// Copyright (c) 2006-2007  INRIA Sophia-Antipolis (France).
// Copyright (c) 2008,2011 GeometryFactory Sarl (France)
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org).
//
// $URL: https://github.com/CGAL/cgal/blob/v6.2/Mesh_3/include/CGAL/Compact_mesh_cell_base_3.h $
// $Id: include/CGAL/Compact_mesh_cell_base_3.h cac3e9d75e2 $
// SPDX-License-Identifier: GPL-3.0-or-later OR LicenseRef-Commercial
//
// Author(s)     : Laurent Rineau, Stephane Tayeb, Andreas Fabri


#ifndef CGAL_COMPACT_MESH_CELL_BASE_3_H
#define CGAL_COMPACT_MESH_CELL_BASE_3_H

#include <CGAL/license/Mesh_3.h>

#include <CGAL/Mesh_3/config.h>

#include <CGAL/array.h>
#include <CGAL/assertions.h>
#include <CGAL/basic.h>
#include <CGAL/Has_timestamp.h>
#include <CGAL/IO/io.h>
#include <CGAL/Kernel_traits.h>
#include <CGAL/Regular_triangulation_cell_base_3.h>
#include <CGAL/SMDS_3/io_signature.h>
#include <CGAL/tags.h>
#include <CGAL/TDS_3/internal/Dummy_tds_3.h>
#include <CGAL/Time_stamper.h>

#include <array>
#include <cstddef>
#include <istream>
#include <ostream>
#include <string>
#include <type_traits>

#ifdef CGAL_LINKED_WITH_TBB
# include <atomic>
#endif

namespace internal_tbb
{
//classic pointer{
//normal
template<typename T>
void set_weighted_circumcenter(T* &t, T* value)
{
  t = value;
}

//overload for nullptr
template<typename T>
void set_weighted_circumcenter(T* &t, std::nullptr_t)
{
  t = nullptr;
}
template<typename T>
bool is_null(T* t)
{
  return t == nullptr;
}

template<typename T>
void delete_circumcenter(T* &t )
{
  delete t;
}
//} atomic {
//normal
template<typename T>
void set_weighted_circumcenter(std::atomic<T*>& t, T* value)
{
  t.load() = value;
}

//nullptr
template<typename T>
void set_weighted_circumcenter(std::atomic<T*>& t, std::nullptr_t)
{
  t = nullptr;
}

template<typename T>
bool is_null(std::atomic<T*>& t)
{
  return t.load() == nullptr;
}
template<typename T>
void delete_circumcenter(std::atomic<T*>& t)
{
  delete t.load();
}
//}
} //end internal_tbb

namespace CGAL {

// Class Compact_mesh_cell_base_3_base
// Base for Compact_mesh_cell_base_3, with specializations
// for different values of Concurrency_tag
// Sequential
template <typename Point_3, typename Concurrency_tag>
class Compact_mesh_cell_base_3_base
{
protected:
  Compact_mesh_cell_base_3_base()
    : bits_(0)
  {
    internal_tbb::set_weighted_circumcenter(weighted_circumcenter_, nullptr);
  }

public:
#if defined(CGAL_MESH_3_USE_LAZY_SORTED_REFINEMENT_QUEUE) \
 || defined(CGAL_MESH_3_USE_LAZY_UNSORTED_REFINEMENT_QUEUE)

  // Erase counter (cf. Compact_container)
  unsigned int erase_counter() const
  {
    return this->m_erase_counter;
  }
  void set_erase_counter(unsigned int c)
  {
    this->m_erase_counter = c;
  }
  void increment_erase_counter()
  {
    ++this->m_erase_counter;
  }
#endif

  /// Marks `facet` as visited
  void set_facet_visited (const int facet)
  {
    CGAL_precondition(facet>=0 && facet <4);
    bits_ |= char(1 << facet);
  }

  /// Marks `facet` as not visited
  void reset_visited (const int facet)
  {
    CGAL_precondition(facet>=0 && facet<4);
    bits_ = char(bits_ & (15 & ~(1 << facet)));
  }

