//C++ header - Open Scene Graph - Copyright (C) 1998-2002 Robert Osfield
//Distributed under the terms of the GNU Library General Public License (LGPL)
//as published by the Free Software Foundation.

#ifndef OSGGA_GUIEVENTHANDLER
#define OSGGA_GUIEVENTHANDLER 1

#include <vector>

#include <osg/Referenced>

#include <osgGA/Export>
#include <osgGA/GUIEventAdapter>
#include <osgGA/GUIActionAdapter>
#include <osgGA/GUIEventHandlerVisitor>

namespace osgGA{

class CompositeGUIEventHandler;

/**

GUIEventHandler provides a basic interface for any class which wants to handle
a GUI Events.

The GUIEvent is supplied by a GUIEventAdapter. Feedback resulting from the
handle method is supplied by a GUIActionAdapter, which allows the GUIEventHandler
to ask the GUI to take some action in response to an incoming event.

For example, consider a Trackball Viewer class which takes mouse events and
manipulates a scene camera in response. The Trackball Viewer is a GUIEventHandler,
and receives the events via the handle method. If the user 'throws' the model,
the Trackball Viewer class can detect this via the incoming events, and
request that the GUI set up a timer callback to continually redraw the view.
This request is made via the GUIActionAdapter class.

*/

class OSGGA_EXPORT GUIEventHandler : public osg::Referenced
{
    public:

        /** Handle events, return true if handled, false otherwise.*/
        virtual bool handle(const GUIEventAdapter& ea,GUIActionAdapter& us)=0;

        /** Is this const GUIEventHandler a composite? */
        virtual const CompositeGUIEventHandler* getComposite() const { return 0; }

        /** Is this non-const GUIEventHandler a composite? */
        virtual CompositeGUIEventHandler* getComposite() { return 0; }

        /** Accept visits from GUIEventHandler visitors */
        virtual void accept(GUIEventHandlerVisitor&) = 0;
        //virtual void accept(GUIEventHandlerVisitor&) { }

};


/**
CompositeGUIEventHandler allows GUIEventHandlers to be composed into hierarchies.
*/

class OSGGA_EXPORT CompositeGUIEventHandler : public GUIEventHandler
{
    public:

        typedef std::vector< osg::ref_ptr<GUIEventHandler> > ChildList;

        virtual bool handle(const GUIEventAdapter& ea,GUIActionAdapter& aa);

        virtual const CompositeGUIEventHandler* getComposite() const { return this; }

        virtual CompositeGUIEventHandler* getComposite() { return this; }

        virtual void accept(GUIEventHandlerVisitor& v)    { v.visit(*this); }



        /* Composite-specific methods below */

        virtual bool addChild(GUIEventHandler *geh);

        virtual bool removeChild(GUIEventHandler *geh);

        const int  getNumChildren() const { return _children.size(); }

        GUIEventHandler *getChild( int i) { return _children[i].get(); }

        const GUIEventHandler *getChild( int i ) const { return _children[i].get(); }

        bool containsNode( const GUIEventHandler* node ) const
        {
            
            for (ChildList::const_iterator itr=_children.begin();
                 itr!=_children.end();
                 ++itr)
            {
                if (itr->get()==node) return true;
            }
            return false;
        }

        ChildList::iterator findChild( const GUIEventHandler* node )
        {
            for (ChildList::iterator itr=_children.begin();
                 itr!=_children.end();
                 ++itr)
            {
                if (itr->get()==node) return itr;
            }
            return _children.end();
        }

    private:

        ChildList   _children;

};


}

#endif