/*=========================================================================

  Program:   ParaView
  Module:    vtkSMUndoStack.h

  Copyright (c) Kitware, Inc.
  All rights reserved.
  See Copyright.txt or http://www.paraview.org/HTML/Copyright.html for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notice for more information.

=========================================================================*/
// .NAME vtkSMUndoStack
// .SECTION Description
// This is the undo/redo stack for the Server Manager. This provides a 
// unified face for undo/redo irrespective of number of connections, their
// type etc etc.
// 
// On every undo/redo, it fetches the XML state change from the server.
// vtkSMUndoRedoStateLoader is used to generate a vtkUndoSet object from
// the XML. GUI can subclass vtkSMUndoRedoStateLoader to handle GUI specific
// XML elements. The loader instance must be set before performing the undo,
// otherwise vtkSMUndoRedoStateLoader is used.
//
// This class also provides API to push any vtkUndoSet instance on to a 
// server. GUI can use this to push its own changes that is undoable across
// connections.
// 
// .SECTION See Also
// vtkSMUndoStackBuilder


#ifndef __vtkSMUndoStack_h
#define __vtkSMUndoStack_h

#include "vtkPVServerManagerCoreModule.h" //needed for exports
#include "vtkUndoStack.h"

class vtkSMUndoRedoStateLoader;
class vtkSMUndoStackObserver;
class vtkUndoSet;
class vtkCollection;

class VTKPVSERVERMANAGERCORE_EXPORT vtkSMUndoStack : public vtkUndoStack
{
public:
  static vtkSMUndoStack* New();
  vtkTypeMacro(vtkSMUndoStack, vtkUndoStack);
  void PrintSelf(ostream& os, vtkIndent indent);

  // Description:
  // Push an undo set on the Undo stack. This will clear
  // any sets in the Redo stack.
  virtual void Push(const char* label, vtkUndoSet* changeSet);

  // Description:
  // Performs an Undo using the set on the top of the undo stack. The set is poped from
  // the undo stack and pushed at the top of the redo stack. 
  // Before undo begins, it fires vtkCommand::StartEvent and when undo completes,
  // it fires vtkCommand::EndEvent.
  // \returns the status of the operation.
  virtual int Undo();

  // Description:
  // Performs a Redo using the set on the top of the redo stack. The set is poped from
  // the redo stack and pushed at the top of the undo stack. 
  // Before redo begins, it fires vtkCommand::StartEvent and when redo completes,
  // it fires vtkCommand::EndEvent.
  // \returns the status of the operation.
  virtual int Redo();

//BTX

  enum EventIds
    {
    PushUndoSetEvent = 1987,
    ObjectCreationEvent = 1988

    };

protected:
  vtkSMUndoStack();
  ~vtkSMUndoStack();

  // Helper method used to push all vtkSMRemoteObject to the collection of
  // all the sessions that have been used across that undoset.
  // (It is more than likely that only one session will be find but in case of
  // collaboration, we might want to support a set of sessions.)
  // This is usefull when we execute the undoset to prevent automatic
  // object deletion between 2 undo element calls when a proxy registration
  // is supposed to happen.
  void FillWithRemoteObjects( vtkUndoSet *undoSet, vtkCollection *collection);

private:
  vtkSMUndoStack(const vtkSMUndoStack&); // Not implemented.
  void operator=(const vtkSMUndoStack&); // Not implemented.

  class vtkInternal;
  vtkInternal* Internal;
  
  vtkSMUndoStackObserver* Observer;
//ETX
};


#endif
