// Copyright (c) 1997  Tel-Aviv University (Israel).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org); you may redistribute it under
// the terms of the Q Public License version 1.0.
// See the file LICENSE.QPL distributed with CGAL.
//
// Licensees holding a valid commercial license may use this file in
// accordance with the commercial license agreement provided with the software.
//
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
//
// $URL: svn+ssh://scm.gforge.inria.fr/svn/cgal/branches/CGAL-3.4-branch/Arrangement_on_surface_2/include/CGAL/Sweep_line_2/Arr_insertion_sl_visitor.h $
// $Id: Arr_insertion_sl_visitor.h 40964 2007-11-21 10:23:08Z efif $
// 
//
// Author(s)     : Baruch Zukerman <baruchzu@post.tau.ac.il>
//                 Ron Wein <wein@post.tau.ac.il>

#ifndef CGAL_ARR_INSERTION_SL_VISITOR_H
#define CGAL_ARR_INSERTION_SL_VISITOR_H

/*!
 * Definition of the Arr_insertion_sl_visitor class-template.
 */

#include <CGAL/Sweep_line_2/Arr_basic_insertion_sl_visitor.h>

CGAL_BEGIN_NAMESPACE

/*! \class Arr_insertion_sl_visitor
 * A sweep-line visitor for inserting new curves into an existing arrangement
 * embedded on a surface.
 */
template <class Helper_> 
class Arr_insertion_sl_visitor : 
  public Arr_basic_insertion_sl_visitor<Helper_>
{
public:

  typedef Helper_                                      Helper;
 
  typedef Arr_basic_insertion_sl_visitor<Helper>       Base;

  typedef typename Base::Traits_2                      Traits_2;
  typedef typename Base::Arrangement_2                 Arrangement_2;
  typedef typename Base::Event                         Event;
  typedef typename Base::Subcurve                      Subcurve;
  
  typedef typename Base::Halfedge_handle          Halfedge_handle;
  typedef typename Base::X_monotone_curve_2       X_monotone_curve_2;
  typedef typename Base::Point_2                  Point_2;

private:

  X_monotone_curve_2   sub_cv1;         // Auxiliary variables
  X_monotone_curve_2   sub_cv2;         // (used for splitting curves).

public:

  /*! Constructor. */
  Arr_insertion_sl_visitor (Arrangement_2 *arr) :
    Base (arr)
  {}

  /// \name Edge-split functions (to be overridden by the child visitor).
  //@{

  /*!
   * Check if the halfedge associated with the given subcurve will be split
   * at the given event.
   * \param sc The subcurve.
   * \param event The event.
   */
  virtual bool is_split_event(Subcurve *sc, Event *event);

  /*!
   * Split the given edge edge.
   * \param he The edge to split.
   * \param sc The associated subcurve.
   * \param The split point.
   * \return A handle to the split edge.
   */
  virtual Halfedge_handle split_edge (Halfedge_handle he,
                                      Subcurve *sc,
                                      const Point_2& pt);
  //@}   
};

//-----------------------------------------------------------------------------
// Memeber-function definitions:
//-----------------------------------------------------------------------------

//-----------------------------------------------------------------------------
// Check if the halfedge associated with the given subcurve will be split
// at the given event.
//
template <class Hlpr> 
bool Arr_insertion_sl_visitor<Hlpr>::is_split_event
    (Subcurve *sc, Event *event)
{
  if(sc->last_curve().halfedge_handle() == Halfedge_handle(NULL))
    return (false);

  if(! sc->originating_subcurve1())
  {
    return (reinterpret_cast<Event*>(sc->left_event())!= 
            this->current_event());
  }
  return
    (this->is_split_event
     (reinterpret_cast<Subcurve*>(sc->originating_subcurve1()), event) || 
     this->is_split_event
     (reinterpret_cast<Subcurve*>(sc->originating_subcurve2()), event));
  }

//-----------------------------------------------------------------------------
// Split an edge.
//
template <class Hlpr>
typename Arr_insertion_sl_visitor<Hlpr>::Halfedge_handle
Arr_insertion_sl_visitor<Hlpr>::split_edge
    (Halfedge_handle he, Subcurve *sc, const Point_2& pt)
{
  // Make sure that the halfedge associated with sc is the directed from
  // right to left, since we always "look" above , and the incident face 
  //is on the left of the  halfedge
  CGAL_assertion (he->direction() == ARR_RIGHT_TO_LEFT);
    
  this->traits()->split_2_object() (he->curve(), pt, 
                                    sub_cv2, sub_cv1);

  Halfedge_handle new_he =  
    this->m_arr_access.split_edge_ex (he,
                                      pt.base(),
                                      sub_cv1.base(),
                                      sub_cv2.base());

  Event* last_event_on_sc = reinterpret_cast<Event*>(sc->last_event());

  if(last_event_on_sc->halfedge_handle() == he)
    last_event_on_sc->set_halfedge_handle(new_he->next());

  return (new_he);
}

CGAL_END_NAMESPACE

#endif