  /// Returns `true` if `facet` is marked as visited
  bool is_facet_visited (const int facet) const
  {
    CGAL_precondition(facet>=0 && facet<4);
    return ( (bits_ & (1 << facet)) != 0 );
  }

  /// Precondition weighted_circumcenter_ == nullptr
  void try_to_set_circumcenter(Point_3 *cc) const
  {
    CGAL_precondition(weighted_circumcenter_ == nullptr);
    weighted_circumcenter_ = cc;
  }

private:
  char bits_;

#if defined(CGAL_MESH_3_USE_LAZY_SORTED_REFINEMENT_QUEUE) \
 || defined(CGAL_MESH_3_USE_LAZY_UNSORTED_REFINEMENT_QUEUE)

  typedef unsigned int              Erase_counter_type;
  Erase_counter_type                m_erase_counter;
#endif

protected:
  mutable Point_3* weighted_circumcenter_;
};


#ifdef CGAL_LINKED_WITH_TBB
// Class Compact_mesh_cell_base_3_base
// Specialization for parallel
template <typename Point_3>
class Compact_mesh_cell_base_3_base<Point_3, Parallel_tag>
{
protected:
  Compact_mesh_cell_base_3_base()
  {
    bits_ = 0;
    weighted_circumcenter_ = nullptr;
  }

public:
  // Erase counter (cf. Compact_container)
  unsigned int erase_counter() const
  {
    return this->m_erase_counter;
  }
  void set_erase_counter(unsigned int c)
  {
    this->m_erase_counter = c;
  }
  void increment_erase_counter()
  {
    ++this->m_erase_counter;
  }

  /// Marks `facet` as visited
  void set_facet_visited (const int facet)
  {
    CGAL_precondition(facet>=0 && facet<4);
    char current_bits = bits_;

    while (!bits_.compare_exchange_weak(current_bits, current_bits | char(1 << facet)))
    {
      current_bits = bits_;
    }
  }

  /// Marks `facet` as not visited
  void reset_visited (const int facet)
  {
    CGAL_precondition(facet>=0 && facet<4);
    char current_bits = bits_;
    char mask = char(15 & ~(1 << facet));
    char wanted_value = current_bits & mask;
    while (!bits_.compare_exchange_weak(current_bits, wanted_value))
    {
      current_bits = bits_;
    }
  }

  /// Returns `true` if `facet` is marked as visited
  bool is_facet_visited (const int facet) const
  {
    CGAL_precondition(facet>=0 && facet<4);
    return ( (bits_ & char(1 << facet)) != 0 );
  }

  /// If the circumcenter is already set (weighted_circumcenter_ != nullptr),
  /// this function "deletes" cc
  void try_to_set_circumcenter(Point_3 *cc) const
  {
    Point_3* base_test = nullptr;
    if (!weighted_circumcenter_.compare_exchange_strong(base_test, cc))
      delete cc;
  }

private:
  typedef std::atomic<unsigned int> Erase_counter_type;
  Erase_counter_type                m_erase_counter;
  /// Stores visited facets (4 first bits)
  std::atomic<char> bits_;

protected:
  mutable std::atomic<Point_3*> weighted_circumcenter_;
};

#endif // CGAL_LINKED_WITH_TBB


// Class Compact_mesh_cell_base_3
// Cell base class used in 3D meshing process.
// Adds information to Cb about the cell of the input complex containing it
template< class Point_3,
          class Weighted_point_3,
          class Subdomain_index_,
          class Surface_patch_index_,
          class Index_,
          class TDS>
class Compact_mesh_cell_3
  : public Compact_mesh_cell_base_3_base<Point_3, typename TDS::Concurrency_tag>
{
  typedef Compact_mesh_cell_base_3_base<Point_3,typename TDS::Concurrency_tag> Base;
  using Base::weighted_circumcenter_;

public:
  typedef TDS                          Triangulation_data_structure;
  typedef typename TDS::Vertex_handle  Vertex_handle;
  typedef typename TDS::Cell_handle    Cell_handle;
  typedef typename TDS::Vertex         Vertex;
  typedef typename TDS::Cell           Cell;
  typedef typename TDS::Cell_data      TDS_data;


