/*  Clzip - A data compressor based on the LZMA algorithm
    Copyright (C) 2010 Antonio Diaz Diaz.

    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 3 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, see <http://www.gnu.org/licenses/>.
*/

enum { Ib_buffer_size = 65536 };

struct Input_buffer
  {
  uint8_t * buffer;
  int pos;
  int stream_pos;		// when reached, a new block must be read
  int infd_;			// input file descriptor
  bool at_stream_end;
  };

bool Ib_read_block( struct Input_buffer * const ibuf );

static inline void Ib_init( struct Input_buffer * const ibuf, const int infd )
  {
  ibuf->buffer = (uint8_t *)malloc( Ib_buffer_size );
  if( !ibuf->buffer )
    {
    show_error( "not enough memory. Find a machine with more memory", 0, false );
    cleanup_and_fail( 1 );
    }
  ibuf->pos = 0;
  ibuf->stream_pos = 0;
  ibuf->infd_ = infd;
  ibuf->at_stream_end = false;
  }

static inline void Ib_free( struct Input_buffer * const ibuf )
  { free( ibuf->buffer ); ibuf->buffer = 0; }

static inline bool Ib_finished( struct Input_buffer * const ibuf )
  { return ibuf->at_stream_end && ibuf->pos >= ibuf->stream_pos; }

static inline uint8_t Ib_get_byte( struct Input_buffer * const ibuf )
  {
  if( ibuf->pos >= ibuf->stream_pos && !Ib_read_block( ibuf ) )
    return 0;
  return ibuf->buffer[ibuf->pos++];
  }


struct Range_decoder
  {
  long long member_pos;
  uint32_t code;
  uint32_t range;
  struct Input_buffer * ibuf;
  };

static inline uint8_t Rd_get_byte( struct Range_decoder * const range_decoder )
  {
  ++range_decoder->member_pos;
  return Ib_get_byte( range_decoder->ibuf );
  }

static inline void Rd_init( struct Range_decoder * const range_decoder,
                            struct Input_buffer * const buf )
  {
  range_decoder->member_pos = sizeof (File_header);
  range_decoder->code = 0;
  range_decoder->range = 0xFFFFFFFF;
  range_decoder->ibuf = buf;
  for( int i = 0; i < 5; ++i )
    range_decoder->code = (range_decoder->code << 8) |
                          Rd_get_byte( range_decoder );
  }

static inline bool Rd_code_is_zero( struct Range_decoder * const range_decoder )
  { return ( range_decoder->code == 0 ); }
static inline bool Rd_finished( struct Range_decoder * const range_decoder )
  { return Ib_finished( range_decoder->ibuf ); }
static inline long long Rd_member_position( struct Range_decoder * const range_decoder )
  { return range_decoder->member_pos; }

static inline void Rd_reload( struct Range_decoder * const range_decoder )
  {
  range_decoder->code = 0;
  range_decoder->range = 0xFFFFFFFF;
  for( int i = 0; i < 5; ++i )
    range_decoder->code = (range_decoder->code << 8) |
                          Rd_get_byte( range_decoder );
  }

static inline void Rd_normalize( struct Range_decoder * const range_decoder )
  {
  if( range_decoder->range <= 0x00FFFFFF )
    {
    range_decoder->range <<= 8;
    range_decoder->code = (range_decoder->code << 8) |
                          Rd_get_byte( range_decoder );
    }
  }

static inline int Rd_decode( struct Range_decoder * const range_decoder,
                             const int num_bits )
  {
  int symbol = 0;
  for( int i = num_bits; i > 0; --i )
    {
    symbol <<= 1;
    if( range_decoder->range <= 0x00FFFFFF )
      {
      range_decoder->range <<= 7;
      range_decoder->code = (range_decoder->code << 8) |
                            Rd_get_byte( range_decoder );
      if( range_decoder->code >= range_decoder->range )
        { range_decoder->code -= range_decoder->range; symbol |= 1; }
      }
    else
      {
      range_decoder->range >>= 1;
      if( range_decoder->code >= range_decoder->range )
        { range_decoder->code -= range_decoder->range; symbol |= 1; }
      }
    }
  return symbol;
  }

static inline int Rd_decode_bit( struct Range_decoder * const range_decoder,
                                 Bit_model * const probability )
  {
  Rd_normalize( range_decoder );
  const uint32_t bound = ( range_decoder->range >> bit_model_total_bits ) *
                         *probability;
  if( range_decoder->code < bound )
    {
    range_decoder->range = bound;
    *probability += (bit_model_total - *probability) >> bit_model_move_bits;
    return 0;
    }
  else
    {
    range_decoder->range -= bound;
    range_decoder->code -= bound;
    *probability -= *probability >> bit_model_move_bits;
    return 1;
    }
  }

