/**
 * FreeRDP: A Remote Desktop Protocol Implementation
 * ZGFX (RDP8) Bulk Data Compression
 *
 * Copyright 2014 Marc-Andre Moreau <marcandre.moreau@gmail.com>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <winpr/crt.h>
#include <winpr/print.h>
#include <winpr/bitstream.h>

#include <freerdp/codec/zgfx.h>

/**
 * RDP8 Compressor Limits:
 *
 * Maximum number of uncompressed bytes in a single segment: 65535
 * Maximum match distance / minimum history size: 2500000 bytes.
 * Maximum number of segments: 65535
 * Maximum expansion of a segment (when compressed size exceeds uncompressed): 1000 bytes
 * Minimum match length: 3 bytes
 */

struct _ZGFX_TOKEN
{
	int prefixLength;
	int prefixCode;
	int valueBits;
	int tokenType;
	UINT32 valueBase;
};
typedef struct _ZGFX_TOKEN ZGFX_TOKEN;

static const ZGFX_TOKEN ZGFX_TOKEN_TABLE[] =
{
	// len code vbits type  vbase
	{  1,    0,   8,   0,           0 },    // 0
	{  5,   17,   5,   1,           0 },    // 10001
	{  5,   18,   7,   1,          32 },    // 10010
	{  5,   19,   9,   1,         160 },    // 10011
	{  5,   20,  10,   1,         672 },    // 10100
	{  5,   21,  12,   1,        1696 },    // 10101
	{  5,   24,   0,   0,  0x00       },    // 11000
	{  5,   25,   0,   0,  0x01       },    // 11001
	{  6,   44,  14,   1,        5792 },    // 101100
	{  6,   45,  15,   1,       22176 },    // 101101
	{  6,   52,   0,   0,  0x02       },    // 110100
	{  6,   53,   0,   0,  0x03       },    // 110101
	{  6,   54,   0,   0,  0xFF       },    // 110110
	{  7,   92,  18,   1,       54944 },    // 1011100
	{  7,   93,  20,   1,      317088 },    // 1011101
	{  7,  110,   0,   0,  0x04       },    // 1101110
	{  7,  111,   0,   0,  0x05       },    // 1101111
	{  7,  112,   0,   0,  0x06       },    // 1110000
	{  7,  113,   0,   0,  0x07       },    // 1110001
	{  7,  114,   0,   0,  0x08       },    // 1110010
	{  7,  115,   0,   0,  0x09       },    // 1110011
	{  7,  116,   0,   0,  0x0A       },    // 1110100
	{  7,  117,   0,   0,  0x0B       },    // 1110101
	{  7,  118,   0,   0,  0x3A       },    // 1110110
	{  7,  119,   0,   0,  0x3B       },    // 1110111
	{  7,  120,   0,   0,  0x3C       },    // 1111000
	{  7,  121,   0,   0,  0x3D       },    // 1111001
	{  7,  122,   0,   0,  0x3E       },    // 1111010
	{  7,  123,   0,   0,  0x3F       },    // 1111011
	{  7,  124,   0,   0,  0x40       },    // 1111100
	{  7,  125,   0,   0,  0x80       },    // 1111101
	{  8,  188,  20,   1,     1365664 },    // 10111100
	{  8,  189,  21,   1,     2414240 },    // 10111101
	{  8,  252,   0,   0,  0x0C       },    // 11111100
	{  8,  253,   0,   0,  0x38       },    // 11111101
	{  8,  254,   0,   0,  0x39       },    // 11111110
	{  8,  255,   0,   0,  0x66       },    // 11111111
	{  9,  380,  22,   1,     4511392 },    // 101111100
	{  9,  381,  23,   1,     8705696 },    // 101111101
	{  9,  382,  24,   1,    17094304 },    // 101111110
	{ 0 }
};

#define zgfx_GetBits(_zgfx, _nbits) \
	while (_zgfx->cBitsCurrent < _nbits) { \
		_zgfx->BitsCurrent <<= 8; \
		if (_zgfx->pbInputCurrent < _zgfx->pbInputEnd) \
			_zgfx->BitsCurrent += *(_zgfx->pbInputCurrent)++; \
		_zgfx->cBitsCurrent += 8; \
	} \
	_zgfx->cBitsRemaining -= _nbits; \
	_zgfx->cBitsCurrent -= _nbits; \
	_zgfx->bits = _zgfx->BitsCurrent >> _zgfx->cBitsCurrent; \
	_zgfx->BitsCurrent &= ((1 << _zgfx->cBitsCurrent) - 1);

void zgfx_history_buffer_ring_write(ZGFX_CONTEXT* zgfx, BYTE* src, UINT32 count)
{
	UINT32 front;
	UINT32 residue;

	if (count <= 0)
		return;

