/*=========================================================================

 Program:   Visualization Toolkit
 Module:    vtkStructuredGridConnectivity.h

 Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
 All rights reserved.
 See Copyright.txt or http://www.kitware.com/Copyright.htm for details.

 This software is distributed WITHOUT ANY WARRANTY; without even
 the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 PURPOSE.  See the above copyright notice for more information.

 =========================================================================*/
/**
 * @class   vtkStructuredGridConnectivity
 *
 *
 *  vtkStructuredGridConnectivity is a concrete instance of vtkObject that
 *  implements functionality for computing the neighboring topology within a
 *  single partitioned structured grid dataset. This class implementation does
 *  not have any support for distributed data. For the parallel implementation
 *  see vtkPStructuredGridConnectivity.
 *
 * @sa
 *  vtkGhostArray vtkPStructuredGridConnectivity
*/

#ifndef vtkStructuredGridConnectivity_h
#define vtkStructuredGridConnectivity_h

#define VTK_NO_OVERLAP      0
#define VTK_NODE_OVERLAP    1
#define VTK_EDGE_OVERLAP    2
#define VTK_PARTIAL_OVERLAP 3

// VTK include directives
#include "vtkFiltersGeometryModule.h" // For export macro
#include "vtkAbstractGridConnectivity.h"
#include "vtkStructuredNeighbor.h" // For Structured Neighbor object definition
#include "vtkStructuredData.h" // For data description definitions

// C++ include directives
#include <iostream> // For cout
#include <vector>   // For STL vector
#include <map>      // For STL map
#include <utility>  // For STL pair and overloaded relational operators
#include <cassert>  // For assert()

// Forward Declarations
class vtkIdList;
class vtkUnsignedCharArray;
class vtkPointData;
class vtkCellData;
class vtkPoints;

class VTKFILTERSGEOMETRY_EXPORT vtkStructuredGridConnectivity :
  public vtkAbstractGridConnectivity
{
public:
  static vtkStructuredGridConnectivity* New();
  vtkTypeMacro( vtkStructuredGridConnectivity, vtkAbstractGridConnectivity );
  void PrintSelf(ostream& os, vtkIndent  indent ) override;

  //@{
  /**
   * Set/Get the whole extent of the grid
   */
  vtkSetVector6Macro(WholeExtent,int);
  vtkGetVector6Macro(WholeExtent,int);
  //@}

  //@{
  /**
   * Returns the data dimension based on the whole extent
   */
  vtkGetMacro(DataDimension,int);
  //@}

  /**
   * Set/Get the total number of domains distributed among processors
   */
  void SetNumberOfGrids( const unsigned int N ) override;

  /**
   * Registers the current grid corresponding to the grid ID by its global
   * extent w.r.t. the whole extent.
   */
  virtual void RegisterGrid( const int gridID, int extents[6],
      vtkUnsignedCharArray* nodesGhostArray,
      vtkUnsignedCharArray* cellGhostArray,
      vtkPointData* pointData,
      vtkCellData* cellData,
      vtkPoints* gridNodes );

  /**
   * Returns the grid extent of the grid corresponding to the given grid ID.
   */
  void GetGridExtent( const int gridID, int extent[6] );

  /**
   * Sets the ghosted grid extent for the grid corresponding to the given
   * grid ID to the given extent.
   */
  void SetGhostedGridExtent( const int gridID, int ext[6] );

  /**
   * Returns the ghosted grid extent for the block corresponding the
   */
  void GetGhostedGridExtent( const int gridID, int ext[6] );

  /**
   * Computes neighboring information
   */
  void ComputeNeighbors() override;

  /**
   * Returns the number of neighbors for the grid corresponding to the given
   * grid ID.
   */
  int GetNumberOfNeighbors( const int gridID )
    { return( static_cast<int>(this->Neighbors[ gridID ].size() )); };

  /**
   * Returns the neighbor corresponding to the index nei for the grid with the
   * given (global) grid ID.
   */
  vtkStructuredNeighbor GetGridNeighbor(const int gridID, const int nei);

  /**
   * Returns the list of neighboring blocks for the given grid and the
   * corresponding overlapping extents are filled in the 1-D flat array
   * strided by 6.