static inline int Rd_decode_tree( struct Range_decoder * const range_decoder,
                                  Bit_model bm[], const int num_bits )
  {
  int model = 1;
  for( int i = num_bits; i > 0; --i )
    model = ( model << 1 ) | Rd_decode_bit( range_decoder, &bm[model] );
  return model - (1 << num_bits);
  }

static inline int Rd_decode_tree_reversed( struct Range_decoder * const range_decoder,
                                           Bit_model bm[], const int num_bits )
  {
  int model = 1;
  int symbol = 0;
  for( int i = 0; i < num_bits; ++i )
    {
    const int bit = Rd_decode_bit( range_decoder, &bm[model] );
    model <<= 1;
    if( bit ) { model |= 1; symbol |= (1 << i); }
    }
  return symbol;
  }

static inline int Rd_decode_matched( struct Range_decoder * const range_decoder,
                                     Bit_model bm[], const int match_byte )
  {
  Bit_model *bm1 = bm + 0x100;
  int symbol = 1;
  for( int i = 1; i <= 8; ++i )
    {
    const int match_bit = ( match_byte << i ) & 0x100;
    const int bit = Rd_decode_bit( range_decoder, &bm1[match_bit+symbol] );
    symbol = ( symbol << 1 ) | bit;
    if( ( match_bit && !bit ) || ( !match_bit && bit ) )
      {
      while( ++i <= 8 )
        symbol = ( symbol << 1 ) | Rd_decode_bit( range_decoder, &bm[symbol] );
      break;
      }
    }
  return symbol & 0xFF;
  }


struct Len_decoder
  {
  Bit_model choice1;
  Bit_model choice2;
  Bit_model bm_low[pos_states][len_low_symbols];
  Bit_model bm_mid[pos_states][len_mid_symbols];
  Bit_model bm_high[len_high_symbols];
  };

static inline void Led_init( struct Len_decoder * const len_decoder )
  {
  Bm_init( &len_decoder->choice1 );
  Bm_init( &len_decoder->choice2 );
  for( int i = 0; i < pos_states; ++i )
    for( int j = 0; j < len_low_symbols; ++j )
      Bm_init( &len_decoder->bm_low[i][j] );
  for( int i = 0; i < pos_states; ++i )
    for( int j = 0; j < len_mid_symbols; ++j )
      Bm_init( &len_decoder->bm_mid[i][j] );
  for( int i = 0; i < len_high_symbols; ++i )
    Bm_init( &len_decoder->bm_high[i] );
  }

static inline int Led_decode( struct Len_decoder * const len_decoder,
                              struct Range_decoder * const range_decoder,
                              const int pos_state )
  {
  if( Rd_decode_bit( range_decoder, &len_decoder->choice1 ) == 0 )
    return Rd_decode_tree( range_decoder, len_decoder->bm_low[pos_state],
                        len_low_bits );
  if( Rd_decode_bit( range_decoder, &len_decoder->choice2 ) == 0 )
    return len_low_symbols +
           Rd_decode_tree( range_decoder, len_decoder->bm_mid[pos_state],
                        len_mid_bits );
  return len_low_symbols + len_mid_symbols +
         Rd_decode_tree( range_decoder, len_decoder->bm_high, len_high_bits );
  }


struct Literal_decoder
  {
  Bit_model bm_literal[1<<literal_context_bits][0x300];
  };

static inline void Lid_init( struct Literal_decoder * const literal_decoder )
  {
  for( int i = 0; i < 1<<literal_context_bits; ++i )
    for( int j = 0; j < 0x300; ++j )
      Bm_init( &literal_decoder->bm_literal[i][j] );
  }

static inline int Lid_state( const int prev_byte )
  { return ( prev_byte >> ( 8 - literal_context_bits ) ); }

static inline uint8_t Lid_decode( struct Literal_decoder * const literal_decoder,
                                  struct Range_decoder * const range_decoder,
                                  const uint8_t prev_byte )
  { return Rd_decode_tree( range_decoder, literal_decoder->bm_literal[Lid_state(prev_byte)], 8 ); }

static inline uint8_t Lid_decode_matched( struct Literal_decoder * const literal_decoder,
                                          struct Range_decoder * const range_decoder,
                                          const uint8_t prev_byte,
                                          const uint8_t match_byte )
  { return Rd_decode_matched( range_decoder, literal_decoder->bm_literal[Lid_state(prev_byte)], match_byte ); }


struct LZ_decoder
  {
  long long partial_data_pos;
  int format_version;
  int dictionary_size;
  int buffer_size;
  uint8_t * buffer;
  int pos;
  int stream_pos;		// first byte not yet written to file
  uint32_t crc_;
  int outfd_;			// output file descriptor

