/*

* Copyright (c) 2005-2006 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:  Observer for Publish & Subscribe keys

*

*/

#ifndef CPSPROPERTYOBSERVER_H

#define CPSPROPERTYOBSERVER_H

#include <e32base.h>

#include <e32property.h>

/** 

 * Defines text property with maximum size, that is RProperty::

 * KKMaxPropertySize bytes. 

 */

typedef TBuf8<RProperty::KMaxPropertySize> TPSTextProperty;

/**

 * MPSPropertyChangeObserver

 *

 * Abstract interface for handling property change events.

 */

class MPSPropertyChangeObserver

{

public:

    /**

     * This is a callback function which is called when a property value of 

     * type int is changed.

     *

     * @param aCategory UID of Publish And Subscribe category

     * @param aKey subkey to specify the category event; to be used with 

     * Publish And Subscribe

     *

     * @param aValue the new value

     */

    virtual void HandlePropertyChangeL(

        const TUid& aCategory, 

        const TUint aKey, 

        const TInt aValue ) = 0;

    /**

     * This is a callback function which is called when a property value of 

     * type text is changed.

     *

     * @param aCategory UID of Publish And Subscribe category

     * @param aKey subkey to specify the category event; to be used with 

     * Publish And Subscribe

     * @param aValue the new value

     **/

    /*lint -save -e1053*/

    virtual void HandlePropertyChangeL( 

        const TUid& aCategory, 

        const TUint aKey, 

        const TPSTextProperty& aValue ) = 0;

    /*lint -restore*/

    /**

     * This is a callback function which is called when a P&S components 

     * returns an error

     *

     * @param aCategory UID of Publish And Subscribe category

     * @param aKey subkey to specify the category event

     * @param aError an error code

     */

    virtual void HandlePropertyChangeErrorL(

        const TUid& aCategory, 

        const TUint aKey, 

        TInt aError) = 0;

};

/**

 * Observer class that observes changes of Property values and propogates 

 * them further.

 * The class defines a handle to a property, a single data value representing

 * an item of state information.

 *

 */

 class CPSPropertyObserver : public CActive

	{  

 public:  // Constructors and destructor

    /**

     * Two-phased constructor.

     *

     * @param aObserver a reference to the observer interface implementer

     * @param aCategory UID of Publish And Subscribe category

     * @param aKey subkey to specify the category event; to be used with 

     * Publish And Subscribe

     * @param aPropertyType property type to observe

     */

    static CPSPropertyObserver* NewL(

        MPSPropertyChangeObserver& aObserver, 

        const TUid& aCategory, 

        const TUint aKey, 

        const RProperty::TType aPropertyType);

    /**

     * Destructor.

     */

    ~CPSPropertyObserver();

    /**

     * Updates an int value reference in correspondence with the current 

     * Property value

     *

     * @param aValue handle to a value which will be updated

     **/	

	void GetValue( TInt& aValue ) const;

	/**

     * Updates a text value reference in correspondence with the current 

     * Property value

     *

     * @param aValue handle to a value which will be updated

     */	

    /*lint -save -e1053*/

	void GetValue( TPSTextProperty& aValue ) const;

    /*lint -restore*/

private:

    /**

     * C++ default constructor overload.

     * Two-phased constructor.

     *

     * @param aObserver a reference to the observer interface implementer

     * @param aCategory UID of Publish And Subscribe category

     * @param aKey subkey to specify the category event; to be used with 

     * Publish And Subscribe

     * @param aPropertyType property type to observe

     */

	CPSPropertyObserver(

	    MPSPropertyChangeObserver& aObserver, 

	    const TUid& aCategory, 

	    const TUint aKey, 

	    const RProperty::TType aPropertyType);

    /**

     * By default Symbian 2nd phase constructor is private.

     **/

    void ConstructL();

protected:  

    // from base class Cactive

    /**

     * From CActive

     *

     * @see CActive::RunL()

     */

    void RunL();

    /**

     * From CActive, 

     * 

     * @see CActive::DoCancel()

     */

    void DoCancel();

private:  

 	/** 

 	 * Value of a subscribed category property of type int. 

 	 */

 	TInt iValueInt;

 	/** 

 	 * Value of a subscribed category property of type text. 

 	 */

 	TPSTextProperty iValueText;

    /** 

     * Handle to Publish And Subscribe component

     */ 

    RProperty iProperty;

    /**

     * Observer to be notified when particular Property value has changed

     */

    MPSPropertyChangeObserver& iObserver;

    /** 

     * UID of Publish And Subscribe category

     */

    TUid iCategory;

    /**

     * Subkey to be used with Publish And Subscribe

     */

    TUint iKey;

    /** 

     * Type of the observed property. 

     */

    RProperty::TType iPropertyType;

	};

#endif  // CPSPROPERTYOBSERVER_H