#ifndef DUNE_ALU3DGRIDENTITY_HH
#define DUNE_ALU3DGRIDENTITY_HH

// System includes
#include <type_traits>

// Dune includes
#include <dune/grid/common/entity.hh>
#include <dune/alugrid/common/intersectioniteratorwrapper.hh>
#include <dune/alugrid/common/twists.hh>

// Local includes
#include "alu3dinclude.hh"
#include "iterator.hh"
#include "entityseed.hh"

namespace Dune
{

  // Forward declarations
  template<int cd, int dim, class GridImp>
  class ALU3dGridEntity;
  template<int cd, PartitionIteratorType pitype, class GridImp >
  class ALU3dGridLevelIterator;
  template<int cd, class GridImp >
  class ALU3dGridEntityPointer;
  template<int mydim, int coorddim, class GridImp>
  class ALU3dGridGeometry;
  template<class GridImp>
  class ALU3dGridHierarchicIterator;
  template<class GridImp>
  class ALU3dGridIntersectionIterator;
  template<int codim, PartitionIteratorType, class GridImp>
  class ALU3dGridLeafIterator;
  template<int dim, int dimworld, ALU3dGridElementType, class >
  class ALU3dGrid;

/*!
  A Grid is a container of grid entities. An entity is parametrized by the codimension.
  An entity of codimension c in dimension d is a d-c dimensional object.

  Here: the general template
 */
template<int cd, int dim, class GridImp>
class ALU3dGridEntity :
public EntityDefaultImplementation <cd,dim,GridImp,ALU3dGridEntity>
{
  // default just returns level
  template <class GridType, int cdim>
  struct GetLevel
  {
    template <class ItemType>
    static int getLevel(const GridType & grid, const ItemType & item )
    {
      return item.level();
    }
  };

  // for leaf vertices the level is somewhat difficult to obtain, because
  // this the maximum of levels of elements that have this vertex as sub
  // entity
  template <class GridType>
  struct GetLevel<GridType,dim>
  {
    template <class ItemType>
    static int getLevel(const GridType & grid, const ItemType & item)
    {
      return (item.isLeafEntity()) ? grid.getLevelOfLeafVertex(item) : item.level();
    }
  };

  enum { dimworld = GridImp::dimensionworld };

  typedef typename GridImp::MPICommunicatorType Comm;

  friend class ALU3dGrid< GridImp::dimension, GridImp::dimensionworld, GridImp::elementType, Comm >;
  friend class ALU3dGridEntity < 0, dim, GridImp >;
  friend class ALU3dGridLevelIterator < cd, All_Partition, GridImp >;

  friend class ALU3dGridHierarchicIndexSet< GridImp::dimension, GridImp::dimensionworld, GridImp::elementType, Comm >;

  template< class > friend class ALU3dGridFactory;

  typedef typename GridImp::Traits::template Codim< cd >::GeometryImpl GeometryImpl;

public:
  typedef ALU3dImplTraits< GridImp::elementType, Comm > ImplTraits;
  typedef typename ImplTraits::template Codim<dim, cd>::InterfaceType      HItemType;
  typedef typename ImplTraits::template Codim<dim, cd>::ImplementationType ItemType;
  typedef typename ImplTraits::VertexType   VertexType;
  typedef typename ImplTraits::HBndSegType  HBndSegType;

  typedef typename GridImp::template Codim<cd>::Entity Entity;
  typedef typename GridImp::template Codim<cd>::Geometry Geometry;

  typedef typename GridImp::template Codim<0>::EntityPointer EntityPointer;

  //! typedef of my type
  typedef typename GridImp::template Codim<cd>::EntitySeed EntitySeed;

  //! Constructor
  ALU3dGridEntity();

  //! construct entity from seed
  ALU3dGridEntity( const EntitySeed& seed );

  //! geometry of this entity
  Geometry geometry () const;

  //! type of geometry of this entity
  GeometryType type () const { return geo_.type(); }

  // set element as normal entity
  void setElement(const HItemType & item);
  void setElement(const HItemType & item, const GridImp& grid );
  void setElement(const HItemType & item, const int level, int twist=0);

