// Copyright (c) 2005-2008 Max-Planck-Institute Saarbruecken (Germany).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org).
//
// $URL: https://github.com/CGAL/cgal/blob/v5.6.1/Convex_decomposition_3/include/CGAL/Convex_decomposition_3/Ray_hit_generator.h $
// $Id: Ray_hit_generator.h f8bf2b3 2023-01-18T21:03:36+00:00 Giles Bathgate
// SPDX-License-Identifier: GPL-3.0-or-later OR LicenseRef-Commercial
//
//
// Author(s)     :  Peter Hachenberger <hachenberger@mpi-sb.mpg.de>
#ifndef CGAL_CD3_RAY_HIT_GENERATOR_H
#define CGAL_CD3_RAY_HIT_GENERATOR_H

#include <CGAL/license/Convex_decomposition_3.h>


#include <CGAL/Modifier_base.h>
#include <CGAL/Nef_3/SNC_decorator.h>
#include <CGAL/Nef_3/SNC_point_locator.h>
#include <CGAL/Nef_3/SNC_intersection.h>
#include <CGAL/Convex_decomposition_3/SM_walls.h>

#undef CGAL_NEF_DEBUG
#define CGAL_NEF_DEBUG 233
#include <CGAL/Nef_2/debug.h>

namespace CGAL {

template<typename Nef_>
class Ray_hit_generator : public Modifier_base<typename Nef_::SNC_and_PL> {
protected:
  typedef Nef_                                   Nef_polyhedron;
  typedef typename Nef_polyhedron::SNC_and_PL    SNC_and_PL;
  typedef typename Nef_polyhedron::SNC_structure SNC_structure;
  typedef typename SNC_structure::Items          Items;
  typedef CGAL::SNC_decorator<SNC_structure>     Base;
  typedef CGAL::SNC_point_locator<Base>          SNC_point_locator;
  typedef CGAL::SNC_intersection<SNC_structure>  SNC_intersection;
  typedef CGAL::SNC_constructor<Items, SNC_structure>
    SNC_constructor;

  typedef typename SNC_structure::Sphere_map     Sphere_map;
  typedef CGAL::SM_decorator<Sphere_map>         SM_decorator;
  typedef CGAL::SM_point_locator<SM_decorator>   SM_point_locator;
  typedef CGAL::SM_walls<Sphere_map>             SM_walls;

  typedef typename Base::Segment_3               Segment_3;
  typedef typename Base::Point_3                 Point_3;
  typedef typename Base::Ray_3                   Ray_3;
  typedef typename Base::Vector_3                Vector_3;
  typedef typename Base::Sphere_point            Sphere_point;
  typedef typename Base::Vertex_handle           Vertex_handle;
  typedef typename Base::SVertex_handle          SVertex_handle;
  typedef typename Base::Halfedge_handle         Halfedge_handle;
  typedef typename Base::Halffacet_handle        Halffacet_handle;
  typedef typename Base::Object_handle           Object_handle;

  typedef typename Base::Vertex_iterator         Vertex_iterator;
  typedef typename Base::SVertex_iterator        SVertex_iterator;



  Vector_3 dir;
  SNC_structure* sncp;
  SNC_point_locator* pl;
  int mask;

 public:
  Ray_hit_generator(Vector_3 d = Vector_3()) : dir(d), sncp(nullptr), pl(nullptr), mask(255) {}
  Ray_hit_generator(SNC_structure* sncin, SNC_point_locator* plin, int m = 255)
    : sncp(sncin), pl(plin), mask(m) {}

  Vertex_handle create_vertex_on_first_hit(const Ray_3& r) {

    CGAL_NEF_TRACEN( "shoot ray in SNC " << r );

    Object_handle o = pl->shoot(r, mask);

    Vertex_handle v;
    if(assign(v, o)) {
      CGAL_NEF_TRACEN("Found vertex " << v->point());
      return v;
    }

    Point_3 ip;
    SNC_constructor C(*sncp);

    Halfedge_handle e;
    if(assign(e, o)) {
       CGAL_NEF_TRACEN("Found edge " << e->source()->point()
                       << "->" << e->twin()->source()->point());
      Segment_3 seg(e->source()->point(), e->twin()->source()->point());
      SNC_intersection::does_intersect_internally(r, seg, ip);
      ip = normalized(ip);
      v = C.create_from_edge(e,ip);
      pl->add_vertex(v);

      CGAL_NEF_TRACEN("new vertex " << ip);

      SVertex_iterator svi = v->svertices_begin();
      SVertex_handle svf = svi;
      SVertex_handle svb = ++svi;

      if(svf->point() == e->point()) {
        svb->twin() = e;
        svf->twin() = e->twin();
        e->twin()->twin() = svf;
        e->twin() = svb;
#ifndef CGAL_NEF_NO_INDEXED_ITEMS
        svb->set_index(e->get_index());
        svf->twin()->set_index(svf->new_index());
#endif
      } else {
        svf->twin() = e;
        svb->twin() = e->twin();
        e->twin()->twin() = svb;
        e->twin() = svf;
#ifndef CGAL_NEF_NO_INDEXED_ITEMS
        svf->set_index(e->get_index());
        svb->twin()->set_index(svb->new_index());
#endif
      }

      pl->add_edge(svf);
      pl->add_edge(svb);

      handle_splits(e,svf,svb);
      return v;
    }

    Halffacet_handle f;
    if(assign(f, o)) {
      CGAL_NEF_TRACEN("Found facet ");
      SNC_intersection::does_intersect_internally(r, f, ip);
      ip = normalized(ip);
      v = C.create_from_facet(f,ip);
      pl->add_vertex(v);
      CGAL_NEF_TRACEN("new vertex " << ip);

      return v;
    }

    CGAL_error_msg( "ray should hit vertex, edge, or facet");
    return Vertex_handle();
  }

  virtual void handle_splits(Halfedge_handle, SVertex_handle, SVertex_handle) {
      CGAL_NEF_TRACEN("new edge " << e->source()->point() <<
                      "->" << e->twin()->source()->point());
      CGAL_NEF_TRACEN("new edge " << svf->source()->point() <<
                      "->" << svf->twin()->source()->point());

  }

  virtual void operator()(SNC_and_PL& sncpl) {

    sncp = sncpl.sncp;
    pl = sncpl.pl;

    Vertex_iterator vi;
    for(vi = sncp->vertices_begin(); vi != sncp->vertices_end(); ++vi) {
      SM_walls smw(&*vi);
      SVertex_handle sv1, sv2;
      if(smw.need_to_shoot(Sphere_point(dir),sv1)) {
        Ray_3 r(vi->point(), dir);
        Vertex_handle v_new = create_vertex_on_first_hit(r);
        SM_walls smw(&*v_new);
        sv2 = smw.add_ray_svertex(Sphere_point(-dir));
#ifndef CGAL_NEF_NO_INDEXED_ITEMS
      sv2->set_index(sv1->new_index());
#endif
      }
    }
  }
};

} //namespace CGAL
#endif //CGAL_CD3_RAY_HIT_GENERATOR_H

