// Copyright (c) 2013 OPEN CASCADE SAS
//
// This file is part of Open CASCADE Technology software library.
//
// This library is free software; you can redistribute it and/or modify it under
// the terms of the GNU Lesser General Public License version 2.1 as published
// by the Free Software Foundation, with special exception defined in the file
// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
// distribution for complete text of the license and disclaimer of any warranty.
//
// Alternatively, this file may be used under the terms of Open CASCADE
// commercial license or contractual agreement.

#ifndef _BRepMesh_Edge_HeaderFile
#define _BRepMesh_Edge_HeaderFile

#include <Standard.hxx>
#include <BRepMesh_DegreeOfFreedom.hxx>
#include <BRepMesh_OrientedEdge.hxx>
#include <Standard_HashUtils.hxx>

//! Light weighted structure representing link of the mesh.
class BRepMesh_Edge : public BRepMesh_OrientedEdge
{
public:
  //! Default constructor.
  BRepMesh_Edge()
      : BRepMesh_OrientedEdge(),
        myMovability(BRepMesh_Deleted)
  {
  }

  //! Constructs a link between two vertices.
  BRepMesh_Edge(const Standard_Integer         theFirstNode,
                const Standard_Integer         theLastNode,
                const BRepMesh_DegreeOfFreedom theMovability)
      : BRepMesh_OrientedEdge(theFirstNode, theLastNode),
        myMovability(theMovability)
  {
  }

  //! Returns movability flag of the Link.
  BRepMesh_DegreeOfFreedom Movability() const { return myMovability; }

  //! Sets movability flag of the Link.
  //! @param theMovability flag to be set.
  void SetMovability(const BRepMesh_DegreeOfFreedom theMovability) { myMovability = theMovability; }

  //! Checks if the given edge and this one have the same orientation.
  //! @param theOther edge to be checked against this one.
  //! \return TRUE if edges have the same orientation, FALSE if not.
  Standard_Boolean IsSameOrientation(const BRepMesh_Edge& theOther) const
  {
    return BRepMesh_OrientedEdge::IsEqual(theOther);
  }

  //! Checks for equality with another edge.
  //! @param theOther edge to be checked against this one.
  //! @return TRUE if equal, FALSE if not.
  Standard_Boolean IsEqual(const BRepMesh_Edge& theOther) const
  {
    if (myMovability == BRepMesh_Deleted || theOther.myMovability == BRepMesh_Deleted)
      return Standard_False;

    return IsSameOrientation(theOther)
           || (FirstNode() == theOther.LastNode() && LastNode() == theOther.FirstNode());
  }

  //! Alias for IsEqual.
  Standard_Boolean operator==(const BRepMesh_Edge& Other) const { return IsEqual(Other); }

private:
  BRepMesh_DegreeOfFreedom myMovability;
};

namespace std
{
template <>
struct hash<BRepMesh_Edge>
{
  size_t operator()(const BRepMesh_Edge& theEdge) const noexcept
  {
    union Combination {
      unsigned short Arr[2]; // Node can be represented as a short
      uint32_t       Hash;

    } aCombination;

    aCombination.Arr[0] = static_cast<unsigned short>(theEdge.FirstNode());
    aCombination.Arr[1] = static_cast<unsigned short>(theEdge.LastNode());
    if (aCombination.Arr[0] > aCombination.Arr[1])
    {
      std::swap(aCombination.Arr[0], aCombination.Arr[1]);
    }
    return static_cast<size_t>(aCombination.Hash);
  }
};
} // namespace std

#endif