  /* set entity from seed */
  void setElement(const EntitySeed& seed);

  //! setGhost is not valid for this codim
  void setGhost(const HBndSegType  &ghost);

  //! reset item pointer to NULL
  void removeElement ()
  {
    seed_.clear();
    geo_.invalidate();
  }

  //! compare 2 elements by comparing the item pointers
  bool equals ( const ALU3dGridEntity<cd,dim,GridImp> & org ) const
  {
    return seed_ == org.seed_;
  }

  //! set item from other entity, mainly for copy constructor of entity pointer
  void setEntity ( const ALU3dGridEntity<cd,dim,GridImp> & org );

  // return reference to internal item
  const ItemType& getItem () const { return *(static_cast<ItemType *> (seed_.item())); }

  //! return seed of entity
  EntitySeed seed() const { return seed_; }

  //! level of this element
  int level () const { return seed_.level(); }

  //! return partition type of this entity ( see grid.hh )
  PartitionType partitionType() const { return this->convertBndId( getItem() ); }

protected:
  //! index is unique within the grid hierarchy and per codim
  int getIndex () const { return getItem().getIndex(); }

  //! convert ALUGrid partition type to dune partition type
  PartitionType convertBndId(const HItemType & item) const ;

  //! the cuurent geometry
  mutable GeometryImpl geo_;

  //! the information necessary to make sense of this entity
  EntitySeed seed_;
};

/*!
  A Grid is a container of grid entities. An entity is parametrized by the codimension.
  An entity of codimension c in dimension d is a d-c dimensional object.

  Entities of codimension 0 ("elements") are defined through template specialization. Note
  that this specialization has an extended interface compared to the general case

  Entities of codimension 0  allow to visit all neighbors, where
  a neighbor is an entity of codimension 0 which has a common entity of codimension 1 with the
  These neighbors are accessed via an iterator. This allows the implementation of
  non-matching meshes. The number of neigbors may be different from the number of faces/edges
  of an element!
 */
//***********************
//
//  --ALU3dGridEntity
//  --0Entity
//
//***********************
template<int dim, class GridImp>
class ALU3dGridEntity<0,dim,GridImp>
: public EntityDefaultImplementation<0,dim,GridImp,ALU3dGridEntity>
{
  static const int dimworld = std::remove_const< GridImp >::type::dimensionworld;
  static const ALU3dGridElementType elementType = std::remove_const< GridImp >::type::elementType;

  typedef typename GridImp::MPICommunicatorType Comm;

  typedef ALU3dImplTraits< elementType, Comm > ImplTraits;
  typedef typename ImplTraits::template Codim<dim, 0>::InterfaceType     HElementType;

  typedef typename ImplTraits::GEOElementType  GEOElementType;
  typedef typename ImplTraits::BNDFaceType  BNDFaceType;
  typedef typename ImplTraits::IMPLElementType IMPLElementType;
  typedef typename ImplTraits::HBndSegType     HBndSegType;

  enum { refine_element_t  = ImplTraits::RefinementRules::refine_element_t  };
  enum { bisect_element_t  = ImplTraits::RefinementRules::bisect_element_t  };
  enum { coarse_element_t  = ImplTraits::RefinementRules::coarse_element_t  };
  enum { nosplit_element_t = ImplTraits::RefinementRules::nosplit_element_t };

  typedef typename ImplTraits::MarkRuleType MarkRuleType;

  friend class ALU3dGrid< GridImp::dimension, GridImp::dimensionworld, elementType, Comm >;
  friend class ALU3dGridIntersectionIterator < GridImp >;
  friend class ALU3dGridIntersectionIterator < const GridImp >;
  friend class ALU3dGridHierarchicIterator   < const GridImp >;
  friend class ALU3dGridHierarchicIterator   < GridImp >;
  friend class ALU3dGridLevelIterator <0,All_Partition,GridImp>;
  friend class ALU3dGridLevelIterator <1,All_Partition,GridImp>;
  friend class ALU3dGridLevelIterator <2,All_Partition,GridImp>;
  friend class ALU3dGridLevelIterator <3,All_Partition,GridImp>;
  friend class ALU3dGridLeafIterator <0, All_Partition,GridImp>;
  friend class ALU3dGridLeafIterator <1, All_Partition,GridImp>;
  friend class ALU3dGridLeafIterator <2, All_Partition,GridImp>;
  friend class ALU3dGridLeafIterator <3, All_Partition,GridImp>;

  friend class ALU3dGridHierarchicIndexSet< GridImp::dimension, GridImp::dimensionworld, elementType, Comm >;

  template< class > friend class ALU3dGridFactory;