	if (count > zgfx->HistoryBufferSize)
	{
		residue = count - zgfx->HistoryBufferSize;
		count = zgfx->HistoryBufferSize;
		src += residue;

		zgfx->HistoryIndex = (zgfx->HistoryIndex + residue) % zgfx->HistoryBufferSize;
	}

	if (zgfx->HistoryIndex + count <= zgfx->HistoryBufferSize)
	{
		CopyMemory(&(zgfx->HistoryBuffer[zgfx->HistoryIndex]), src, count);

		if ((zgfx->HistoryIndex += count) == zgfx->HistoryBufferSize)
			zgfx->HistoryIndex = 0;
	}
	else
	{
		front = zgfx->HistoryBufferSize - zgfx->HistoryIndex;
		CopyMemory(&(zgfx->HistoryBuffer[zgfx->HistoryIndex]), src, front);
		CopyMemory(zgfx->HistoryBuffer, &src[front], count - front);
		zgfx->HistoryIndex = count - front;
	}
}

void zgfx_history_buffer_ring_read(ZGFX_CONTEXT* zgfx, int offset, BYTE* dst, UINT32 count)
{
	UINT32 front;
	UINT32 index;
	UINT32 bytes;
	UINT32 valid;
	UINT32 bytesLeft;
	BYTE* dptr = dst;
	BYTE* origDst = dst;

	if (count <= 0)
		return;

	bytesLeft = count;

	index = (zgfx->HistoryIndex + zgfx->HistoryBufferSize - offset) % zgfx->HistoryBufferSize;

	bytes = MIN(bytesLeft, offset);

	if ((index + bytes) <= zgfx->HistoryBufferSize)
	{
		CopyMemory(dptr, &(zgfx->HistoryBuffer[index]), bytes);
	}
	else
	{
		front = zgfx->HistoryBufferSize - index;
		CopyMemory(dptr, &(zgfx->HistoryBuffer[index]), front);
		CopyMemory(&dptr[front], zgfx->HistoryBuffer, bytes - front);
	}

	if ((bytesLeft -= bytes) == 0)
		return;

	dptr += bytes;
	valid = bytes;

	do
	{
		bytes = valid;

		if (bytes > bytesLeft)
			bytes = bytesLeft;

		CopyMemory(dptr, origDst, bytes);
		dptr += bytes;
		valid <<= 1;
	}
	while ((bytesLeft -= bytes) > 0);
}

int zgfx_decompress_segment(ZGFX_CONTEXT* zgfx, BYTE* pbSegment, UINT32 cbSegment)
{
	BYTE c;
	BYTE flags;
	int extra;
	int opIndex;
	int haveBits;
	int inPrefix;
	UINT32 count;
	UINT32 distance;

	if (cbSegment < 1)
		return -1;

	flags = pbSegment[0]; /* header (1 byte) */

	pbSegment++;
	cbSegment--;

	zgfx->OutputCount = 0;

	if (!(flags & PACKET_COMPRESSED))
	{
		zgfx_history_buffer_ring_write(zgfx, pbSegment, cbSegment);
		CopyMemory(zgfx->OutputBuffer, pbSegment, cbSegment);
		zgfx->OutputCount = cbSegment;

		return 1;
	}

	zgfx->pbInputCurrent = pbSegment;
	zgfx->pbInputEnd = &pbSegment[cbSegment - 1];

	/* NumberOfBitsToDecode = ((NumberOfBytesToDecode - 1) * 8) - ValueOfLastByte */
	zgfx->cBitsRemaining = 8 * (cbSegment - 1) - *zgfx->pbInputEnd;
	zgfx->cBitsCurrent = 0;
	zgfx->BitsCurrent = 0;

	while (zgfx->cBitsRemaining)
	{
		haveBits = 0;
		inPrefix = 0;

		for (opIndex = 0; ZGFX_TOKEN_TABLE[opIndex].prefixLength != 0; opIndex++)
		{
			while (haveBits < ZGFX_TOKEN_TABLE[opIndex].prefixLength)
			{
				zgfx_GetBits(zgfx, 1);
				inPrefix = (inPrefix << 1) + zgfx->bits;
				haveBits++;
			}

			if (inPrefix == ZGFX_TOKEN_TABLE[opIndex].prefixCode)
			{
				if (ZGFX_TOKEN_TABLE[opIndex].tokenType == 0)
				{
					/* Literal */

					zgfx_GetBits(zgfx, ZGFX_TOKEN_TABLE[opIndex].valueBits);
					c = (BYTE) (ZGFX_TOKEN_TABLE[opIndex].valueBase + zgfx->bits);

					zgfx->HistoryBuffer[zgfx->HistoryIndex] = c;

					if (++zgfx->HistoryIndex == zgfx->HistoryBufferSize)
						zgfx->HistoryIndex = 0;

