// Copyright (c) 2006,2007,2009,2010,2011 Tel-Aviv University (Israel).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org).
//
// $URL$
// $Id$
// SPDX-License-Identifier: GPL-3.0-or-later OR LicenseRef-Commercial
//
//
// Author(s)     : Ron Wein   <wein@post.tau.ac.il>
//                 (based on old version by Eyal Flato)
//                 Efi Fogel  <efif@post.tau.ac.il>

#ifndef CGAL_ARR_SIMPLE_POINT_LOCATION_H
#define CGAL_ARR_SIMPLE_POINT_LOCATION_H

#include <CGAL/license/Arrangement_on_surface_2.h>

#include <CGAL/disable_warnings.h>

/*! \file
 * Definition of the Arr_simple_point_location<Arrangement> template.
 */

#include <CGAL/Arr_point_location_result.h>
#include <CGAL/Arrangement_2/Arr_traits_adaptor_2.h>

#include <optional>

namespace CGAL {

/*! \class
 * A class that answers point-location and vertical ray-shooting queries
 * on a 2D arrangement using a simple algorithm.
 * The Arrangement parameter corresponds to an arrangement instantiation
 * of type Arrangement_on_surface_2<GeomTraits, TopTraits>.
 */
template <typename Arrangement_>
class Arr_simple_point_location {
public:
  typedef Arrangement_                                   Arrangement_2;
  typedef typename Arrangement_2::Geometry_traits_2      Geometry_traits_2;
  typedef typename Arrangement_2::Topology_traits        Topology_traits;

  typedef typename Arrangement_2::Vertex_const_handle    Vertex_const_handle;
  typedef typename Arrangement_2::Halfedge_const_handle  Halfedge_const_handle;
  typedef typename Arrangement_2::Face_const_handle      Face_const_handle;

  typedef typename Geometry_traits_2::Point_2            Point_2;
  typedef typename Geometry_traits_2::X_monotone_curve_2 X_monotone_curve_2;

  typedef Arr_point_location_result<Arrangement_2>       Result;
  typedef typename Result::Type                          Result_type;

  // Support cpp11::result_of
  typedef Result_type                                    result_type;

protected:
  typedef typename std::optional<Result_type>          Optional_result_type;

  typedef typename Topology_traits::Dcel                 Dcel;
  typedef Arr_traits_basic_adaptor_2<Geometry_traits_2>  Traits_adaptor_2;

  // Data members:
  const Arrangement_2*    m_arr;            // The associated arrangement.
  const Traits_adaptor_2* m_geom_traits;    // Its associated geometry traits.
  const Topology_traits*  m_topol_traits;   // Its associated topology traits.

  inline bool optional_empty(const std::optional<Result_type>& t) const { return (!t); }
  inline const Result_type& optional_assign(const std::optional<Result_type>& t) const { return *t; }

  template<typename T>
  Result_type make_result(T t) const { return Result::make_result(t); }
  inline Optional_result_type make_optional_result() const { return Result::empty_optional_result(); }
  inline Result_type default_result() const { return Result::default_result(); }

public:
  /*! Default constructor. */
  Arr_simple_point_location() :
    m_arr(nullptr),
    m_geom_traits(nullptr),
    m_topol_traits(nullptr)
  {}

  /*! Constructor given an arrangement. */
  Arr_simple_point_location(const Arrangement_2& arr) :
    m_arr(&arr)
  {
    m_geom_traits =
      static_cast<const Traits_adaptor_2*>(m_arr->geometry_traits());
    m_topol_traits = m_arr->topology_traits();
  }

  /*! Attach an arrangement object. */
  void attach(const Arrangement_2& arr)
  {
    m_arr = &arr;
    m_geom_traits =
      static_cast<const Traits_adaptor_2*>(m_arr->geometry_traits());
    m_topol_traits = m_arr->topology_traits();
  }

  /*! Detach from the current arrangement object. */
  void detach()
  {
    m_arr = nullptr;
    m_geom_traits = nullptr;
    m_topol_traits = nullptr;
  }

  /*!
   * Locate the arrangement feature containing the given point.
   * \param p The query point.
   * \return An object representing the arrangement feature containing the
   *         query point. This object is either a Face_const_handle or a
   *         Halfedge_const_handle or a Vertex_const_handle.
   */
  Result_type locate(const Point_2& p) const;

  /*!
   * Locate the arrangement feature which a upward vertical ray emanating from
   * the given point hits.
   * \param p The query point.
   * \return An object representing the arrangement feature the ray hits.
   *         This object is either an empty object or a
   *         Halfedge_const_handle or a Vertex_const_handle.
   */
  Result_type ray_shoot_up(const Point_2& p) const
  { return (_vertical_ray_shoot(p, true)); }

  /*!
   * Locate the arrangement feature which a downward vertical ray emanating
   * from the given point hits.
   * \param p The query point.
   * \return An object representing the arrangement feature the ray hits.
   *         This object is either an empty object or a
   *         Halfedge_const_handle or a Vertex_const_handle.
   */
  Result_type ray_shoot_down(const Point_2& p) const
  { return (_vertical_ray_shoot(p, false)); }

protected:
  /*!
   * Locate the arrangement feature which a vertical ray emanating from the
   * given point hits (not including isolated vertices).
   * \param p The query point.
   * \param shoot_up Indicates whether the ray is directed upward or downward.
   * \return An object representing the arrangement feature the ray hits.
   *         This object is either a Halfedge_const_handle,
   *         a Vertex_const_handle or an empty object.
   */
  Optional_result_type _base_vertical_ray_shoot(const Point_2& p,
                                                bool shoot_up) const;

  /*!
   * Locate the arrangement feature which a vertical ray emanating from the
   * given point hits, considering isolated vertices.
   * \param p The query point.
   * \param shoot_up Indicates whether the ray is directed upward or downward.
   * \return An object representing the arrangement feature the ray hits.
   *         This object is either a Halfedge_const_handle,
   *         a Vertex_const_handle or an empty object.
   */
  Result_type _vertical_ray_shoot(const Point_2& p, bool shoot_up) const;

  /*!
   * Find the first halfedge with a given source vertex, when going clockwise
   * from "6 o'clock" around this vertex.
   * \param v The given vertex.
   * \return The first halfedge.
   */
  Halfedge_const_handle _first_around_vertex(Vertex_const_handle v) const;
};

} //namespace CGAL

// The member-function definitions can be found under:
#include <CGAL/Arr_point_location/Arr_simple_point_location_impl.h>

#include <CGAL/enable_warnings.h>

#endif

