/*

* Copyright (c) 2008 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:  GS utilities.

*

*/

#ifndef GSECOMNOTIFIER_H

#define GSECOMNOTIFIER_H

#include <e32std.h>

#include <ecom/ecom.h>

/**

 *  Utility class to capsulate active object observing ECOM events.

 *  MGSEComObserver is provided as easy callback when GS related ECOM events

 *  occur.

 *

 *  @lib GSFramework.lib

 *  @since S60 5.0

 */

class MGSEComObserver

    {

public:

    /**

     * Not really used yet. To provide more extendability.

     */

    enum TEComEvent

        {

        EPluginRemoved,

        EPluginAdded

        };

public:

    virtual void HandleEComEvent( TEComEvent aEvent ) = 0;

    };

/**

 *  Utility class capsulating active object for observing ECOM events.

 *

 *  @lib GSFramework.lib

 *  @since S60 5.0

 */

NONSHARABLE_CLASS( CGSEComNotifier ) : public CActive

    {

public:

    /**

     * Two-phased constructor.

     *

     * @param aObserver Callback object.

     * @param aImplInfo Initial list of ECOM interfaces against which new list

     *        is compared when ECOM events occur.

     */

    IMPORT_C static CGSEComNotifier* NewL( MGSEComObserver* aObserver,

                                           RImplInfoPtrArray aImplInfo );

    /**

     * Destructor.

     */

    IMPORT_C virtual ~CGSEComNotifier();

protected: // from CActive

    /**

     * See base class.

     */

    void DoCancel();

    /**

     * See base class.

     */

    void RunL();

    /**

     * See base class.

     */

    TInt RunError( TInt aError );

protected:

private:

    /**

     * C++ Constructor.

     *

     * @param aObserver Callback object.

     * @param aImplInfo Initial list of ECOM interfaces against which new list

     *        is compared when ECOM events occur.

     */

    CGSEComNotifier( MGSEComObserver* aObserver,

                     RImplInfoPtrArray aImplInfo );

    /**

     * 2nd phase constructor.

     */

    void ConstructL();

    /**

     * Issues new request.

     */

    void IssueRequest();

    /**

     * @return Difference between old and new list of GS-plugins. Negative

     *         number means plugins are removed, positive means plugins are

     *         added, 0 means no change in plugin count.

     */

    TInt PluginCountDeltaL();

private: // data

    // Callback.

    MGSEComObserver* iObserver;

    // ECom handle.

    REComSession iEComSession;

    // Stored original plugin info. This will be compared against latest info

    // for any changes.

    RImplInfoPtrArray iOriginalImplInfo;

    };

#endif // GSECOMNOTIFIER_H