/**********************************************************************
 *
 * gdbmclass.cpp -- 
 * Copyright (C) 1999-2008  The New Zealand Digital Library Project
 *
 * A component of the Greenstone digital library software
 * from the New Zealand Digital Library Project at the
 * University of Waikato, New Zealand.
 *
 * 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.
 *
 *********************************************************************/

#include "gdbmclass.h"
#include "unitool.h"
#include "gsdlunicode.h"
#include "OIDtools.h"


gdbmclass::~gdbmclass()
{
  closedatabase();
}


// returns true if opened
bool gdbmclass::opendatabase (const text_t &filename, int mode, int num_retrys, 
#ifdef __WIN32__
			      bool need_filelock
#else
                              bool
#endif
			      )
{
  text_t data_location;
  int block_size = 512;
  
  if (gdbmfile != NULL) {
    if (openfile == filename) return true;
    else closedatabase ();
  }

  openfile = filename;

  // Map the DB mode values into GDBM mode values
  int gdbm_mode = GDBM_READER;
  if (mode == DB_WRITER)
  {
    gdbm_mode = GDBM_WRITER;
  }
  else if (mode == DB_WRITER_CREATE)
  {
    gdbm_mode = GDBM_WRCREAT;
  }

  char *namebuffer = filename.getcstr();
  do {
#ifdef __WIN32__
    gdbmfile = gdbm_open (namebuffer, block_size, gdbm_mode, 00664, NULL, (need_filelock) ? 1 : 0);
#else
    gdbmfile = gdbm_open (namebuffer, block_size, gdbm_mode, 00664, NULL);
#endif
    --num_retrys;
  } while (num_retrys>0 && gdbmfile==NULL &&
	   (gdbm_errno==GDBM_CANT_BE_READER || gdbm_errno==GDBM_CANT_BE_WRITER));
  delete []namebuffer;
  
  if (gdbmfile == NULL && logout != NULL) {
    outconvertclass text_t2ascii;
    (*logout) << text_t2ascii << "database open failed on: " << filename << "\n";
  }

  return (gdbmfile != NULL);
}


void gdbmclass::closedatabase ()
{
  if (gdbmfile == NULL) return;
  
  gdbm_close (gdbmfile);
  gdbmfile = NULL;
  openfile.clear();
}


void gdbmclass::deletekey (const text_t &key)
{
  if (gdbmfile == NULL) return;

  // get a utf-8 encoded c string of the unicode key
  datum key_data;
  key_data.dptr = (to_utf8(key)).getcstr();
  if (key_data.dptr == NULL) return;
  key_data.dsize = strlen (key_data.dptr);

  // delete the key
  gdbm_delete (gdbmfile, key_data);

  // free up the key memory
  delete []key_data.dptr;
}


// returns true on success
bool gdbmclass::getkeydata (const text_t& key, text_t &data)
{
  datum key_data;
  datum return_data;

  if (gdbmfile == NULL) return false;
  
  // get a utf-8 encoded c string of the unicode key
  key_data.dptr = (to_utf8(key)).getcstr();
  if (key_data.dptr == NULL) {
    if (logout != NULL) (*logout) << "gdbmclass: out of memory\n";
    return false;
  }
  key_data.dsize = strlen (key_data.dptr);
  
  // fetch the result
  return_data = gdbm_fetch (gdbmfile, key_data);
  delete []key_data.dptr;
  
  if (return_data.dptr == NULL) return false;

  data.setcarr (return_data.dptr, return_data.dsize);
  free (return_data.dptr);
  data = to_uni(data);  // convert to unicode

  return true;
}


// returns array of keys
text_tarray gdbmclass::getkeys ()
{
  text_tarray keys;

  text_t key = getfirstkey();
  while (!key.empty())
  {
    keys.push_back(key);
    key = getnextkey(key);
  }

  return keys;
}


// returns true on success
bool gdbmclass::setkeydata (const text_t &key, const text_t &data)
{
  if (gdbmfile == NULL) return false;
  
  // store the value
  datum key_data;
  datum data_data;

  // get a utf-8 encoded c string of the unicode key
  key_data.dptr = (to_utf8(key)).getcstr();
  if (key_data.dptr == NULL) {
    if (logout != NULL) (*logout) << "gdbmclass: out of memory\n";
    return false;
  }
  key_data.dsize = strlen (key_data.dptr);

  data_data.dptr = (to_utf8(data)).getcstr();
  if (data_data.dptr == NULL) {
    if (logout != NULL) (*logout) << "gdbmclass: out of memory\n";
    delete []key_data.dptr;
    return false;
  }
  data_data.dsize = strlen (data_data.dptr);

  int ret = gdbm_store (gdbmfile, key_data, data_data, GDBM_REPLACE);
  delete []key_data.dptr;
  delete []data_data.dptr;

  return (ret == 0);
}


// ----------------------------------------------------------------------------------------
//   GDBM-ONLY FUNCTIONS
// ----------------------------------------------------------------------------------------

// getfirstkey and getnextkey are used for traversing the database
// no insertions or deletions should be carried out while traversing
// the database. when there are no keys left to visit in the database
// an empty string is returned.
text_t gdbmclass::getfirstkey ()
{
  if (gdbmfile == NULL) return g_EmptyText;

  // get the first key
  datum firstkey_data = gdbm_firstkey (gdbmfile);
  if (firstkey_data.dptr == NULL) return g_EmptyText;

  // convert it to text_t
  text_t firstkey;
  firstkey.setcarr (firstkey_data.dptr, firstkey_data.dsize);
  free (firstkey_data.dptr);
  return to_uni(firstkey);  // convert to unicode
}


text_t gdbmclass::getnextkey (const text_t &key)
{
  if (gdbmfile == NULL || key.empty()) return g_EmptyText;

  // get a utf-8 encoded c string of the unicode key
  datum key_data;
  key_data.dptr = (to_utf8(key)).getcstr();
  if (key_data.dptr == NULL) return g_EmptyText;
  key_data.dsize = strlen (key_data.dptr);
  
  // get the next key
  datum nextkey_data = gdbm_nextkey (gdbmfile, key_data);
  if (nextkey_data.dptr == NULL) {
    delete []key_data.dptr;
    return g_EmptyText;
  }

  // convert it to text_t
  text_t nextkey;
  nextkey.setcarr (nextkey_data.dptr, nextkey_data.dsize);
  free (nextkey_data.dptr);
  delete []key_data.dptr;
  return to_uni(nextkey);  // convert to unicode
}