  // type of reference element
  typedef typename GridImp :: ReferenceElementType ReferenceElementType;

  typedef typename GridImp::Traits::template Codim< 0 >::GeometryImpl GeometryImpl;
  typedef typename GridImp::Traits::template Codim< 0 >::LocalGeometryImpl LocalGeometryImpl;

public:
  typedef typename GridImp::template Codim< 0 >::Geometry Geometry;
  typedef typename GridImp::template Codim< 0 >::LocalGeometry LocalGeometry;
  typedef ALU3dGridIntersectionIterator<GridImp> IntersectionIteratorImp;

  typedef LeafIntersectionIteratorWrapper <GridImp>  ALU3dGridIntersectionIteratorType;
  typedef LeafIntersectionIteratorWrapper <GridImp>  ALU3dGridLeafIntersectionIteratorType;
  typedef LevelIntersectionIteratorWrapper<GridImp>  ALU3dGridLevelIntersectionIteratorType;

  typedef typename GridImp::template Codim<0>::Entity        Entity;
  typedef typename GridImp::template Codim<0>::EntityPointer EntityPointer;

  template <int cd>
  struct Codim
  {
    typedef typename GridImp::Traits::template Codim< cd >::Twists::Twist Twist;
    typedef typename GridImp::template Codim<cd>::EntityPointer EntityPointer;
  };

  //! typedef of my type
  typedef typename GridImp::template Codim<0>::EntitySeed  EntitySeed;

  //! Constructor creating empty Entity
  ALU3dGridEntity();

  //! Constructor taking an EntitySeed
  ALU3dGridEntity( const EntitySeed& seed );

  //! Constructor taking an interior Element
  ALU3dGridEntity( const HElementType& element );

  //! Constructor taking a ghost element
  ALU3dGridEntity( const HBndSegType& ghost );

  //! level of this element
  int level () const ;

  //! geometry of this entity
  Geometry geometry () const;

  //! type of geometry of this entity
  GeometryType type () const;

  //! return partition type of this entity ( see grid.hh )
  PartitionType partitionType() const;

  /*! Intra-element access to entities of codimension cc > codim. Return number of entities
      with codimension cc.
  */
  template<int cc> int count () const ;

  /*! Intra-element access to entities of codimension cc > codim. Return number of entities
      with codimension cc.
   */
  unsigned int subEntities (unsigned int codim) const;

  //! Provide access to mesh entity i of given codimension. Entities
  //!  are numbered 0 ... count<cc>()-1
  template< int codim >
  typename Codim< codim >::EntityPointer subEntity ( int i ) const;

  template< int codim >
  typename Codim< codim >::Twist twist ( int i ) const;

  //! returns true if Entity is leaf (i.e. has no children)
  bool isLeaf () const;

  //! Inter-level access to father element on coarser grid.
  //! Assumes that meshes are nested.
  EntityPointer father () const;

  //! returns true if father entity exists
  bool hasFather () const
  {
    return (this->level()>0);
  }

  /*! Location of this element relative to the reference element
    of the father. This is sufficient to interpolate all
    dofs in conforming case. Nonconforming may require access to
    neighbors of father and computations with local coordinates.
    On the fly case is somewhat inefficient since dofs  are visited
    several times. If we store interpolation matrices, this is tolerable.
    We assume that on-the-fly implementation of numerical algorithms
    is only done for simple discretizations. Assumes that meshes are nested.
  */
  LocalGeometry geometryInFather () const;

  /*! Inter-level access to son elements on higher levels<=maxlevel.
    This is provided for sparsely stored nested unstructured meshes.
    Returns iterator to first son.
  */
  ALU3dGridHierarchicIterator<GridImp> hbegin (int maxlevel) const;

