/*

* Copyright (c) 2007 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:  Device state watcher class.

 *

*/

#ifndef USBDEVICESTATEWATCHER_H

#define USBDEVICESTATEWATCHER_H

// INCLUDE FILES

#include <e32base.h>

#include <usbman.h>

/**

 * A callback interface for informing about device state changes

 */

class MUSBDeviceStateObserver

    {

    public:

        /**

         * Informs the observer that USB device state has changed.

         * @param aPreviousState previous device state.

         * @param aCurrentState current device state.

         */

        virtual void DeviceStateChanged(TUsbDeviceState aPreviousState,

                                        TUsbDeviceState aCurrentState) = 0;

    };

// CLASS DECLARATION

/**

 * Class that listens for USB device state changes and notifies

 * the observer.

 */

class CUSBDeviceStateWatcher : public CActive

    {

    public:  // Constructors and destructor

        /**

         * Two-phased constructor. Uses existing usb manager session.

         * Note that it's not possible (and usually not necessary) to attach

         * more than one USBDeviceStateWatcher to the same session.

         *

         * @param aObserver  Reference to device state observer.

         * @param aUsbMan    Existing usb manager session.

         * @return Pointer to created object.

         */

        static CUSBDeviceStateWatcher* NewL(MUSBDeviceStateObserver& aObserver,

            RUsb& aUsbMan);

        /**

         * Two-phased constructor. Creates its own usb manager session.

         *

         * @param aObserver  Reference to device state observer.

         * @return Pointer to created object.

         */

        static CUSBDeviceStateWatcher* NewL(MUSBDeviceStateObserver& aObserver);

        /**

        * Destructor.

        */

        virtual ~CUSBDeviceStateWatcher();

    public: // from base class CActive

        /**

        * From CActive.

        * This method is called when device state has changed.

        */

        void RunL();

        /**

        * From CActive.

        * In this implementation this method should never be called.

        *

        * @param aError the leave code

        * @return KErrNone

        */

        TInt RunError(TInt aError);

        /**

        * From CActive

        * If there is outstanding request pending when Cancel() is called then

        * this method must cancel request.

        */

        void DoCancel();

    private:

        /**

         * Private constructor.

         *

         * @param aObserver Reference to MUSBDeviceStateObserver.

         */

        CUSBDeviceStateWatcher(MUSBDeviceStateObserver& aObserver);

        /**

         * 2nd phase constructor.

         * Creates its own usb manager session.

         */

        void ConstructL();

        /**

         * 2nd phase constructor.

         * Uses existing usb manager session.

         *

         * @param aUsbMan    Existing usb manager session.

         */

        void ConstructL(RUsb& aUsbMan);

        /**

         * Code shared by all ConstructL methods.

         */

        void CommonConstructL();

        // Disable default C++ behavior that makes no sense

        // for this implementation.

        CUSBDeviceStateWatcher();

        CUSBDeviceStateWatcher(const CUSBDeviceStateWatcher&);

        CUSBDeviceStateWatcher& operator=(const CUSBDeviceStateWatcher&);

    private: // Data

        /**

         * Handle to Usb Manager

         */

        RUsb iUsbMan;

        /**

         * Current device state

         */

        TUsbDeviceState iCurrentState;

        /**

         * Last known device state

         */

        TUsbDeviceState iPreviousState;

        /**

         * Refernce to the observer

         */

        MUSBDeviceStateObserver& iObserver;

    };

#endif   // USBDEVICESTATEWATCHER_H