   * NOTE: the flat array extents must be pre-allocated.
   */
  vtkIdList* GetNeighbors( const int gridID, int *extents );

  /**
   * Fills the mesh property arrays, nodes and cells, for the grid
   * corresponding to the given grid ID.
   * NOTE: this method assumes that ComputeNeighbors() has been called.
   */
  void FillGhostArrays(
     const int gridID,
     vtkUnsignedCharArray *nodesArray,
     vtkUnsignedCharArray *cellsArray ) override;

  /**
   * Creates ghost layers.
   */
  void CreateGhostLayers( const int N=1 ) override;

protected:
  vtkStructuredGridConnectivity();
  ~vtkStructuredGridConnectivity() override;

  /**
   * Returns true iff Lo <= idx <= Hi, otherwise false.
   */
  bool InBounds( const int idx, const int Lo, const int Hi )
  { return( (idx>=Lo) && (idx<=Hi) ); };

  /**
   * Returns true iff Lo < idx < Hi, otherwise false.
   */
  bool StrictlyInsideBounds( const int idx, const int Lo, const int Hi )
  { return( (idx > Lo) && (idx < Hi) ); };

  /**
   * Returns true iff A is a subset of B, otherwise false.
   */
  bool IsSubset( int A[2], int B[2] )
  { return( this->InBounds(A[0], B[0], B[1]) &&
            this->InBounds(A[1], B[0], B[1]) ); };

  /**
   * Returns the cardinality of a range S.
   */
  int Cardinality( int S[2] ) { return( S[1]-S[0]+1 ); };

  //@{
  /**
   * Returns the number of nodes per cell according to the given dimension.
   */
  int GetNumberOfNodesPerCell( const int dim )
  {
      int numNodes = 0;
      switch( dim )
      {
        case 1:
         numNodes = 2; // line cell
         break;
        case 2:
         numNodes = 4; // quad cell
         break;
        case 3:
         numNodes = 8; // hex cell
         break;
        default:
         assert( "ERROR: code should not reach here!" && false );
      } // END switch
      return( numNodes );
  }
  //@}

  /**
   * Fills the ghost array for the nodes
   */
  void FillNodesGhostArray(
      const int gridID, const int dataDescription,
      int GridExtent[6], int RealExtent[6], vtkUnsignedCharArray *nodeArray );

  /**
   * Fills the ghost array for the grid cells
   */
  void FillCellsGhostArray(
      const int dataDescription, const int numNodesPerCell,
      int dims[3], int CellExtent[6], vtkUnsignedCharArray *nodesArray,
      vtkUnsignedCharArray *cellsArray );

  /**
   * Given a point (i,j,k) belonging to the grid corresponding to the given
   * gridID, this method searches for the grids that this point is neighboring
   * with.
   */
  void SearchNeighbors(
      const int gridID,
      const int i, const int j, const int k,
      vtkIdList *neiList );

  /**
   * Marks the node properties with the node with the given global i,j,k
   * grid coordinates w.r.t. to the grid defined by the given extent ext.
   */
  void MarkNodeProperty(
      const int gridID,
      const int i, const int j, const int k,
      int ext[6], int RealExtent[6], unsigned char &pfield );

  /**
   * Marks the cell property for the cell composed by the nodes with the
   * given ghost fields.
   */
  void MarkCellProperty(
      unsigned char &pfield,
      unsigned char *nodeGhostFields, const int numNodes );

  /**
   * Given a grid extent, this method computes the RealExtent.
   */
  void GetRealExtent( const int gridID, int GridExtent[6],int RealExtent[6] );

  /**
   * Checks if the node corresponding to the given global i,j,k coordinates
   * is a ghost node or not.
   */
  bool IsGhostNode(
      int GridExtent[6], int RealExtent[6],
      const int i, const int j, const int k );

  /**
   * Checks if the node corresponding to the given global i,j,k coordinates
   * is on the boundary of the given extent.
   */
  bool IsNodeOnBoundaryOfExtent(
      const int i, const int j, const int k, int ext[6] );

  /**
   * Checks if the node corresponding to the given global i,j,k coordinates
   * is on the shared boundary, i.e., a partition interface.
   * NOTE: A node on a shared boundary, may also be on a real boundary.
   */
  bool IsNodeOnSharedBoundary(
      const int gridID, int RealExtent[6],
      const int i, const int j, const int k );

  /**
   * Checks if the node corresponding to the given global i,j,k coordinates
   * touches the real boundaries of the domain given the whole extent.
   */
  bool IsNodeOnBoundary( const int i, const int j, const int k );

  /**
   * Checks if the node, corresponding to the given global i,j,k coordinates
   * is within the interior of the given global grid extent.
   */
  bool IsNodeInterior(
      const int i, const int j, const int k,
      int GridExtent[6] );

