/*
	 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.

	 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., 59 Temple Place - Suite 330, Boston, MA	02111-1307, USA
  */

#include "define.h"
#include "libpst.h"
#include <sys/types.h>
#include <string.h>
#include <stdio.h>

#ifndef _MSC_VER
#include <stdint.h>
#endif

#ifdef _MSC_VER
#define uint32_t unsigned int
#endif

#include "lzfu.h"

#define LZFU_COMPRESSED 		0x75465a4c
#define LZFU_UNCOMPRESSED		0x414c454d

// initital dictionary
#define LZFU_INITDICT	"{\\rtf1\\ansi\\mac\\deff0\\deftab720{\\fonttbl;}" \
												 "{\\f0\\fnil \\froman \\fswiss \\fmodern \\fscrip" \
												 "t \\fdecor MS Sans SerifSymbolArialTimes Ne" \
												 "w RomanCourier{\\colortbl\\red0\\green0\\blue0" \
												 "\r\n\\par \\pard\\plain\\f0\\fs20\\b\\i\\u\\tab" \
												 "\\tx"
// initial length of dictionary
#define LZFU_INITLENGTH 207

// header for compressed rtf
typedef struct _lzfuheader {
	uint32_t cbSize;
	uint32_t cbRawSize;
	uint32_t dwMagic;
	uint32_t dwCRC;
} lzfuheader;


/**
	We always need to add 0x10 to the buffer offset because we need to skip past the header info
*/

unsigned char* lzfu_decompress (unsigned char* rtfcomp, size_t *size) {
	// the dictionary buffer
	unsigned char dict[4096];
	// the dictionary pointer
	unsigned int dict_length=0;
	// the header of the lzfu block
	lzfuheader lzfuhdr;
	// container for the data blocks
	unsigned char flags;
	// temp value for determining the bits in the flag
	unsigned char flag_mask;
	unsigned int i, in_size;
	unsigned char *out_buf;
	unsigned int out_ptr = 0;

	memcpy(dict, LZFU_INITDICT, LZFU_INITLENGTH);
	dict_length = LZFU_INITLENGTH;
	memcpy(&lzfuhdr, rtfcomp, sizeof(lzfuhdr));
	LE32_CPU(lzfuhdr.cbSize);
	LE32_CPU(lzfuhdr.cbRawSize);
	LE32_CPU(lzfuhdr.dwMagic);
	LE32_CPU(lzfuhdr.dwCRC);
	/*	printf("total size: %d\n", lzfuhdr.cbSize+4);
	printf("raw size  : %d\n", lzfuhdr.cbRawSize);
	printf("compressed: %s\n", (lzfuhdr.dwMagic == LZFU_COMPRESSED ? "yes" : "no"));
	printf("CRC       : %#x\n", lzfuhdr.dwCRC);
	printf("\n");*/
	out_buf = (unsigned char*)xmalloc(lzfuhdr.cbRawSize+20); //plus 4 cause we have 2x'}' and a \0
	in_size = 0;
	// we add plus one here cause when referencing an array, the index is always one less
	// (ie, when accessing 2 element array, highest index is [1])
	while (in_size+0x11 < lzfuhdr.cbSize) {
		memcpy(&flags, &(rtfcomp[in_size+0x10]), 1);
		in_size += 1;

		flag_mask = 1;
		while (flag_mask != 0 && in_size+0x11 < lzfuhdr.cbSize) {
			if (flag_mask & flags) {
				// read 2 bytes from input
				unsigned short int blkhdr, offset, length;
				memcpy(&blkhdr, &(rtfcomp[in_size+0x10]), 2);
				LE16_CPU(blkhdr);
				in_size += 2;
				/* swap the upper and lower bytes of blkhdr */
				blkhdr = (((blkhdr&0xFF00)>>8)+
					  ((blkhdr&0x00FF)<<8));
				/* the offset is the first 24 bits of the 32 bit value */
				offset = (blkhdr&0xFFF0)>>4;
				/* the length of the dict entry are the last 8 bits */
				length = (blkhdr&0x000F)+2;
				// add the value we are about to print to the dictionary
				for (i=0; i < length; i++) {
					unsigned char c1;
					c1 = dict[(offset+i)%4096];
					dict[dict_length]=c1;
					dict_length = (dict_length+1) % 4096;
					out_buf[out_ptr++] = c1;
				}
			} else {
				// uncompressed chunk (single byte)
				char c1 = rtfcomp[in_size+0x10];
				in_size ++;
				dict[dict_length] = c1;
				dict_length = (dict_length+1)%4096;
				out_buf[out_ptr++] = c1;
			}
			flag_mask <<= 1;
		}
	}
	// the compressed version doesn't appear to drop the closing braces onto the doc.
	// we should do that
	out_buf[out_ptr++] = '}';
	out_buf[out_ptr++] = '}';
	*size = out_ptr;
	out_buf[out_ptr++] = '\0';
	return out_buf;
}