/*
* 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:

    /**
    * Attended transfer to given call recipient.
    * There needs to exist two calls. a call between A-B and A-C. A wants to transfer the call to B-C. 
    * Both calls A-B and A-C will be disconnected after transfer.
    * In above case C will be the aTransferTargetCall call recipient. B is the recipient of the 
    * current call between A-B - called on A's call object transfer provider. 
    * The A-B call is on hold.
    * Actual request result indication comes via observer classes
    * @param aTransferTargetCall Call containing the transfer target info.
    * @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
    * @since S60 3.2
    */
    virtual TInt AttendedTransfer( MCCPCall& aTransferTargetCall ) = 0;

    /**
    * TODO is this used at all? remove? only the call param one is used?
    * Attended transfer to given address. There does not need to be 
    * a current call between the given transfer target.
    * Actual request result indication comes via observer class
    * @param aTransferTarget Transfer target address
    * @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
    * @since S60 3.2
    */
    virtual TInt AttendedTransfer( const TDesC& aTransferTarget ) = 0;

    /**
    * Unattended transfer. Call is requested to be transferred to given address.
    * After MCCPTransferObserver::ECCPRemoteTransferring event current call will be 
    * disconnected and no transfer status is checked from the operation. 
    * Actual request result indication comes via observer classes
    * @since S60 3.2
    * @param aTransferTarget Address of the target
    * @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
    */
    virtual TInt UnattendedTransfer( const TDesC& aTransferTarget ) = 0;

    /**
    * Accept incoming call transfer request from the call remote party.
    * Actual request result indication comes via observer class
    * @since Series 60 3.2
    * @param aAccept ETrue - accept transfer, EFalse do not accept transfer request.
    * @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
    * @pre MCCPObserver::CallCreated is called with the newly created call
    */
    virtual TInt AcceptTransfer( const TBool aAccept ) = 0;
      
    /**
    * 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.
    * @since Series 60 3.2
    * @param none
    * @return new recipient for the call after transfer
    * @return KNullDesC if no transfer target is available
    * @pre Call state is MCCPCallObserver::ECCPStateConnected or MCCPCallObserver::ECCPStateHold
    * @pre MCCPObserver::CallCreated is called with the newly created call
    */
    virtual const TDesC& TransferTarget() const = 0;
    
    /**
    * 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