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

  Program:   Visualization Toolkit
  Module:    vtkCellLinks.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.

=========================================================================*/
// .NAME vtkCellLinks - object represents upward pointers from points to list of cells using each point
// .SECTION Description
// vtkCellLinks is a supplemental object to vtkCellArray and vtkCellTypes, 
// enabling access from points to the cells using the points. vtkCellLinks is
// a list of Links, each link represents a dynamic list of cell id's using the 
// point. The information provided by this object can be used to determine 
// neighbors and construct other local topological information.
// .SECTION See Also
// vtkCellArray vtkCellTypes

#ifndef __vtkCellLinks_h
#define __vtkCellLinks_h

#include "vtkObject.h"
class vtkDataSet;
class vtkCellArray;

class VTK_COMMON_EXPORT vtkCellLinks : public vtkObject 
{
public:

  //BTX
  class Link {
  public:
    unsigned short ncells;
    vtkIdType *cells;
  };
  //ETX

  static vtkCellLinks *New();
  vtkTypeRevisionMacro(vtkCellLinks,vtkObject);

  // Description:
  // Allocate the specified number of links (i.e., number of points) that
  // will be built.
  void Allocate(vtkIdType numLinks, vtkIdType ext=1000);

  // Description:
  // Get a link structure given a point id.
  Link &GetLink(vtkIdType ptId) {return this->Array[ptId];};

  // Description:
  // Get the number of cells using the point specified by ptId.
  unsigned short GetNcells(vtkIdType ptId) { return this->Array[ptId].ncells;};

  // Description:
  // Build the link list array.
  void BuildLinks(vtkDataSet *data);

  // Description:
  // Build the link list array.
  void BuildLinks(vtkDataSet *data, vtkCellArray *Connectivity);

  // Description:
  // Return a list of cell ids using the point.
  vtkIdType *GetCells(vtkIdType ptId) {return this->Array[ptId].cells;};

  // Description:
  // Insert a new point into the cell-links data structure. The size parameter
  // is the initial size of the list.
  vtkIdType InsertNextPoint(int numLinks);

  // Description:
  // Insert a cell id into the list of cells (at the end) using the cell id 
  // provided. (Make sure to extend the link list (if necessary) using the
  // method ResizeCellList().)
  void InsertNextCellReference(vtkIdType ptId, vtkIdType cellId);

  // Description:
  // Delete point (and storage) by destroying links to using cells.
  void DeletePoint(vtkIdType ptId);

  // Description:
  // Delete the reference to the cell (cellId) from the point (ptId). This
  // removes the reference to the cellId from the cell list, but does not
  // resize the list (recover memory with ResizeCellList(), if necessary).
  void RemoveCellReference(vtkIdType cellId, vtkIdType ptId);

  // Description:
  // Add the reference to the cell (cellId) from the point (ptId). This
  // adds a reference to the cellId from the cell list, but does not resize
  // the list (extend memory with ResizeCellList(), if necessary).
  void AddCellReference(vtkIdType cellId, vtkIdType ptId);

  // Description:
  // Change the length of a point's link list (i.e., list of cells using a
  // point) by the size specified.
  void ResizeCellList(vtkIdType ptId, int size);

  // Description:
  // Reclaim any unused memory.
  void Squeeze();

  // Description:
  // Reset to a state of no entries without freeing the memory.
  void Reset();

  // Description:
  // Return the memory in kilobytes consumed by this cell links array. 
  // Used to support streaming and reading/writing data. The value 
  // returned is guaranteed to be greater than or equal to the memory 
  // required to actually represent the data represented by this object. 
  // The information returned is valid only after the pipeline has 
  // been updated.
  unsigned long GetActualMemorySize();
  
  // Description:
  // Standard DeepCopy method.  Since this object contains no reference
  // to other objects, there is no ShallowCopy.
  void DeepCopy(vtkCellLinks *src);

protected:
  vtkCellLinks():Array(NULL),Size(0),MaxId(-1),Extend(1000) {};
  ~vtkCellLinks();

  // Description:
  // Increment the count of the number of cells using the point.
  void IncrementLinkCount(vtkIdType ptId) { this->Array[ptId].ncells++;};

  void AllocateLinks(vtkIdType n);

  // Description:
  // Insert a cell id into the list of cells using the point.
  void InsertCellReference(vtkIdType ptId, unsigned short pos,
                           vtkIdType cellId);

  Link *Array;   // pointer to data
  vtkIdType Size;       // allocated size of data
  vtkIdType MaxId;     // maximum index inserted thus far
  vtkIdType Extend;     // grow array by this point
  Link *Resize(vtkIdType sz);  // function to resize data
private:
  vtkCellLinks(const vtkCellLinks&);  // Not implemented.
  void operator=(const vtkCellLinks&);  // Not implemented.
};


inline void vtkCellLinks::InsertCellReference(vtkIdType ptId,
                                              unsigned short pos,
                                              vtkIdType cellId) 
{
  this->Array[ptId].cells[pos] = cellId;
}

inline void vtkCellLinks::DeletePoint(vtkIdType ptId)
{
  this->Array[ptId].ncells = 0;
  delete [] this->Array[ptId].cells;
  this->Array[ptId].cells = NULL;
}

inline void vtkCellLinks::InsertNextCellReference(vtkIdType ptId,
                                                  vtkIdType cellId) 
{
  this->Array[ptId].cells[this->Array[ptId].ncells++] = cellId;
}

inline void vtkCellLinks::RemoveCellReference(vtkIdType cellId, vtkIdType ptId)
{
  vtkIdType *cells=this->Array[ptId].cells;
  int ncells=this->Array[ptId].ncells;

  for (int i=0; i < ncells; i++)
    {
    if (cells[i] == cellId)
      {
      for (int j=i; j < (ncells-1); j++)
        {
        cells[j] = cells[j+1];
        }
      this->Array[ptId].ncells--;
      break;
      }
    }
}

inline void vtkCellLinks::AddCellReference(vtkIdType cellId, vtkIdType ptId)
{
  this->Array[ptId].cells[this->Array[ptId].ncells++] = cellId;
}

inline void vtkCellLinks::ResizeCellList(vtkIdType ptId, int size)
{
  int newSize;
  vtkIdType *cells;
  
  newSize = this->Array[ptId].ncells + size;
  cells = new vtkIdType[newSize];
  memcpy(cells, this->Array[ptId].cells,
         this->Array[ptId].ncells*sizeof(vtkIdType));
  delete [] this->Array[ptId].cells;
  this->Array[ptId].cells = cells;
}

#endif

