/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2003 Robert Osfield 
 *
 * This library is open source and may be redistributed and/or modified under  
 * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or 
 * (at your option) any later version.  The full license is in LICENSE file
 * included with this distribution, and on the openscenegraph.org website.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 * OpenSceneGraph Public License for more details.
*/

#ifndef OSG_NODECALLBACK
#define OSG_NODECALLBACK 1

#include <osg/Object>
#include <osg/ref_ptr>

namespace osg {

class Node;
class NodeVisitor;

class SG_EXPORT NodeCallback : public virtual Object {

    public :
    

        NodeCallback(){}

        NodeCallback(const NodeCallback&,const CopyOp&):
            _nestedCallback(_nestedCallback) {}

        
        META_Object(osg,NodeCallback)
        
        
        /** Callback method called by the NodeVisitor when visiting a node.*/
        virtual void operator()(Node* node, NodeVisitor* nv)
        { 
            // note, callback is responsible for scenegraph traversal so
            // should always include call traverse(node,nv) to ensure 
            // that the rest of cullbacks and the scene graph are traversed.
            traverse(node,nv);
        }
        
        /** Call any nested callbacks and then traverse the scene graph. */
        void traverse(Node* node,NodeVisitor* nv);
        
        void setNestedCallback(NodeCallback* nc) { _nestedCallback = nc; }
        NodeCallback* getNestedCallback() { return _nestedCallback.get(); }
        
        inline void addNestedCallback(NodeCallback* nc)
        {
            if (nc)
            {
                if (_nestedCallback.valid())
                {
                    nc->addNestedCallback(_nestedCallback.get());
                    _nestedCallback = nc;
                }
                else
                {
                    _nestedCallback = nc;
                }
            }
        }
        
        inline void removeNestedCallback(NodeCallback* nc)
        {
            if (nc)
            {
                if (_nestedCallback==nc)
                {
                    _nestedCallback = _nestedCallback->getNestedCallback();
                }
                else if (_nestedCallback.valid())
                {
                    _nestedCallback->removeNestedCallback(nc);
                }
            }
        }
        
    public:

        ref_ptr<NodeCallback> _nestedCallback;
        
    protected:
    
        virtual ~NodeCallback() {}
};

} // namespace

#endif