/*

* Copyright (c) 2005 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:  Handles the communication with DM Tree Module (client). 

* 				 Transfers adapter commands to DM Plug In Adapters.

*

*/

#ifndef __NSMLDMHOSTSERVERSESSION_H__

#define __NSMLDMHOSTSERVERSESSION_H__

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

// Includes

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

#include <e32base.h>

#include <ecom.h>

#include <smldmadapter.h>

#include "nsmldmclientandserver.h"

#include "nsmldmtreedtd.h"

#include "nsmldmcmdarghandler.h"

#include <nsmldmtreedbclient.h>

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

// Data fórmats

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

struct TNSmlDmAdapter

	{

	CSmlDmAdapter* adapterPtr;

	TUint32 adapterId;

	TBool startAtomicCalled;

	TBool commandsCalled;

	TInt streamingLimit;

	};	

struct TNSmlDmCallbackRef

	{

	TNSmlDmHostCallbackType callBack;

	TInt reference;

	};

struct TNSmlDmWriteStream

	{

    RWriteStream* streamPtr;

	TUint32 adapterId;

	};

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

// Class forwards

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

class CNSmlDMHostServer;

/**

* Class CNSmlDMHostSession. Handles communication with the DM TreeModule (client).

* Transfers adapter commands to DM Plug In Adapters.

*

* @lib nsmldmhostserver.lib

*/

class CNSmlDMHostSession : public CSession2, public MSmlDmCallback

	{

public:

	enum TNSmlDmResultAnalysis

		{

		ENSmlDmAllWillFit = 0,

		ENSmlDmSomeWillFit,

		ENSmlDmStreamed,

		ENSmlDmLargeDoesntFit

		};

	/**

	* Creates a new session object.

	* @param aServer. Reference to server is needed in order to increase and decrease session counts.

	* @return CNSmlDMHostSession*. New instance of this class.

	*/

	static CNSmlDMHostSession* NewL ( CNSmlDMHostServer& aServer );

	/**

	* Handles the servicing of client requests.

	*  Entry point for arriving messages.

	* @param aMessage. An object which encapsulates a client request.

	*/

	void ServiceL ( const RMessage2 &aMessage );

	/**

	* Extracts the operation code from the message. 

	*  Based on that calls the right private function.

	* @param aMessage. An object which encapsulates a client request.

	*/

	void DispatchMessageL ( const RMessage2 &aMessage );

	/**

	* MSmlDmCallback - callback interface.

 	*  For returning fetch results from dm plug-in adapters.

	* @param aResultsRef. Reference to correct command.

	* @param aObject. The data which should be returned.

	* @param aType. MIME type of the object.

	*/

	void SetResultsL ( TInt aResultsRef, CBufBase& aObject, const TDesC8& aType );

	/**

	* MSmlDmCallback - callback interface.

 	*  For returning fetch results from dm plug-in adapters (using streaming).

	* @param aResultsRef. Reference to correct command.

	* @param aStream. Large data which should be returned.

	* @param aType. MIME type of the object.

	*/

	void SetResultsL ( TInt aResultsRef, RReadStream*& aStream, const TDesC8& aType );

	/**

	* MSmlDmCallback - callback interface.

 	*  For returning statuses for dm adapter commands.

	* @param aStatusRef. Reference to correct command.

	* @param aErrorCode. Information about the command success.

	*/

	void SetStatusL ( TInt aStatusRef, MSmlDmAdapter::TError aErrorCode );

	/**

	* MSmlDmCallback - callback interface.

 	*  This function is called for a new management object, 

 	*  both for node objects and for leaf objects by dm adapter.

	* @param aURI	URI of the object. 

	* @param aLUID	Typically this is ID for the database table.

	*/

	void SetMappingL ( const TDesC8& aURI, const TDesC8& aLUID );

	/**

	* MSmlDmCallback - callback interface.

 	*  The function is used to make a fetch to other adapters. 

	* @param aURI. URI of the object. 

	* @param aData. Reference to data, i.e. data is returned here

	* @param aStatus. The status of fetch command is returned here

	*/

	void FetchLinkL ( const TDesC8& aURI, CBufBase& aData, MSmlDmAdapter::TError& aStatus );

	/**

	* MSmlDmCallback - callback interface.

 	*  The function returns the LUID which is mapped to aURI. 

