/*

* 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:    Cache implementation for media items sharing the same Id space

*

*/

#ifndef C_GLXCACHE_H

#define C_GLXCACHE_H

#include <e32base.h>

#include "glxmediaid.h"

// Forward declarations

class CMPXMedia;

class CGlxMedia;

class T_CacheTestHelpers;

class TMPXAttribute;

class CGlxCacheManager;

/**

 *  CGlxCache

 *

 *  Individual cache of media items sharing the same Id space

 */

NONSHARABLE_CLASS( CGlxCache ) : public CBase

	{

public:

    /**

     * Constructor

     * @param aIdSpaceId The id of the id address space of this cache 

	 * @param aCacheManager Instance of cachemanager to cleanup the media

     */

    CGlxCache( const TGlxIdSpaceId& aIdSpaceId, CGlxCacheManager* aCacheManager );

    /**

     * Destructor

     */

    ~CGlxCache();

    /**

     * Returns the Id space covered by this cache

     * @return The Id space covered by this cache    

     */

    TGlxIdSpaceId IdSpaceId() const;    

    /**

     * Notify the cache that attributes have changed on media item(s)

     * @param aMedia The updated media item or array of updated media items

     */

    void MediaUpdatedL( const CMPXMedia& aMedia );

    /**

     * Update media item

     *

     * @param aMedia The updated media item

     */

    void UpdateMediaL( const CMPXMedia& aMedia );

    /**

     * Cleanup the media of the given media id: broadcast this to all observers

	 * @param aMediaId The media id of the item

     */ 

    void CleanupMedia(const TGlxMediaId& aMediaId);

    /**

     * Handles modifications of item in cache

     *

     * @param aId Media item id

     * @param aAttributes Attributes that have been modified

     */

    void HandleItemModified( const TGlxMediaId& aId, const RArray<TMPXAttribute>& aAttributes );

    /**

     * Access to the items stored in the cache: return the item matching the given media Id

     * @param aId The media Id

     * @return The media item, or NULL if not found

     */

    CGlxMedia* Media( const TGlxMediaId& aId ) const;

    /**

     * Access to the items stored in the cache: return the item matching the given media Id.

     * If not found, a new item is created

     * @param aId The media Id

     * @return The media item

     */

    CGlxMedia* FindItemForceCreateL( const TGlxMediaId& aId );

    /**

     * Number of items in cache

     * @return Number of items in cache

     */

    TInt Count();

    /**

     * Cached item by index

     * @param aIndex index of the item

     * @return Cached item

     */

    CGlxMedia& Media( TInt aIndex );

    /**

     * Delete an item at index from the cache.

     * @param aIndex Index of the item to delete

     */

    void Delete( TInt aIndex );

    /**

     * Reserve space for a number of users, for all items in the cache

     *

     * @param aCount The number of users to reserve space for

     */

    void ReserveUsersL( TInt aCount );

    /**

	 * Finds the media index present in cache

	 * @returns the index of media

	 */    

    TInt FindMediaIndexInCache(TGlxMediaId aMediaId);

private:

    /**

     * Copy the new and modified attributes from aSource to aTarget

     * @param aTarget The target media item

     * @param aSource The source media item

     * @param aNewAttributes The new and modified attributes

     */

    void CopyNewAndModifiedL( CGlxMedia& aTarget, const CMPXMedia& aSource, 

        RArray<TMPXAttribute>& aNewAttributes );

    /**

     * Function for TLinearOrder() for comparing two CGlxMedias 

     * Used from ordering the iItemPool by id

     * @param aItem1 The first item to compare

     * @param aItem2 The second item to compare

     * @return -1 if aItem1 < aItem2; 1 if aItem1 > aItem2; 0 if aItem1 == aItem2

     */

    static TInt MediaItemOrderById( const CGlxMedia& aItem1, const CGlxMedia& aItem2 );

    /**

     * Function for comparing a TGlxMediaId with a CGlxMedia 

     * Used from ordering iItemPool by media id

     * @param aMediaId The media id to compare against aItem2

     * @param aItem2 The second item to compare

     * @return -1 if aMediaId < aItem2.Id(); 1 if aMediaId > aItem2.Id(); 0 if aMediaId == aItem2.Id()

     */

    static TInt MediaItemOrderByKey( const TGlxMediaId* aMediaId, const CGlxMedia& aItem2 );

    /**

     * Create and add an item to the item pool

     * @param aId Id for the new item

     * @return Pointer to the created item

     */

    CGlxMedia* CreateItemL( const TGlxMediaId& aId );

private:

    /// Id space that this cache covers

    TGlxIdSpaceId iIdSpaceId;

    /// Pool of media items. Owned

    RPointerArray<CGlxMedia> iItemPool; 

    ///Instance of cacheManager to cleanup cache

    CGlxCacheManager* iCacheManager;

    friend class T_CacheTestHelpers;

    };

#endif // C_GLXCACHE_H