/***************************************************************************

                      EngineObserver.h  -  Observer pattern for engine

                         -------------------

begin                : Mar 14 2003

copyright            : (C) 2003 by Frederik Holljen

email                : fh@ez.no

***************************************************************************/

/***************************************************************************

 *                                                                         *

 *   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.                                   *

 *                                                                         *

 ***************************************************************************/

#ifndef AMAROK_ENGINEOBSERVER_H

#define AMAROK_ENGINEOBSERVER_H

#include "amarok_export.h"

#include <Phonon/MediaObject>

#include <QHash>

#include <QSet>

class EngineSubject;

class QString;

/**

 * If you want to observe the engine, inherit from this class.

 * Note that all positional information and times are in milliseconds

 */

class AMAROK_EXPORT EngineObserver

{

public:

    enum PlaybackEndedReason

    {

        EndedStopped = 0,

        EndedQuit    = 1

    };

    EngineObserver( EngineSubject* );

    virtual ~EngineObserver();

    virtual void engineStateChanged( Phonon::State currentState, Phonon::State oldState = Phonon::StoppedState );

    virtual void enginePlaybackEnded( int finalPosition, int trackLength, PlaybackEndedReason reason );

    virtual void engineNewTrackPlaying();

    virtual void engineNewMetaData( const QHash<qint64, QString> &newMetaData, bool trackChanged );

    virtual void engineVolumeChanged( int percent );

    virtual void engineMuteStateChanged( bool mute );

    virtual void engineTrackPositionChanged( long position, bool userSeek );

    virtual void engineTrackLengthChanged( long seconds );

private:

    EngineSubject *m_subject;

};

/**

 * Inherited by EngineController.

 * Notify observer functionality is captured in this class.

 */

class EngineSubject

{

    friend class EngineObserver;

protected:

    EngineSubject();

    virtual ~EngineSubject();

    void stateChangedNotify( Phonon::State newState, Phonon::State oldState );

    void playbackEnded( int /*finalPosition*/, int /*trackLength*/, EngineObserver::PlaybackEndedReason reason );

    void newMetaDataNotify( const QHash<qint64, QString> &newMetaData, bool trackChanged );

    void volumeChangedNotify( int /*percent*/ );

    void muteStateChangedNotify( bool /*mute*/ );

    /* userSeek means the position didn't change due to normal playback */

    void trackPositionChangedNotify( long /*position*/ , bool userSeek=false );

    void trackLengthChangedNotify( long /*seconds*/ );

    void newTrackPlaying() const;

private:

    void attach( EngineObserver *observer );

    void detach( EngineObserver *observer );

    bool isMetaDataSpam( QHash<qint64, QString> newMetaData );

    QList<QHash<qint64, QString> > m_metaDataHistory;

    QSet<EngineObserver*> Observers;

    Phonon::State m_realState; // To work around the buffering issue

};

#endif // AMAROK_ENGINEOBSERVER_H