/* This file is part of the KDE libraries
   Copyright (C) 1998 Sven Radej <sven@lisa.exp.univie.ac.at>

   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., 51 Franklin Street, Fifth Floor,
   Boston, MA 02110-1301, USA.
*/
#ifndef _KDIRWATCH_H
#define _KDIRWATCH_H

#include <QtCore/QDateTime>
#include <QtCore/QObject>
#include <QtCore/QString>

#include <kdecore_export.h>

class KDirWatchPrivate;

 /**
  * @short Class for watching directory and file changes.
  *
  * Watch directories and files for changes.
  * The watched directories or files don't have to exist yet.
  *
  * When a watched directory is changed, i.e. when files therein are
  * created or deleted, KDirWatch will emit the signal dirty().
  *
  * When a watched, but previously not existing directory gets created,
  * KDirWatch will emit the signal created().
  *
  * When a watched directory gets deleted, KDirWatch will emit the
  * signal deleted(). The directory is still watched for new
  * creation.
  *
  * When a watched file is changed, i.e. attributes changed or written
  * to, KDirWatch will emit the signal dirty().
  *
  * Scanning of particular directories or files can be stopped temporarily
  * and restarted. The whole class can be stopped and restarted.
  * Directories and files can be added/removed from the list in any state.
  *
  * The implementation uses the INOTIFY functionality on LINUX.
  * Otherwise the FAM service is used, when available.
  * As a last resort, a regular polling for change of modification times
  * is done; the polling interval is a global config option:
  * DirWatch/PollInterval and DirWatch/NFSPollInterval for NFS mounted
  * directories.
  * The choice of implementation can be adjusted by the user, with the key
  * [DirWatch] PreferredMethod={Fam|Stat|QFSWatch|inotify}
  *
  * @see self()
  * @author Sven Radej (in 1998)
  */
class KDECORE_EXPORT KDirWatch : public QObject
{
  Q_OBJECT

  public:

   /**
   * Available watch modes for directory monitoring
   **/
    enum WatchMode {
      WatchDirOnly = 0,  ///< Watch just the specified directory
      WatchFiles = 0x01, ///< Watch also all files contained by the directory
      WatchSubDirs = 0x02 ///< Watch also all the subdirs contained by the directory
    };
    Q_DECLARE_FLAGS(WatchModes, WatchMode)

   /**
    * Constructor.
    *
    * Scanning begins immediately when a dir/file watch
    * is added.
    * @param parent the parent of the QObject (or 0 for parent-less KDataTools)
    */
   KDirWatch(QObject* parent = 0);

   /**
    * Destructor.
    *
    * Stops scanning and cleans up.
    */
   ~KDirWatch();

   /**
    * Adds a directory to be watched.
    *
    * The directory does not have to exist. When @p watchModes is set to
    * WatchDirOnly (the default), the signals dirty(), created(), deleted()
    * can be emitted, all for the watched directory.
    * When @p watchModes is set to WatchFiles, all files in the watched
    * directory are watched for changes, too. Thus, the signals dirty(),
    * created(), deleted() can be emitted.
    * When @p watchModes is set to WatchSubDirs, all subdirs are watched using
    * the same flags specified in @p watchModes (symlinks aren't followed).
    * If the @p path points to a symlink to a directory, the target directory
    * is watched instead. If you want to watch the link, use @p addFile().
    *
    * @param path the path to watch
    * @param watchModes watch modes
    *
    * @sa  KDirWatch::WatchMode
    */
   void addDir(const QString& path, WatchModes watchModes = WatchDirOnly);

   /**
    * Adds a file to be watched.
    * If it's a symlink to a directory, it watches the symlink itself.
    * @param file the file to watch
    */
   void addFile(const QString& file);

   /**
    * Returns the time the directory/file was last changed.
    * @param path the file to check
    * @return the date of the last modification
    */
   QDateTime ctime(const QString& path) const;

   /**
    * Removes a directory from the list of scanned directories.
    *
    * If specified path is not in the list this does nothing.
    * @param path the path of the dir to be removed from the list
    */
   void removeDir(const QString& path);

   /**
    * Removes a file from the list of watched files.
    *
    * If specified path is not in the list this does nothing.
    * @param file the file to be removed from the list
    */
   void removeFile(const QString& file);

