// Copyright (c) 2003,2004,2005,2006  INRIA Sophia-Antipolis (France).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org).
//
// $URL: https://github.com/CGAL/cgal/blob/v6.1/Segment_Delaunay_graph_2/include/CGAL/Segment_Delaunay_graph_2/Arrangement_type_C2.h $
// $Id: include/CGAL/Segment_Delaunay_graph_2/Arrangement_type_C2.h b26b07a1242 $
// SPDX-License-Identifier: GPL-3.0-or-later OR LicenseRef-Commercial
//
//
// Author(s)     : Menelaos Karavelas <mkaravel@iacm.forth.gr>




#ifndef CGAL_SEGMENT_DELAUNAY_GRAPH_2_ARRANGEMENT_TYPE_C2_H
#define CGAL_SEGMENT_DELAUNAY_GRAPH_2_ARRANGEMENT_TYPE_C2_H

#include <CGAL/license/Segment_Delaunay_graph_2.h>


#include <CGAL/enum.h>
#include <CGAL/determinant.h>
#include <CGAL/Segment_Delaunay_graph_2/Basic_predicates_C2.h>
#include <CGAL/Segment_Delaunay_graph_2/Are_same_points_C2.h>
#include <CGAL/Segment_Delaunay_graph_2/Arrangement_enum.h>

#include <iostream>

namespace CGAL {

namespace SegmentDelaunayGraph_2 {

//---------------------------------------------------------------------
//---------------------------------------------------------------------

template<class K>
class Arrangement_type_C2
  : public Basic_predicates_C2<K>, public Internal::Arrangement_enum
{
private:
  typedef Internal::Arrangement_enum         Enum;

  typedef Basic_predicates_C2<K>             Base;

  typedef typename Base::Point_2             Point_2;
  typedef typename Base::Segment_2           Segment_2;
  typedef typename Base::Site_2              Site_2;
  typedef typename Base::Line_2              Line_2;

  typedef typename Base::FT                  FT;
  typedef typename Base::RT                  RT;

  typedef typename Base::Orientation         Orientation;
  typedef typename Base::Comparison_result   Comparison_result;
  typedef typename Base::Oriented_side       Oriented_side;
  typedef typename Base::Sign                Sign;
  typedef typename Base::Boolean             Boolean;

  typedef typename K::Orientation_2          Orientation_2;

  typedef Are_same_points_C2<K>              Are_same_points_2;

  using Base::compute_supporting_line;
  using Base::oriented_side_of_line;
  using Base::compute_perpendicular;
  using Base::opposite_line;

private:
  Are_same_points_2     same_points;

public:
  typedef typename Enum::Arrangement_type    Arrangement_type;

private:
  Arrangement_type compute_type_C2(const RT& x1, const RT& y1,
                                   const RT& x2, const RT& y2,
                                   const RT& x3, const RT& y3,
                                   const RT& x4, const RT& y4) const
  {
    RT delta = -determinant<RT>(x2 - x1, x4 - x3, y2 - y1, y4 - y3);

    Sign s = CGAL::sign( delta );
    if ( s != CGAL::ZERO ) {
      return non_parallel_C2(x1, y1, x2, y2, x3, y3, x4, y4, delta);
    } else {
      return parallel_C2(x1, y1, x2, y2, x3, y3, x4, y4);
    }
  }

  Arrangement_type
  non_parallel_C2(const RT& x1, const RT& y1, const RT& x2, const RT& y2,
                  const RT& x3, const RT& y3, const RT& x4, const RT& y4,
                  const RT& D) const
  {
    RT Dt = -determinant<RT>(x3 - x1, x4 - x3, y3 - y1, y4 - y3);
    RT Ds = determinant<RT>(x2 - x1, x3 - x1, y2 - y1, y3 - y1);

    Sign s_D = CGAL::sign( D );
    Sign s_Dt = CGAL::sign( Dt );
    Sign s_Ds = CGAL::sign( Ds );

    Sign s_tdiff = CGAL::sign(Dt - D);
    Sign s_sdiff = CGAL::sign(Ds - D);

