// Copyright (c) 2005,2006,2007,2009,2010,2011 Tel-Aviv University (Israel).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org).
//
// $URL: https://github.com/CGAL/cgal/blob/v6.1.1/Arrangement_on_surface_2/include/CGAL/Arr_point_location/Td_active_vertex.h $
// $Id: include/CGAL/Arr_point_location/Td_active_vertex.h 08b27d3db14 $
// SPDX-License-Identifier: GPL-3.0-or-later OR LicenseRef-Commercial
//
// Author(s): Oren Nechushtan   <theoren@math.tau.ac.il>
//            Michal Balas      <balasmic@post.tau.ac.il>
//            Efi Fogel         <efifogel@gmail.com>

#ifndef CGAL_TD_ACTIVE_VERTEX_H
#define CGAL_TD_ACTIVE_VERTEX_H

#include <CGAL/license/Arrangement_on_surface_2.h>

/*! \file
 * Definition of the Td_active_vertex<Td_traits> class.
 */

#include <CGAL/Arr_point_location/Trapezoidal_decomposition_2.h>
#include <variant>
#include <memory>


#ifdef CGAL_TD_DEBUG
#define CGAL_TD_INLINE
#else
#define CGAL_TD_INLINE inline
#endif

namespace CGAL {

/*! \class
 * Implementation of a pseudo-trapezoid as two halfedges(top,bottom)
 * and two curve-ends(left,right).
 * Trapezoids are represented as two curve-ends called right and left and
 * two halfedges called top and bottom. The curve-ends (points) lie on the
 * right and left boundaries of the trapezoid respectively and the halfedges
 * bound the trapezoid from above and below.
 * There exist degenerate trapezoids called infinite trapezoid; this happens
 * when one of the four sides is on the parameter space boundary.
 * Trapezoids are created as active and become inactive when Remove() member
 * function called.
 * Each trapezoid has at most four neighboring trapezoids.
 * X_trapezoid structure can represent a real trapezoid, a Td-edge or an
 * edge-end (end point).
 */
template <typename Td_traits_>
class Td_active_vertex : public Handle {
public:

  //type of traits class
  typedef Td_traits_                                    Traits;

  //type of point (Point_2)
  typedef typename Traits::Point                        Point;

  //type of X_monotone_curve_2
  typedef typename Traits::X_monotone_curve_2           X_monotone_curve_2;

  //type of Curve_end
  typedef typename Traits::Curve_end                    Curve_end;

  //type of Halfedge_const_handle (trapezoid edge)
  typedef typename Traits::Halfedge_const_handle        Halfedge_const_handle;

  //type of Vertex_const_handle (trapezoid vertex)
  typedef typename Traits::Vertex_const_handle          Vertex_const_handle;

  //type of Halfedge_around_vertex_const_circulator
  typedef typename Traits::Halfedge_around_vertex_const_circulator
    Halfedge_around_vertex_const_circulator;

  //type of Td_active_vertex (Self)
  typedef typename Traits::Td_active_vertex             Self;

  typedef typename Traits::Td_map_item                  Td_map_item;

  //type of Trapezoidal decomposition
  typedef Trapezoidal_decomposition_2<Traits>           TD;

  //type of In face iterator
  typedef typename TD::In_face_iterator                 In_face_iterator;

  //type of Trapezoidal map search structure
  typedef typename TD::Dag_node                         Dag_node;


  //friend class declarations:

  friend class Trapezoidal_decomposition_2<Traits>;

#ifdef CGAL_PM_FRIEND_CLASS
#if defined(__SUNPRO_CC) || defined(__PGI) || defined(__INTEL_COMPILER)
  friend class Trapezoidal_decomposition_2<Traits>::In_face_iterator;
#elif (__GNUC__ > 0)
  friend class Trapezoidal_decomposition_2<Traits>::In_face_iterator;
#else
  friend class In_face_iterator;
#endif
#endif

