/*

* Copyright (c) 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:     

*

*/

#include "HgScrollBufferManager.h"

#include <ganes/HgScrollBufferObserverIface.h>

#include <e32debug.h>

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

// CHgScrollBufferManager::NewL()

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

//

CHgScrollBufferManager* CHgScrollBufferManager::NewL( 

        MHgScrollBufferObserver& aObserver, 

        TInt aBufferSize,

        TInt aBufferTreshold,

        TInt aInitialPosition,

        TInt aTotalCount )

    {

    CHgScrollBufferManager* self = new (ELeave) CHgScrollBufferManager(

                                                        aObserver, 

                                                        aBufferSize, 

                                                        aBufferTreshold, 

                                                        aInitialPosition, 

                                                        aTotalCount );

    CleanupStack::PushL(self);

    self->ConstructL();

    CleanupStack::Pop(self);

    return self;

    }

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

// CHgScrollBufferManager::CHgScrollBufferManager()

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

//

CHgScrollBufferManager::CHgScrollBufferManager(

        MHgScrollBufferObserver& aObserver, 

        TInt aBufferSize,

        TInt aBufferTreshold,

        TInt aInitialPosition,

        TInt aTotalCount )

: CActive( CActive::EPriorityHigh ), 

    iObserver( aObserver ),

    iBufferSize( aBufferSize ),

    iBufferTreshold( aBufferTreshold ),

    iBufferPosition( aInitialPosition ),

    iTotalCount( aTotalCount )

    {

    }

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

// CHgScrollBufferManager::ConstructL()

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

//

void CHgScrollBufferManager::ConstructL()

    {

    CActiveScheduler::Add(this);

    iResetOrdered = ETrue;

    ResetBuffer(iBufferPosition, iTotalCount);

    }

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

// CHgScrollBufferManager::~CHgScrollBufferManager()

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

//

CHgScrollBufferManager::~CHgScrollBufferManager()

    {

    Cancel();

    }

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

// CHgScrollBufferManager::RunL()

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

//

void CHgScrollBufferManager::RunL()

    {

    MHgScrollBufferObserver::THgScrollDirection direction = MHgScrollBufferObserver::EHgBufferNoMove;

    if(iResetOrdered)

        {

        iResetOrdered = EFalse;

        direction = MHgScrollBufferObserver::EHgBufferReset;

        }

    else

        {

        if(iDiff < 0)

            {

            iReleaseStart = iBufferPosition;

            iRequestStart = iBufferPosition + iBufferSize;

            direction = MHgScrollBufferObserver::EHgBufferScrollDown;

            }

        else if( iDiff > 0)

            {

            iReleaseStart = iBufferPosition + iBufferSize - iDiff;

            iRequestStart = iBufferPosition - iDiff;

            direction = MHgScrollBufferObserver::EHgBufferScrollUp;

            }

        }

    // Release 

    TInt end = iReleaseStart + iReleaseCount < iTotalCount ?

        iReleaseStart + iReleaseCount: iTotalCount; 

    end--;

    if(end >= iReleaseStart )

        {

        iObserver.Release(iReleaseStart, end);

        if(iOwner) iOwner->Release( iReleaseStart, end );

        }

    iReleaseCount = 0;

    // Request

    end = iRequestStart + iRequestCount < iTotalCount ? 

        iRequestStart + iRequestCount : iTotalCount;

    end--;

    if(end >= iRequestStart )

        iObserver.Request(iRequestStart, end, direction);

    iRequestCount = 0;

    // Move Buffer

    iBufferPosition -= iDiff;

    // Reset Diff

    iDiff = 0;

    }

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

// CHgScrollBufferManager::DoCancel()

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

//

void CHgScrollBufferManager::DoCancel()

    {

    // Nothing to do here

    }

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

// CHgScrollBufferManager::RunError()

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

//

TInt CHgScrollBufferManager::RunError( TInt /*aError*/ )

    {

    return KErrNone;

    }

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

// CHgScrollBufferManager::SetPosition()

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

//

void CHgScrollBufferManager::SetPosition( TInt aIndex )

    {

    // If all the items fit in the buffer no need to move the buffer

    if(iTotalCount <= iBufferSize) return;

    TBool forceUpdate = EFalse;

    aIndex -= iBufferSize / 2; // normalize index to Buffer start

    if(aIndex < 0)

        {

        aIndex = 0;

        forceUpdate = ETrue;

        }

    else if( aIndex > iTotalCount - iBufferSize )

