/* -*-c++-*- */
/* osgEarth - Geospatial SDK for OpenSceneGraph
 * Copyright 2020 Pelican Mapping
 * http://osgearth.org
 *
 * osgEarth is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 */

#ifndef OSGEARTH_PRIMITIVE_INTERSECTOR_H
#define OSGEARTH_PRIMITIVE_INTERSECTOR_H 1

#include <osgUtil/IntersectionVisitor>
#include <osgEarth/Common>

namespace osgEarth { namespace Util
{
/** Concrete class for implementing line intersections with the scene graph.
  * To be used in conjunction with IntersectionVisitor. */
class OSGEARTH_EXPORT PrimitiveIntersector : public osgUtil::Intersector
{
public:

    /** Convenience constructor for supporting picking in WINDOW, or PROJECTION coordinates
      * In WINDOW coordinates creates a start value of (x,y,0) and end value of (x,y,1).
      * In PROJECTION coordinates (clip space cube) creates a start value of (x,y,-1) and end value of (x,y,1).*/
    PrimitiveIntersector(CoordinateFrame cf, double x, double y, double thickness);

    /** Constructor for initializing with full start and end vectors. */
    PrimitiveIntersector(CoordinateFrame cf, const osg::Vec3d& start, const osg::Vec3d& end, double thickness, bool overlayIgnore=false);

    struct OSGEARTH_EXPORT Intersection
    {
        Intersection():
            ratio(-1.0),
            primitiveIndex(0) {}

        Intersection(const Intersection &rhs)
        {
            ratio = rhs.ratio;
            nodePath = rhs.nodePath;
            drawable = rhs.drawable;
            matrix = rhs.matrix;
            localIntersectionPoint = rhs.localIntersectionPoint;
            localIntersectionNormal = rhs.localIntersectionNormal;
            indexList = rhs.indexList;
            ratioList = rhs.ratioList;
            primitiveIndex = rhs.primitiveIndex;
        }

        bool operator < (const Intersection& rhs) const { return ratio < rhs.ratio; }

        typedef std::vector<unsigned int>   IndexList;
        typedef std::vector<double>         RatioList;

        double                          ratio;
        osg::NodePath                   nodePath;
        osg::ref_ptr<osg::Drawable>     drawable;
        osg::ref_ptr<osg::RefMatrix>    matrix;
        osg::Vec3d                      localIntersectionPoint;
        osg::Vec3d                      localIntersectionNormal;
        IndexList                       indexList;
        RatioList                       ratioList;
        unsigned int                    primitiveIndex;

        const osg::Vec3d& getLocalIntersectPoint() const { return localIntersectionPoint; }
        osg::Vec3d getWorldIntersectPoint() const { return matrix.valid() ? localIntersectionPoint * (*matrix) : localIntersectionPoint; }

        const osg::Vec3d& getLocalIntersectNormal() const { return localIntersectionNormal; }
        osg::Vec3d getWorldIntersectNormal() const { return matrix.valid() ? osg::Matrix::transform3x3(osg::Matrix::inverse(*matrix),localIntersectionNormal) : localIntersectionNormal; }
    };

    typedef std::multiset<Intersection> Intersections;

    inline void insertIntersection(const Intersection& intersection) { getIntersections().insert(intersection); }

    inline Intersections& getIntersections() { return _parent ? _parent->_intersections : _intersections; }

    inline Intersection getFirstIntersection() { Intersections& intersections = getIntersections(); return intersections.empty() ? Intersection() : *(intersections.begin()); }

    inline void setStart(const osg::Vec3d& start) { _start = start; }
    inline const osg::Vec3d& getStart() const { return _start; }

    inline void setEnd(const osg::Vec3d& end) { _end = end; }
    inline const osg::Vec3d& getEnd() const { return _end; }

    void setThickness(double thickness);
    inline double getThickness() const { return _thicknessVal; }

    inline bool getOverlayIgnore() const { return _overlayIgnore; }

public:

    virtual Intersector* clone(osgUtil::IntersectionVisitor& iv);

    virtual bool enter(const osg::Node& node);

    virtual void leave();

    virtual void intersect(osgUtil::IntersectionVisitor& iv, osg::Drawable* drawable);

    virtual void reset();

    virtual bool containsIntersections() { return !getIntersections().empty(); }

protected:

    // Internal constructor used for clone request
    PrimitiveIntersector();

    bool intersects(const osg::BoundingSphere& bs);
    bool intersectAndClip(osg::Vec3d& s, osg::Vec3d& e,const osg::BoundingBox& bb);

    unsigned int findPrimitiveIndex(osg::Drawable* drawable, unsigned int index);

    PrimitiveIntersector* _parent;

    osg::Vec3d  _start;
    osg::Vec3d  _end;
    osg::Vec3d  _thickness;
    double _thicknessVal;
    bool _overlayIgnore;

    Intersections _intersections;

};

} } // namespace osgEarth

#endif //OSGEARTH_PRIMITIVE_INTERSECTOR_H