/*

* Copyright (c) 2008-2009 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:   Blocking attribute retriever

*

*/

#include "glxattributeretriever.h"

#include <bautils.h>

#include <data_caging_path_literals.hrh>

#include <mpxattributespecs.h>

#include <mpxcollectionpath.h>

#include <glxlog.h>

#include <glxmedialist.h>

#include <glxpanic.h>

#include <mglxfetchcontext.h>

#include <mglxmedialistobserver.h>

/**

 * Observer that should be implemented by users of the

 * CGlxAttributeRetriever class to inform them when attribute retrieval is complete

 */

class MGlxAttributeRetrieverObserver

    {

public:

    /**

     * Called when attribute retrieval is complete

     * @param aError symbian os error code.

     */

    virtual void AttributeRetrievalCompleteL(TInt aError) = 0;

    };

/**

 *  CGlxAttributeRetriever

 *  This class informs the MGlxAttributeRetrieverObserver when all

 *  requested metadata has been retrived.

 *	@ingroup mlm_media_list_manager_design

 *  @lib glxuiutlities.lib

 */

NONSHARABLE_CLASS( CGlxAttributeRetriever ) 

    : public CActive, public MGlxMediaListObserver

    {

public:

    /**

     * Constructor

     *  @param aObserver observer to be informed when attribute retrieval is complete

     */

    CGlxAttributeRetriever(MGlxAttributeRetrieverObserver& aObserver);

    /**

    * Destructor

    */

    ~CGlxAttributeRetriever();

    /**

    * Retrieve the attrubutes

    * @param aContext the fetch context containing the attribute to be retrieved

    * @param aList the medialist containing the item for which the attributes are retrieved

    * @return Error code

    */

    void RetrieveL(const MGlxFetchContext* aContext, MGlxMediaList* aList);

    void CancelRetrieve();

private: // from CActive

    void RunL();

    void DoCancel();

public: // From MGlxMediaListObserver

    void HandleAttributesAvailableL(TInt aItemIndex, const RArray<TMPXAttribute>& aAttributes, MGlxMediaList* aList);

    void HandleItemAddedL(TInt aStartIndex, TInt aEndIndex, MGlxMediaList* aList);

    void HandleItemRemovedL(TInt aStartIndex, TInt aEndIndex, MGlxMediaList* aList);

    void HandleItemModifiedL(const RArray<TInt>& aItemIndexes, MGlxMediaList* aList);

    void HandleFocusChangedL(NGlxListDefs::TFocusChangeType aType, TInt aNewIndex, TInt aOldIndex, MGlxMediaList* aList);

    void HandleMediaL(TInt aListIndex, MGlxMediaList* aList);

    void HandleItemSelectedL(TInt aIndex, TBool aSelected, MGlxMediaList* aList);

    void HandleMessageL(const CMPXMessage& aMessage, MGlxMediaList* aList);

    void HandlePopulatedL(MGlxMediaList* aList);

	void HandleError(TInt aError);

private:

    /**

     * Asynchronously notifies the observer is attribute retrieval is complete

     */

    void NotifyObserverIfCompleteL();

    /**

     * Completes the active object causing a call from the 

     * active scheduler to RunL()

     * @param aError error code passed to RunL()

     * (test in RunL using iStatus.Int())

     */

    void CompleteSelf(TInt aError);

private:

    /// pointer to a Fetch Context associated with the desired attribute. Not owned

    const MGlxFetchContext* iContext;

    /// pointer to the Media List. Not owned

    MGlxMediaList* iList;

    /**

     * observer

     */

    MGlxAttributeRetrieverObserver& iObserver;

    /**

     * Internal cache of objects still to retrieve

     */

    TInt iRequestCount;

    };

/**

 * Abstract interface for a blocking attribute retriever

 */

class MGlxBlockingAttributeRetriever

    {

public:    

    /**

     * Retrieve the attrubutes (call blocks until attribute retrieval is complete)

     * @param aContext the fetch context containing the attribute to be retrieved

     * @param aList the medialist containing the item for which the attributes are retrieved

     * @return Error code

     */

    virtual TInt RetrieveL(const MGlxFetchContext* aContext, MGlxMediaList* aList) = 0;

    virtual ~MGlxBlockingAttributeRetriever() {};

    };

/**

 *  This class blocks until all requested metadata has been retrieved

 */  

class CGlxSynchronousAttributeRetriever : public CBase,

                                          public MGlxBlockingAttributeRetriever,

                                          public MGlxAttributeRetrieverObserver

    {

public:

    static CGlxSynchronousAttributeRetriever* NewLC();

public: // from MGlxBlockingAttributeRetriever

    /**

     * See @ref MGlxBlockingAttributeRetriever::RetrieveL

     */

    TInt RetrieveL(const MGlxFetchContext* aContext, MGlxMediaList* aList);

private: // from MGlxAttributeRetrieverObserver

    /**

     * See @ref MGlxAttributeRetrieverObserver::AttributeRetrievalCompleteL

     */

    void AttributeRetrievalCompleteL(TInt aError);

private:

