/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * $URL$
 * $Id$
 *
 */

//
// This file is heavily based on the arj code available under the GPL
// from http://arj.sourceforge.net/ , version 3.10.22 .

#include "common/scummsys.h"
#include "common/util.h"
#include "common/unarj.h"

namespace Common {

#define HEADER_ID     0xEA60
#define HEADER_ID_HI    0xEA
#define HEADER_ID_LO    0x60

#define FIRST_HDR_SIZE    30
#define HEADERSIZE_MAX   (FIRST_HDR_SIZE + 10 + ARJ_FILENAME_MAX + ARJ_COMMENT_MAX)
#define CRC_MASK        0xFFFFFFFFL
#define HSLIMIT_ARJ		524288L

#define CBIT		 9
#define PBIT		 5
#define TBIT		 5

//
// Source for InitCRC, GetCRC: crc32.c
//

static uint32 CRCtable[256];

static void	InitCRC(void) {
	const uint32 poly = 0xEDB88320;
	int i, j;
	uint32 r;

	for (i = 0; i < 256; i++) {
		r = i;
		for (j = 0; j < 8; j++)
			if (r & 1)
				r = (r >> 1) ^ poly;
			else
				r >>= 1;
		CRCtable[i] = r;
	}
}

static uint32 GetCRC(byte *data, int len) {
	uint32 CRC = 0xFFFFFFFF;
	int i;
	for (i = 0; i < len; i++)
		CRC = (CRC >> 8) ^ CRCtable[(CRC ^ data[i]) & 0xFF];
	return CRC ^ 0xFFFFFFFF;
}

ArjFile::ArjFile() : _uncompressedData(NULL) {
	InitCRC();
	_isOpen = false;
	_fallBack = false;
}

ArjFile::~ArjFile() {
	close();

	for (uint i = 0; i < _headers.size(); i++)
		delete _headers[i];

	_headers.clear();
	_fileMap.clear();
	_archMap.clear();
}

void ArjFile::registerArchive(const String &filename) {
	int32 first_hdr_pos;
	ArjHeader *header;

	if (!_currArchive.open(filename))
		return;

	first_hdr_pos = findHeader();

	if (first_hdr_pos < 0) {
		warning("ArjFile::registerArchive(): Could not find a valid header");
		return;
	}

	_currArchive.seek(first_hdr_pos, SEEK_SET);
	if (readHeader() == NULL)
		return;

	while ((header = readHeader()) != NULL) {
		_headers.push_back(header);

		_currArchive.seek(header->compSize, SEEK_CUR);

		_fileMap[header->filename] = _headers.size() - 1;
		_archMap[header->filename] = filename;
	}

	_currArchive.close();

	debug(0, "ArjFile::registerArchive(%s): Located %d files", filename.c_str(), _headers.size());
}

//
// Source for findHeader and readHeader: arj_arcv.c
//

int32 ArjFile::findHeader(void) {
	long end_pos, tmp_pos;
	int id;
	byte header[HEADERSIZE_MAX];
	uint32 crc;
	uint16 basic_hdr_size;

	tmp_pos = _currArchive.pos();
	_currArchive.seek(0L, SEEK_END);
	end_pos = _currArchive.pos() - 2;
	if (end_pos >= tmp_pos + HSLIMIT_ARJ)
		end_pos = tmp_pos + HSLIMIT_ARJ;

	while (tmp_pos < end_pos) {
		_currArchive.seek(tmp_pos, SEEK_SET);
		id = _currArchive.readByte();
		while (tmp_pos < end_pos) {
			if (id == HEADER_ID_LO)
				if ((id = _currArchive.readByte()) == HEADER_ID_HI)
					break;
			else
				id = _currArchive.readByte();
			tmp_pos++;
		}
		if (tmp_pos >= end_pos)
			return -1;
		if ((basic_hdr_size = _currArchive.readUint16LE()) <= HEADERSIZE_MAX) {
			_currArchive.read(header, basic_hdr_size);
			crc = GetCRC(header, basic_hdr_size);
			if (crc == _currArchive.readUint32LE()) {
				_currArchive.seek(tmp_pos, SEEK_SET);
				return tmp_pos;
			}
		}
		tmp_pos++;
	}
	return -1;
}