    Sign s_t = s_Dt * s_D;
    Sign s_s = s_Ds * s_D;

    Sign s_t_minus_1 = s_tdiff * s_D;
    Sign s_s_minus_1 = s_sdiff * s_D;

    if ( s_t == CGAL::NEGATIVE || s_t_minus_1 == CGAL::POSITIVE ||
         s_s == CGAL::NEGATIVE || s_s_minus_1 == CGAL::POSITIVE ) {
      //  t < 0 or t > 1 or s < 0 or s > 1
      return Enum::DISJOINT;
    }

    int it(0), is(0);
    if ( s_t == CGAL::ZERO ) {
      it = 0;
    } else if ( s_t_minus_1 == CGAL::ZERO ) {
      it = 1;
    } else {
      it = 2;
    }
    if ( s_s == CGAL::ZERO ) {
      is = 0;
    } else if ( s_s_minus_1 == CGAL::ZERO ) {
      is = 1;
    } else {
      is = 2;
    }

    if ( it == 0 ) {
      if ( is == 0 ) {
        return Enum::TOUCH_11;
      } else if ( is == 1 ) {
        return Enum::TOUCH_12;
      } else {
        return Enum::TOUCH_INTERIOR_12;
      }
    } else if ( it == 1 ) {
      if ( is == 0 ) {
        return Enum::TOUCH_21;
      } else if ( is == 1 ) {
        return Enum::TOUCH_22;
      } else {
        return Enum::TOUCH_INTERIOR_22;
      }
    } else {
      if ( is == 0 ) {
        return Enum::TOUCH_INTERIOR_11;
      } else if ( is == 1 ) {
        return Enum::TOUCH_INTERIOR_21;
      } else {
        return Enum::CROSSING;
      }
    }
  }


  Arrangement_type
  parallel_C2(const RT& x1, const RT& y1, const RT& x2, const RT& y2,
              const RT& x3, const RT& y3, const RT& x4, const RT& y4) const
  {
    RT D1 = determinant<RT>(x2 - x1, x3 - x1,        y2 - y1, y3 - y1);

    if ( CGAL::sign( D1 ) != CGAL::ZERO ) {
      return Enum::DISJOINT;
    }

    RT Dt3, Dt4, Dt;
    if ( CGAL::compare(x2, x1) != CGAL::EQUAL ) {
      Dt  = x2 - x1;
      Dt3 = x3 - x1;
      Dt4 = x4 - x1;
    } else {
      Dt  = y2 - y1;
      Dt3 = y3 - y1;
      Dt4 = y4 - y1;
    }

    Sign s_Dt = CGAL::sign( Dt );
    Sign s_Dt3 = CGAL::sign( Dt3 );
    Sign s_Dt4 = CGAL::sign( Dt4 );

    Sign s_t3 = s_Dt3 * s_Dt;
    Sign s_t4 = s_Dt4 * s_Dt;

    Sign s_t3diff = CGAL::sign( Dt3 - Dt );
    Sign s_t4diff = CGAL::sign( Dt4 - Dt );

    Sign s_t3_minus_1 = s_t3diff * s_Dt;
    Sign s_t4_minus_1 = s_t4diff * s_Dt;

    int it3(0), it4(0);
    if ( s_t3 == CGAL::ZERO ) { // t3 == 0
      it3 = 0;
    } else if ( s_t3_minus_1 == CGAL::ZERO ) { // t3 == 1
      it3 = 1;
    } else if ( s_t3 == CGAL::POSITIVE &&
                s_t3_minus_1 == CGAL::NEGATIVE ) { // 0 < t3 < 1
      it3 = 2;
    } else if ( s_t3 == CGAL::NEGATIVE ) { // t3 < 0
      it3 = -1;
    } else { // t3 > 1
      it3 = 3;
    }

    if ( s_t4 == CGAL::ZERO ) { // t4 == 0
      it4 = 0;
    } else if ( s_t4_minus_1 == CGAL::ZERO ) { // t4 == 1
      it4 = 1;
    } else if ( s_t4 == CGAL::POSITIVE &&
                s_t4_minus_1 == CGAL::NEGATIVE ) { // 0 < t4 < 1
      it4 = 2;
    } else if ( s_t4 == CGAL::NEGATIVE ) { // t4 < 0
      it4 = -1;
    } else { // t4 > 1
      it4 = 3;
    }

