/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2005 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 OSGUTIL_CULLVISITOR
#define OSGUTIL_CULLVISITOR 1

#include <map>
#include <vector>

#include <osg/NodeVisitor>
#include <osg/BoundingSphere>
#include <osg/BoundingBox>
#include <osg/Matrix>
#include <osg/Drawable>
#include <osg/StateSet>
#include <osg/State>
#include <osg/ClearNode>
#include <osg/CameraNode>
#include <osg/Notify>

#include <osg/CullStack>

#include <osgUtil/StateGraph>
#include <osgUtil/RenderStage>

#include <osg/Vec3>

namespace osgUtil {

/**
 * Basic NodeVisitor implementation for rendering a scene.
 * This visitor traverses the scene graph, collecting transparent and
 * opaque osg::Drawables into a depth sorted transparent bin and a state
 * sorted opaque bin.  The opaque bin is rendered first, and then the
 * transparent bin is rendered in order from the furthest osg::Drawable
 * from the eye to the one nearest the eye. 
 */
class OSGUTIL_EXPORT CullVisitor : public osg::NodeVisitor, public osg::CullStack
{
    public:
    
        typedef osg::Matrix::value_type value_type;
    

        CullVisitor();
        virtual ~CullVisitor();

        virtual CullVisitor* cloneType() const { return new CullVisitor(); }

        virtual void reset();

        virtual osg::Vec3 getEyePoint() const { return getEyeLocal(); }
        virtual float getDistanceToEyePoint(const osg::Vec3& pos, bool withLODScale) const;
        virtual float getDistanceFromEyePoint(const osg::Vec3& pos, bool withLODScale) const;

        virtual void apply(osg::Node&);
        virtual void apply(osg::Geode& node);
        virtual void apply(osg::Billboard& node);
        virtual void apply(osg::LightSource& node);
        virtual void apply(osg::ClipNode& node);
        virtual void apply(osg::TexGenNode& node);

        virtual void apply(osg::Group& node);
        virtual void apply(osg::Transform& node);
        virtual void apply(osg::Projection& node);
        virtual void apply(osg::Switch& node);
        virtual void apply(osg::LOD& node);
        virtual void apply(osg::ClearNode& node);
        virtual void apply(osg::CameraNode& node);
        virtual void apply(osg::OccluderNode& node);

        void setClearNode(const osg::ClearNode* earthSky) { _clearNode = earthSky; }
        const osg::ClearNode* getClearNode() const { return _clearNode.get(); }

        /** Push state set on the current state group.
          * If the state exists in a child state group of the current
          * state group then move the current state group to that child.
          * Otherwise, create a new state group for the state set, add
          * it to the current state group then move the current state
          * group pointer to the new state group.
          */
        inline void pushStateSet(const osg::StateSet* ss)
        {
            _currentStateGraph = _currentStateGraph->find_or_insert(ss);
            if (ss->useRenderBinDetails())
            {
                _currentRenderBin = _currentRenderBin->find_or_insert(ss->getBinNumber(),ss->getBinName());
            }
        }
        
        /** Pop the top state set and hence associated state group.
          * Move the current state group to the parent of the popped
          * state group.
          */
        inline void popStateSet()
        {
            if (_currentStateGraph->_stateset->useRenderBinDetails())
            {
                _currentRenderBin = _currentRenderBin->getParent();
            }
            _currentStateGraph = _currentStateGraph->_parent;
        }
        
        inline void setStateGraph(StateGraph* rg)
        {
            _rootStateGraph = rg;
            _currentStateGraph = rg;
        }

        inline StateGraph* getRootStateGraph()
        {
            return _rootStateGraph.get();
        }

        inline StateGraph* getCurrentStateGraph()
        {
            return _currentStateGraph;
        }

        inline void setRenderStage(RenderStage* rg)
        {
            _rootRenderStage = rg;
            _currentRenderBin = rg;
        }

        inline RenderStage* getRenderStage()
        {
            return _rootRenderStage.get();
        }

        inline RenderBin* getCurrentRenderBin()
        {
            return _currentRenderBin;
        }

        inline void setCurrentRenderBin(RenderBin* rb)
        {
            _currentRenderBin = rb;
        }

        inline value_type getCalculatedNearPlane() const { return _computed_znear; }
        
        inline value_type getCalculatedFarPlane() const { return _computed_zfar; }

        value_type computeNearestPointInFrustum(const osg::Matrix& matrix, const osg::Polytope::PlaneList& planes,const osg::Drawable& drawable);

        bool updateCalculatedNearFar(const osg::Matrix& matrix,const osg::BoundingBox& bb);

        bool updateCalculatedNearFar(const osg::Matrix& matrix,const osg::Drawable& drawable, bool isBillboard=false);
        
        void updateCalculatedNearFar(const osg::Vec3& pos);
        