ArjHeader *ArjFile::readHeader() {
	ArjHeader header;
	ArjHeader *head;
	byte headData[HEADERSIZE_MAX];

	// Strictly check the header ID
	header.id = _currArchive.readUint16LE();
	if (header.id != HEADER_ID) {
		warning("ArjFile::readHeader(): Bad header ID (%x)", header.id);

		return NULL;
	}

	header.headerSize = _currArchive.readUint16LE();
	if (header.headerSize == 0)
		return NULL;			// end of archive
	if (header.headerSize > HEADERSIZE_MAX) {
		warning("ArjFile::readHeader(): Bad header");

		return NULL;
	}

	int rSize = _currArchive.read(headData, header.headerSize);

	MemoryReadStream readS(headData, rSize);

	header.headerCrc = _currArchive.readUint32LE();
	if (GetCRC(headData, header.headerSize) != header.headerCrc) {
		warning("ArjFile::readHeader(): Bad header CRC");
		return NULL;
	}

	header.firstHdrSize = readS.readByte();
	header.nbr = readS.readByte();
	header.xNbr = readS.readByte();
	header.hostOs = readS.readByte();
	header.flags = readS.readByte();
	header.method = readS.readByte();
	header.fileType = readS.readByte();
	(void)readS.readByte(); // password_modifier
	header.timeStamp = readS.readUint32LE();
	header.compSize = readS.readSint32LE();
	header.origSize = readS.readSint32LE();
	header.fileCRC = readS.readUint32LE();
	header.entryPos = readS.readUint16LE();
	header.fileMode = readS.readUint16LE();
	header.hostData = readS.readUint16LE();

	// static int check_file_size()
	if (header.origSize < 0 || header.compSize < 0) {
		warning("ArjFile::readHeader(): Wrong file size");
		return NULL;
	}

	strncpy(header.filename, (const char *)&headData[header.firstHdrSize], ARJ_FILENAME_MAX);

	strncpy(header.comment, (const char *)&headData[header.firstHdrSize + strlen(header.filename) + 1], ARJ_COMMENT_MAX);

    // Process extended headers, if any
    uint16 extHeaderSize;
	while ((extHeaderSize = _currArchive.readUint16LE()) != 0)
		_currArchive.seek((long)(extHeaderSize + 4), SEEK_CUR);

	header.pos = _currArchive.pos();

	head = new ArjHeader(header);

	return head;
}


bool ArjFile::open(const Common::String &filename) {
	if (_isOpen)
		error("Attempt to open another instance of archive");

	_isOpen = false;

	if (_fallBack) {
		_currArchive.open(filename);
		if (_currArchive.isOpen()) {
			_isOpen = true;
			_uncompressed = &_currArchive;
			return true;
		}
	}

	if (!_fileMap.contains(filename))
		return false;

	_isOpen = true;

	ArjHeader *hdr = _headers[_fileMap[filename]];

	_compsize = hdr->compSize;
	_origsize = hdr->origSize;

	// FIXME: This hotfix prevents Drascula from leaking memory.
	// As far as sanity checks go this is not bad, but the engine should be fixed.
	if (_uncompressedData)
		free(_uncompressedData);

	_uncompressedData = (byte *)malloc(_origsize);
	_outstream = new MemoryWriteStream(_uncompressedData, _origsize);

	_currArchive.open(_archMap[filename]);
	_currArchive.seek(hdr->pos, SEEK_SET);

	if (hdr->method == 0) { // store
        _currArchive.read(_uncompressedData, _origsize);
	} else {
		_compressedData = (byte *)malloc(_compsize);
		_currArchive.read(_compressedData, _compsize);