  // Index Type
  typedef Subdomain_index_      Subdomain_index;
  typedef Surface_patch_index_  Surface_patch_index;
  typedef Index_                Index;

  typedef Weighted_point_3      Point;


  typedef Point*                            Point_container;
  typedef Point*                            Point_iterator;
  typedef const Point*                      Point_const_iterator;

public:
  void invalidate_weighted_circumcenter_cache() const
  {
    if (!internal_tbb::is_null(weighted_circumcenter_)) {
      internal_tbb::delete_circumcenter(weighted_circumcenter_);
      internal_tbb::set_weighted_circumcenter(weighted_circumcenter_, nullptr);
    }
  }

public:
  // Constructors
  Compact_mesh_cell_3()
  {}

  Compact_mesh_cell_3(const Compact_mesh_cell_3& rhs)
    : N(rhs.N)
    , V(rhs.V)
#ifdef CGAL_INTRUSIVE_LIST
    , next_intrusive_(rhs.next_intrusive_)
    , previous_intrusive_(rhs.previous_intrusive_)
#endif
    , time_stamp_(rhs.time_stamp_)
    , sliver_value_(rhs.sliver_value_)
    , subdomain_index_(rhs.subdomain_index_)
    , sliver_cache_validity_(false)
  {
    for(int i=0; i <4; i++){
      surface_index_table_[i] = rhs.surface_index_table_[i];
      surface_center_table_[i]= rhs.surface_center_table_[i];
      surface_center_index_table_[i] = rhs.surface_center_index_table_[i];
    }
  }

  Compact_mesh_cell_3 (Vertex_handle v0,
                       Vertex_handle v1,
                       Vertex_handle v2,
                       Vertex_handle v3)
    : V(CGAL::make_array(v0, v1, v2, v3))
  {
  }


  Compact_mesh_cell_3 (Vertex_handle v0,
                       Vertex_handle v1,
                       Vertex_handle v2,
                       Vertex_handle v3,
                       Cell_handle n0,
                       Cell_handle n1,
                       Cell_handle n2,
                       Cell_handle n3)
    : N(CGAL::make_array(n0, n1, n2, n3))
    , V(CGAL::make_array(v0, v1, v2, v3))
  {
  }

  ~Compact_mesh_cell_3()
  {
    if(!internal_tbb::is_null(weighted_circumcenter_)){
      internal_tbb::delete_circumcenter(weighted_circumcenter_);
      internal_tbb::set_weighted_circumcenter(weighted_circumcenter_, nullptr);
    }
  }

  // ACCESS FUNCTIONS

  Vertex_handle vertex(int i) const
  {
    CGAL_precondition( i >= 0 && i <= 3 );
    return V[i];
  }

  bool has_vertex(Vertex_handle v) const
  {
    return (V[0] == v) || (V[1] == v) || (V[2]== v) || (V[3]== v);
  }

  bool has_vertex(Vertex_handle v, int & i) const
  {
    if (v == V[0]) { i = 0; return true; }
    if (v == V[1]) { i = 1; return true; }
    if (v == V[2]) { i = 2; return true; }
    if (v == V[3]) { i = 3; return true; }
    return false;
  }

  int index(Vertex_handle v) const
  {
    if (v == V[0]) { return 0; }
    if (v == V[1]) { return 1; }
    if (v == V[2]) { return 2; }
    CGAL_assertion( v == V[3] );
    return 3;
  }

  Cell_handle neighbor(int i) const
  {
    CGAL_precondition( i >= 0 && i <= 3);
    return N[i];
  }

  bool has_neighbor(Cell_handle n) const
  {
    return (N[0] == n) || (N[1] == n) || (N[2] == n) || (N[3] == n);
  }

  bool has_neighbor(Cell_handle n, int & i) const
  {
    if(n == N[0]){ i = 0; return true; }
    if(n == N[1]){ i = 1; return true; }
    if(n == N[2]){ i = 2; return true; }
    if(n == N[3]){ i = 3; return true; }
    return false;
  }

  int index(Cell_handle n) const
  {
    if (n == N[0]) return 0;
    if (n == N[1]) return 1;
    if (n == N[2]) return 2;
    CGAL_assertion( n == N[3] );
    return 3;
  }

