/*
    lzfu.cpp

    Copyright (C) 2003 Michael Goffioul <kdeprint@swing.be>

    This file is part of KTNEF, the KDE TNEF support library/program.

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

    This library 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
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public License
    along with this library; see the file COPYING.LIB.  If not, write to
    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
    Boston, MA 02110-1301, USA.
 */
/**
 * @file
 * This file is part of the API for handling TNEF data and
 * provides the @acronym LZFU decompression functionality.
 *
 * @author Michael Goffioul
 */

#include "lzfu.h"

#include <QtCore/QIODevice>

#include <sys/types.h>
#include <string.h>
#include <stdio.h>

//#define DO_DEBUG

//@cond IGNORE
#define LZFU_COMPRESSED    0x75465a4c
#define LZFU_UNCOMPRESSED  0x414c454d

#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"
#define LZFU_INITLENGTH 207
//@endcond

//@cond PRIVATE
typedef struct _lzfuheader
{
  quint32 cbSize;
  quint32 cbRawSize;
  quint32 dwMagic;
  quint32 dwCRC;
} lzfuheader;
//@endcond

//@cond IGNORE
#define FLAG(f,n) (f>>n)&0x1

/*typedef struct _blockheader {
  unsigned int offset:12;
  unsigned int length:4;
  } blockheader;*/

#define OFFSET(b) (b>>4)&0xFFF
#define LENGTH(b) ((b&0xF)+2)
//@endcond

int lzfu_decompress( QIODevice *input, QIODevice *output )
{
  unsigned char window[4096];
  unsigned int  wlength = 0, cursor = 0, ocursor = 0;
  lzfuheader    lzfuhdr;
  //blockheader blkhdr;
  quint16      blkhdr;
  char          bFlags;
  int           nFlags;

  memcpy( window, LZFU_INITDICT, LZFU_INITLENGTH );
  wlength = LZFU_INITLENGTH;
  if ( input->read( (char *)&lzfuhdr, sizeof(lzfuhdr) ) != sizeof(lzfuhdr) ) {
    fprintf( stderr, "unexpected eof, cannot read LZFU header\n" );
    return -1;
  }
  cursor += sizeof( lzfuhdr );
#ifdef DO_DEBUG
  fprintf( stdout, "total size : %d\n", lzfuhdr.cbSize+4 );
  fprintf( stdout, "raw size   : %d\n", lzfuhdr.cbRawSize );
  fprintf( stdout, "compressed : %s\n", ( lzfuhdr.dwMagic == LZFU_COMPRESSED ? "yes" : "no" ) );
  fprintf( stdout, "CRC        : %x\n", lzfuhdr.dwCRC );
  fprintf( stdout, "\n" );
#endif

  while ( cursor < lzfuhdr.cbSize+4 && ocursor < lzfuhdr.cbRawSize && !input->atEnd() ) {
    if ( input->read( &bFlags, 1 ) != 1 ) {
      fprintf( stderr, "unexpected eof, cannot read chunk flag\n" );
      return -1;
    }
    nFlags = 8;
    cursor++;
#ifdef DO_DEBUG
    fprintf( stdout, "Flags : " );
    for ( int i=nFlags-1; i>=0; i-- ) {
      fprintf( stdout, "%d", FLAG( bFlags, i ) );
    }
    fprintf( stdout, "\n" );
#endif
    for ( int i=0; i<nFlags && ocursor<lzfuhdr.cbRawSize && cursor<lzfuhdr.cbSize+4; i++ ) {
      if ( FLAG( bFlags, i ) ) {
        // compressed chunck
        char c1, c2;
        if ( input->read( &c1, 1 ) != 1 || input->read( &c2, 1 ) != 1 ) {
          fprintf( stderr, "unexpected eof, cannot read block header\n" );
          return -1;
        }
        blkhdr = c1;
        blkhdr <<= 8;
        blkhdr |= ( 0xFF & c2 );
        unsigned int offset = OFFSET( blkhdr ), length = LENGTH( blkhdr );
        cursor += 2;
#ifdef DO_DEBUG
        fprintf( stdout, "block : offset=%.4d [%d], length=%.2d (0x%04X)\n",
                 OFFSET( blkhdr ), wlength, LENGTH( blkhdr ), blkhdr );
#endif
        //if ( offset >= wlength ) {
        //     break;
        //}
#ifdef DO_DEBUG
        fprintf( stdout, "block : " );
#endif
        for ( unsigned int i=0; i<length; i++ ) {
          c1 = window[( offset + i ) % 4096];
          //if ( wlength < 4096 ) {
          window[wlength] = c1;
          wlength = ( wlength + 1 ) % 4096;
          //}
#ifdef DO_DEBUG
          if ( c1 == '\n' ) {
            fprintf( stdout, "\nblock : " );
          } else {
            fprintf( stdout, "%c", c1 );
          }
#endif
          output->putChar( c1 );
          ocursor++;
        }
#ifdef DO_DEBUG
        fprintf( stdout, "\n" );
#endif
      } else {
        // uncompressed chunk (char)
        char c;
        if ( !input->getChar( &c ) ) {
          if ( !input->atEnd() ) {
            fprintf( stderr, "unexpected eof, cannot read character\n" );
            return -1;
          }
          break;
        }
#ifdef DO_DEBUG
        fprintf( stdout, "char  : %c\n", c );
#endif
        cursor++;
        //if ( wlength < 4096 ) {
        window[wlength] = c;
        wlength = ( wlength+1 ) % 4096;
        //}
        output->putChar( c );
        ocursor++;
      }
    }

  }

  return 0;
}