//============================================================================
//  Copyright (c) Kitware, Inc.
//  All rights reserved.
//  See LICENSE.txt 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.
//============================================================================
// Copyright (c) 2018, The Regents of the University of California, through
// Lawrence Berkeley National Laboratory (subject to receipt of any required approvals
// from the U.S. Dept. of Energy).  All rights reserved.
//
// Redistribution and use in source and binary forms, with or without modification,
// are permitted provided that the following conditions are met:
//
// (1) Redistributions of source code must retain the above copyright notice, this
//     list of conditions and the following disclaimer.
//
// (2) Redistributions in binary form must reproduce the above copyright notice,
//     this list of conditions and the following disclaimer in the documentation
//     and/or other materials provided with the distribution.
//
// (3) Neither the name of the University of California, Lawrence Berkeley National
//     Laboratory, U.S. Dept. of Energy nor the names of its contributors may be
//     used to endorse or promote products derived from this software without
//     specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
// IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
// INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
// BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
// OF THE POSSIBILITY OF SUCH DAMAGE.
//
//=============================================================================
//
//  This code is an extension of the algorithm presented in the paper:
//  Parallel Peak Pruning for Scalable SMP Contour Tree Computation.
//  Hamish Carr, Gunther Weber, Christopher Sewell, and James Ahrens.
//  Proceedings of the IEEE Symposium on Large Data Analysis and Visualization
//  (LDAV), October 2016, Baltimore, Maryland.
//
//  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_bract_maker_propagate_boundary_counts_subtract_dependent_counts_worklet_h
#define vtk_m_worklet_contourtree_distributed_bract_maker_propagate_boundary_counts_subtract_dependent_counts_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 bract_maker
{

/// Worklet to Subtract out the dependent count of the prefix to the entire hyperarc
/// Part of the BoundaryRestrictedAugmentedContourTree.PropagateBoundaryCounts function
class PropagateBoundaryCountsSubtractDependentCountsWorklet : public vtkm::worklet::WorkletMapField
{
public:
  using ControlSignature = void(FieldIn supernodeIndex, // (input) index of supernodes for iteration
                                WholeArrayIn hyperparents, // (input) contour tree hyperparents
                                WholeArrayIn hypernodes,   // (input) contour tree hypernodes
                                WholeArrayIn superarcDependentBoundaryCount,      // (input)
                                WholeArrayInOut newSuperArcDependentBoundaryCount // (input/output)
  );
  using ExecutionSignature = void(_1, _2, _3, _4, _5);
  using InputDomain = _1;

  // Default Constructor
  VTKM_EXEC_CONT
  PropagateBoundaryCountsSubtractDependentCountsWorklet(vtkm::Id firstSupernode,
                                                        vtkm::Id firstHypernode)
    : FirstSupernode(firstSupernode)
    , FirstHypernode(firstHypernode)
  {
  }

  template <typename InFieldPortalType, typename InOutFieldPortalType>
  VTKM_EXEC void operator()(
    const vtkm::Id& supernode,
    const InFieldPortalType& hyperparentsPortal,
    const InFieldPortalType& hypernodesPortal,
    const InFieldPortalType& superarcDependentBoundaryCountPortal,
    const InOutFieldPortalType& newSuperArcDependentBoundaryCountPortal) const
  {
    // A. Retrieve hyperparent & convert to supernode ID
    vtkm::Id hyperparent = hyperparentsPortal.Get(supernode);
    vtkm::Id hyperparentSuperId = hypernodesPortal.Get(hyperparent);

    // B. If hyperparent is first in sequence, count is already correct
    if (hyperparent == this->FirstHypernode)
    {
      return;
    }
    // C. Otherwise, subtract out the immediately previous count to get correct value
    vtkm::Id supernodeOffset = supernode - this->FirstSupernode;
    newSuperArcDependentBoundaryCountPortal.Set(
      supernodeOffset,
      newSuperArcDependentBoundaryCountPortal.Get(supernodeOffset) -
        superarcDependentBoundaryCountPortal.Get(hyperparentSuperId - 1));

    // In serial this worklet implements the following operation
    /*
    for (vtkm::Id supernode = lastSupernode-1; supernode > firstSupernode; supernode--)
        //		NB: Loops backward to use the correct values, also tests > firstSupernode (the first one is guaranteed to be correct already - see ComputeWeights())
        { // iv. per supernode
        //		A.	Retrieve hyperparent & convert to supernode ID
        vtkm::Id hyperparent = contourTree->hyperparents[supernode];
        vtkm::Id hyperparentSuperID = contourTree->hypernodes[hyperparent];

        //		B.	If hyperparent is first in sequence, count is already correct
        if (hyperparent == firstHypernode)
            continue;

        //		C.	Otherwise, subtract out the immediately previous count to get correct value
        vtkm::Id supernodeOffset = supernode - firstSupernode;
        newSuperArcDependentBoundaryCount[supernodeOffset] -= superarcDependentBoundaryCount[hyperparentSuperID-1];
        } // iv. per supernode
    */
  }

private:
  vtkm::Id FirstSupernode;
  vtkm::Id FirstHypernode;

}; // PropagateBoundaryCountsSubtractDependentCountsWorklet


} // namespace bract_maker
} // namespace contourtree_distributed
} // namespace worklet
} // namespace vtkm

#endif