					zgfx->OutputBuffer[zgfx->OutputCount++] = c;
				}
				else
				{
					zgfx_GetBits(zgfx, ZGFX_TOKEN_TABLE[opIndex].valueBits);
					distance = ZGFX_TOKEN_TABLE[opIndex].valueBase + zgfx->bits;

					if (distance != 0)
					{
						/* Match */

						zgfx_GetBits(zgfx, 1);

						if (zgfx->bits == 0)
						{
							count = 3;
						}
						else
						{
							count = 4;
							extra = 2;

							zgfx_GetBits(zgfx, 1);

							while (zgfx->bits == 1)
							{
								count *= 2;
								extra++;

								zgfx_GetBits(zgfx, 1);
							}

							zgfx_GetBits(zgfx, extra);
							count += zgfx->bits;
						}

						zgfx_history_buffer_ring_read(zgfx, distance, &(zgfx->OutputBuffer[zgfx->OutputCount]), count);
						zgfx_history_buffer_ring_write(zgfx, &(zgfx->OutputBuffer[zgfx->OutputCount]), count);
						zgfx->OutputCount += count;
					}
					else
					{
						/* Unencoded */

						zgfx_GetBits(zgfx, 15);
						count = zgfx->bits;

						zgfx->cBitsRemaining -= zgfx->cBitsCurrent;
						zgfx->cBitsCurrent = 0;
						zgfx->BitsCurrent = 0;

						CopyMemory(&(zgfx->OutputBuffer[zgfx->OutputCount]), zgfx->pbInputCurrent, count);
						zgfx_history_buffer_ring_write(zgfx, zgfx->pbInputCurrent, count);

						zgfx->pbInputCurrent += count;
						zgfx->cBitsRemaining -= (8 * count);
						zgfx->OutputCount += count;
					}
				}

				break;
			}
		}
	}

	return 1;
}

int zgfx_decompress(ZGFX_CONTEXT* zgfx, BYTE* pSrcData, UINT32 SrcSize, BYTE** ppDstData, UINT32* pDstSize, UINT32 flags)
{
	int status;
	BYTE descriptor;

	if (SrcSize < 1)
		return -1;

	descriptor = pSrcData[0]; /* descriptor (1 byte) */

	if (descriptor == ZGFX_SEGMENTED_SINGLE)
	{
		status = zgfx_decompress_segment(zgfx, &pSrcData[1], SrcSize - 1);

		*ppDstData = (BYTE*) malloc(zgfx->OutputCount);
		*pDstSize = zgfx->OutputCount;

		CopyMemory(*ppDstData, zgfx->OutputBuffer, zgfx->OutputCount);
	}
	else if (descriptor == ZGFX_SEGMENTED_MULTIPART)
	{
		UINT32 segmentSize;
		UINT16 segmentNumber;
		UINT16 segmentCount;
		UINT32 segmentOffset;
		UINT32 uncompressedSize;
		BYTE* pConcatenated;

		segmentOffset = 7;
		segmentCount = *((UINT16*) &pSrcData[1]); /* segmentCount (2 bytes) */
		uncompressedSize = *((UINT32*) &pSrcData[3]); /* uncompressedSize (4 bytes) */

		pConcatenated = (BYTE*) malloc(uncompressedSize);

		*ppDstData = pConcatenated;
		*pDstSize = uncompressedSize;

		for (segmentNumber = 0; segmentNumber < segmentCount; segmentNumber++)
		{
			segmentSize = *((UINT32*) &pSrcData[segmentOffset]); /* segmentSize (4 bytes) */
			segmentOffset += 4;

			status = zgfx_decompress_segment(zgfx, &pSrcData[segmentOffset], segmentSize);
			segmentOffset += segmentSize;

			CopyMemory(pConcatenated, zgfx->OutputBuffer, zgfx->OutputCount);
			pConcatenated += zgfx->OutputCount;
		}
	}
	else
	{
		return -1;
	}

	return 1;
}

int zgfx_compress(ZGFX_CONTEXT* zgfx, BYTE* pSrcData, UINT32 SrcSize, BYTE** ppDstData, UINT32* pDstSize, UINT32* pFlags)
{
	return 1;
}

void zgfx_context_reset(ZGFX_CONTEXT* zgfx, BOOL flush)
{
	zgfx->HistoryIndex = 0;
}

ZGFX_CONTEXT* zgfx_context_new(BOOL Compressor)
{
	ZGFX_CONTEXT* zgfx;

	zgfx = (ZGFX_CONTEXT*) calloc(1, sizeof(ZGFX_CONTEXT));

	if (zgfx)
	{
		zgfx->Compressor = Compressor;

		zgfx->HistoryBufferSize = sizeof(zgfx->HistoryBuffer);

		zgfx_context_reset(zgfx, FALSE);
	}

	return zgfx;
}

void zgfx_context_free(ZGFX_CONTEXT* zgfx)
{
	if (zgfx)
	{
		free(zgfx);
	}
}