	* @param aURI. URI of the object. 

	* @return HBufC8*. If LUID is not found, the function allocates a null length string.

	*/	

	HBufC8* GetLuidAllocL ( const TDesC8& aURI );

	/**

	* C++ destructor.

	*/

	~CNSmlDMHostSession();	

private:

	/**        

	* Symbian 2nd phase constructor

	*/

	void ConstructL();

	/**

	* C++ constructor.

	* @param aServer. The server instance, owner of session.

	*/

	CNSmlDMHostSession ( CNSmlDMHostServer& aServer);

	/**

	* Panics the client

	* @param aMessage. Message from client to panic.

	* @param aReason. Reason code.

	*/

    void PanicClient ( const RMessage2& aMessage, TInt aReason ) const;

	/**

	* Empty function.

	*  Kept here for possible future needs. 

	*  Freeing of resources is done in the destructor.

	*/

    void CloseSessionL() const;

	/**

	* Gets DDF structure from the dm adapters.

	*  aMessage parameter contains a list of adapters which are already loaded.

	*  Writes the combined DDF structure to the chunk in the WBXML format.

	*  Returns also a checksum of the DDF structure to the client. 

	* @param aMessage. A list of already loaded adapters, and place for checksum.

	*/

    void GetDDFStructureL ( const RMessage2& aMessage );

	/**

	* Auxiliary function called by GetDDFStructureL.

	*  Reads the UIDs of the loaded adapters from the message, 

	*  and stores those to internal list. 

	* @param aMessage. An object which encapsulates a client request.

	* @param aUids. A reference parameter, a place for extracted list of UIDs.

	*/

    void ReadUidsL ( const RMessage2& aMessage, RArray<TUint32>& aUids ) const;

	/**

	* Auxiliary function called by GetDDFStructureL.

	*  Gets a list of all the potential dm adapters.

	*  Removes from it those which are alreay loaded.  

	* @param aAllAds. A reference parameter, after this function call 

	*                 contains the acceptable adapters.

	* @param aUids. A list of adapters which are already loaded.

	*/

	void RemoveAlreadyLoadedL ( RImplInfoPtrArray& aAllAds, RArray<TUint32>& aUids ) const;    

	/**

	* Auxiliary function called by GetDDFStructureL.

	*  Asks initial information from the loaded dm adapter.

	*  E.g. whether the adapter supports streaming or not.

	* @param aAdapter. A pointer to the just loaded dm plug-in adapter. 

	* @param aVersions. A list of DDF versions collected from the adapters. 

	* @param aUids. A list of adapter UIDs. Note that aVersions and aUids

	*               are always ordered to ascending order in order to prevent

	*               a checksum to change value if ECom framework gives a list

	*				of potential plug-in adapters in different order.

	* @param aAdapterId. Identifier of the dm plug-in adapter.

	*/

	void AskInfoFromAdapterL ( CSmlDmAdapter* aAdapter, RPointerArray<HBufC8>& aVersions, RArray<TInt32>& aUids, TInt32 aAdapterId );

	/**

	* Auxiliary function called by GetDDFStructureL.

	*  Writes a combined DDF stucture to the chunk using DM Utils services.

	*/

    void WriteTreeToChunkL();

	/**

	* Auxiliary function called by GetDDFStructureL.

	*  Calculates a CCITT CRC checksum from the collected DDF versions and adapter UIDs 

	* @param aVersions. A collected list from adapters containing versions of the DDF structure. 

	* @param aUids. A list of adapter UIDs. 

	* @return TUint16. Calculated checksum value.

	*/

    TUint16 CalcCheckSumL ( RPointerArray<HBufC8>& aVersions, RArray<TInt32>& aUids ) const;

	/**

	* Common function for handling UpdateLeafObject and Execute DM commands.

	*  Reads parameters from the chunk.

	*  Loads the requested adapter if this is a first command to it in this session.

	*  Checks the need to inform adapter at atomic command situation.

	*  Decides whether or not use streaming for passing data to dm plug-in adapter.

	*  Informs the client (DM Tree Module) if there are unread statuses, results or mappings.

	* @param aMessage. An object which encapsulates a client request. 

	* @param aCommand. Needed to choose between Update and Execute commands. 

	*/

    void UpdateLeafOrExecuteL ( const RMessage2& aMessage, TNSmlDmHostOperationCodes aCommand );

	/**

	* Common function for handling UpdateLeafObject and Execute DM commands for large objects.

