/*

* 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: Class to watch key value changes in Central Repository.

*

*/

#ifndef C_CENTRALREPOSITORYWATCH_H

#define C_CENTRALREPOSITORYWATCH_H

#include    <e32base.h>

#include    <centralrepository.h>

#include "centralrepositoryobserver.h"

/**

 *  Class to watch key value changes in Central Repository.

 *

 *  @code

 *   ?good_class_usage_example(s)

 *  @endcode

 *

 *  @lib none.

 *  @since TB 9.2

 */

NONSHARABLE_CLASS( CCentralRepositoryWatch ): public CActive

    {

public:

    /**

    * Two-phased constructor.

    * @param aObserver Observer's callback interface.

    * @param aRepositoryUid Identifier of a repositor.

    * @param aKeyId Identifier of a key.

    */

    static CCentralRepositoryWatch* NewL(

            MCentralRepositoryObserver&   aObserver,

            TUid aRepositoryUid,

            TUint32 aKeyId

            );

    /**

    * Two-phased constructor.

    * @param aObserver Observer's callback interface.

    * @param aRepositoryUid Identifier of a repositor.

    * @param aKeyId Identifier of a key.

    */

    static CCentralRepositoryWatch* NewLC(

            MCentralRepositoryObserver&   aObserver,

            TUid aRepositoryUid,

            TUint32 aKeyId

            );

    /**

    * Destructor.

    */

    virtual ~CCentralRepositoryWatch();

    /**

    * Watch value changes of a specified key in a specified CenRep.

    * @param None

    * @return void

    */

    void Watch();

    /**

    * Get current value of a specified key in a specified CenRep.

    * @param aValue Reference to a variable to which current value is to be assigned.

    * @return TInt Error code. 

    *       KErrNone if successful, 

    *       KErrAbort if in a transaction that has previously failed 

    *       KErrPermissionDenied if caller fails capability check, 

    *       KErrNotFound if the setting does not exist, 

    *       KErrArgument if the setting exists but is not an integer, plus other system-wide error codes.

    */

    TInt GetCurrentValue( TInt& aValue );

protected:

    /**

    * Active object cancellation

    * @param None

    * @return void

    */

    void DoCancel();

private:

    /**

    * C++ default constructor.

    * @param aObserver Observer's callback interface.

    * @param aRepositoryId Identifier of a repositor.

    * @param aKeyId Identifier of a key.

    */

    CCentralRepositoryWatch(

            MCentralRepositoryObserver& aObserver,

            TUid aRepositoryId,

            TUint32 aKeyId );

    /**

    * By default Symbian OS constructor is private.

    * @return void

    */

    void ConstructL(  );

    /**

    * Completion

    * @param None

    * @return void

    */

    void RunL();

    /**

    * Error handling.

    * @param aError Error code.

    * @return void

    */

    TInt RunError( TInt aError );

    /**

    * By default, prohibit copy constructor

    */

   CCentralRepositoryWatch( const CCentralRepositoryWatch& );

   /**

   * By default, prohibit assignment operator

   */

    CCentralRepositoryWatch& operator= ( const CCentralRepositoryWatch& );

private: // data

    /**

     * Observer objects callback interface.

     * Not own.

     */

    MCentralRepositoryObserver&   iObserver;

    /**

     * Repository pointer.

     * Own.

     */

    CRepository*               iRepository;

    /**

     * Identifier of the repositor.

     */

    TUid                       iRepositoryUid;

    /**

     * Identifier of a key.

     */

    TInt32                     iKey;

    };

#endif // C_CENTRALREPOSITORYWATCH_H