		_compressed = new MemoryReadStream(_compressedData, _compsize);

		if (hdr->method == 1 || hdr->method == 2 || hdr->method == 3)
			decode();
		else if (hdr->method == 4)
			decode_f();

		delete _compressed;
		free(_compressedData);
	}

	_currArchive.close();
	delete _outstream;
	_outstream = NULL;

	_uncompressed = new MemoryReadStream(_uncompressedData, _origsize);

	return true;
}

void ArjFile::close() {
	if (!_isOpen)
		return;

	_isOpen = false;

	if (_fallBack) {
		_currArchive.close();
		return;
	} else {
		delete _uncompressed;
	}

	_uncompressed = NULL;

	free(_uncompressedData);
	_uncompressedData = NULL;
}

uint32 ArjFile::read(void *dataPtr, uint32 dataSize) {
	return _uncompressed->read(dataPtr, dataSize);
}

bool ArjFile::eos() {
	return _uncompressed->eos();
}

int32 ArjFile::pos() {
	return _uncompressed->pos();
}

int32 ArjFile::size() {
	return _uncompressed->size();
}

bool ArjFile::seek(int32 offset, int whence) {
	return _uncompressed->seek(offset, whence);
}

//
// Source for init_getbits: arj_file.c (decode_start_stub)
//

void ArjFile::init_getbits() {
	_bitbuf = 0;
	_bytebuf = 0;
	_bitcount = 0;
	fillbuf(ARJ_CHAR_BIT * 2);
}

//
// Source for fillbuf, getbits: decode.c 
//

void ArjFile::fillbuf(int n) {
	while (_bitcount < n) {
		_bitbuf = (_bitbuf << _bitcount) | (_bytebuf >> (8 - _bitcount));
		n -= _bitcount;
		if (_compsize > 0) {
			_compsize--;
			_bytebuf = _compressed->readByte();
		} else {
			_bytebuf = 0;
		}
		_bitcount = 8;
	}
	_bitcount -= n;
	_bitbuf = ( _bitbuf << n) | (_bytebuf >> (8-n));
	_bytebuf <<= n;
}

// Reads a series of bits into the input buffer */
uint16 ArjFile::getbits(int n) {
	uint16 rc;

	rc = _bitbuf >> (ARJ_CODE_BIT - n);
	fillbuf(n);
	return rc;
}



//
// Huffman decode routines
// Source: decode.c
//

// Creates a table for decoding
void ArjFile::make_table(int nchar, byte *bitlen, int tablebits, uint16 *table, int tablesize) {
	uint16 count[17], weight[17], start[18];
	uint16 *p;
	uint i, k, len, ch, jutbits, avail, nextcode, mask;

	for (i = 1; i <= 16; i++)
		count[i] = 0;
	for (i = 0; (int)i < nchar; i++)
		count[bitlen[i]]++;

	start[1] = 0;
	for (i = 1; i <= 16; i++)
		start[i + 1] = start[i] + (count[i] << (16 - i));
	if (start[17] != (uint16) (1 << 16))
		error("ArjFile::make_table(): bad file data");

	jutbits = 16 - tablebits;
	for (i = 1; (int)i <= tablebits; i++) {
		start[i] >>= jutbits;
		weight[i] = 1 << (tablebits - i);
	}
	while (i <= 16) {
		weight[i] = 1 << (16 - i);
		i++;
	}

	i = start[tablebits + 1] >> jutbits;
	if (i != (uint16) (1 << 16)) {
		k = 1 << tablebits;
		while (i != k)
			table[i++] = 0;
	}

