/*

* 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:  Header for CIRDiskSpaceSession

*

*/

#ifndef C_IRDISKSPACESESSION_H

#define C_IRDISKSPACESESSION_H

#include <e32base.h>

#include <f32file.h>

class MIRDiskSpaceWatcherObserver;

/**

 * Defines disk space observer. 

 *

 * Observers defined disk and notifies observer if disk space drops below

 * certain level.

 */

NONSHARABLE_CLASS( CIRDiskSpaceSession ) : public CActive

    {

public:

    /**

     * Static constructor 

     *

     * @param aDiskSpaceSessionObserver Observer who is interested if disk 

     * space drops below certain level.

     * @param aDriveNumber drive to observe

     * @param aCriticalLevel critical disk space level in bytes. If disk 

     * space falls below this observer is notified.

     */

    static CIRDiskSpaceSession* NewL(MIRDiskSpaceWatcherObserver& 

							         aDiskSpaceSessionObserver, 

							         const TDriveNumber& aDriveNumber, 

							         const TInt64& aCriticalLevel,

							         RFs& aFs );

    /**

     * Destructor

     */

    ~CIRDiskSpaceSession();

    /**

     * Tells observed drive.

     *

     * @return Drive number which is been observed by this session.

     */

    TDriveNumber DriveNumber();

    /**

     * Sets observer count

     *

     * @param aObserverCount observer count

     */

    void SetObserverCount( TInt aObserverCount );

    /**

     * Returns observer count

     *

     * @return observer count

     */    

    TInt ObserverCount();

    /**

     * IsBelowCriticalLevel Returns whether or disk defined by parameter 

     * contains less than the critical level free disk space.

     *

     * @param aDriveNumber drive which space is checked

     * @return ETrue if there is less free disk space than the critical 

     * level, otherwise EFalse.

     */

    TBool IsBelowCriticalLevel( const TDriveNumber& aDriveNumber ) const;

protected:

    // from base class CActive

    /**

     * From CActive 

     * 

     * @see CActive::DoCancel()

     */

    void DoCancel();

    /**

     * From CActive 

     *

     * Invoked when the observed disk's free disk space has run 

     * below the supplied critical level.

     * Notifies the observer and regenerates the request to RFs' 

     * NotifyDiskSpace.

     * @see CActive::RunL()

     */

    void RunL();

private:

    /**

     * C++ default constructor. Sets references.

     *

     * @param aDiskSpaceSessionObserver Observer who is interested if disk 

     * space drops below certain level.

     * @param aDriveNumber drive to observe

     * @param aCriticalLevel critical disk space level in bytes. If disk 

     * space falls below this observer is notified.     

     */

    CIRDiskSpaceSession(MIRDiskSpaceWatcherObserver& 

				        aDiskSpaceSessionObserver, 

				        const TDriveNumber& aDriveNumber, 

				        const TInt64& aCriticalLevel,

				        RFs& aFs );

    /**

     * Second phase constructor

     */

    void ConstructL();

private: 

	/** 

	 * The observer to be notified when critical disk space limit is reached. 

	 */

    MIRDiskSpaceWatcherObserver& iObserver;

    /** 

     * Drive to be observed. 

     */

    const TDriveNumber iDriveNumber;

    /** 

     * Critical disk space level. 

     */

    const TInt64 iCriticalLevel;

    /** 

     * Handle to the file system. 

     */

    RFs& iFs;

    /** 

     * Number of observers of this drive. When observer count drops to 

     * zero drive observation can be stopped.

     */

    TInt iObserverCount;

    };

#endif // C_IRDISKSPACESESSION_H