class GZHeader {
public:
	struct Fields {
		enum { Size = 10 };
		unsigned char Identification1;
		unsigned char Identification2;
		unsigned char CompressionMethod;
		unsigned char Flags;
		XPackedULong_LE(ModificationTime);
		unsigned char ExtraFlags;
		unsigned char OperatingSystem;
		inline bool GetFTEXT() const { return (Flags & (1 << 0))? true : false; }
		inline bool GetFHCRC() const { return (Flags & (1 << 1))? true : false; }
		inline bool GetFEXTRA() const { return (Flags & (1 << 2))? true : false; }
		inline bool GetFNAME() const { return (Flags & (1 << 3))? true : false; }
		inline bool GetFCOMMENT() const { return (Flags & (1 << 4))? true : false; }
	};
private:
	Fields _fields;
	Binary _extra;
	String _fileName;
	String _comment;
public:
	GZHeader();
	bool Read(Signal sig, Stream &stream);
	bool Write(Signal sig, Stream &stream);
	inline Fields &GetFields() { return _fields; }
	inline const char *GetFileName() const { return _fileName.c_str(); }
	inline const char *GetComment() const { return _comment.c_str(); }
	inline void SetModificationTime(unsigned long time) {
		XPackULong(_fields.ModificationTime, time);
	}
	inline void SetExtra(const Binary &extra) {
		_extra = extra;
		_fields.Flags |= (1 << 2);
	}
	inline void SetFileName(const char *fileName) {
		_fileName = fileName;
		_fields.Flags |= (1 << 3);
	}
	inline void SetComment(const char *comment) {
		_comment = comment;
		_fields.Flags |= (1 << 4);
	}
private:
	inline void SetError_InvalidFormat(Signal sig) {
		sig.SetError(ERR_FormatError, "invalid gzip format");
	}
};

GZHeader::GZHeader()
{
	::memset(&_fields, 0x00, Fields::Size);
	_fields.Identification1		= 0x1f;
	_fields.Identification2		= 0x8b;
	_fields.CompressionMethod	= 0x08;
	_fields.Flags				= 0x00;
	_fields.ExtraFlags			= 0x00;
	_fields.OperatingSystem		= 0x00;
}

bool GZHeader::Read(Signal sig, Stream &stream)
{
	if (stream.Read(sig, &_fields, Fields::Size) < Fields::Size) {
		SetError_InvalidFormat(sig);
		return false;
	}
	if (_fields.Identification1 != 0x1f || _fields.Identification2 != 0x8b) {
		SetError_InvalidFormat(sig);
		return false;
	}
	if (_fields.GetFEXTRA()) {
		struct {
			XPackedUShort_LE(ExtraLength);
		} fields;
		if (stream.Read(sig, &fields, 2) < 2) {
			SetError_InvalidFormat(sig);
			return false;
		}
		unsigned short ExtraLength = XUnpackUShort(fields.ExtraLength);
		if (!stream.Seek(sig, ExtraLength, Stream::SeekCur)) {
			SetError_InvalidFormat(sig);
			return false;
		}
	}
	if (_fields.GetFNAME()) {
		char ch;
		for (;;) {
			if (stream.Read(sig, &ch, 1) < 1) {
				SetError_InvalidFormat(sig);
				return false;
			}
			if (ch == '\0') break;
			_fileName += ch;
		}
	}
	if (_fields.GetFCOMMENT()) {
		char ch;
		for (;;) {
			if (stream.Read(sig, &ch, 1) < 1) {
				SetError_InvalidFormat(sig);
				return false;
			}
			if (ch == '\0') break;
			_comment += ch;
		}
	}
	if (_fields.GetFHCRC()) {
		if (!stream.Seek(sig, 2, Stream::SeekCur)) {
			SetError_InvalidFormat(sig);
			return false;
		}
	}
	return true;
}

