///###////////////////////////////////////////////////////////////////////////
//
// Burton Computer Corporation
// http://www.burton-computer.com
// http://www.cooldevtools.com
// $Id: FrequencyDBImpl_hash.h 272 2007-01-06 19:37:27Z brian $
//
// Copyright (C) 2007 Burton Computer Corporation
// ALL RIGHTS RESERVED
//
// This program is open source software; you can redistribute it
// and/or modify it under the terms of the Q Public License (QPL)
// version 1.0. Use of this software in whole or in part, including
// linking it (modified or unmodified) into other programs is
// subject to the terms of the QPL.
//
// 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
// Q Public License for more details.
//
// You should have received a copy of the Q Public License
// along with this program; see the file LICENSE.txt.  If not, visit
// the Burton Computer Corporation or CoolDevTools web site
// QPL pages at:
//
//    http://www.burton-computer.com/qpl.html
//    http://www.cooldevtools.com/qpl.html
//

#ifndef _FrequencyDBImpl_hash_h
#define _FrequencyDBImpl_hash_h

#ifdef USE_MMAP

#include "FrequencyDBImpl.h"
#include "HashDataFile.h"

class ifstream;
class LockFD;

class FrequencyDBImpl_hash : public FrequencyDBImpl
{
public:
  FrequencyDBImpl_hash(int _size = 32);
  ~FrequencyDBImpl_hash();

  bool open(const string &filename,
            bool read_only,
            int create_mode);
  void close();

  void flush();

  void writeWord(const string &word,
                 const WordData &word_data);

  bool readWord(const string &word,
                WordData &word_data);

  bool firstWord(string &word,
                 WordData &counts);

  bool nextWord(string &word,
                WordData &counts);

  string getDatabaseType() const;

  void sweepOutOldTerms(const CleanupManager &cleanman);

  static FrequencyDBImpl *factory(const DatabaseConfig *);
  static const char *SEARCH_SUFFIX;

private:
  HashDataFile::ulong_t computeKeyForWord(const string &word);
  string getWordForIndex(int index, HashDataFile::ulong_t key);

  void initializeHeaderRecords();
  bool validateHeaderRecords();

  void copyToNewDataFile(const CleanupManager &cleanman,
                         const string &rehash_filename);
  void swapDataFilesAndReopen(const string &live_filename,
                              const string &rehash_filename,
                              const string &temp_filename);

private:
  /// Not implemented.
  FrequencyDBImpl_hash(const FrequencyDBImpl_hash &);

  /// Not implemented.
  FrequencyDBImpl_hash& operator=(const FrequencyDBImpl_hash &);

private:
  HashDataFile::ulong_t m_cursor;
  HashDataFile m_dataFile;
};

#endif // USE_MMAP

#endif // _FrequencyDBImpl_hash_h