  //! Returns iterator to one past the last son
  ALU3dGridHierarchicIterator<GridImp> hend (int maxlevel) const;

  //***************************************************************
  //  Interface for Adaptation
  //***************************************************************

  //! returns true, if entity was created during last adaptation cycle
  bool isNew () const;

  //! returns true, if entity might be coarsened during next adaptation cycle
  bool mightVanish () const;

  //! returns true, if entity has intersections with boundary
  bool hasBoundaryIntersections () const;

  // private method
  //! marks an element for refCount refines. if refCount is negative the
  //! element is coarsend -refCount times
  //! mark returns true if element was marked, otherwise false
  bool mark( const int refCount, const bool conformingRefinement ) const;

  //! \brief return current adaptation mark for this entity
  int getMark() const;

  /*! private methods, but public because of datahandle and template
      arguments of these methods
  */
  void setElement(HElementType &element);

  /* set entity from seed */
  void setElement(const EntitySeed& seed);

  //! set original element pointer to fake entity
  void setGhost(HBndSegType & ghost);

  //! set actual walk level
  void reset ( int l );

  //! set item pointer to NULL
  void removeElement();

  //! compare 2 entities, which means compare the item pointers
  bool equals ( const ALU3dGridEntity<0,dim,GridImp> & org ) const;

  void setEntity ( const ALU3dGridEntity<0,dim,GridImp> & org );

  //! return index of sub entity with codim = cc and local number i
  //! i.e. return global number of vertex i
  //! for use in hierarchical index set
  template<int cc> int getSubIndex (int i) const;

  //! return index of sub entity with codim = cc and local number i
  //! i.e. return global number of vertex i
  //! for use in hierarchical index set
  int subIndex(int i, unsigned int codim) const;

  // return reference to internal item
  const IMPLElementType& getItem () const { return *item_; }

  // return reference to internal item
  const BNDFaceType& getGhost () const
  {
    alugrid_assert ( isGhost() );
    return *ghost_;
  }

  //! returns true if entity is ghost
  bool isGhost () const{ return ImplTraits::isGhost( ghost_ ); }

  //! return key for this entity
  EntitySeed seed() const
  {
    if( isGhost() )
      return EntitySeed( getGhost () );
    else
      return EntitySeed( getItem() );
  }

  //! return macro id of this entity
  int macroId() const
  {
    return (isGhost()) ? getGhost().ldbVertexIndex() : getItem().ldbVertexIndex();
  }

  //! weight of entity (ie number of leaf elements underneath)
  int weight() const
  {
    return (isGhost()) ? 0 : getItem().weight();
  }

  //! return rank number of master process
  int master() const
  {
    return (isGhost()) ? getGhost().master() : getItem().master();
  }

protected:
  //! index is unique within the grid hierachy and per codim
  int getIndex () const;

  //! the entity's geometry
  mutable GeometryImpl geo_;

  // the current element of grid
  mutable IMPLElementType* item_;

  //! not zero if entity is ghost entity
  mutable BNDFaceType*  ghost_;

}; // end of ALU3dGridEntity codim = 0



//**********************************************************************
//
// --ALU3dGridEntityPointer
// --EntityPointer
// --EnPointer
/*!
 Enables iteration over all entities of a given codimension and level of a grid.
 */
template< int codim, class GridImp >
class ALU3dGridEntityPointerBase
{
  typedef ALU3dGridEntityPointerBase< codim, GridImp > ThisType;
  enum { dim       = GridImp::dimension };
  enum { dimworld  = GridImp::dimensionworld };

  typedef typename GridImp::MPICommunicatorType Comm;

  friend class ALU3dGridEntity<codim,dim,GridImp>;
  friend class ALU3dGridEntity< 0,dim,GridImp>;
  friend class ALU3dGrid < GridImp::dimension, GridImp::dimensionworld, GridImp::elementType, Comm >;

  typedef ALU3dImplTraits< GridImp::elementType, Comm > ImplTraits;
  typedef typename ImplTraits::template Codim<dim, codim>::InterfaceType HElementType;

  typedef typename ImplTraits::HBndSegType  HBndSegType;
  typedef typename ImplTraits::BNDFaceType BNDFaceType;
public:
  enum { codimension = codim };