    // decode now
    if ( it3 == -1 ) {
      if ( it4 == -1 ) {
        return Enum::DISJOINT;
      } else if ( it4 == 0 ) {
        return Enum::TOUCH_12;
      } else if ( it4 == 1 ) {
        return Enum::TOUCH_22_INTERIOR_2;
      } else if ( it4 == 2 ) {
        return Enum::OVERLAPPING_12;
      } else { // it4 == 3
        return Enum::INTERIOR_2;
      }
    } else if ( it3 == 0 ) {
      CGAL_assertion( it4 != 0 );
      if ( it4 == -1 ) {
        return Enum::TOUCH_11;
      } else if ( it4 == 1 ) {
        return Enum::IDENTICAL;
      } else if ( it4 == 2 ) {
        return Enum::TOUCH_11_INTERIOR_1;
      } else { // it4 == 3
        return Enum::TOUCH_11_INTERIOR_2;
      }
    } else if ( it3 == 1 ) {
      CGAL_assertion( it4 != 1 );
      if ( it4 == -1 ) {
        return Enum::TOUCH_21_INTERIOR_2;
      } else if ( it4 == 0 ) {
        return Enum::IDENTICAL;
      } else if ( it4 == 2 ) {
        return Enum::TOUCH_21_INTERIOR_1;
      } else { // it4 == 3
        return Enum::TOUCH_21;
      }
    } else if ( it3 == 2 ) {
      if ( it4 == -1 ) {
        return Enum::OVERLAPPING_11;
      } else if ( it4 == 0 ) {
        return Enum::TOUCH_12_INTERIOR_1;
      } else if ( it4 == 1 ) {
        return Enum::TOUCH_22_INTERIOR_1;
      } else if ( it4 == 2 ) {
        return Enum::INTERIOR_1;
      } else { // it4 == 3
        return Enum::OVERLAPPING_21;
      }
    } else { // it3 == 3  ( t3 > 1 )
      if ( it4 == -1 ) {
        return Enum::INTERIOR_2;
      } else if ( it4 == 0 ) {
        return Enum::TOUCH_12_INTERIOR_2;
      } else if ( it4 == 1 ) {
        return Enum::TOUCH_22;
      } else if ( it4 == 2 ) {
        return Enum::OVERLAPPING_22;
      } else { // it4 == 3
        return Enum::DISJOINT;
      }
    }
  }


  Boolean   inside_segment(const Site_2& s, const Site_2& p) const
  {
    CGAL_precondition( s.is_segment() && p.is_point() );

    Line_2 l = compute_supporting_line( s.supporting_site() );
    // do geometric filtering here...

    Point_2 pp = p.point();

    Oriented_side os =  oriented_side_of_line(l, pp );

    if (certainly( os != ON_ORIENTED_BOUNDARY ) )
      // the point does not belong to the same line as the segment
      return false;
    if (! is_certain( os != ON_ORIENTED_BOUNDARY ) )
      return indeterminate<Boolean>();

    Line_2 lp1 = compute_perpendicular(l, s.segment().source());

    Oriented_side os1 = oriented_side_of_line(lp1, pp);

    CGAL_assertion( os1 != ON_ORIENTED_BOUNDARY );

    if ( os1 == ON_POSITIVE_SIDE ) {
      return false;
    }

    Line_2 lp2 = compute_perpendicular(l, s.segment().target());
    lp2 = opposite_line(lp2);

    Oriented_side os2 = oriented_side_of_line(lp2, pp);