  // SETTING


  void set_neighbor(int i, Cell_handle n)
  {
    CGAL_precondition( i >= 0 && i <= 3);
    CGAL_precondition( this != n.operator->() );
    N[i] = n;
  }


  void set_neighbors()
  {
    N[0] = N[1] = N[2] = N[3] = Cell_handle();
  }

  void set_neighbors(Cell_handle n0, Cell_handle n1,
                     Cell_handle n2, Cell_handle n3)
  {
    CGAL_precondition( this != n0.operator->() );
    CGAL_precondition( this != n1.operator->() );
    CGAL_precondition( this != n2.operator->() );
    CGAL_precondition( this != n3.operator->() );
    N[0] = n0;
    N[1] = n1;
    N[2] = n2;
    N[3] = n3;
  }

  // CHECKING

  // the following trivial is_valid enables
  // the user of derived cell base classes
  // to add their own purpose checking
  bool is_valid(bool = false, int = 0) const
  { return true; }

  // For use by Compact_container.
  void * for_compact_container() const { return N[0].for_compact_container(); }
  void for_compact_container(void *p) { N[0].for_compact_container(p); }

  // TDS internal data access functions.
        TDS_data& tds_data()       { return _tds_data; }
  const TDS_data& tds_data() const { return _tds_data; }


  Point_iterator hidden_points_begin() const { return hidden_points_end(); }
  Point_iterator hidden_points_end() const { return nullptr; }
  void hide_point (const Point&) const { }

  // We must override the functions that modify the vertices.
  // And if the point inside a vertex is modified, we fail,
  // but there's not much we can do for this now.
  void set_vertex(int i, Vertex_handle v)
  {
    CGAL_precondition( i >= 0 && i <= 3);
    invalidate_weighted_circumcenter_cache();
    V[i] = v;
  }

  void set_vertices()
  {
    invalidate_weighted_circumcenter_cache();
    V[0] = V[1] = V[2] = V[3] = Vertex_handle();
  }

  void set_vertices(Vertex_handle v0, Vertex_handle v1,
                    Vertex_handle v2, Vertex_handle v3)
  {
    invalidate_weighted_circumcenter_cache();
    V[0] = v0;
    V[1] = v1;
    V[2] = v2;
    V[3] = v3;
  }

  template<typename GT_>
  const Point_3& weighted_circumcenter(const GT_& gt) const
  {
    static_assert(std::is_same<Point_3,
      typename GT_::Construct_weighted_circumcenter_3::result_type>::value);
    if (internal_tbb::is_null(weighted_circumcenter_)) {
      this->try_to_set_circumcenter(
        new Point_3(gt.construct_weighted_circumcenter_3_object()
                        (this->vertex(0)->point(),
                         this->vertex(1)->point(),
                         this->vertex(2)->point(),
                         this->vertex(3)->point())));
    } else {
      CGAL_expensive_assertion(gt.construct_weighted_circumcenter_3_object()
                                (this->vertex(0)->point(),
                                 this->vertex(1)->point(),
                                 this->vertex(2)->point(),
                                 this->vertex(3)->point()) == *weighted_circumcenter_);
    }
    return *weighted_circumcenter_;
  }

  // Returns the index of the cell of the input complex that contains the cell
  Subdomain_index subdomain_index() const { return subdomain_index_; }

  // Sets the index of the cell of the input complex that contains the cell
  void set_subdomain_index(const Subdomain_index& index)
  { subdomain_index_ = index; }

  void set_sliver_value(double value)
  {
    sliver_cache_validity_ = true;
    sliver_value_ = value;
  }

  double sliver_value() const
  {
    CGAL_assertion(is_cache_valid());
    return sliver_value_;
  }

  bool is_cache_valid() const { return sliver_cache_validity_; }
  void reset_cache_validity() const { sliver_cache_validity_ = false;  }