bool GZHeader::Write(Signal sig, Stream &stream)
{
	if (stream.Write(sig, &_fields, Fields::Size) < Fields::Size) {
		SetError_InvalidFormat(sig);
		return false;
	}
	if (_fields.GetFEXTRA()) {
		struct {
			XPackedUShort_LE(ExtraLength);
		} fields;
		XPackUShort(fields.ExtraLength, static_cast<unsigned short>(_extra.size()));
		if (stream.Write(sig, &fields, 2) < 2) {
			SetError_InvalidFormat(sig);
			return false;
		}
	}
	if (_fields.GetFNAME()) {
		size_t bytes = _fileName.size() + 1;
		if (stream.Write(sig, _fileName.c_str(), bytes) < bytes) {
			SetError_InvalidFormat(sig);
			return false;
		}
	}
	if (_fields.GetFCOMMENT()) {
		size_t bytes = _comment.size() + 1;
		if (stream.Write(sig, _comment.c_str(), bytes) < bytes) {
			SetError_InvalidFormat(sig);
			return false;
		}
	}
	if (_fields.GetFHCRC()) {
		unsigned short crc16 = 0x0000;
		struct {
			XPackedUShort_LE(CRC16);
		} fields;
		XPackUShort(fields.CRC16, crc16);
		if (stream.Write(sig, &fields, 2) < 2) {
			SetError_InvalidFormat(sig);
			return false;
		}
	}
	return true;
}

//-----------------------------------------------------------------------------
// Stream_Inflater
//-----------------------------------------------------------------------------
class Stream_Inflater : public Stream {
private:
	Stream *_pStream;
	OAL::Memory _memory;
	size_t _bytesSrc;
	size_t _bytesBuff;
	size_t _bytesOut;
	size_t _offsetOut;
	z_stream _zstrm;
	unsigned char *_buffOut;
	unsigned char *_buffIn;
public:
	inline Stream_Inflater(Signal sig, Stream *pStream, size_t bytesSrc, size_t bytesBuff = 32768) :
		Stream(sig, ATTR_Readable), _pStream(pStream), _bytesSrc(bytesSrc),
		_bytesBuff(bytesBuff), _bytesOut(0),
		_offsetOut(0), _buffOut(NULL), _buffIn(NULL) {}
	~Stream_Inflater();
	bool Initialize(Signal sig, int windowBits = 15);
	virtual const char *GetName() const;
	virtual size_t DoWrite(Signal sig, const void *buff, size_t len);
	virtual size_t DoRead(Signal sig, void *buff, size_t bytes);
	virtual bool DoSeek(Signal sig, long offset, size_t offsetPrev, SeekMode seekMode);
	virtual bool DoFlush(Signal sig);
	virtual bool DoClose(Signal sig);
};

Stream_Inflater::~Stream_Inflater()
{
	Stream::Delete(_pStream);
	::inflateEnd(&_zstrm);
}

bool Stream_Inflater::Initialize(Signal sig, int windowBits)
{
	::memset(&_zstrm, 0x00, sizeof(_zstrm));
	_zstrm.zalloc = Z_NULL;
	_zstrm.zfree = Z_NULL;
	_zstrm.opaque = Z_NULL;
	_zstrm.avail_in = 0;
	if (::inflateInit2(&_zstrm, windowBits) != Z_OK) {
		sig.SetError(ERR_IOError, "%s",
					(_zstrm.msg == NULL)? "zlib error" : _zstrm.msg);
		return false;
	}
	_memory.Allocate(_bytesBuff * 2);
	_buffOut = reinterpret_cast<unsigned char *>(_memory.GetPointer(0));
	_buffIn = reinterpret_cast<unsigned char *>(_memory.GetPointer(_bytesBuff));
	return true;
}

const char *Stream_Inflater::GetName() const
{
	return _pStream->GetName();
}

size_t Stream_Inflater::DoWrite(Signal sig, const void *buff, size_t len)
{
	return 0;
}