    /**

     * StopScheduler

     */

     void StopScheduler();

private:

    /**

     * Second stage constructor

     */

    void ConstructL();

    /**

     * Destructor

     */

    ~CGlxSynchronousAttributeRetriever();

private:

    /// Active scheduler wait object. Owned

    CActiveSchedulerWait* iSchedulerWait;

    /**

     * Attribute retriever (owned)

     */

    CGlxAttributeRetriever* iAttributeRetriever;

    /**

     * Attribute retrieval error

     */

    TInt iError;

    };

// -----------------------------------------------------------------------------

// RetrieveL

// -----------------------------------------------------------------------------

//

EXPORT_C TInt GlxAttributeRetriever::RetrieveL(const MGlxFetchContext& aContext, 

    {

    TInt err = retriever->RetrieveL(&aContext, &aList);

    return err;

    }

// -----------------------------------------------------------------------------

// Constructor

// -----------------------------------------------------------------------------

//  

CGlxAttributeRetriever::CGlxAttributeRetriever(MGlxAttributeRetrieverObserver& aObserver)

    : CActive(EPriorityHigh), iObserver(aObserver)  // We want out RunL to be serviced ASAP

    {

    CActiveScheduler::Add(this);

    }

// -----------------------------------------------------------------------------

// Destructor

// -----------------------------------------------------------------------------

//	

CGlxAttributeRetriever::~CGlxAttributeRetriever()

    {

    Cancel();

    if ( iList )

        {

        iList->RemoveMediaListObserver( this );

        }

    }

// -----------------------------------------------------------------------------

// CGlxAttributeRetriever::RetrieveL

// -----------------------------------------------------------------------------

//	

void CGlxAttributeRetriever::RetrieveL(const MGlxFetchContext* aContext, MGlxMediaList* aList)

    {

    iContext = aContext;

    iList = aList;

    iList->AddMediaListObserverL(this);

    if(iList->IsPopulated())

        {

        NotifyObserverIfCompleteL();

        }

    }

void CGlxAttributeRetriever::CancelRetrieve()

    {

    // Simply remove media list observer to prevent call backs from the media list

    iList->RemoveMediaListObserver(this);

    }

// -----------------------------------------------------------------------------

// CGlxAttributeRetriever::RunL

// -----------------------------------------------------------------------------

//  

void CGlxAttributeRetriever::RunL()

    {

    iObserver.AttributeRetrievalCompleteL(iStatus.Int());

    }

// -----------------------------------------------------------------------------

// CGlxAttributeRetriever::DoCancel

// -----------------------------------------------------------------------------

// 

void CGlxAttributeRetriever::DoCancel()

    {

    // No need to do anything

    }

// -----------------------------------------------------------------------------

// CGlxAttributeRetriever::NotifyObserverIfCompleteL()

// -----------------------------------------------------------------------------

//

void CGlxAttributeRetriever::NotifyObserverIfCompleteL()

    {

    iRequestCount--;

    if( iRequestCount <= 0 )

        {

        iRequestCount = iContext->RequestCountL(iList);

        if(iRequestCount <= 0)

            {

            iList->RemoveMediaListObserver(this); // prevent any more callbacks from the media list

            CompleteSelf(iRequestCount); // request count is an error

            }

         }

    }

// ---------------------------------------------------------------------------

// CGlxDataSource::CompleteSelf

// ---------------------------------------------------------------------------

//

void CGlxAttributeRetriever::CompleteSelf(TInt aError)

    {

    TRequestStatus* status=&iStatus;

    User::RequestComplete(status, aError);

    SetActive();    

    }

// -----------------------------------------------------------------------------

// HandleAttributesAvailableL

// -----------------------------------------------------------------------------

//

void CGlxAttributeRetriever::HandleAttributesAvailableL(TInt /* aItemIndex */, 

    const RArray<TMPXAttribute>& /* aAttributes */, MGlxMediaList* /*aList*/)

    {

    NotifyObserverIfCompleteL();

    }

// -----------------------------------------------------------------------------

// HandleItemAddedL

// -----------------------------------------------------------------------------

//

void CGlxAttributeRetriever::HandleItemAddedL(TInt /* aStartIndex */, 

        TInt /* aEndIndex */, MGlxMediaList* /* aList */)

    {

    // No implementaion

    }

// -----------------------------------------------------------------------------

// HandleItemRemovedL

// -----------------------------------------------------------------------------

//

void CGlxAttributeRetriever::HandleItemRemovedL(TInt /* aStartIndex */, 

        TInt /* aEndIndex */, MGlxMediaList* /* aList */)