  /// Set surface index of `facet` to `index`
  void set_surface_patch_index(const int facet, const Surface_patch_index& index)
  {
    CGAL_precondition(facet>=0 && facet<4);
    surface_index_table_[facet] = index;
  }

  /// Returns surface index of facet `facet`
  Surface_patch_index surface_patch_index(const int facet) const
  {
    CGAL_precondition(facet>=0 && facet<4);
    return surface_index_table_[facet];
  }

  /// Sets surface center of `facet` to `point`
  void set_facet_surface_center(const int facet, const Point_3& point)
  {
    CGAL_precondition(facet>=0 && facet<4);
    surface_center_table_[facet] = point;
  }

  /// Returns surface center of `facet`
  Point_3 get_facet_surface_center(const int facet) const
  {
    CGAL_precondition(facet>=0 && facet<4);
    return surface_center_table_[facet];
  }

  /// Sets surface center index of `facet` to `index`
  void set_facet_surface_center_index(const int facet, const Index& index)
  {
    CGAL_precondition(facet>=0 && facet<4);
    surface_center_index_table_[facet] = index;
  }

  /// Returns surface center of `facet`
  Index get_facet_surface_center_index(const int facet) const
  {
    CGAL_precondition(facet>=0 && facet<4);
    return surface_center_index_table_[facet];
  }

  /// Returns true if facet lies on a surface patch
  bool is_facet_on_surface(const int facet) const
  {
    CGAL_precondition(facet>=0 && facet<4);
    return ( !( Surface_patch_index() == surface_index_table_[facet] ));
  }

  // -----------------------------------
  // Backward Compatibility
  // -----------------------------------
#ifndef CGAL_MESH_3_NO_DEPRECATED_SURFACE_INDEX
  typedef Surface_patch_index   Surface_index;

  void set_surface_index(const int facet, const Surface_index& index)
  { set_surface_patch_index(facet,index); }

  /// Returns surface index of facet `facet`
  Surface_index surface_index(const int facet) const
  { return surface_patch_index(facet); }
#endif // CGAL_MESH_3_NO_DEPRECATED_SURFACE_INDEX
  // -----------------------------------
  // End backward Compatibility
  // -----------------------------------

  static
  std::string io_signature()
  {
    using Geom_traits = typename Kernel_traits<Point>::type;
    return
      Get_io_signature<Subdomain_index>()() + "+" +
      Get_io_signature<Regular_triangulation_cell_base_3<Geom_traits> >()()
      + "+(" + Get_io_signature<Surface_patch_index>()() + ")[4]";
  }

#ifdef CGAL_INTRUSIVE_LIST
public:
  Cell_handle next_intrusive() const { return next_intrusive_; }
  void set_next_intrusive(Cell_handle c)
  {
    next_intrusive_ = c;
  }

  Cell_handle previous_intrusive() const { return previous_intrusive_; }
  void set_previous_intrusive(Cell_handle c)
  {
    previous_intrusive_ = c;
  }
#endif // CGAL_INTRUSIVE_LIST

  /// For the determinism of Compact_container iterators
  ///@{
  typedef Tag_true Has_timestamp;

  std::size_t time_stamp() const {
    return time_stamp_;
  }
  void set_time_stamp(const std::size_t& ts) {
    time_stamp_ = ts;
  }
  ///@}

private:


  /// Stores surface_index for each facet of the cell
  std::array<Surface_patch_index, 4> surface_index_table_ = {};
  /// Stores surface center of each facet of the cell
  std::array<Point_3, 4> surface_center_table_ = {};
  /// Stores surface center index of each facet of the cell

  std::array<Cell_handle, 4> N;
  std::array<Vertex_handle, 4> V;

#ifdef CGAL_INTRUSIVE_LIST
  Cell_handle next_intrusive_ = {}, previous_intrusive_ = {};
#endif
  std::size_t time_stamp_ = Time_stamper<void>::invalid_time_stamp;

  std::array<Index, 4> surface_center_index_table_ = {};
  /// Stores visited facets (4 first bits)

  //  Point_container _hidden;

  double sliver_value_ = 0.;