  //! type of Entity
  typedef typename GridImp::template Codim<codimension>::Entity Entity;
  typedef Entity  EntityObject;
  typedef ALU3dGridEntity<codimension,dim, GridImp> EntityImp;

  //! typedef of my type
  typedef ThisType ALU3dGridEntityPointerType;

  //! make type of entity pointer implementation available in derived classes
  typedef ALU3dGridEntityPointer<codimension,GridImp> EntityPointerImp;

  //! type of entity seed
  typedef ALU3dGridEntitySeed<codimension, GridImp> ALU3dGridEntitySeedType;

  //! Constructor for EntityPointer that points to an element
  ALU3dGridEntityPointerBase(const HElementType & item);

  //! Constructor for EntityPointer that points to an ghost
  ALU3dGridEntityPointerBase(const HBndSegType & ghostFace );

  //! Constructor for EntityPointer that points to an ghost
  ALU3dGridEntityPointerBase(const ALU3dGridEntitySeedType& seed );

  //! copy constructor
  ALU3dGridEntityPointerBase(const ALU3dGridEntityPointerType & org);

  //! equality
  bool equals (const ALU3dGridEntityPointerType& i) const;

  //! assignment operator
  ThisType & operator = (const ThisType & org);

  //! dereferencing
  Entity
//#if ! DUNE_VERSION_NEWER(DUNE_GRID,2,4)
    & // need reference here for older versions
//#endif
  dereference () const
  {

    // don't dereference empty entity pointer
    alugrid_assert ( seed_.isValid() );
    alugrid_assert ( seed_.item() == & entityImp().getItem() );
    return entity_;
  }

  //! ask for level of entities
  int level () const { return seed_.level(); }

  //! default empty constructor
  ALU3dGridEntityPointerBase();

protected:
  // clones object
  void clone (const ALU3dGridEntityPointerType & org);

  //! has to be called when iterator is finished
  void done ();

  // update underlying item pointer and set ghost entity
  void updateGhostPointer( HBndSegType & ghostFace );

  // update underlying item pointer and set entity
  void updateEntityPointer( HElementType * item , int level = -1 );

  // key to gererate entity
  ALU3dGridEntitySeedType seed_;

  // entity that this EntityPointer points to
  mutable EntityObject entity_;

  // return reference to internal entity implementation
  EntityImp & entityImp () const {
    return GridImp :: getRealImplementation(entity_);
  }
};

//! ALUGridEntityPointer points to an entity
//! this class is the specialisation for codim 0,
//! it has exactly the same functionality as the ALU3dGridEntityPointerBase
template<class GridImp>
class ALU3dGridEntityPointer<0,GridImp> :
public ALU3dGridEntityPointerBase<0,GridImp>
{
protected:
  typedef ALU3dGridEntityPointerBase<0,GridImp> BaseType;

  enum { cd = 0 };
  typedef ALU3dGridEntityPointer <cd,GridImp> ThisType;
  enum { dim       = GridImp::dimension };
  enum { dimworld  = GridImp::dimensionworld };

  typedef typename GridImp::MPICommunicatorType Comm;

  friend class ALU3dGridEntity<cd,dim,GridImp>;
  friend class ALU3dGridEntity< 0,dim,GridImp>;
  friend class ALU3dGrid < GridImp::dimension, GridImp::dimensionworld, GridImp::elementType, Comm >;

  typedef ALU3dImplTraits< GridImp::elementType, Comm > ImplTraits;
  typedef typename ImplTraits::template Codim<dim, cd>::InterfaceType HElementType;

  typedef typename ImplTraits::HBndSegType HBndSegType;
  typedef typename ImplTraits::BNDFaceType BNDFaceType;

  typedef ALU3dGridEntity< 0,dim,GridImp> ALU3dGridEntityType ;

  using BaseType :: seed_;
  using BaseType :: entity_;
  using BaseType :: entityImp;
public:
  //! type of entity seed
  typedef ALU3dGridEntitySeed<cd, GridImp> ALU3dGridEntitySeedType;