        /** Add a drawable to current render graph.*/
        inline void addDrawable(osg::Drawable* drawable,osg::RefMatrix* matrix);

        /** Add a drawable and depth to current render graph.*/
        inline void addDrawableAndDepth(osg::Drawable* drawable,osg::RefMatrix* matrix,float depth);

        /** Add an attribute which is positioned relative to the modelview matrix.*/
        inline void addPositionedAttribute(osg::RefMatrix* matrix,const osg::StateAttribute* attr);

        /** Add an attribute which is positioned relative to the modelview matrix.*/
        inline void addPositionedTextureAttribute(unsigned int textureUnit, osg::RefMatrix* matrix,const osg::StateAttribute* attr);

        /** Re-implement CullStack's popProjectionMatrix() adding clamping of the projection matrix to
          * the computed near and far.*/
        virtual void popProjectionMatrix();
        

        /** CullVisitor's default clamping of the projection float matrix to computed near and far values.
          * Note, do not call this method directly, use clampProjectionMatrix(..) instead, unless you want to bypass the callback.*/
        virtual bool clampProjectionMatrixImplementation(osg::Matrixf& projection, double& znear, double& zfar) const;

        /** CullVisitor's default clamping of the projection double matrix to computed near and far values.
          * Note, do not call this method directly, use clampProjectionMatrix(..) instead, unless you want to bypass the callback.*/
        virtual bool clampProjectionMatrixImplementation(osg::Matrixd& projection, double& znear, double& zfar) const;

        /** Clamp the projection float matrix to computed near and far values, use callback if it exists,
          * otherwise use default CullVisitor implementation.*/
        inline bool clampProjectionMatrix(osg::Matrixf& projection, value_type& znear, value_type& zfar) const
        {
            double zn = znear;
            double zf = zfar;
            bool result = false;
            if (_clampProjectionMatrixCallback.valid()) result = _clampProjectionMatrixCallback->clampProjectionMatrixImplementation(projection, zn, zf);
            else result = clampProjectionMatrixImplementation(projection, zn, zf);

            if (result)
            {
                znear = zn;
                zfar = zn;
                return true;
            }
            else 
                return false;
        }

        /** Clamp the projection double matrix to computed near and far values, use callback if it exists,
          * otherwise use default CullVisitor implementation.*/
        inline bool clampProjectionMatrix(osg::Matrixd& projection, value_type& znear, value_type& zfar) const
        {
            double zn = znear;
            double zf = zfar;
            bool result = false;

            if (_clampProjectionMatrixCallback.valid()) result = _clampProjectionMatrixCallback->clampProjectionMatrixImplementation(projection, zn, zf);
            else result = clampProjectionMatrixImplementation(projection, zn, zf);

            if (result)
            {
                znear = zn;
                zfar = zn;
                return true;
            }
            else 
                return false;
        }
        

        void setState(osg::State* state) { _state = state; }
        osg::State* getState() { return _state.get(); }
        const osg::State* getState() const { return _state.get(); }

    protected:

        /** Prevent unwanted copy operator.*/
        CullVisitor& operator = (const CullVisitor&) { return *this; }
        
        inline void handle_cull_callbacks_and_traverse(osg::Node& node)
        {
            osg::NodeCallback* callback = node.getCullCallback();
            if (callback) (*callback)(&node,this);
            else traverse(node);
        }

        inline void handle_cull_callbacks_and_accept(osg::Node& node,osg::Node* acceptNode)
        {
            osg::NodeCallback* callback = node.getCullCallback();
            if (callback) (*callback)(&node,this);
            else acceptNode->accept(*this);
        }

        osg::ref_ptr<const osg::ClearNode>                          _clearNode;

        osg::ref_ptr<StateGraph>                                   _rootStateGraph;
        StateGraph*                                                _currentStateGraph;

        osg::ref_ptr<RenderStage>                                   _rootRenderStage;        
        RenderBin*                                                  _currentRenderBin;


        value_type               _computed_znear;
        value_type               _computed_zfar;
        
        
        typedef std::vector< osg::ref_ptr<RenderLeaf> > RenderLeafList;
        RenderLeafList _reuseRenderLeafList;
        unsigned int _currentReuseRenderLeafIndex;
    
        inline RenderLeaf* createOrReuseRenderLeaf(osg::Drawable* drawable,osg::RefMatrix* projection,osg::RefMatrix* matrix, float depth=0.0f);
        
        osg::ref_ptr<osg::State>                    _state;