	*  Reads parameters from the chunk.

	*  Loads the requested adapter if this is a first command to it in this session.

	*  Checks the need to inform adapter at atomic command situation.

	*  Decides whether or not use streaming for passing data to dm plug-in adapter.

	*  In case this is last package of the large object, closes and commits stream,

	*  provided streaming was used for passing a data.

	*  Informs the client (DM Tree Module) if there are unread statuses, results or mappings.

	* @param aMessage. An object which encapsulates a client request. 

	* @param aCommand. Needed to choose between Update and Execute commands. 

	*/

    void UpdateLeafOrExecuteLargeL ( const RMessage2& aMessage, TNSmlDmHostOperationCodes aCommand );

	/**

	* Auxiliary function of UpdateLeafOrExecuteLargeL.

	*  Provided the dm plug-in adapter doesn't support streaming, this function

	*  takes care of appending large object piece by piece.

	*  When the last package arrives, calls the adapter and gives the built-up 

	*  large object as a parameter.

	* @param aMessage. An object which encapsulates a client request. 

	* @param aAdIndex. Identifies the assigned adapter. 

	* @param aCommand. Needed to choose between Update and Execute commands. 

	*/

    void UpdateOrExecuteLargeNoStreamL ( const RMessage2& aMessage, TInt aAdIndex, TNSmlDmHostOperationCodes aCommand );

	/**

	* Common function for handling Add Interior Node, Copy Node, or Delete Object DM commands.

	*  Reads parameters from the chunk.

	*  Loads the requested adapter if this is a first command to it in this session.

	*  Checks the need to inform adapter at atomic command situation.

	*  Informs the client (DM Tree Module) if there are unread statuses, results or mappings.

	* @param aMessage. An object which encapsulates a client request. 

	* @param aCommand. Needed to choose between Add, Copy, and Delete commands. 

	*/

    void AddCopyOrDeleteL ( const RMessage2& aMessage, TNSmlDmHostOperationCodes aCommand );

	/**

	* Common function for handling Fetch Leaf Object, Get Child URI List, or Fetch Leaf Object Size 

	* DM commands.

	*  Reads parameters from the chunk.

	*  Loads the requested adapter if this is a first command to it in this session.

	*  Checks the need to inform adapter at atomic command situation.

	*  Informs the client (DM Tree Module) if there are unread statuses, results or mappings.

	* @param aMessage. An object which encapsulates a client request. 

	* @param aCommand. Needed to choose between Fetch, Get Child URI List, and Fetch Size commands. 

	*/

	void FetchLeafChildUrisOrSizeL ( const RMessage2& aMessage, TNSmlDmHostOperationCodes aCommand );

	/**

	* Called only from other DM Host Servers when they need to cross-reference AP -adapter. 

	*  Loads the AP dm plug in adapter (i.e. Internet adapter).

	*  Asks the DDF structure from the AP adapter.

	*  Checks that the given URI is found from the DDF structure.

	*  If the above actions are successful, calls the Fetch Leaf Object or Get Child URI List 

	*  commands of AP adapter.

	*  Writes the returned result to the chunk.

	* @param aMessage. An object which encapsulates a client (other DM Host Server in this case) request. 

	*/

	void FetchLinkL ( const RMessage2& aMessage );

	/**

	* Sets a general atomic command state. 

	*  When this state is set, StartAtomicL function of the adapters

	*  is called when the first 'normal' command arrives.

	*  In addition informs the client (DM Tree Module) if there are unread statuses, results or mappings.

	* @param aMessage. An object which encapsulates a client request. 

	*/

   	void StartAtomicL ( const RMessage2& aMessage );

	/**

	* Resets the general atomic command state (When atomic commands were successful). 

	*  This command is forwarded only to those adapters which have received StartAtomicL call.

	*  In addition informs the client (DM Tree Module) if there are unread statuses, results or mappings.

	* @param aMessage. An object which encapsulates a client request. 

	*/

   	void CommitAtomicL ( const RMessage2& aMessage );

	/**

	* Resets the general atomic command state (When one or more atomic commands failed). 

	*  This command is forwarded only to those adapters which have received StartAtomicL call.

	*  In addition informs the client (DM Tree Module) if there are unread statuses, results or mappings.