  // The index of the cell of the input complex that contains me
  Subdomain_index subdomain_index_ = {};

  TDS_data      _tds_data;
  mutable bool sliver_cache_validity_ = false;

public:

  friend std::istream& operator>>(std::istream &is, Compact_mesh_cell_3 &c)
  {
    Subdomain_index index;
    if(IO::is_ascii(is))
      is >> index;
    else
      read(is, index);
    if(is) {
      c.set_subdomain_index(index);
      for(int i = 0; i < 4; ++i)
        {
          Surface_patch_index i2;
          if(IO::is_ascii(is))
            is >> IO::iformat(i2);
          else
            {
              read(is, i2);
            }
          c.set_surface_patch_index(i, i2);
        }
    }
    return is;
  }

  friend
  std::ostream& operator<<(std::ostream &os, const Compact_mesh_cell_3 &c)
  {
    if(IO::is_ascii(os))
      os << c.subdomain_index();
    else
      write(os, c.subdomain_index());
    for(int i = 0; i < 4; ++i)
      {
        if(IO::is_ascii(os))
          os << ' ' << IO::oformat(c.surface_patch_index(i));
        else
          write(os, c.surface_patch_index(i));
      }
    return os;
  }

};  // end class Compact_mesh_cell_3

/*!
\ingroup PkgMesh3MeshClasses

The class `Compact_mesh_cell_base_3<GT, MD>` is a model of the concept `MeshCellBase_3`.
It is designed to serve as cell base class for the 3D triangulation
used in the 3D mesh generation process. It is more compact in memory than
`Mesh_cell_base_3`.

\tparam GT is the geometric traits class.
It has to be a model of the concept `MeshTriangulationTraits_3`.

\tparam MD provides the types of indices used to identify
the faces of the input complex. It has to be a model
of the concept `MeshDomain_3`.

\tparam TDS is the triangulation data structure class to which cells
belong. That parameter is only used by the rebind mechanism (see
`::TriangulationDSCellBase_3::Rebind_TDS`). Users should always use the
default parameter value `void`.

\cgalModels{MeshCellBase_3}

\sa `CGAL::Mesh_complex_3_in_triangulation_3<Tr,CornerIndex,CurveIndex>`
\sa `CGAL::Mesh_cell_base_3<GT, MD, Cb>`

*/
template< class GT,
          class MD,
          class TDS = void >
class Compact_mesh_cell_base_3;

// Specialization for void.
template <typename GT, typename MD>
class Compact_mesh_cell_base_3<GT, MD, void>
{
public:
#ifdef DOXYGEN_RUNNING
  typedef unspecified_type                              Triangulation_data_structure;
#else
  typedef internal::Dummy_tds_3                         Triangulation_data_structure;
#endif
  typedef Triangulation_data_structure::Vertex_handle   Vertex_handle;
  typedef Triangulation_data_structure::Cell_handle     Cell_handle;
  template <typename TDS2>
  struct Rebind_TDS {
    typedef Compact_mesh_cell_3<typename GT::Point_3,
                                typename GT::Weighted_point_3,
                                typename MD::Subdomain_index,
                                typename MD::Surface_patch_index,
                                typename MD::Index,
                                TDS2> Other;
  };
};

template <typename GT,
  typename Subdomain_index,
  typename Surface_patch_index,
  typename Index>
class Compact_mesh_cell_generator_3
{
public:
#ifdef DOXYGEN_RUNNING
  typedef unspecified_type                              Triangulation_data_structure;
#else
  typedef internal::Dummy_tds_3                         Triangulation_data_structure;
#endif
  typedef Triangulation_data_structure::Vertex_handle   Vertex_handle;
  typedef Triangulation_data_structure::Cell_handle     Cell_handle;
  template <typename TDS2>
  struct Rebind_TDS {
    typedef Compact_mesh_cell_3<typename GT::Point_3,
                                typename GT::Weighted_point_3,
                                Subdomain_index,
                                Surface_patch_index,
                                Index,
                                TDS2> Other;
  };
};

}  // end namespace CGAL


#endif // CGAL_COMPACT_MESH_CELL_BASE_3_H