size_t Stream_Inflater::DoRead(Signal sig, void *buff, size_t bytes)
{
	size_t bytesRead = 0;
	char *buffp = reinterpret_cast<char *>(buff);
	bool continueFlag = true;
	for (size_t bytesRest = bytes; bytesRest > 0 && continueFlag; ) {
		if (_offsetOut >= _bytesOut) {
			if (_zstrm.avail_in == 0) {
				size_t bytesRead = _pStream->Read(sig,
								_buffIn, ChooseMin(_bytesBuff, _bytesSrc));
				if (sig.IsSignalled()) {
					::inflateEnd(&_zstrm);
					return 0;
				}
				if (bytesRead == 0) break;
				if (_bytesSrc != InvalidSize) {
					_bytesSrc -= bytesRead;
				}
				_zstrm.avail_in = static_cast<uInt>(bytesRead);
				_zstrm.next_in = _buffIn;
			}
			_zstrm.avail_out = static_cast<uInt>(_bytesBuff);
			_zstrm.next_out = _buffOut;
			int ret = ::inflate(&_zstrm, Z_NO_FLUSH);
			if (ret == Z_OK) {
				// nothing to do
			} else if (ret == Z_STREAM_END) {
				continueFlag = false;
			} else {
				sig.SetError(ERR_IOError, "%s",
					(_zstrm.msg == NULL)? "zlib error" : _zstrm.msg);
				::inflateEnd(&_zstrm);
				return 0;
			}
			_bytesOut = _bytesBuff - _zstrm.avail_out;
			_offsetOut = 0;
			if (_bytesOut == 0) break;
		}
		size_t bytesToCopy = _bytesOut - _offsetOut;
		if (bytesToCopy > bytesRest) bytesToCopy = bytesRest;
		if (buffp != NULL) {
			::memcpy(buffp + bytesRead, _buffOut + _offsetOut, bytesToCopy);
		}
		_offsetOut += bytesToCopy;
		bytesRest -= bytesToCopy;
		bytesRead += bytesToCopy;
	}
	return bytesRead;
}

bool Stream_Inflater::DoSeek(Signal sig, long offset, size_t offsetPrev, SeekMode seekMode)
{
	if (seekMode == SeekSet) {
		if (static_cast<size_t>(offset) >= offsetPrev) {
			size_t bytesToRead = static_cast<size_t>(offset) - offsetPrev;
			if (bytesToRead == 0) return true;
			return DoRead(sig, NULL, bytesToRead) == static_cast<size_t>(bytesToRead);
		}
	} else if (seekMode == SeekCur) {
		if (offset == 0) {
			return true;
		} else if (offset > 0) {
			return DoRead(sig, NULL, offset) == static_cast<size_t>(offset);
		}
	}
	sig.SetError(ERR_SystemError, "backward seeking is not supported");
	return false;
}

bool Stream_Inflater::DoFlush(Signal sig)
{
	return false;
}

bool Stream_Inflater::DoClose(Signal sig)
{
	return true;
}

//-----------------------------------------------------------------------------
// Stream_Deflater
//-----------------------------------------------------------------------------
class Stream_Deflater : public Stream {
private:
	Stream *_pStream;
	OAL::Memory _memory;
	size_t _bytesBuff;
	size_t _offsetOut;
	z_stream _zstrm;
	unsigned char *_buffOut;
	unsigned char *_buffIn;
public:
	inline Stream_Deflater(Signal sig, Stream *pStream, size_t bytesBuff = 32768) :
		Stream(sig, ATTR_Writable), _pStream(pStream),
		_bytesBuff(bytesBuff), _offsetOut(0), _buffOut(NULL), _buffIn(NULL) {}
	~Stream_Deflater();
	bool Initialize(Signal sig, int windowBits, int memLevel);
	virtual const char *GetName() const;
	virtual size_t DoWrite(Signal sig, const void *buff, size_t len);
	virtual bool DoFlush(Signal sig);
	virtual bool DoClose(Signal sig);
	virtual size_t DoRead(Signal sig, void *buff, size_t bytes);
	virtual bool DoSeek(Signal sig, long offset, size_t offsetPrev, SeekMode seekMode);
};