	* @param aMessage. An object which encapsulates a client request. 

	*/

   	void RollbackAtomicL ( const RMessage2& aMessage );

	/**

	* Calls CompleteOutstandingCmdsL -function of the DM plug-in adapters.

	*  This command is issued only to those adapters which have received some adapter 

	*  commands during the session.

	*  In addition informs the client (DM Tree Module) if there are unread statuses, results or mappings.

	* @param aMessage. An object which encapsulates a client request. 

	*/

   	void CompleteCommandsL ( const RMessage2& aMessage );

	/**

	* Sets a handle to the global memory chunk. 

	*  The chunk is a common data area between the client (DM Tree Module) and the server

	*  (DM Host Server).

	*  Additionally, a server id is sent in the message.

	*  This id tells to the (common) session class which server session is serving.  

	* @param aMessage. An object which encapsulates a client request. 

	*/

    void SetChunkHandleL ( const RMessage2& aMessage );

	/**

	* Gets the URI / Luid mappings which have been received from the dm adapters 

	*  via callback function calls. 

	*  These mappings are buffered by the session class, and - during this call,

	*  all written to the chunk at once.

	*  Additionally informs the client (DM Tree Module) if there are also unread statuses or results.

	* @param aMessage. An object which encapsulates a client request. 

	*/

   	void GetMappingsL ( const RMessage2& aMessage ); 

	/**

	* Gets the DM command statuses received from the dm adapters via callback function calls. 

	*  These statuse are buffered by the session class, and - during this call,

	*  all written to the chunk at once.

	*  Additionally informs the client (DM Tree Module) if there are also unread mappings or results.

	* @param aMessage. An object which encapsulates a client request. 

	*/

   	void GetStatusesL ( const RMessage2& aMessage ); 

	/**

	* Gets the DM command results received from the dm adapters via callback function calls.

	*  In practice, these are the results from the 'FetchLeafObject', 'FecthLeafObjectSize', 

	*  and 'GetChildURIList' commands.

	*  The results are all written to the chunk at once if they just fit there.

	*  In case of large objects the result item is cut into pieces by writing one 'chunkfull' at time.

	*  Informs the client (DM Tree Module) if the result is cut up and needs thus additional 

	*  GetResultsL -function calls. Additionally, informs the client if there are unread mappings 

	*  or statuses.

	* @param aMessage. An object which encapsulates a client request. 

	*/

   	void GetResultsL ( const RMessage2& aMessage ); 

	/**

	* Auxiliary function called by the command handling functions (e.g. AddCopyOrDeleteL).

	*  Loads the ECom plug-in Dm Adapter.

	*  The adapter is identified with the given implementation UID.

	* @param aIndex. A place in the internal list where the adpater pointer is stored. 

	* @param aAdapterId. The implementation UID of the requested DM adapter. 

	* @return CSmlDmAdapter*. New instance of the ECom plug-in DM adapter.

	*/

   	CSmlDmAdapter* LoadNewAdapterL ( TInt aIndex, TUint32 aAdapterId );

	/**

	* Auxiliary function called by the command handling functions (e.g. UpdateLeafOrExecuteL).

	*  Reads the DM command parameters from the message and from the chunk.

	*  Utilizes the DM Utils services for parsing data in the chunk.

	* @param aMessage. An object which encapsulates a client request. 

	*/

   	void ReadCmdParamsL ( const RMessage2& aMessage );

	/**

	* Auxiliary function called by the FetchLeafChildUrisOrSizeL.

	*  Reads the DM command parameters from the message and from the chunk.

	*  Utilizes the DM Utils services for parsing data in the chunk.

	* @param aMessage. An object which encapsulates a client request. 

	* @param aPreviousLuids. A reference parameter, needed for freeing the reserved 

	*                        heap memory when the luids can be destroyed. 

	*/

   	void ReadCmdFetchParamsL ( const RMessage2& aMessage, RPointerArray<HBufC8>& aPreviousLuids );

	/**

	* Auxiliary function called by the AddCopyOrDeleteL.

	*  Reads the DM command parameters from the message and from the chunk.

	*  Utilizes the DM Utils services for parsing data in the chunk.

	* @param aMessage. An object which encapsulates a client request. 

	*/

   	void ReadCopyCmdParamsL ( const RMessage2& aMessage );

	/**

	* Auxiliary function for deleting previous set of DM command parameters.

