/*  This file is part of the KDE libraries
 *  Copyright (C) 1999 Waldo Bastian <bastian@kde.org>
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Library General Public
 *  License version 2 as published by the Free Software Foundation;
 *
 *  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., 59 Temple Place - Suite 330,
 *  Boston, MA 02111-1307, USA.
 **/

#ifndef __ksycoca_h__
#define __ksycoca_h__

#include <dcopobject.h>
#include <qobject.h>
#include <qstringlist.h>
#include "ksycocatype.h"
#include <kdelibs_export.h>

class QDataStream;
class KSycocaPrivate;
class KSycocaFactory;
class KSycocaFactoryList;

/*
 * Sycoca file version number.
 * If the existing file is outdated, it will not get read
 * but instead we'll ask kded to regenerate a new one...
*/
#define KSYCOCA_VERSION 79

/**
 * @internal
 * Read-only SYstem COnfiguration CAche
 */
class KDECORE_EXPORT KSycoca : public QObject, public DCOPObject
{
  Q_OBJECT
  K_DCOP

protected:
   /**
    * @internal
    * Building database
    */
   KSycoca( bool /* buildDatabase */ );

public:

   /**
    * Read-only database
    */
   KSycoca();

   /**
    * Get or create the only instance of KSycoca (read-only)
    */
   static KSycoca *self();

   virtual ~KSycoca();

   static int version();

   /**
    * @internal - called by factories in read-only mode
    * This is how factories get a stream to an entry
    */
   QDataStream *findEntry(int offset, KSycocaType &type);
   /**
    * @internal - called by factories in read-only mode
    */
   QDataStream *findFactory( KSycocaFactoryId id);
   /**
    * @internal - returns kfsstnd stored inside database
    */
   QString kfsstnd_prefixes();
   /**
    * @internal - returns language stored inside database
    */
   QString language();

   /**
    * @internal - returns timestamp of database
    *
    * The database contains all changes made _before_ this time and
    * _might_ contain changes made after that.
    */
   Q_UINT32 timeStamp();

   /**
    * @internal - returns update signature of database
    *
    * Signature that keeps track of changes to
    * $KDEDIR/share/services/update_ksycoca
    *
    * Touching this file causes the database to be recreated
    * from scratch.
    */
   Q_UINT32 updateSignature();

   /**
    * @internal - returns all directories with information
    * stored inside sycoca.
    */
   QStringList allResourceDirs();

   /**
    * @internal - add a factory
    */
   void addFactory( KSycocaFactory * );

   /**
    * @internal
    * @return true if building (i.e. if a KBuildSycoca);
    */
   virtual bool isBuilding() { return false; }

   /**
    * @internal - disables launching of kbuildsycoca
    */
   void disableAutoRebuild();

   /**
    * Determine relative path for a .desktop file from a full path and a resource name
    */
   static QString determineRelativePath( const QString & _fullpath, const char *_resource );

   /**
    * When you receive a "databaseChanged" signal, you can query here if
    * a change has occurred in a specific resource type.
    * @see KStandardDirs for the various resource types.
    */
   static bool isChanged(const char *type);

   /**
    * A read error occurs.
    */
   static void flagError();

   /**
    * Returns read error status and clears flag.
    */
   static bool readError();

k_dcop:
   /**
    * internal function for receiving kded/kbuildsycoca's signal, when the sycoca file changes
    */
   void notifyDatabaseChanged(const QStringList &);

signals:
   /**
        * Connect to this to get notified when the database changes
        * (Usually apps showing icons do a 'refresh' to take into account the new mimetypes)
        */
   void databaseChanged();

protected:
   bool checkVersion(bool abortOnError=true);
   bool openDatabase(bool openDummyIfNotFound=true);
   void closeDatabase();
   KSycocaFactoryList *m_lstFactories;
   QDataStream *m_str;
   bool bNoDatabase;
   size_t m_sycoca_size;
   const char *m_sycoca_mmap;
   Q_UINT32 m_timeStamp;

public:
   static KSycoca *_self; // Internal use only.

protected:
  virtual void virtual_hook( int id, void* data );
private:
   KSycocaPrivate *d;
};

#endif