Stream_Deflater::~Stream_Deflater()
{
	DoClose(_sig);
}

bool Stream_Deflater::Initialize(Signal sig, int windowBits, int memLevel)
{
	::memset(&_zstrm, 0x00, sizeof(_zstrm));
	_zstrm.zalloc = Z_NULL;
	_zstrm.zfree = Z_NULL;
	_zstrm.opaque = Z_NULL;
	if (::deflateInit2(&_zstrm, Z_DEFAULT_COMPRESSION,
				Z_DEFLATED, windowBits, memLevel, Z_DEFAULT_STRATEGY) != Z_OK) {
		sig.SetError(ERR_IOError, "%s",
					(_zstrm.msg == NULL)? "zlib error" : _zstrm.msg);
		return false;
	}
	_memory.Allocate(_bytesBuff * 2);
	_buffOut = reinterpret_cast<unsigned char *>(_memory.GetPointer(0));
	_buffIn = reinterpret_cast<unsigned char *>(_memory.GetPointer(_bytesBuff));
	_zstrm.next_out = _buffOut;
	_zstrm.avail_out = static_cast<uInt>(_bytesBuff);
	return true;
}

const char *Stream_Deflater::GetName() const
{
	return _pStream->GetName();
}

size_t Stream_Deflater::DoWrite(Signal sig, const void *buff, size_t len)
{
	if (_pStream == NULL) return 0;
	_zstrm.next_in = reinterpret_cast<Bytef *>(const_cast<void *>(buff));
	_zstrm.avail_in = static_cast<uInt>(len);
	while (_zstrm.avail_in > 0) {
		if (_zstrm.avail_out == 0) {
			_pStream->Write(sig, _buffOut, _bytesBuff);
			if (sig.IsSignalled()) return 0;
			_zstrm.next_out = _buffOut;
			_zstrm.avail_out = static_cast<uInt>(_bytesBuff);
		}
		if (::deflate(&_zstrm, Z_NO_FLUSH) != Z_OK) {
			sig.SetError(ERR_IOError, "%s",
					(_zstrm.msg == NULL)? "zlib error" : _zstrm.msg);
			return 0;
		}
	}
	return len;
}

bool Stream_Deflater::DoFlush(Signal sig)
{
	return DoClose(sig);
}

bool Stream_Deflater::DoClose(Signal sig)
{
	if (_pStream == NULL) return true;
	for (;;) {
		if (_zstrm.avail_out == 0) {
			_pStream->Write(sig, _buffOut, _bytesBuff);
			if (sig.IsSignalled()) return 0;
			_zstrm.next_out = _buffOut;
			_zstrm.avail_out = static_cast<uInt>(_bytesBuff);
		}
		int rtn = ::deflate(&_zstrm, Z_FINISH);
		if (rtn == Z_STREAM_END) break;
		if (rtn != Z_OK) {
			sig.SetError(ERR_IOError, "%s",
					(_zstrm.msg == NULL)? "zlib error" : _zstrm.msg);
			return false;
		}
	}
	size_t bytesOut = _bytesBuff - _zstrm.avail_out;
	if (bytesOut > 0) {
		_pStream->Write(sig, _buffOut, bytesOut);
	}
	::deflateEnd(&_zstrm);
	if (sig.IsSignalled()) return false;
	bool rtn = _pStream->Flush(sig);
	Stream::Delete(_pStream);
	_pStream = NULL;
	return rtn;
}

size_t Stream_Deflater::DoRead(Signal sig, void *buff, size_t bytes)
{
	return 0;
}

bool Stream_Deflater::DoSeek(Signal sig, long offset, size_t offsetPrev, SeekMode seekMode)
{
	return false;
}

}
}
#endif