   /**
    * Stops scanning the specified path.
    *
    * The @p path is not deleted from the internal list, it is just skipped.
    * Call this function when you perform an huge operation
    * on this directory (copy/move big files or many files). When finished,
    * call restartDirScan(path).
    *
    * @param path the path to skip
    * @return true if the @p path is being watched, otherwise false
    * @see restartDirScanning()
    */
   bool stopDirScan(const QString& path);

   /**
    * Restarts scanning for specified path.
    *
    * It doesn't notify about the changes (by emitting a signal).
    * The ctime value is reset.
    *
    * Call it when you are finished with big operations on that path,
    * @em and when @em you have refreshed that path.
    *
    * @param path the path to restart scanning
    * @return true if the @p path is being watched, otherwise false
    * @see stopDirScanning()
    */
   bool restartDirScan(const QString& path);

   /**
    * Starts scanning of all dirs in list.
    *
    * @param notify If true, all changed directories (since
    * stopScan() call) will be notified for refresh. If notify is
    * false, all ctimes will be reset (except those who are stopped,
    * but only if @p skippedToo is false) and changed dirs won't be
    * notified. You can start scanning even if the list is
    * empty. First call should be called with @p false or else all
    * directories
    * in list will be notified.
    * @param skippedToo if true, the skipped directoris (scanning of which was
    * stopped with stopDirScan() ) will be reset and notified
    * for change. Otherwise, stopped directories will continue to be
    * unnotified.
    */
   void startScan( bool notify=false, bool skippedToo=false );

   /**
    * Stops scanning of all directories in internal list.
    *
    * The timer is stopped, but the list is not cleared.
    */
   void stopScan();

   /**
    * Is scanning stopped?
    * After creation of a KDirWatch instance, this is false.
    * @return true when scanning stopped
    */
   bool isStopped();

   /**
    * Check if a directory is being watched by this KDirWatch instance
    * @param path the directory to check
    * @return true if the directory is being watched
    */
   bool contains( const QString& path ) const;

   void deleteQFSWatcher();

   /**
    * Dump statistic information about the KDirWatch::self() instance.
    * This checks for consistency, too.
    */
   static void statistics(); // TODO implement a QDebug operator for KDirWatch instead.

   enum Method { FAM, INotify, DNotify /*now unused*/, Stat, QFSWatch };
   /**
    * Returns the preferred internal method to
    * watch for changes.
    */
   Method internalMethod(); // TODO KDE5: make const

   /**
    * The KDirWatch instance usually globally used in an application.
    * It is automatically deleted when the application exits.
    *
    * However, you can create an arbitrary number of KDirWatch instances
    * aside from this one - for those you have to take care of memory management.
    *
    * This function returns an instance of KDirWatch. If there is none, it
    * will be created.
    *
    * @return a KDirWatch instance
    */
   static KDirWatch* self();
   /**
    * Returns true if there is an instance of KDirWatch.
    * @return true if there is an instance of KDirWatch.
    * @see KDirWatch::self()
    */
   static bool exists();

public Q_SLOTS:

   /**
    * Emits created().
    * @param path the path of the file or directory
    */
   void setCreated( const QString &path );

   /**
    * Emits dirty().
    * @param path the path of the file or directory
    */
   void setDirty( const QString &path );

   /**
    * Emits deleted().
    * @param path the path of the file or directory
    */
   void setDeleted( const QString &path );

 Q_SIGNALS:

   /**
    * Emitted when a watched object is changed.
    * For a directory this signal is emitted when files
    * therein are created or deleted.
    * For a file this signal is emitted when its size or attributes change.
    *
    * When you watch a directory, changes in the size or attributes of
    * contained files may or may not trigger this signal to be emitted
    * depending on which backend is used by KDirWatch.
    *
    * The new ctime is set before the signal is emitted.
    * @param path the path of the file or directory
    */
   void dirty(const QString &path);

   /**
    * Emitted when a file or directory is created.
    * @param path the path of the file or directory
    */
   void created(const QString &path);

   /**
    * Emitted when a file or directory is deleted.
    *
    * The object is still watched for new creation.
    * @param path the path of the file or directory
    */
   void deleted(const QString &path);

 private:
   KDirWatchPrivate *const d;
};

Q_DECLARE_OPERATORS_FOR_FLAGS(KDirWatch::WatchModes)

#endif

// vim: sw=3 et