	avail = nchar;
	mask = 1 << (15 - tablebits);
	for (ch = 0; (int)ch < nchar; ch++) {
		if ((len = bitlen[ch]) == 0)
			continue;
		k = start[len];
		nextcode = k + weight[len];
		if ((int)len <= tablebits) {
			if (nextcode > (uint)tablesize)
				error("ArjFile::make_table(): bad file data");
			for (i = start[len]; i < nextcode; i++)
				table[i] = ch;
		} else {
			p = &table[k >> jutbits];
			i = len - tablebits;
			while (i != 0) {
				if (*p == 0) {
					_right[avail] = _left[avail] = 0;
					*p = avail;
					avail++;
				}
				if (k & mask)
					p = &_right[*p];
				else
					p = &_left[*p];
				k <<= 1;
				i--;
			}
			*p = ch;
		}
		start[len] = nextcode;
	}
}

// Reads length of data pending
void ArjFile::read_pt_len(int nn, int nbit, int i_special) {
	int i, n;
	int16 c;
	uint16 mask;

	n = getbits(nbit);
	if (n == 0) {
		c = getbits(nbit);
		for (i = 0; i < nn; i++)
			_pt_len[i] = 0;
		for (i = 0; i < 256; i++)
			_pt_table[i] = c;
	} else {
		i = 0;
		while (i < n) {
			c = _bitbuf >> 13;
			if (c == 7) {
				mask = 1 << 12;
				while (mask & _bitbuf) {
					mask >>= 1;
					c++;
				}
			}
			fillbuf((c < 7) ? 3 : (int)(c - 3));
			_pt_len[i++] = (byte)c;
			if (i == i_special) {
				c = getbits(2);
				while (--c >= 0)
					_pt_len[i++] = 0;
			}
		}
		while (i < nn)
			_pt_len[i++] = 0;
		make_table(nn, _pt_len, 8, _pt_table, ARJ_PTABLESIZE);
	}
}

// Reads a character table
void ArjFile::read_c_len() {
	int16 i, c, n;
	uint16 mask;

	n = getbits(CBIT);
	if (n == 0) {
		c = getbits(CBIT);
		for (i = 0; i < ARJ_NC; i++)
			_c_len[i] = 0;
		for (i = 0; i < ARJ_CTABLESIZE; i++)
			_c_table[i] = c;
	} else {
		i = 0;
		while (i < n) {
			c = _pt_table[_bitbuf >> (8)];
			if (c >= ARJ_NT) {
				mask = 1 << 7;
				do {
					if (_bitbuf & mask)
						c = _right[c];
					else
						c = _left[c];
					mask >>= 1;
				} while (c >= ARJ_NT);
			}
			fillbuf((int)(_pt_len[c]));
			if (c <= 2) {
				if (c == 0)
					c = 1;
				else if (c == 1) {
					c = getbits(4);
					c += 3;
				} else {
					c = getbits(CBIT);
					c += 20;
				}
				while (--c >= 0)
					_c_len[i++] = 0;
			}
			else
				_c_len[i++] = (byte)(c - 2);
		}
		while (i < ARJ_NC)
			_c_len[i++] = 0;
		make_table(ARJ_NC, _c_len, 12, _c_table, ARJ_CTABLESIZE);
	}
}

// Decodes a single character
uint16 ArjFile::decode_c() {
	uint16 j, mask;

	if (_blocksize == 0) {
		_blocksize = getbits(ARJ_CODE_BIT);
		read_pt_len(ARJ_NT, TBIT, 3);
		read_c_len();
		read_pt_len(ARJ_NP, PBIT, -1);
	}
	_blocksize--;
	j = _c_table[_bitbuf >> 4];
	if (j >= ARJ_NC) {
		mask = 1 << 3;
		do {
			if (_bitbuf & mask)
				j = _right[j];
			else
				j = _left[j];
			mask >>= 1;
		} while (j >= ARJ_NC);
	}
	fillbuf((int)(_c_len[j]));
	return j;
}

