/* -*-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 OSGGA_GUIEVENTHANDLER
#define OSGGA_GUIEVENTHANDLER 1

#include <vector>

#include <osg/Referenced>
#include <osg/ApplicationUsage>

#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:

        virtual const char* className() { return "GUIEventHandler"; }

        /** Returns 0 if this GUIEventHandler is not a CompositeGUIEventHandler. */
        virtual const CompositeGUIEventHandler* getComposite() const { return 0; }

        /** Returns 0 if this GUIEventHandler is not a CompositeGUIEventHandler. */
        virtual CompositeGUIEventHandler* getComposite() { return 0; }

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

        /** Accept visits from GUIEventHandler visitors */
        virtual void accept(GUIEventHandlerVisitor&) = 0;
        
        /** Get the keyboard and mouse usage of this manipulator.*/
        virtual void getUsage(osg::ApplicationUsage&) const {}
};


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

class OSGGA_EXPORT CompositeGUIEventHandler : public GUIEventHandler
{
public:

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

        virtual const char* className() { return "CompositeGUIEventHandler"; }

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

        virtual CompositeGUIEventHandler* getComposite() { return this; }

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

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

        /** Get the keyboard and mouse usage of this manipulator.*/
        virtual void getUsage(osg::ApplicationUsage& usage) const;


        // 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