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

  Program:   ParaView
  Module:    vtkKdTreeGenerator.h

  Copyright (c) Kitware, Inc.
  All rights reserved.
  See Copyright.txt or http://www.paraview.org/HTML/Copyright.html 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   vtkKdTreeGenerator
 * @brief   creates a vtkPKdTree using the partitioning
 * information provided by a vtkExtentTranslator.
 * generates the KdTree
 *
 * vtkKdTreeGenerator is used to generate a KdTree using the partitioning
 * information garnered from a vtkExtentTranslator (or subclass). Since we need
 * spatial bounds for the KdTree, we assume that structured data corresponding
 * to the vtkExtentTranslator is an ImageData with the provided spacing and
 * origin.
 * The algorithm used can be summarized as under:
 * \li Inputs: * Extent Translator, * Number of Pieces
 * \li Determine the bounds for every piece/region using the extent translator.
 * \li Given a set of pieces (number of pieces > 1), we iteratively determine
 *     the plane along which the the pieces can be split into two
 *     non-intersecting non-empty groups.
 * \li If number of pieces in a set of regions = 1, then we create a leaf node
 *     representing that region.
 * \li If number of pieces > 1, a new non-leaf node is creates with children
 *     as the subtree generated by repeating the same process on the
 *     two non-intersecting, non-empty groups of pieces.
 *
 *  vtkKdTreeGenerator also needs to determine the assignment of regions to
 *  the processors. Since vtkPKdTree assigns Ids to the leaf nodes in inorder,
 *  we can determine the assignment by assigning temporary ids to all
 *  leaf nodes indication the piece number they represent and simply
 *  traversing the tree in inorder, and recording only the leaf
 *  IDs.
*/

#ifndef vtkKdTreeGenerator_h
#define vtkKdTreeGenerator_h

#include "vtkObject.h"
#include "vtkPVVTKExtensionsFiltersRenderingModule.h" // needed for export macro

class vtkDataObject;
class vtkExtentTranslator;
class vtkInformation;
class vtkKdNode;
class vtkKdTreeGeneratorVector;
class vtkPKdTree;

class VTKPVVTKEXTENSIONSFILTERSRENDERING_EXPORT vtkKdTreeGenerator : public vtkObject
{
public:
  static vtkKdTreeGenerator* New();
  vtkTypeMacro(vtkKdTreeGenerator, vtkObject);
  void PrintSelf(ostream& os, vtkIndent indent) override;

  //@{
  /**
   * Get/Set the kdtree which is updated in BuildTree.
   */
  void SetKdTree(vtkPKdTree*);
  vtkGetObjectMacro(KdTree, vtkPKdTree);
  //@}

  //@{
  /**
   * Get/Set the number of pieces.
   */
  vtkSetMacro(NumberOfPieces, int);
  vtkGetMacro(NumberOfPieces, int);
  //@}

  /**
   * Builds the KdTree using the partitioning of the data.
   */
  bool BuildTree(vtkExtentTranslator* translator, const int extents[6], const double origin[3],
    const double spacing[4]);

protected:
  vtkKdTreeGenerator();
  ~vtkKdTreeGenerator() override;

  //@{
  /**
   * Get/Set the extent translator.
   */
  void SetExtentTranslator(vtkExtentTranslator*);
  vtkGetObjectMacro(ExtentTranslator, vtkExtentTranslator);
  //@}

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

  //@{
  vtkSetVector3Macro(Origin, double);
  vtkSetVector3Macro(Spacing, double);
  //@}

  /**
   * Obtains information from the extent translator about the partitioning of
   * the input dataset among processes.
   */
  void FormRegions();

  int FormTree(vtkKdNode* parent, vtkKdTreeGeneratorVector& regions_ids);
  int CanPartition(int division_point, int dimension, vtkKdTreeGeneratorVector& ids,
    vtkKdTreeGeneratorVector& left, vtkKdTreeGeneratorVector& right);

  // Converts extents to bounds in the kdtree.
  bool ConvertToBounds(vtkKdNode* node);

  vtkPKdTree* KdTree;
  vtkExtentTranslator* ExtentTranslator;

  double Origin[3];
  double Spacing[3];

  int WholeExtent[6];
  int NumberOfPieces;

  int* Regions;

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

#endif
