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// Copyright (c) 2018, The Regents of the University of California, through
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//=============================================================================
//  The PPP2 algorithm and software were jointly developed by
//  Hamish Carr (University of Leeds), Gunther H. Weber (LBNL), and
//  Oliver Ruebel (LBNL)
//==============================================================================

#ifndef vtk_m_worklet_contourtree_distributed_hierarchical_augmenter_update_hyperstructure_set_superchildren_worklet_h
#define vtk_m_worklet_contourtree_distributed_hierarchical_augmenter_update_hyperstructure_set_superchildren_worklet_h

#include <vtkm/filter/scalar_topology/worklet/contourtree_augmented/Types.h>
#include <vtkm/worklet/WorkletMapField.h>

namespace vtkm
{
namespace worklet
{
namespace contourtree_distributed
{
namespace hierarchical_augmenter
{

/// Worklet used in HierarchicalAugmenter::UpdateHyperstructure to set the superchildren
/// The worklet  finds the number of superchildren as the delta between the super Id
/// and the next hypernode's super Id
class UpdateHyperstructureSetSuperchildrenWorklet : public vtkm::worklet::WorkletMapField
{
public:
  /// Control signature for the worklet
  using ControlSignature = void(
    WholeArrayIn augmentedTreeHypernodes, // input (we need both this and the next value)
    FieldOut augmentedTreeSuperchildren   // output
  );
  using ExecutionSignature = void(InputIndex, _1, _2);
  using InputDomain = _1;

  // Default Constructor
  VTKM_EXEC_CONT
  UpdateHyperstructureSetSuperchildrenWorklet(const vtkm::Id& augmentedTreeNumSupernodes)
    : AugmentedTreeNumSupernodes(augmentedTreeNumSupernodes)
  {
  }


  template <typename InFieldPortalType>
  VTKM_EXEC void operator()(
    const vtkm::Id& hypernode,
    const InFieldPortalType& augmentedTreeHypernodesPortal,
    vtkm::Id&
      augmentedTreeSuperchildrenValue // same as augmentedTree->superchildren[InputIndex] = ...
  ) const
  {
    // per hypernode
    // retrieve the new superId
    vtkm::Id superId = augmentedTreeHypernodesPortal.Get(hypernode);
    // and the next one over
    vtkm::Id nextSuperId;
    if (hypernode == augmentedTreeHypernodesPortal.GetNumberOfValues() - 1)
    {
      nextSuperId = this->AugmentedTreeNumSupernodes;
    }
    else
    {
      nextSuperId = augmentedTreeHypernodesPortal.Get(hypernode + 1);
    }
    // the difference is the number of superchildren
    augmentedTreeSuperchildrenValue = nextSuperId - superId;

    // In serial this worklet implements the following operation
    /*
      for (vtkm::Id hypernode = 0; hypernode < augmentedTree->hypernodes.size(); hypernode++)
      { // per hypernode
        // retrieve the new super ID
        vtkm::Id superID = augmentedTree->hypernodes[hypernode];
        // and the next one over
        vtkm::Id nextSuperID;
        if (hypernode == augmentedTree->hypernodes.size() - 1)
          nextSuperID = augmentedTree->supernodes.size();
        else
          nextSuperID = augmentedTree->hypernodes[hypernode+1];
        // the difference is the number of superchildren
        augmentedTree->superchildren[hypernode] = nextSuperID - superID;
      } // per hypernode

    */
  } // operator()()

private:
  const vtkm::Id AugmentedTreeNumSupernodes;
}; // UpdateHyperstructureSetSuperchildrenWorklet

} // namespace hierarchical_augmenter
} // namespace contourtree_distributed
} // namespace worklet
} // namespace vtkm

#endif