// Decodes a control character
uint16 ArjFile::decode_p() {
	uint16 j, mask;

	j = _pt_table[_bitbuf >> 8];
	if (j >= ARJ_NP) {
		mask = 1 << 7;
		do {
			if (_bitbuf & mask)
				j = _right[j];
			else
				j = _left[j];
			mask >>= 1;
		} while (j >= ARJ_NP);
	}
	fillbuf((int)(_pt_len[j]));
	if (j != 0) {
		j--;
		j = (1 << j) + getbits((int)j);
	}
	return j;
}

// Initializes memory for decoding
void ArjFile::decode_start() {
	_blocksize = 0;
	init_getbits();
}

// Decodes the entire file
void ArjFile::decode() {
	int16 i;
	int16 r;
	int16 c;
	int16 j;
	int32 count;

	decode_start();
	count = _origsize;
	r = 0;

	while (count > 0) {
		if ((c = decode_c()) <= ARJ_UCHAR_MAX) {
			_ntext[r] = (byte) c;
			count--;
			if (++r >= ARJ_DICSIZ) {
				r = 0;
				_outstream->write(_ntext, ARJ_DICSIZ);
			}
		} else {
			j = c - (ARJ_UCHAR_MAX + 1 - ARJ_THRESHOLD);
			count -= j;
			i = r - decode_p() - 1;
			if (i < 0)
				i += ARJ_DICSIZ;
			if (r > i && r < ARJ_DICSIZ - ARJ_MAXMATCH - 1) {
				while (--j >= 0)
					_ntext[r++] = _ntext[i++];
			} else {
				while (--j >= 0) {
					_ntext[r] = _ntext[i];
					if (++r >= ARJ_DICSIZ) {
						r = 0;
						_outstream->write(_ntext, ARJ_DICSIZ);
					}
					if (++i >= ARJ_DICSIZ)
						i = 0;
				}
			}
		}
	}
	if (r > 0)
		_outstream->write(_ntext, r);
}

// Backward pointer decoding
int16 ArjFile::decode_ptr() {
	int16 c = 0;
	int16 width;
	int16 plus;
	int16 pwr;

	plus = 0;
	pwr = 1 << 9; 
	for (width = 9; width < 13; width++) {
		c = getbits(1);
		if (c == 0)
			break;
		plus += pwr;
		pwr <<= 1;
	}
	if (width != 0)
		c = getbits(width);
	c += plus;
	return c;
}

// Reference length decoding
int16 ArjFile::decode_len() {
	int16 c = 0;
	int16 width;
	int16 plus;
	int16 pwr;

	plus = 0;
	pwr = 1;
	for (width = 0; width < 7; width++) {
		c = getbits(1);
		if (c == 0)
			break;
		plus += pwr;
		pwr <<= 1;
	}
	if (width != 0)
		c = getbits(width);
	c += plus;
	return c;
}

// Decodes the entire file, using method 4
void ArjFile::decode_f() {
	int16 i;
	int16 j;
	int16 c;
	int16 r;
	uint32 ncount;

	init_getbits();
	ncount = 0;
	_getlen = _getbuf = 0;
	r = 0;

	while (ncount < (uint32)_origsize) {
		c = decode_len();
		if (c == 0) {
			ncount++;
			_ntext[r] = (byte)getbits(8);
			if (++r >= ARJ_FDICSIZ) {
				r = 0;
				_outstream->write(_ntext, ARJ_FDICSIZ);
			}
		} else {
			j = c - 1 + ARJ_THRESHOLD;
			ncount += j;
			if ((i = r - decode_ptr() - 1) < 0)
				i += ARJ_FDICSIZ;
			while (j-- > 0) {
				_ntext[r] = _ntext[i];
				if (++r >= ARJ_FDICSIZ) {
					r = 0;
					_outstream->write(_ntext, ARJ_FDICSIZ);
				}
				if (++i >= ARJ_FDICSIZ)
					i = 0;
			}
		}
	}
	if (r != 0)
		_outstream->write(_ntext, r);
}


} // End of namespace Common