  /**
   * Checks if the node corresponding to the given global i,j,k coordinates
   * is within the given extent, inclusive of the extent bounds.
   */
  bool IsNodeWithinExtent(
      const int i, const int j, const int k,
      int GridExtent[6] )
  {
    bool status = false;

    switch( this->DataDescription )
    {
      case VTK_X_LINE:
        if( (GridExtent[0] <= i) && (i <= GridExtent[1]) )
        {
          status = true;
        }
        break;
      case VTK_Y_LINE:
        if( (GridExtent[2] <= j) && (j <= GridExtent[3] ) )
        {
          status = true;
        }
        break;
      case VTK_Z_LINE:
        if( (GridExtent[4] <= k) && (k <= GridExtent[5] ) )
        {
          status = true;
        }
        break;
      case VTK_XY_PLANE:
        if( (GridExtent[0] <= i) && (i <= GridExtent[1]) &&
            (GridExtent[2] <= j) && (j <= GridExtent[3])  )
        {
          status = true;
        }
        break;
      case VTK_YZ_PLANE:
        if( (GridExtent[2] <= j) && (j <= GridExtent[3] ) &&
            (GridExtent[4] <= k) && (k <= GridExtent[5] ) )
        {
          status = true;
        }
        break;
      case VTK_XZ_PLANE:
        if( (GridExtent[0] <= i) && (i <= GridExtent[1] ) &&
            (GridExtent[4] <= k) && (k <= GridExtent[5] ) )
        {
          status = true;
        }
        break;
      case VTK_XYZ_GRID:
        if( (GridExtent[0] <= i) && (i <= GridExtent[1]) &&
            (GridExtent[2] <= j) && (j <= GridExtent[3]) &&
            (GridExtent[4] <= k) && (k <= GridExtent[5]) )
        {
          status = true;
        }
        break;
      default:
        std::cout << "Data description is: " << this->DataDescription << "\n";
        std::cout.flush();
        assert( "pre: Undefined data-description!" && false );
    } // END switch

    return( status );
  }

  /**
   * Creates a neighbor from i-to-j and from j-to-i.
   */
  void SetNeighbors(
      const int i, const int j,
      int i2jOrientation[3], int j2iOrientation[3],
      int overlapExtent[6] );

  /**
   * Given two overlapping extents A,B and the corresponding overlap extent
   * this method computes A's relative neighboring orientation
   * w.r.t to its neighbor, B. The resulting orientation is stored in an
   * integer 3-tuple that holds the orientation of A relative to B alone each
   * axis, i, j, k. See vtkStructuredNeighbor::NeighborOrientation for a list
   * of valid orientation values.
   */
  void DetermineNeighborOrientation(
      const int  idx, int A[2], int B[2], int overlap[2], int orient[3] );

  /**
   * Detects if the two extents, ex1 and ex2, corresponding to the grids
   * with grid IDs i,j respectively, are neighbors, i.e, they either share
   * a corner, an edge or a plane in 3-D.
   */
  void DetectNeighbors(
      const int i, const int j, int ex1[6], int ex2[6],
      int orientation[3], int ndim);

  /**
   * Checks if the intervals A,B overlap. The intersection of A,B is returned
   * in the overlap array and a return code is used to indicate the type of
   * overlap. The return values are defined as follows:
   * VTK_NO_OVERLAP      0
   * VTK_NODE_OVERLAP    1
   * VTK_EDGE_OVERLAP    2
   * VTK_PARTIAL_OVERLAP 3
   */
  int IntervalOverlap( int A[2], int B[2], int overlap[2] );

  /**
   * Checks if the internals s,S partially overlap where |s| < |S|.
   * The intersection of s,S is stored in the supplied overlap array and a
   * return code is used to indicate the type of overlap. The return values
   * are defined as follows:
   * VTK_NO_OVERLAP      0
   * VTK_NODE_OVERLAP    1
   * VTK_PARTIAL_OVERLAP 3
   */
  int DoPartialOverlap( int s[2], int S[2], int overlap[2] );

  /**
   * Checks if the intervals A,B partially overlap. The region of partial
   * overlap is returned in the provided overlap array and a return code is
   * used to indicate whether there is partial overlap or not. The return
   * values are defined as follows:
   * VTK_NO_OVERLAP      0
   * VTK_NODE_OVERLAP    1
   * VTK_PARTIAL_OVERLAP 3
   */
  int PartialOverlap(
      int A[2], const int CofA,
      int B[2], const int CofB,
      int overlap[2] );

