/*

* Copyright (c) 2009 Nokia Corporation and/or its subsidiary(-ies).

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description: VideoThumbnailFetcher class definition

*

*/

#ifndef __VIDEOTHUMBNAILDATAFETCHER_H__

#define __VIDEOTHUMBNAILDATAFETCHER_H__

// INCLUDES

#include <qobject.h>

#include <qicon.h>

#include <qlist.h>

#include <qhash.h>

#include <thumbnailmanager_qt.h>

// FORWARD DECLARATIONS

class VideoThumbnailFetcher : public QObject

{

    /**

     * defined to be able to use signals and slots

     */

    Q_OBJECT

public:

    /**

     * Default constructor

     */

    VideoThumbnailFetcher();

    /**

     * Desctructor

     */

    ~VideoThumbnailFetcher();

    /**

     * Adds thumbnail fetch to the fetch list. pauseFetching should be called 

     * before adding fetches for performance reasons. After all fetches have

     * been added, call continueFetching to start the fetch process which passes 

     * the internal data to thumbnail manager. Signal thumbnailReady is emitted 

     * when fetch is complete. 

     * 

     * @param fileName path to the media.

     * @param internal data identifying the media.

     * @param priority priority for the fetch.

     * 

     */

    void addFetch(const QString fileName, void *internal, int priority);    

    /**

     * Empties fetch list. This does not cancel the possible ongoing fetch on

     * thumbnail manager side.

     * 

     */

    void cancelFetches();

    /**

     * Returns count of the fetches.

     * 

     */

    int fetchCount();

    /**

     * Pauses thumbnail fetching process. This does not pause the possible 

     * ongoing fetch on thumbnail manager side. 

     * 

     */

    void pauseFetching();

    /**

     * Continues the fetching process. All fetches added with addFetch are 

     * started without create thumbnail flag. If there's not any of those, 

     * starts creating thumbnails for fetches that have no thumbnail yet. 

     * Signal allThumbnailsFetched is emitted if there's nothing to do.

     * 

     */

    void continueFetching();

    /**

     * Enables or disables the thumbnail creation for videos that do  

     * not have thumbnail already in the database.

     * 

     * @param enable true enables thumbnail creation, false disables. 

     * 

     */

    void enableThumbnailCreation(bool enable);

private:

    class ThumbnailFetchData

    {

        public:         

        ThumbnailFetchData() { mInternal = 0; };

            QString mFileName;

            int mPriority;

            void *mInternal;

    };

protected:

    /**

     * Starts fetching all the thumbnails in fetch list. Create flag is 

     * disabled. Thumbnail manager signals to thumbnailReadySlot. If thumbnail 

     * fetch fails with -1 the fetch is added to thumbnail creation list, 

     * otherwise signal thumbnailReady signal emitted.

     * 

     */

    void startThumbnailFetches();

    /**

     * Starts fetching thumbnail with highest priority from creation list. 

     * Create flag is enabled. Thumbnail manager signals to thumbnailReadySlot,

     * from there signal thumbnailReady is emitted.

     *  

     */

    void startThumbnailCreation();

signals:

    /**

     * Signaled after signal from thumbnail manager has been processed and

     * thumbnail fetch process is complete.

     *

     * @param tnData thumbnail

     * @param internal internal data to identify the request

     * @param error possible error code from thumbnail manager ( 0 == ok )

     * 

     */

    void thumbnailReady(QPixmap tnData, void *internal, int error);

    /**

     * Signaled when all the fetches have been done.

     * 

     */

    void allThumbnailsFetched();

private slots:

    /**

     * Thumbnail manager signals this slot when thumbnail is ready

     * for some item.

     *

     * @param tnData thumbnail

     * @param internal internal data to identify the request

     * @param requestId thumbnail manager request id

     * @param error: possible error code from thumbnail manager ( 0 == ok )

     *

     */

    void thumbnailReadySlot(QPixmap tnData, void *internal, int requestId, int error);

private: // Data

    /**

     * Thumbnail manager object.

     */

    ThumbnailManager                *mThumbnailManager;

    /**

     * List containing not started thumbnail fetches.

     */

    QList<ThumbnailFetchData *>     mFetchList;

    /**

     * Hash containing ongoing thumbnail fetches.

     * 

     * key is thumbnail request id.

     * value is thumbnail fetch data.  

     */

    QHash<int, ThumbnailFetchData *> mStartedFetchList;

    /**

     * List containing thumbnails that have not been created yet.

     */

    QList<ThumbnailFetchData *>      mCreationList;    

    /**

     * Flag indicating if fetching has been paused.

     */

    bool                             mPaused;

    /**

     * Flag indicating if thumbnail creation is enabled.

     */

    bool                             mTbnCreationEnabled;

};

#endif // __VIDEOTHUMBNAILDATAFETCHER_H__