  //! type of Entity
  typedef typename GridImp::template Codim<cd>::Entity Entity;

  //! typedef of my type
  typedef ThisType ALU3dGridEntityPointerType;

  //! Constructor for EntityPointer that points to an interior element
  ALU3dGridEntityPointer(const HElementType & item)
    : ALU3dGridEntityPointerBase<cd,GridImp> ( item )
  {}

  //! Constructor for EntityPointer that points to an ghost
  ALU3dGridEntityPointer(const HBndSegType & ghostFace )
    : ALU3dGridEntityPointerBase<cd,GridImp> ( ghostFace )
  {}

  //! Constructor for EntityPointer that points to given entity
  ALU3dGridEntityPointer(const ALU3dGridEntitySeedType& seed)
    : ALU3dGridEntityPointerBase<cd,GridImp> ( seed )
  {
  }

  //! Constructor for EntityPointer that points to an entity (interior or ghost)
  ALU3dGridEntityPointer(const ALU3dGridEntityType& entity)
    : ALU3dGridEntityPointerBase<cd,GridImp> ( entity.seed() )
  {
  }

  //! Constructor for EntityPointer init of Level-, and Leaf-, and
  //! HierarchicIterator
  ALU3dGridEntityPointer()
    : ALU3dGridEntityPointerBase<cd,GridImp> ()
  {}
};


template<int cd, class GridImp>
class ALU3dGridEntityPointer :
public ALU3dGridEntityPointerBase<cd,GridImp>
{
protected:
  typedef ALU3dGridEntityPointerBase<cd,GridImp> BaseType ;
  typedef ALU3dGridEntityPointer <cd,GridImp> ThisType;
  enum { dim       = GridImp::dimension };
  enum { dimworld  = GridImp::dimensionworld };

  typedef typename GridImp::MPICommunicatorType Comm;

  friend class ALU3dGridEntity<cd,dim,GridImp>;
  friend class ALU3dGridEntity< 0,dim,GridImp>;
  friend class ALU3dGrid < GridImp::dimension, GridImp::dimensionworld, GridImp::elementType, Comm >;

  typedef ALU3dImplTraits< GridImp::elementType, Comm > ImplTraits;
  typedef typename ImplTraits::template Codim<dim, cd>::InterfaceType HElementType;

  typedef typename ImplTraits::HBndSegType HBndSegType;
  typedef typename ImplTraits::BNDFaceType BNDFaceType;
  typedef ALU3dGridEntity<cd,dim,GridImp> ALU3dGridEntityType;

  using BaseType :: seed_;
  using BaseType :: entity_;
  using BaseType :: entityImp;

public:
  //! type of entity seed
  typedef ALU3dGridEntitySeed<cd, GridImp> ALU3dGridEntitySeedType;

  //! type of Entity
  typedef typename GridImp::template Codim<cd>::Entity Entity;

  //! typedef of my type
  typedef ALU3dGridEntityPointer<cd,GridImp> ALU3dGridEntityPointerType;

protected:
  static const int defaultValue = -665; //ALU3dGridEntityPointerType :: defaultValue;

public:
  //! Constructor for EntityPointer that points to given entity
  ALU3dGridEntityPointer(const ALU3dGridEntityType& entity)
    : ALU3dGridEntityPointerBase<cd,GridImp> ( entity.seed() )
  {}

  //! Constructor for EntityPointer that points to given entity
  ALU3dGridEntityPointer(const ALU3dGridEntitySeedType& seed)
    : ALU3dGridEntityPointerBase<cd,GridImp> ( seed )
  {}

  //! Constructor for EntityPointer init of Level-, and Leaf-, and
  //! HierarchicIterator
  ALU3dGridEntityPointer()
    : ALU3dGridEntityPointerBase<cd,GridImp> ()
  {}

protected:
  void updateEntityPointer( HElementType * item , int level );
};

} // end namespace Dune

#include "entity_inline.hh"

#if COMPILE_ALUGRID_INLINE
  #include "entity_imp.cc"
#endif

#endif