  /**
   * Establishes the neighboring information between the two grids
   * corresponding to grid ids "i" and "j" with i < j.
   */
  void EstablishNeighbors( const int i, const int j );

  /**
   * Based on the user-supplied WholeExtent, this method determines the
   * topology of the structured domain, e.g., VTK_XYZ_GRID, VTK_XY_PLANE, etc.
   */
  void AcquireDataDescription();

  /**
   * Checks if the block corresponding to the given grid ID has a block
   * adjacent to it in the given block direction.
   * NOTE: The block direction is essentially one of the 6 faces of the
   * block defined as follows:
   * <ul>
   * <li> FRONT  = 0 (+k diretion)  </li>
   * <li> BACK   = 1 (-k direction) </li>
   * <li> RIGHT  = 2 (+i direction) </li>
   * <li> LEFT   = 3 (-i direction) </li>
   * <li> TOP    = 4 (+j direction) </li>
   * <li> BOTTOM = 5 (-j direction) </li>
   * </ul>
   */
  bool HasBlockConnection( const int gridID, const int blockDirection );

  /**
   * Removes a block connection along the given direction for the block
   * corresponding to the given gridID.
   * NOTE: The block direction is essentially one of the 6 faces of the
   * block defined as follows:
   * <ul>
   * <li> FRONT  = 0 (+k diretion)  </li>
   * <li> BACK   = 1 (-k direction) </li>
   * <li> RIGHT  = 2 (+i direction) </li>
   * <li> LEFT   = 3 (-i direction) </li>
   * <li> TOP    = 4 (+j direction) </li>
   * <li> BOTTOM = 5 (-j direction) </li>
   * </ul>
   */
  void RemoveBlockConnection( const int gridID, const int blockDirection );

  /**
   * Adds a block connection along the given direction for the block
   * corresponding to the given gridID.
   * NOTE: The block direction is essentially one of the 6 faces of the
   * block defined as follows:
   * <ul>
   * <li> FRONT  = 0 (+k diretion)  </li>
   * <li> BACK   = 1 (-k direction) </li>
   * <li> RIGHT  = 2 (+i direction) </li>
   * <li> LEFT   = 3 (-i direction) </li>
   * <li> TOP    = 4 (+j direction) </li>
   * <li> BOTTOM = 5 (-j direction) </li>
   * </ul>
   */
  void AddBlockConnection( const int gridID, const int blockDirection );

  /**
   * Clears all block connections for the block corresponding to the given
   * grid ID.
   */
  void ClearBlockConnections( const int gridID );

  /**
   * Returns the number of faces of the block corresponding to the given grid
   * ID that are adjacent to at least one other block. Note, this is not the
   * total number of neighbors for the block. This method simply checks how
   * many out of the 6 block faces have connections. Thus, the return value
   * has an upper-bound of 6.
   */
  int GetNumberOfConnectingBlockFaces( const int gridID );

  /**
   * Sets the block topology connections for the grid corresponding to gridID.
   */
  void SetBlockTopology( const int gridID );

  /**
   * Given i-j-k coordinates and the grid defined by tis extent, ext, this
   * method determines IJK orientation with respect to the block boundaries,
   * i.e., the 6 block faces. If the node is not on a boundary, then
   * orientation[i] = BlockFace::NOT_ON_BLOCK_FACE for all i in [0,2].
   */
  void GetIJKBlockOrientation(
      const int i, const int j, const int k, int ext[6], int orientation[3] );

  /**
   * A helper method that computes the 1-D i-j-k orientation to facilitate the
   * implementation of GetNodeBlockOrientation.
   */
  int Get1DOrientation(
      const int idx, const int ExtentLo, const int ExtentHi,
      const int OnLo, const int OnHi, const int NotOnBoundary );

  /**
   * Creates the ghosted extent of the grid corresponding to the given
   * gridID.
   */
  void CreateGhostedExtent( const int gridID, const int N );

  /**
   * Gets the ghosted extent from the given grid extent along the dimension
   * given by minIdx and maxIdx. This method is a helper method for the
   * implementation of CreateGhostedExtent.
   */
  void GetGhostedExtent(
      int *ghostedExtent, int GridExtent[6],
      const int minIdx, const int maxIdx, const int N);