	*/

    void DeletePrevParams();

	/**

	* Auxiliary function called by the UpdateLeafOrExecuteLargeL.

	*  Checks that the arrived command is not to different adapter,

	*  during the large object update to the other. 

	*/

    void CheckIfCorrectAdapterL() const;

	/**

	* Auxiliary function called by the the command handling functions, 

	* when the streaming is not used.

	*  Calls the chosen DM adapter function of the given adapter.

	*  The function parameters are set from the internal member variables.

	* @param aCommand. Identifies the chosen adapter command. 

	* @param aAdIndex. Identifies the chosen DM plug-in adapter. 

	* @param aLargeObject. If the data is a large object, a different 

	*                      internal variable is chosen. 

	*/

    void CallAdapterCommandL ( TNSmlDmHostOperationCodes aCommand, TInt aAdIndex, TBool aLargeObject = EFalse );

	/**

	* Auxiliary function called by the the command handling functions, 

	* when the streaming is used.

	*  Calls the chosen DM adapter function of the given adapter.

	*  The function parameters are set from the internal member variables.

	* @param aCommand. Identifies the chosen adapter command. 

	* @param aAdIndex. Identifies the chosen DM plug-in adapter. 

	* @param aWriteStream. A reference parameter. The adapter sets this parameter to point

	*                      to the correct place. 

	*/

    void CallAdapterCommandL ( TNSmlDmHostOperationCodes aCommand, TInt aAdIndex, RWriteStream*& aWriteStream );

	/**

	* Serves the FetchLink callback when the AP adapter is not found from the server.

	*  Issues an IPC -FetchLink command to the other DM Host Server 

	*  using RNSmlDMFetchLink -client API.

	* @param aURI. A path to the requested interior node object or leaf object. 

	* @param aData. A reference parameter, i.e. a place for fetch result. 

	* @param aStatus. A reference parameter telling the command success (e.g. EOk or ENotFound).

	*/

    void FetchLinkViaIPCL ( const TDesC8& aURI, CBufBase& aData, MSmlDmAdapter::TError& aStatus ) const;

	/**

	* Serves the FetchLink callback when the AP adapter is owned this server.

	*  Asks first a luid from the callback server.

	*  Calls FetchLeafObjectL -function of the DM adapter if the requested object is a leaf. 

	*  Calls ChildURIListL -function of the DM adapter if the requested object is an interior node. 

	* @param aURI. A path to the requested interior node object or leaf object. 

	* @param aAdapterId. Identifies the requested adapter. 

	* @param aData. A reference parameter, i.e. a place for fetch result. 

	* @param aStatus. A reference parameter telling the command success (e.g. EOk or ENotFound).

	* @param aNodeType. Defines whether the object is a leaf or a node.

	*/

    void FetchLinkFromAdapterL ( const TDesC8& aURI, TUint32 aAdapterId, CBufBase& aData, MSmlDmAdapter::TError& aStatus, TNSmlDmDDFFormat aNodeType );

	/**

	* Checks if the given URI can be found from the combined DDF structure.

	*  If not, most probably the URI belongs to some other DM adapter which this server

	*  is not capable of loading.  

	* @param aURI. A path to the requested interior node object or leaf object. 

	* @param aAdapterId. A reference parameter, to which DM Utils service writes the implementation

	*                    UID of the adapter - if the URI was found. 

	* @param aNodeType. A reference parameter defining whether the object is a leaf or a node.

	* @return TBool. ETrue if both the URI and the adapter id were found, EFalse otherwise.

	*/

	TBool AdapterIdFromUriL ( const TDesC8& aURI, TUint32& aAdapterId, TNSmlDmDDFFormat& aNodeType );

	/**

	* Auxiliary function which is called from FetchLinkFromAdapterL.

	*  Gets a previous URI segment list from the callback server. 

	*  This function is called only during the fetchlink callback and when

	*  the requested object is an interior node object.

	* @param aAdapterId. Identifies the requested adapter. 

	* @param aURI. A path to the requested interior node object. 

	* @param aURISegList. A reference parameter where callback server writes a list of the child nodes.

	*/

	void PrevURISegListL ( TUint32 aAdapterId, const TDesC8& aURI, CArrayFixFlat<TSmlDmMappingInfo>& aURISegList );

	/**