/**************************************************************************
 *
 * mg_perf_hash_build.c -- Program to build a perfect hash function
 * Copyright (C) 1994  Neil Sharman
 *
 * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * $Id: mg_perf_hash_build.c 25147 2012-02-28 00:59:00Z kjdon $
 *
 **************************************************************************/

#include "sysfuncs.h"
#include "memlib.h"
#include "messages.h"
#include "timing.h"
#include "local_strings.h"
#include "perf_hash.h"
#include "netorder.h"  /* [RPAP - Jan 97: Endian Ordering] */

#include "mg_files.h"
#include "invf.h"
#include "locallib.h"
#include "words.h"
#include "mg.h"

/*
   $Log$
   Revision 1.1  2003/02/20 21:18:24  mdewsnip
   Addition of MG package for search and retrieval

   Revision 1.1  1999/08/10 21:18:13  sjboddie
   renamed mg-1.3d directory mg

   Revision 1.2  1998/11/25 07:55:47  rjmcnab

   Modified mg to that you can specify the stemmer you want
   to use via a command line option. You specify it to
   mg_passes during the build process. The number of the
   stemmer that you used is stored within the inverted
   dictionary header and the stemmed dictionary header so
   the correct stemmer is used in later stages of building
   and querying.

   Revision 1.1  1998/11/17 09:35:15  rjmcnab
   *** empty log message ***

   * Revision 1.3  1994/10/20  03:56:58  tes
   * I have rewritten the boolean query optimiser and abstracted out the
   * components of the boolean query.
   *
   * Revision 1.2  1994/09/20  04:41:53  tes
   * For version 1.1
   *
 */

static char *RCSID = "$Id: mg_perf_hash_build.c 25147 2012-02-28 00:59:00Z kjdon $";



#define POOL_SIZE 1024*1024

static void process_files (char *filename);

int r = -1;

int main (int argc, char **argv)
{
  ProgTime start;
  char *file_name = "";
  int ch;
  msg_prefix = argv[0];
  opterr = 0;
  while ((ch = getopt (argc, argv, "f:d:r:h")) != -1)
    switch (ch)
      {
      case 'f':		/* input file */
	file_name = optarg;
	break;
      case 'd':
	set_basepath (optarg);
	break;
      case 'r':
	r = atoi (optarg);
	break;
      case 'h':
      case '?':
	fprintf (stderr, "usage: %s [-f input_file]"
		 "[-d data directory] [-r random seed] [-h]\n", argv[0]);
	exit (1);
      }

  GetTime (&start);
  process_files (file_name);
  Message ("%s\n", ElapsedTime (&start, NULL));
  return 0;
}





static void 
process_files (char *filename)
{
  FILE *dict, *hash;
  mg_u_long i;
  u_char prev[MAXSTEMLEN + 1];
  struct invf_dict_header idh;
  perf_hash_data *phd;
  u_char *pool;
  int pool_left;
  u_char **starts;


  dict = open_file (filename, INVF_DICT_SUFFIX, "rb",
		    MAGIC_STEM_BUILD, MG_ABORT);  /* [RPAP - Feb 97: WIN32 Port] */

  fread ((char *) &idh, sizeof (idh), 1, dict);

  /* [RPAP - Jan 97: Endian Ordering] */
  NTOHUL(idh.lookback);
  NTOHUL(idh.dict_size);
  NTOHUL(idh.total_bytes);
  NTOHUL(idh.index_string_bytes);
  NTOHD(idh.input_bytes); /* [RJM 07/97: 4G limit] */
  NTOHUL(idh.num_of_docs);
  NTOHUL(idh.static_num_of_docs);
  NTOHUL(idh.num_of_words);
  NTOHUL(idh.stemmer_num);
  NTOHUL(idh.stem_method);

  hash = create_file (filename, INVF_DICT_HASH_SUFFIX, "wb",
		      MAGIC_HASH, MG_ABORT);  /* [RPAP - Feb 97: WIN32 Port] */

  if (!(pool = Xmalloc (POOL_SIZE)))
    FatalError (1, "Out of memory");
  pool_left = POOL_SIZE;

  if (!(starts = Xmalloc (sizeof (u_char *) * idh.dict_size)))
    FatalError (1, "Out of memory");

  for (i = 0; i < idh.dict_size; i++)
    {
      register mg_u_long copy, suff, l;
      mg_u_long wcnt, fcnt;

      /* build a new word on top of prev */
      copy = getc (dict);
      suff = getc (dict);
      *prev = copy + suff;
      fread (prev + copy + 1, sizeof (u_char), suff, dict);

      /* read other data, but no need to store it */
      fread (&fcnt, sizeof (fcnt), 1, dict);
      fread (&wcnt, sizeof (wcnt), 1, dict);

      l = *prev + 1;
      if (pool_left < l)
	{
	  pool = Xmalloc (POOL_SIZE);
	  pool_left = POOL_SIZE;
	}
      starts[i] = pool;
      bcopy ((char *) prev, (char *) pool, l);
      pool += l;
      pool_left -= l;
    }
  if (!(phd = gen_hash_func (idh.dict_size, starts, r)))
    FatalError (1, "Unable to generate hash function");
  if (write_perf_hash_data (hash, phd) == -1)
    FatalError (1, "Unable to write hash function");
  fclose (dict);
  fclose (hash);
}