  /**
   * This method creates the ghosted mask arrays, i.e., the NodeGhostArrays
   * and the CellGhostArrays for the grid corresponding to the given gridID.
   */
  void CreateGhostedMaskArrays(const int gridID);

  /**
   * This method initializes the ghost data according to the computed ghosted
   * grid extent for the grid with the given grid ID. Specifically, PointData,
   * CellData and grid coordinates are allocated for the ghosted grid
   * accordingly.
   */
  void InitializeGhostData( const int gridID );

  /**
   * Adds/creates all the arrays in the reference grid point data, RPD, to
   * the user-supplied point data instance, PD, where the number of points
   * is given by N.
   */
  void AllocatePointData( vtkPointData *RPD, const int N, vtkPointData *PD );

  /**
   * Adds/creates all the arrays in the reference grid cell data, RCD, to the
   * user-supplied cell data instance, CD, where the number of cells is given
   * by N.
   */
  void AllocateCellData( vtkCellData *RCD, const int N, vtkCellData *CD );

  /**
   * This method transfers the registered grid data to the corresponding
   * ghosted grid data.
   */
  void TransferRegisteredDataToGhostedData( const int gridID );

  /**
   * This method computes, the send and rcv extents for each neighbor of
   * each grid.
   */
  void ComputeNeighborSendAndRcvExtent( const int gridID, const int N );

  /**
   * This method transfers the fields (point data and cell data) to the
   * ghost extents from the neighboring grids of the grid corresponding
   * to the given gridID.
   */
  virtual void TransferGhostDataFromNeighbors( const int gridID );

  /**
   * This method transfers the fields
   */
  void TransferLocalNeighborData(
      const int gridID, const vtkStructuredNeighbor& Neighor);

  /**
   * Copies the coordinates from the source points to the target points.
   */
  void CopyCoordinates(
      vtkPoints *source, vtkIdType sourceIdx,
      vtkPoints *target, vtkIdType targetIdx );

  /**
   * Loops through all arrays in the source and for each array, it copies the
   * tuples from sourceIdx to the target at targetIdx. This method assumes
   * that the source and target have a one-to-one array correspondence, that
   * is array i in the source corresponds to array i in the target.
   */
  void CopyFieldData(
      vtkFieldData *source, vtkIdType sourceIdx,
      vtkFieldData *target, vtkIdType targetIdx );

  /**
   * Given a global grid ID and the neighbor grid ID, this method returns the
   * neighbor index w.r.t. the Neighbors list of the grid with grid ID
   * gridIdx.
   */
  int GetNeighborIndex( const int gridIdx, const int NeighborGridIdx );

  /**
   * Prints the extent, used for debugging
   */
  void PrintExtent( int extent[6] );

  int DataDimension;
  int DataDescription;
  int WholeExtent[6];

  std::vector< int > GridExtents;
  std::vector< int > GhostedExtents;
  std::vector< unsigned char  > BlockTopology;
  std::vector< std::vector<vtkStructuredNeighbor> > Neighbors;
  std::map< std::pair< int,int >, int > NeighborPair2NeighborListIndex;

private:
  vtkStructuredGridConnectivity( const vtkStructuredGridConnectivity& ) = delete;
  void operator=(const vtkStructuredGridConnectivity& ) = delete;
};

//=============================================================================
//  INLINE METHODS
//=============================================================================

//------------------------------------------------------------------------------
inline int vtkStructuredGridConnectivity::GetNeighborIndex(
    const int gridIdx, const int NeighborGridIdx )
{
  assert("pre: Grid index is out-of-bounds!" &&
         (gridIdx >= 0) &&
         (gridIdx < static_cast<int>(this->NumberOfGrids)));
  assert("pre: Neighbor grid index is out-of-bounds!" &&
         (NeighborGridIdx >= 0) &&
         (NeighborGridIdx < static_cast<int>(this->NumberOfGrids) ) );

  std::pair<int,int> gridPair = std::make_pair(gridIdx,NeighborGridIdx);
  assert("pre: Neighboring grid pair does not exist in hash!" &&
         (this->NeighborPair2NeighborListIndex.find(gridPair) !=
             this->NeighborPair2NeighborListIndex.end() ) );

  return(this->NeighborPair2NeighborListIndex[gridPair]);
}

//------------------------------------------------------------------------------
inline void vtkStructuredGridConnectivity::GetGhostedExtent(
    int *ghostedExtent, int GridExtent[6],
    const int minIdx, const int maxIdx, const int N )
{
  assert( "pre: Number of ghost layers must be N >= 1" && (N >= 1) );
  assert( "pre: ghosted extent pointer is nullptr" && ghostedExtent != nullptr);

  ghostedExtent[minIdx] = GridExtent[minIdx]-N;
  ghostedExtent[maxIdx] = GridExtent[maxIdx]+N;