        {

        aIndex = iTotalCount - iBufferSize;

        forceUpdate = ETrue;

        }

    iDiff = iBufferPosition - aIndex; 

    // Too large change reset whole buffer

    if( iDiff >= iBufferSize || -iDiff >= iBufferSize || iResetOrdered ) 

        {

        ResetBuffer(aIndex + (iBufferSize/2), iTotalCount);

        }

    // Move Up

    else if( iDiff >= iBufferTreshold ) 

        {

        iRequestCount = iDiff;

        iReleaseCount = iDiff;

        NotifyObserver();

        }

    // Move Down

    else if( -iDiff >= iBufferTreshold ) 

        {

        iRequestCount = -iDiff;

        iReleaseCount = -iDiff;

        NotifyObserver();

        }

    // Top or bottom has been reached

    else if( forceUpdate && iDiff )

        {

        TInt diff = iDiff < 0 ? -iDiff : iDiff;

        iRequestCount = diff;

        iReleaseCount = diff;

        NotifyObserver();

        }

    }

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

// CHgScrollBufferManager::SetTotalCount()

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

//

void CHgScrollBufferManager::SetTotalCount( TInt aTotalCount )

    {

    iTotalCount = aTotalCount;

    }

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

// CHgScrollBufferManager::SetBufferOwner()

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

//

void CHgScrollBufferManager::SetBufferOwner( MHgBufferOwner& aOwner )

    {

    iOwner = &aOwner;

    }

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

// CHgScrollBufferManager::ResetBuffer()

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

//

void CHgScrollBufferManager::ResetBuffer( TInt aPosition, TInt aTotalCount)

    {

    if( !iResetOrdered )

        {

        // release Old buffer

        iReleaseStart = iBufferPosition;

        iReleaseCount = iBufferSize;

        }

    // set position and count

    iBufferPosition = aPosition - (iBufferSize / 2);

    iTotalCount = aTotalCount;

    iDiff = 0;

    if( iBufferPosition + iBufferSize > iTotalCount - 1 )

        {

        iBufferPosition = iTotalCount - iBufferSize;

        }

    if(iBufferPosition < 0 )

        {

        iBufferPosition = 0;

        }

    //request new Buffer

    iRequestStart = iBufferPosition;

    iRequestCount = iBufferSize;

    iResetOrdered = ETrue;

    NotifyObserver();

    }

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

// CHgScrollBufferManager::NotifyObserver()

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

//

void CHgScrollBufferManager::NotifyObserver()

    {

    if( !IsActive() )

        {

        SetActive();

        TRequestStatus* status = &iStatus;

        User::RequestComplete(status, KErrNone);

        }

    }

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

// CHgScrollBufferManager::ItemChanged()

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

//

void CHgScrollBufferManager::ItemCountChanged( 

        TInt aIndex, 

        TBool aRemoved,

        TInt aNewTotalCount )

    {  

    iTotalCount = aNewTotalCount;

    if ( aIndex >= iBufferPosition && aIndex < iBufferPosition + iBufferSize )

        {

        // Change inside the buffer

        MHgScrollBufferObserver::THgScrollDirection direction = MHgScrollBufferObserver::EHgBufferNoMove;

        if( aRemoved )

            {

            // Release removed item ( Item deleted already from the owner )

            iObserver.Release( aIndex, aIndex );

            if( iTotalCount >= iBufferSize )

                {

                // There are more items to keep the buffer filled

                if( iBufferPosition + iBufferSize <= iTotalCount )

                    {

                    // Requested from the end

                    iObserver.Request( iBufferPosition + iBufferSize - 1, 

                            iBufferPosition + iBufferSize - 1, direction );

                    }

                else if( iBufferPosition > 0 )

                    {

                    // Move buffer and request from the beginning 

                    iBufferPosition--;

                    iObserver.Request( iBufferPosition, iBufferPosition, direction );

                    }

                }

            }            

        else

            {

            if( iTotalCount > iBufferSize )

                {

                // One item needs to be released

                if( iBufferPosition + iBufferSize < iTotalCount )

                    {

                    // Release from the end of the buffer

                    iObserver.Release(iBufferPosition + iBufferSize, iBufferPosition + iBufferSize);

                    if(iOwner)

                        iOwner->Release(iBufferPosition + iBufferSize, iBufferPosition + iBufferSize);

                    }

                }

            // Request added item

            iObserver.Request(aIndex, aIndex, direction);

            }

        }

    }