    CGAL_assertion( os2 != ON_ORIENTED_BOUNDARY );

    if ( os2 == ON_POSITIVE_SIDE ) {
      return false;
    }

    return true;
  }

  //------------------------------------------------------------------------

  Arrangement_type
  arrangement_type_same_point(const Site_2& p, const Site_2& q,
                              unsigned int ip, unsigned int iq) const
  {
    CGAL_precondition( ip < 2 && iq < 2 );

    Point_2 p1 = p.supporting_site().source();
    Point_2 p2 = p.supporting_site().target();
    Point_2 p3;

    if ( iq == 0 ) {
      p3 = q.supporting_site().target();
    } else {
      p3 = q.supporting_site().source();
    }

    if ( Orientation_2()(p1, p2, p3) != COLLINEAR ) {
      if ( ip == 0 ) {
        if ( iq == 0 ) {
          return TOUCH_11;
        } else {
          return TOUCH_12;
        }
      } else {
        if ( iq == 0 ) {
          return TOUCH_21;
        } else {
          return TOUCH_22;
        }
      }

    } else {
      Segment_2 s1 = p.segment();
      Segment_2 s2 = q.segment();

      return parallel_C2( s1.source().x(), s1.source().y(),
                          s1.target().x(), s1.target().y(),
                          s2.source().x(), s2.source().y(),
                          s2.target().x(), s2.target().y() );
    }
  }

  Arrangement_type
  arrangement_type_ss(const Site_2& p, const Site_2& q) const
  {
    bool same_p1q1 = same_points(p.source_site(), q.source_site());
    bool same_p1q2 = same_points(p.source_site(), q.target_site());
    bool same_p2q1 = same_points(p.target_site(), q.source_site());
    bool same_p2q2 = same_points(p.target_site(), q.target_site());

    if ( (same_p1q1 && same_p2q2) || (same_p1q2 && same_p2q1) ) {
      return IDENTICAL;
    }

    if ( same_p1q1 ) {
      return arrangement_type_same_point(p, q, 0, 0);
    } if ( same_p1q2 ) {
      return arrangement_type_same_point(p, q, 0, 1);
    } else if ( same_p2q1 ) {
      return arrangement_type_same_point(p, q, 1, 0);
    } else if ( same_p2q2 ) {
      return arrangement_type_same_point(p, q, 1, 1);
    }

    Segment_2 s1 = p.segment();
    Segment_2 s2 = q.segment();

    Arrangement_type res = compute_type_C2(s1.source().x(), s1.source().y(),
                                           s1.target().x(), s1.target().y(),
                                           s2.source().x(), s2.source().y(),
                                           s2.target().x(), s2.target().y() );

    return res;
  }

  //--------------------------------------------------------------------

  Arrangement_type
  arrangement_type_ps(const Site_2& p, const Site_2& q) const
  {
    if ( same_points(p, q.source_site()) ) {
      return TOUCH_1;
    } else if ( same_points(p, q.target_site()) ) {
      return TOUCH_2;
    } else if ( inside_segment(q, p) ) {
      return INTERIOR;
    } else {
      return DISJOINT;
    }
  }

  //--------------------------------------------------------------------

  Arrangement_type
  arrangement_type_pp(const Site_2& p, const Site_2& q) const
  {
    if ( same_points(p, q) ) {
      return IDENTICAL;
    } else {
      return DISJOINT;
    }
  }

  //--------------------------------------------------------------------

public:
  Arrangement_type
  operator()(const Site_2& p, const Site_2& q) const
  {
    CGAL_precondition( p.is_defined() && q.is_defined() );

    if ( p.is_point() ) {
      if ( q.is_point() ) {
        return arrangement_type_pp(p, q);
      } else {
        return arrangement_type_ps(p, q);
      }
    } else {
      if ( q.is_point() ) {
        return opposite( arrangement_type_ps(q, p) );
      } else {
        return arrangement_type_ss(p, q);
      }
    }
  }
};

//---------------------------------------------------------------------

} //namespace SegmentDelaunayGraph_2

} //namespace CGAL

#endif // CGAL_SEGMENT_DELAUNAY_GRAPH_2_ARRANGEMENT_TYPE_C2_H