        struct MatrixPlanesDrawables
        {
            MatrixPlanesDrawables(const osg::Matrix& matrix, const osg::Drawable* drawable, const osg::Polytope& frustum):
                _matrix(matrix),
                _drawable(drawable)
            {
                // create a new list of planes from the active walls of the frustum.
                osg::Polytope::ClippingMask result_mask = frustum.getResultMask();
                osg::Polytope::ClippingMask selector_mask = 0x1;
                for(osg::Polytope::PlaneList::const_iterator itr=frustum.getPlaneList().begin();
                    itr!=frustum.getPlaneList().end();
                    ++itr)
                {
                    if (result_mask&selector_mask) _planes.push_back(*itr);
                    selector_mask <<= 1; 
                }
            }
            
            MatrixPlanesDrawables(const MatrixPlanesDrawables& mpd):
                _matrix(mpd._matrix),
                _drawable(mpd._drawable),
                _planes(mpd._planes) {}
                
            MatrixPlanesDrawables& operator = (const MatrixPlanesDrawables& mpd)
            {
                _matrix = mpd._matrix;
                _drawable = mpd._drawable;
                _planes = mpd._planes;
                return *this;
            }
            
            osg::Matrix                 _matrix;
            const osg::Drawable*        _drawable;
            osg::Polytope::PlaneList    _planes;
        };
        
        typedef std::multimap<value_type, MatrixPlanesDrawables>   DistanceMatrixDrawableMap;
        DistanceMatrixDrawableMap                                  _nearPlaneCandidateMap;
    
};

inline void CullVisitor::addDrawable(osg::Drawable* drawable,osg::RefMatrix* matrix)
{
    if (_currentStateGraph->leaves_empty())
    {
        // this is first leaf to be added to StateGraph
        // and therefore should not already know to current render bin,
        // so need to add it.
        _currentRenderBin->addStateGraph(_currentStateGraph);
    }
    //_currentStateGraph->addLeaf(new RenderLeaf(drawable,matrix));
    _currentStateGraph->addLeaf(createOrReuseRenderLeaf(drawable,_projectionStack.back().get(),matrix));
}

/** Add a drawable and depth to current render graph.*/
inline void CullVisitor::addDrawableAndDepth(osg::Drawable* drawable,osg::RefMatrix* matrix,float depth)
{
    if (_currentStateGraph->leaves_empty())
    {
        // this is first leaf to be added to StateGraph
        // and therefore should not already know to current render bin,
        // so need to add it.
        _currentRenderBin->addStateGraph(_currentStateGraph);
    }
    //_currentStateGraph->addLeaf(new RenderLeaf(drawable,matrix,depth));
    _currentStateGraph->addLeaf(createOrReuseRenderLeaf(drawable,_projectionStack.back().get(),matrix,depth));
}

/** Add an attribute which is positioned relative to the modelview matrix.*/
inline void CullVisitor::addPositionedAttribute(osg::RefMatrix* matrix,const osg::StateAttribute* attr)
{
    _currentRenderBin->getStage()->addPositionedAttribute(matrix,attr);
}

/** Add an attribute which is positioned relative to the modelview matrix.*/
inline void CullVisitor::addPositionedTextureAttribute(unsigned int textureUnit, osg::RefMatrix* matrix,const osg::StateAttribute* attr)
{
    _currentRenderBin->getStage()->addPositionedTextureAttribute(textureUnit,matrix,attr);
}

inline RenderLeaf* CullVisitor::createOrReuseRenderLeaf(osg::Drawable* drawable,osg::RefMatrix* projection,osg::RefMatrix* matrix, float depth)
{
    // Skips any already reused renderleaf.
    while (_currentReuseRenderLeafIndex<_reuseRenderLeafList.size() && 
           _reuseRenderLeafList[_currentReuseRenderLeafIndex]->referenceCount()>1)
    {
        osg::notify(osg::NOTICE)<<"Warning:createOrReuseRenderLeaf() skipping multiply refrenced entry."<< std::endl;
        ++_currentReuseRenderLeafIndex;
    }

    // If still within list, element must be singularly referenced then return it to be reused.
    if (_currentReuseRenderLeafIndex<_reuseRenderLeafList.size())
    {
        RenderLeaf* renderleaf = _reuseRenderLeafList[_currentReuseRenderLeafIndex++].get();
        renderleaf->set(drawable,projection,matrix,depth);
        return renderleaf;
    }

    // Otherwise need to create new renderleaf.
    RenderLeaf* renderleaf = new RenderLeaf(drawable,projection,matrix,depth);
    _reuseRenderLeafList.push_back(renderleaf);
    ++_currentReuseRenderLeafIndex;
    return renderleaf;
}


}

#endif