  // Clamp the ghosted extent to be within the WholeExtent
  ghostedExtent[minIdx] =
   (ghostedExtent[minIdx] < this->WholeExtent[minIdx] )?
       this->WholeExtent[minIdx] : ghostedExtent[minIdx];
  ghostedExtent[maxIdx] =
   (ghostedExtent[maxIdx] > this->WholeExtent[maxIdx])?
       this->WholeExtent[maxIdx] : ghostedExtent[maxIdx];
}

//------------------------------------------------------------------------------
inline void vtkStructuredGridConnectivity::SetGhostedGridExtent(
    const int gridID, int ext[6] )
{
  assert( "pre: gridID is out-of-bounds" &&
          (gridID >= 0) && (gridID < static_cast<int>(this->NumberOfGrids)));
  assert( "pre: ghosted-extents vector has not been allocated" &&
          (this->NumberOfGrids == this->GhostedExtents.size()/6 ) );

  for( int i=0; i < 6; ++i )
  {
    this->GhostedExtents[ gridID*6+i ] = ext[i];
  }
}

//------------------------------------------------------------------------------
inline void vtkStructuredGridConnectivity::GetGridExtent(
    const int gridID, int ext[6])
{
  assert( "pre: gridID out-of-bounds!" &&
        (gridID >= 0  && gridID < static_cast<int>(this->NumberOfGrids)));
  for( int i=0; i < 6; ++i )
  {
    ext[i] = this->GridExtents[ gridID*6+i ];
  }
}

//------------------------------------------------------------------------------
inline void vtkStructuredGridConnectivity::GetGhostedGridExtent(
    const int gridID, int ext[6])
{
  assert( "pre: gridID out-of-bounds!" &&
        (gridID >= 0  && gridID < static_cast<int>(this->NumberOfGrids)));

  if( this->GhostedExtents.size() == 0 )
  {
    ext[0] = ext[2] = ext[4] = -1;
    ext[1] = ext[3] = ext[5] = 0;
    vtkErrorMacro( "No ghosted extents found for registered grid extends!!!" );
    return;
  }

  assert( "GhostedExtents are not aligned with registered grid extents" &&
        ( this->GhostedExtents.size() == this->GridExtents.size() ) );
  for( int i=0; i < 6; ++i )
  {
    ext[i] = this->GhostedExtents[ gridID*6+i ];
  }
}

//------------------------------------------------------------------------------
inline bool vtkStructuredGridConnectivity::IsNodeOnBoundaryOfExtent(
    const int i, const int j, const int k, int ext[6] )
{
  if( !this->IsNodeWithinExtent( i,j,k, ext) )
  {
    return false;
  }

  bool status = false;
  switch( this->DataDescription )
  {
    case VTK_X_LINE:
       if( i==ext[0] || i==ext[1] )
       {
         status = true;
       }
       break;
     case VTK_Y_LINE:
       if( j==ext[2] || j==ext[3] )
       {
         status = true;
       }
       break;
     case VTK_Z_LINE:
       if( k==ext[4] || k==ext[5] )
       {
         status = true;
       }
       break;
     case VTK_XY_PLANE:
       if( (i==ext[0] || i==ext[1]) ||
           (j==ext[2] || j==ext[3]) )
       {
         status = true;
       }
       break;
     case VTK_YZ_PLANE:
       if( (j==ext[2] || j==ext[3]) ||
           (k==ext[4] || k==ext[5]) )
       {
         status = true;
       }
       break;
     case VTK_XZ_PLANE:
       if( (i==ext[0] || i==ext[1]) ||
           (k==ext[4] || k==ext[5]) )
       {
         status = true;
       }
       break;
     case VTK_XYZ_GRID:
       if( (i==ext[0] || i==ext[1]) ||
           (j==ext[2] || j==ext[3]) ||
           (k==ext[4] || k==ext[5]) )
       {
         status = true;
       }
       break;
     default:
       std::cout << "Data description is: " << this->DataDescription << "\n";
       std::cout.flush();
       assert( "pre: Undefined data-description!" && false );
  } // END switch