    {

    // No implementaion

    }

// -----------------------------------------------------------------------------

// HandleItemModifiedL

// -----------------------------------------------------------------------------

//

void CGlxAttributeRetriever::HandleItemModifiedL(const RArray<TInt>& /* aItemIndexes */, 

        MGlxMediaList* /* aList */)

    {

    // No implementaion

    }

// -----------------------------------------------------------------------------

// HandleFocusChangedL

// -----------------------------------------------------------------------------

//

void CGlxAttributeRetriever::HandleFocusChangedL(NGlxListDefs::TFocusChangeType /* aType */, 

        TInt /* aNewIndex */, TInt /* aOldIndex */, MGlxMediaList* /* aList */)

    {

    // No implementaion

    }

// -----------------------------------------------------------------------------

// HandleMediaL

// -----------------------------------------------------------------------------

//

void CGlxAttributeRetriever::HandleMediaL(TInt /* aListIndex */, 

        MGlxMediaList* /* aList */)

    {

    // No implementaion

    }

// -----------------------------------------------------------------------------

// HandleItemSelectedL

// -----------------------------------------------------------------------------

//

void CGlxAttributeRetriever::HandleItemSelectedL(TInt /* aIndex */, 

        TBool /* aSelected */, MGlxMediaList* /* aList */)

    {

    // No implementaion

    }

// -----------------------------------------------------------------------------

// HandleMessageL

// -----------------------------------------------------------------------------

//

void CGlxAttributeRetriever::HandleMessageL(const CMPXMessage& /* aMessage */, 

    MGlxMediaList* /* aList */)

    {

    // No implementaion

    }

// -----------------------------------------------------------------------------

// HandleError

// -----------------------------------------------------------------------------

//

void CGlxAttributeRetriever::HandleError(TInt /* aError */)

    {

    // An error has been reported. But is it ours?

    // If the request is not complete then the error is not ours

    iRequestCount = 0;

    TRAP_IGNORE(NotifyObserverIfCompleteL());

    }

// -----------------------------------------------------------------------------

// HandlePopulatedL

// -----------------------------------------------------------------------------

//

void CGlxAttributeRetriever::HandlePopulatedL(MGlxMediaList* /*aList*/)

    {

    // If the media list is empty we will never get the HandleAttributesAvailableL callback,

    // therefore the call to NotifyObserversIfCompleteL below is necessary.

    NotifyObserverIfCompleteL();

    }

// -----------------------------------------------------------------------------

// CGlxSynchronousAttributeRetriever

// -----------------------------------------------------------------------------

//

// -----------------------------------------------------------------------------

// CGlxSynchronousAttributeRetriever::NewLC

// -----------------------------------------------------------------------------

//  

CGlxSynchronousAttributeRetriever* CGlxSynchronousAttributeRetriever::NewLC()

    {

    CGlxSynchronousAttributeRetriever* self = new (ELeave) CGlxSynchronousAttributeRetriever();

    CleanupStack::PushL(self);

    self->ConstructL();

    return self;

    }

// -----------------------------------------------------------------------------

// CGlxSynchronousAttributeRetriever::RetrieveL

// -----------------------------------------------------------------------------

//  

TInt CGlxSynchronousAttributeRetriever::RetrieveL(const MGlxFetchContext* aContext, MGlxMediaList* aList)

    {

    iAttributeRetriever->RetrieveL(aContext,aList);

    iSchedulerWait->Start();

    return iError;

    }

// -----------------------------------------------------------------------------

// CGlxSynchronousAttributeRetriever::AttributeRetrievalCompleteL

// -----------------------------------------------------------------------------

//

void CGlxSynchronousAttributeRetriever::AttributeRetrievalCompleteL(TInt aError)

    {

    iError = aError;

    StopScheduler();

    }

// -----------------------------------------------------------------------------

// StopScheduler

// -----------------------------------------------------------------------------

//

void CGlxSynchronousAttributeRetriever::StopScheduler()

    {

    if (iSchedulerWait)

        {

        if (iSchedulerWait->IsStarted())

            {

            iSchedulerWait->AsyncStop();

            }

        }

    }

// -----------------------------------------------------------------------------

// CGlxSynchronousAttributeRetriever::ConstructL

// -----------------------------------------------------------------------------

//  

void CGlxSynchronousAttributeRetriever::ConstructL()

    {

    iSchedulerWait = new (ELeave) CActiveSchedulerWait();

    iAttributeRetriever = new (ELeave) CGlxAttributeRetriever(*this);

    }

// -----------------------------------------------------------------------------

// Destructor

// -----------------------------------------------------------------------------

//  

CGlxSynchronousAttributeRetriever::~CGlxSynchronousAttributeRetriever()

    {

    delete iSchedulerWait;

    delete iAttributeRetriever;

    }