// SPDX-FileCopyrightText: Copyright (c) Kitware Inc.
// SPDX-FileCopyrightText: Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
// SPDX-License-Identifier: BSD-3-Clause
/**
 * @class   vtkEquivalenceSet
 * @brief   records groups of integers that are equivalent.
 *
 * Useful for connectivity on multiple processes.  Run connectivity
 * on each processes, then make touching fragments equivalent.
 */

#ifndef vtkEquivalenceSet_h
#define vtkEquivalenceSet_h

#include "vtkObject.h"
#include "vtkPVVTKExtensionsFiltersGeneralModule.h" //needed for exports
class vtkIntArray;

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

  void Initialize();
  void AddEquivalence(int id1, int id2);

  // The length of the equivalent array...
  // The Domain of the equivalance map is [0, numberOfMembers).
  int GetNumberOfMembers();

  // Valid only after set is resolved.
  // The range of the map is [0 numberOfResolvedSets)
  int GetNumberOfResolvedSets() { return this->NumberOfResolvedSets; }

  // Return the id of the equivalent set.
  int GetEquivalentSetId(int memberId);

  // Equivalent set ids are reassinged to be sequential.
  // You cannot add anymore equivalences after this is called.
  virtual int ResolveEquivalences();

  void DeepCopy(vtkEquivalenceSet* in);

  // Needed for sending the set over MPI.
  // Be very careful with the pointer.
  // I guess this means do not write to the memory.
  int* GetPointer();

  // Free unused memory
  void Squeeze();

  // Report used memory
  vtkIdType Capacity();

  // We should fix the pointer API and hide this ivar.
  int Resolved;

  int GetReference(int memberId);

protected:
  vtkEquivalenceSet();
  ~vtkEquivalenceSet() override;

  int NumberOfResolvedSets;

  // To merge connected framgments that have different ids because they were
  // traversed by different processes or passes.
  vtkIntArray* EquivalenceArray;

  // Return the id of the equivalent set.
  void EquateInternal(int id1, int id2);

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

#endif