  return( status );
}

//------------------------------------------------------------------------------
inline bool vtkStructuredGridConnectivity::IsNodeInterior(
    const int i, const int j, const int k,
    int GridExtent[6] )
{
  bool status = false;

  switch( this->DataDescription )
  {
    case VTK_X_LINE:
      if( (GridExtent[0] < i) && (i < GridExtent[1]) )
      {
        status = true;
      }
      break;
    case VTK_Y_LINE:
      if( (GridExtent[2] < j) && (j < GridExtent[3] ) )
      {
        status = true;
      }
      break;
    case VTK_Z_LINE:
      if( (GridExtent[4] < k) && (k < GridExtent[5] ) )
      {
        status = true;
      }
      break;
    case VTK_XY_PLANE:
      if( (GridExtent[0] < i) && (i < GridExtent[1]) &&
          (GridExtent[2] < j) && (j < GridExtent[3])  )
      {
        status = true;
      }
      break;
    case VTK_YZ_PLANE:
      if( (GridExtent[2] < j) && (j < GridExtent[3] ) &&
          (GridExtent[4] < k) && (k < GridExtent[5] ) )
      {
        status = true;
      }
      break;
    case VTK_XZ_PLANE:
      if( (GridExtent[0] < i) && (i < GridExtent[1] ) &&
          (GridExtent[4] < k) && (k < GridExtent[5] ) )
      {
        status = true;
      }
      break;
    case VTK_XYZ_GRID:
      if( (GridExtent[0] < i) && (i < GridExtent[1]) &&
          (GridExtent[2] < j) && (j < GridExtent[3]) &&
          (GridExtent[4] < k) && (k < GridExtent[5]) )
      {
        status = true;
      }
      break;
    default:
      std::cout << "Data description is: " << this->DataDescription << "\n";
      std::cout.flush();
      assert( "pre: Undefined data-description!" && false );
  } // END switch

  return( status );
}

//------------------------------------------------------------------------------
inline void vtkStructuredGridConnectivity::DetermineNeighborOrientation(
    const int idx, int A[2], int B[2], int overlap[2], int orient[3] )
{
  assert( "pre: idx is out-of-bounds" && (idx >= 0) && (idx < 3)  );

  // A. Non-overlapping cases
  if( overlap[0] == overlap[1] )
  {
    if( A[1] == B[0] )
    {
      orient[ idx ] = vtkStructuredNeighbor::HI;
    }
    else if( A[0] == B[1] )
    {
      orient[ idx ] = vtkStructuredNeighbor::LO;
    }
    else
    {
      orient[ idx ] = vtkStructuredNeighbor::UNDEFINED;
      assert( "ERROR: Code should not reach here!" && false );
    }
  } // END non-overlapping cases
  // B. Sub-set cases
  else if( this->IsSubset( A, B) )
  {
    if( (A[0] == B[0]) && (A[1] == B[1]) )
    {
      orient[ idx ] = vtkStructuredNeighbor::ONE_TO_ONE;
    }
    else if( this->StrictlyInsideBounds( A[0], B[0], B[1] ) &&
             this->StrictlyInsideBounds( A[1], B[0], B[1] ) )
    {
      orient[ idx ] = vtkStructuredNeighbor::SUBSET_BOTH;
    }
    else if( A[0] == B[0] )
    {
      orient[ idx ] = vtkStructuredNeighbor::SUBSET_HI;
    }
    else if( A[1] == B[1] )
    {
      orient[ idx ] = vtkStructuredNeighbor::SUBSET_LO;
    }
    else
    {
      orient[ idx ] = vtkStructuredNeighbor::UNDEFINED;
      assert( "ERROR: Code should not reach here!" && false );
    }
  }
  // C. Super-set cases
  else if( this->IsSubset( B, A ) )
  {
    orient[ idx ] = vtkStructuredNeighbor::SUPERSET;
  }
  // D. Partially-overlapping (non-subset) cases
  else if( !(this->IsSubset(A,B) || this->IsSubset(A,B)) )
  {
    if( this->InBounds( A[0], B[0], B[1] ) )
    {
      orient[ idx ] = vtkStructuredNeighbor::LO;
    }
    else if( this->InBounds( A[1], B[0], B[1] ) )
    {
      orient[ idx ] = vtkStructuredNeighbor::HI;
    }
    else
    {
      orient[ idx ] = vtkStructuredNeighbor::UNDEFINED;
      assert( "ERROR: Code should not reach here!" && false );
    }
  }
  else
  {
    orient[ idx ] = vtkStructuredNeighbor::UNDEFINED;
    assert( "ERROR: Code should not reach here!" && false );
  }
}