   /*! \class
    * Inner class Data derived from Rep class
    */
  class Data : public Rep {
    friend class Td_active_vertex<Td_traits_>;

  public:
    //c'tors
    Data(Vertex_const_handle _v, Halfedge_const_handle _cw_he,
         Dag_node* _p_node) :
      v(_v), cw_he(_cw_he), p_node(_p_node)
    {
      CGAL_assertion( _cw_he==Halfedge_const_handle()
                     || _cw_he->source() == v );
    }

    ~Data() {}

  protected:
    Vertex_const_handle v;
    Halfedge_const_handle cw_he; //holds the first edge going cw starting at 12 o'clock
    Dag_node* p_node;
  };

private:
  Data* ptr() const { return (Data*)(PTR); }

  Curve_end vtx_to_ce(Vertex_const_handle v) const
  {
    //the circulator is of incoming halfedges
    Halfedge_around_vertex_const_circulator he = v->incident_halfedges();
    //if the vertex is associated with a point on the bounded coords,
    // we can take any incident halfedge. o/w if the vertex lies at infinity,
    //  it has 2 fictitious incident halfedges
    if (v->is_at_open_boundary() && he->source()->is_at_open_boundary()) ++he;
    if (v->is_at_open_boundary() && he->source()->is_at_open_boundary()) ++he;

    return Curve_end(he->curve(), ((he->direction() == ARR_RIGHT_TO_LEFT) ?
                                   ARR_MIN_END : ARR_MAX_END));
  }

#ifndef CGAL_TD_DEBUG
#ifdef CGAL_PM_FRIEND_CLASS
protected:
#else
public: // workaround
#endif
#else //CGAL_TD_DEBUG
public:
#endif //CGAL_TD_DEBUG

  /*! Set the DAG node. */
  inline void set_dag_node(Dag_node* p) { ptr()->p_node = p; }

  /*! Set the vertex handle (Vertex_const_handle). */
  inline void set_vertex(Vertex_const_handle v) { ptr()->v = v; }

  /*! Set the first he going clockwise starting at 12 o'clock.
   */
  inline void set_cw_he(Halfedge_const_handle he)
  {
    ptr()->cw_he = he->twin()->source()==ptr()->v ? he->twin() : he;
    CGAL_assertion( ptr()->v == ptr()->cw_he->source() );
  }

  /*! Reset the first he going clockwise starting at 12 o'clock.
   */
  inline void reset_cw_he() { ptr()->cw_he = Traits::empty_he_handle(); }

public:
  /// \name Constructors.
  //@{

  Td_active_vertex()
  {
    PTR = new Data(Traits::empty_vtx_handle(), Traits::empty_he_handle(), nullptr);
  }

  /*! Constructor given Vertex & Halfedge handles. */
  Td_active_vertex(Vertex_const_handle v, Halfedge_const_handle cw_he,
                   Dag_node* node = 0)

  { PTR = new Data(v, cw_he, node); }


  /*! Copy constructor. */
  Td_active_vertex(const Self& tr) : Handle(tr) {}

  //@}

  /// \name Operator overloading.
  //@{

  /*! Assignment operator.
  *   operator= should not copy m_dag_node (or otherwise update
  *     Dag_node::replace)
    */
  inline Self& operator=(const Self& t2)
  {
    Handle::operator=(t2);
    return *this;
  }

  /*! Operator==. */
  inline bool operator==(const Self& t2) const { return (ptr() == t2.ptr()); }

  /*! Operator!=. */
  inline bool operator!=(const Self& t2) const { return !(operator==(t2)); }

  //@}

  /// \name Access methods.
  //@{

  inline Self& self() { return *this; }

  inline const Self& self() const { return *this; }

  /*! Access the trapezoid id (PTR). */
  inline unsigned long id() const { return (unsigned long) PTR; }

  inline Vertex_const_handle vertex() const { return ptr()->v; }

  Curve_end curve_end() const { return vtx_to_ce(vertex()); }

  inline const Point& point() const { return vertex()->point(); }

  /*! Access the first he starting at 12 o'clock clockwise.
   */
  inline Halfedge_const_handle cw_he() const { return ptr()->cw_he; }

  /*! Access DAG node. */
  Dag_node* dag_node() const { return ptr()->p_node; }

  //@}
};

} //namespace CGAL

#endif
