/*

* Copyright (c) 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:  CCP transfer functionality for a call.

*

*/

#ifndef MCCPTRANSFERPROVIDER_H

#define MCCPTRANSFERPROVIDER_H

//  INCLUDES

#include <e32cmn.h> // TDesC

class MCCPCall;

class MCCPTransferObserver;

/**

* Call transfer methods. In case plug-in support call transferring these methods can be fetched from 

* MCCPCall::TransferProviderL.

* MCCPTransferObserver is used for transfer specific events. 

* MCCPCallObserver is used for general call related status, event, error etc notifications.

*

*  @since S60 3.2

*/

class MCCPTransferProvider

protected:

    /** 

    * Protected destructor. Object cannot be deleted from plug-in client (CCE).

    * @since S60 3.2

    */

    virtual inline ~MCCPTransferProvider() {};

public:

    /**

    * Actual request result indication comes via observer classes

    * @return KErrNone if request was started succesfully. 

    * @return KErrNotReady if call is not in connected or on-hold state.

    * @return KErrArgument transfer traget address was illegal.

    * @pre Call state is MCCPCallObserver::ECCPStateConnected or MCCPCallObserver::ECCPStateHold

    /**

    * TODO is this used at all? remove? only the call param one is used?

    * Actual request result indication comes via observer class

    * @return KErrNone if request was started succesfully. 

    * @return KErrNotReady if call is not in connected or on-hold state.

    * @return KErrArgument transfer address was illegal.

    * @pre Call state is MCCPCallObserver::ECCPStateConnected or MCCPCallObserver::ECCPStateHold

    * Actual request result indication comes via observer classes

    * @return KErrNone if request was started succesfully. 

    * @return KErrNotReady if call is not in connected or on-hold state.

    * @return KErrArgument transfer address was illegal.

    * @pre Call state is MCCPCallObserver::ECCPStateConnected or MCCPCallObserver::ECCPStateHold

    * Actual request result indication comes via observer class

    * @return KErrNone if request was started succesfully. 

    * @return KErrNotReady if call is not in connected or on-hold state.

    * @return KErrArgument transfer address was illegal.

    * @pre Call state is MCCPCallObserver::ECCPStateConnected or MCCPCallObserver::ECCPStateHold

    /**

    * When the other end of the call has requested call transfer to third party it is notified to 

    * MCCPTransferObserver::TransferEventOccurred(MCCPTransferObserver::ECCPRemoteTransferring).

    * The new recipient of the call can be fetched via this method.

    * @pre Call state is MCCPCallObserver::ECCPStateConnected or MCCPCallObserver::ECCPStateHold

    /**

    * Add an observer for transfer related events.

    * Currently CCE will set only one observer.

    * @since S60 v3.2

    * @param aObserver Observer to add.

    * @return none

    * @leave system error if observer adding fails

    */

    virtual void AddObserverL( const MCCPTransferObserver& aObserver ) = 0;

    /**

    * Remove an observer.

    * @since S60 v3.2

    * @param aObserver Observer to remove.

    * @return KErrNone if removed succesfully. 

    * @return KErrNotFound if observer was not found.

    */

    virtual TInt RemoveObserver( const MCCPTransferObserver& aObserver ) = 0;

    };

#endif // MCCPTRANSFERPROVIDER_H