//------------------------------------------------------------------------------
inline int vtkStructuredGridConnectivity::Get1DOrientation(
        const int idx, const int ExtentLo, const int ExtentHi,
        const int OnLo, const int OnHi, const int NotOnBoundary )
{
  if( idx == ExtentLo )
  {
    return OnLo;
  }
  else if( idx == ExtentHi )
  {
    return OnHi;
  }
  return NotOnBoundary;
}

//------------------------------------------------------------------------------
inline bool vtkStructuredGridConnectivity::HasBlockConnection(
    const int gridID, const int blockDirection )
{
  // Sanity check
  assert("pre: gridID is out-of-bounds" &&
        (gridID >=0) && (gridID < static_cast<int>(this->NumberOfGrids)));
  assert("pre: BlockTopology has not been properly allocated" &&
        (this->NumberOfGrids == this->BlockTopology.size()));
  assert("pre: blockDirection is out-of-bounds" &&
        (blockDirection >= 0) && (blockDirection < 6) );
  bool status = false;
  if( this->BlockTopology[ gridID ] & (1 << blockDirection) )
  {
    status = true;
  }
  return( status );
}

//------------------------------------------------------------------------------
inline void vtkStructuredGridConnectivity::RemoveBlockConnection(
    const int gridID, const int blockDirection )
{
  // Sanity check
  assert("pre: gridID is out-of-bounds" &&
        (gridID >=0) && (gridID < static_cast<int>(this->NumberOfGrids)));
  assert("pre: BlockTopology has not been properly allocated" &&
        (this->NumberOfGrids == this->BlockTopology.size()));
  assert("pre: blockDirection is out-of-bounds" &&
        (blockDirection >= 0) && (blockDirection < 6) );

  this->BlockTopology[ gridID ] &= ~(1 << blockDirection);
}

//------------------------------------------------------------------------------
inline void vtkStructuredGridConnectivity::AddBlockConnection(
    const int gridID, const int blockDirection )
{
  // Sanity check
  assert("pre: gridID is out-of-bounds" &&
        (gridID >=0) && (gridID < static_cast<int>(this->NumberOfGrids)));
  assert("pre: BlockTopology has not been properly allocated" &&
        (this->NumberOfGrids == this->BlockTopology.size()));
  assert("pre: blockDirection is out-of-bounds" &&
        (blockDirection >= 0) && (blockDirection < 6) );
  this->BlockTopology[ gridID ] |= (1 << blockDirection);
}

//------------------------------------------------------------------------------
inline void vtkStructuredGridConnectivity::ClearBlockConnections(
    const int gridID )
{
  // Sanity check
  assert("pre: gridID is out-of-bounds" &&
        (gridID >=0) && (gridID < static_cast<int>(this->NumberOfGrids)));
  assert("pre: BlockTopology has not been properly allocated" &&
        (this->NumberOfGrids == this->BlockTopology.size()));
  for( int i=0; i < 6; ++i )
  {
    this->RemoveBlockConnection( gridID, i );
  } // END for all block directions
}

//------------------------------------------------------------------------------
inline int vtkStructuredGridConnectivity::GetNumberOfConnectingBlockFaces(
    const int gridID )
{
  // Sanity check
  assert("pre: gridID is out-of-bounds" &&
        (gridID >=0) && (gridID < static_cast<int>(this->NumberOfGrids)));
  assert("pre: BlockTopology has not been properly allocated" &&
        (this->NumberOfGrids == this->BlockTopology.size()));

  int count = 0;
  for( int i=0; i < 6; ++i )
  {
    if( this->HasBlockConnection( gridID, i ) )
    {
      ++count;
    }
  }
  assert( "post: count must be in [0,5]" && (count >=0 && count <= 6) );
  return( count );
}

//------------------------------------------------------------------------------
inline void vtkStructuredGridConnectivity::SetNumberOfGrids(
    const unsigned int N )
{
  if (N == 0)
  {
    vtkErrorMacro("Number of grids cannot be 0.");
    return;
  }

  this->NumberOfGrids = N;
  this->AllocateUserRegisterDataStructures();

  this->GridExtents.resize( 6*N,-1);
  this->Neighbors.resize( N );
  this->BlockTopology.resize( N );
}
#endif /* vtkStructuredGridConnectivity_h */
