/*

* 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: Email message iterator

*

*/

#ifndef CMESSAGEITERATOR_H

#define CMESSAGEITERATOR_H

#include "emailapidefs.h"

#include "CFSMailCommon.h"

using namespace EmailInterface;

class MFSMailIterator;

class CPluginData;

class CFSMailMessage;

class CEmailMessage;

/**

 * Iterator for email messages

 * @since S60 v5.2

 */

NONSHARABLE_CLASS( CMessageIterator ) : public CBase, public MMessageIterator

{

public:

    /**

    * Constructor

    * @param aIterator

    * @param aPluginData

    * @return new iterator

    */

    static CMessageIterator* NewL( MFSMailIterator* aIterator,

                                   CPluginData& aPluginData,

                                   TUint aCount );

    ~CMessageIterator();

private:

    CMessageIterator( MFSMailIterator* aIterator, CPluginData& aPluginData, TUint aCount );

    void ConstructL();

public: // from MEmailInterface              

    virtual TEmailTypeId InterfaceId() const;

    virtual void Release();

public: // from MMessageIterator

    /** @see MMessageIterator */

    virtual MEmailMessage* NextL();

    /** @see MMessageIterator 

     (not implemented) */

    virtual MEmailMessage* PreviousL();

    virtual TUint Count() const;

private:   

    // Reads next chunk of messages from protocol plugin

    TBool ReadNextChunkL();

    TBool ReadPreviousChunkL();

    MEmailMessage* ReadFromChunkL();

    void CleanCache();    

    void AddToCacheL( CFSMailMessage* aFsMsg );    

private: // data

    /**

    * Iterator internal states. "Consuming" in state names mean getting and 

    * returning next message from the iterator.

    */

    enum TState {

        // No messages available in iterator, read them from protocl plugin.

        // NextL returns a message from chunk (or NULL if folder is empty)

        // This is initial state.

        EReadNextMessageChunk,

        EReadPreviousMessageChunk,

        // Message(s) are available (retrieved from plugin). No remaining 

        // messages excepted from the plugin. NextL returns a message from chunk.

        EConsumeFromChunk,

        // Message(s) are available in chunk and more in protocol plugin.

        EConsumeFromChunkWithMoreChunksToFollow,

        // Iterator is iterated throuh and NextL would return NULL.

        EIteratorConsumed

    };

    // plugin iterator, owned

    MFSMailIterator* iIterator;

    // reference to plugin data

    CPluginData&    iPluginData;

    CFSMailPlugin*  iPlugin;

    // message id used for reading messages from plugin

    TFSMailMsgId    iStartMsgId;

    // Internal state  

    TState           iState;

    // pointer array of messages read from protocol plugin (aka message chunk)

    RPointerArray<CFSMailMessage> iFsMessageArray;

    RPointerArray<CEmailMessage> iMessageArray;

    TUint iCount;

    TInt iCursor;

    TFSMailMsgId iFirstMsgId;

    TBool iHasMoreNextItems;

    TBool iHasMorePrevItems;

};

#endif // CMESSAGEITERATOR_H

// End of file.