  Bit_model bm_match[St_states][pos_states];
  Bit_model bm_rep[St_states];
  Bit_model bm_rep0[St_states];
  Bit_model bm_rep1[St_states];
  Bit_model bm_rep2[St_states];
  Bit_model bm_len[St_states][pos_states];
  Bit_model bm_dis_slot[max_dis_states][1<<dis_slot_bits];
  Bit_model bm_dis[modeled_distances-end_dis_model];
  Bit_model bm_align[dis_align_size];

  struct Range_decoder range_decoder;
  struct Len_decoder len_decoder;
  struct Len_decoder rep_match_len_decoder;
  struct Literal_decoder literal_decoder;
  };

void LZd_flush_data( struct LZ_decoder * const decoder );

static inline uint8_t LZd_get_byte( struct LZ_decoder * const decoder,
                                    const int distance )
  {
  int i = decoder->pos - distance - 1;
  if( i < 0 ) i += decoder->buffer_size;
  return decoder->buffer[i];
  }

static inline void LZd_put_byte( struct LZ_decoder * const decoder,
                                 const uint8_t b )
  {
  decoder->buffer[decoder->pos] = b;
  if( ++decoder->pos >= decoder->buffer_size )
    LZd_flush_data( decoder );
  }

static inline void LZd_copy_block( struct LZ_decoder * const decoder,
                                   const int distance, int len )
  {
  int i = decoder->pos - distance - 1;
  if( i < 0 ) i += decoder->buffer_size;
  if( len < decoder->buffer_size - max( decoder->pos, i ) &&
      len <= abs( decoder->pos - i ) )
    {
    memcpy( decoder->buffer + decoder->pos, decoder->buffer + i, len );
    decoder->pos += len;
    }
  else for( ; len > 0 ; --len )
    {
    decoder->buffer[decoder->pos] = decoder->buffer[i];
    if( ++decoder->pos >= decoder->buffer_size )
      LZd_flush_data( decoder );
    if( ++i >= decoder->buffer_size ) i = 0;
    }
  }

bool LZd_verify_trailer( struct LZ_decoder * const decoder,
                         struct Pretty_print * const pp );

static inline void LZd_init( struct LZ_decoder * const decoder,
                             const File_header header,
                             struct Input_buffer * const ibuf, const int outfd )
  {
  decoder->partial_data_pos = 0;
  decoder->format_version = Fh_version( header );
  decoder->dictionary_size = Fh_get_dictionary_size( header );
  decoder->buffer_size = max( 65536, decoder->dictionary_size );
  decoder->buffer = (uint8_t *)malloc( decoder->buffer_size );
  if( !decoder->buffer )
    {
    show_error( "not enough memory. Find a machine with more memory", 0, false );
    cleanup_and_fail( 1 );
    }
  decoder->pos = 0;
  decoder->stream_pos = 0;
  decoder->crc_ = 0xFFFFFFFF;
  decoder->outfd_ = outfd;

  for( int i = 0; i < St_states; ++i )
    {
    for( int j = 0; j < pos_states; ++j )
      {
      Bm_init( &decoder->bm_match[i][j] );
      Bm_init( &decoder->bm_len[i][j] );
      }
    Bm_init( &decoder->bm_rep[i] );
    Bm_init( &decoder->bm_rep0[i] );
    Bm_init( &decoder->bm_rep1[i] );
    Bm_init( &decoder->bm_rep2[i] );
    }
  for( int i = 0; i < max_dis_states; ++i )
    for( int j = 0; j < 1<<dis_slot_bits; ++j )
      Bm_init( &decoder->bm_dis_slot[i][j] );
  for( int i = 0; i < modeled_distances-end_dis_model; ++i )
    Bm_init( &decoder->bm_dis[i] );
  for( int i = 0; i < dis_align_size; ++i )
    Bm_init( &decoder->bm_align[i] );

  Rd_init( &decoder->range_decoder, ibuf );
  Led_init( &decoder->len_decoder );
  Led_init( &decoder->rep_match_len_decoder );
  Lid_init( &decoder->literal_decoder );
  decoder->buffer[decoder->buffer_size-1] = 0;	// prev_byte of first_byte
  }

static inline void LZd_free( struct LZ_decoder * const decoder )
  { free( decoder->buffer ); decoder->buffer = 0; }

static inline uint32_t LZd_crc( struct LZ_decoder * const decoder )
  { return decoder->crc_ ^ 0xFFFFFFFF; }
int LZd_decode_member( struct LZ_decoder * const decoder,
                       struct Pretty_print * const pp );

static inline long long LZd_member_position( struct LZ_decoder * const decoder )
  { return Rd_member_position( &decoder->range_decoder ); }
static inline long long LZd_data_position( struct LZ_decoder * const decoder )
  { return decoder->partial_data_pos + decoder->pos; }