//============================================================================
//  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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//=============================================================================
//
//  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_transfer_cumulative_counts_worklet_h
#define vtk_m_worklet_contourtree_distributed_bract_maker_propagate_boundary_counts_transfer_cumulative_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 transfer the cumulative counts for hyperarcs
/// Part of the BoundaryRestrictedAugmentedContourTree.PropagateBoundaryCounts function
///
/// 4. The partial sum is now over ALL hypertargets, so within each group we need to subtract the first from the last
/// To do so, the last hyperarc in each cluster copies its cumulative count to the output array
class PropagateBoundaryCountsTransferCumulativeCountsWorklet : public vtkm::worklet::WorkletMapField
{
public:
  using ControlSignature = void(
    WholeArrayIn hyperarcTargetSortPermutation,          // (input)
    WholeArrayIn hyperarcs,                              // (input) contour tree hyperarcs
    WholeArrayIn accumulatedBoundaryCountPortal,         // (input)
    WholeArrayInOut supernodeTransferBoundaryCountPortal // (input/output)
  );
  using ExecutionSignature = void(InputIndex, _1, _2, _3, _4);
  using InputDomain = _1;

  // Default Constructor
  VTKM_EXEC_CONT
  PropagateBoundaryCountsTransferCumulativeCountsWorklet() {}

  template <typename InFieldPortalType, typename InOutFieldPortalType>
  VTKM_EXEC void operator()(const vtkm::Id& hyperarc,
                            const InFieldPortalType& hyperarcTargetSortPermutationPortal,
                            const InFieldPortalType& hyperarcsPortal,
                            const InFieldPortalType& accumulatedBoundaryCountPortal,
                            const InOutFieldPortalType& supernodeTransferBoundaryCountPortal) const
  {
    // per hyperarc
    // retrieve the hypertarget
    vtkm::Id hyperarcTarget =
      hyperarcsPortal.Get(hyperarcTargetSortPermutationPortal.Get(hyperarc));

    // in the last loop, no transfer is needed
    if (vtkm::worklet::contourtree_augmented::NoSuchElement(hyperarcTarget))
    {
      return;
    }

    // now mask out the flag
    hyperarcTarget = vtkm::worklet::contourtree_augmented::MaskedIndex(hyperarcTarget);

    // the last one of all has a different rule
    if (hyperarc == hyperarcTargetSortPermutationPortal.GetNumberOfValues() - 1)
    { // last hyperarc
      supernodeTransferBoundaryCountPortal.Set(
        hyperarcTarget,
        supernodeTransferBoundaryCountPortal.Get(hyperarcTarget) +
          accumulatedBoundaryCountPortal.Get(hyperarc));
    } // last hyperarc
    // the others compute a delta
    else
    { // not last hyperarc
      vtkm::Id nextHyperarcTarget = vtkm::worklet::contourtree_augmented::MaskedIndex(
        hyperarcsPortal.Get(hyperarcTargetSortPermutationPortal.Get(hyperarc + 1)));
      // only write for the last one in the cluster
      // note that this is an addition because a target may accumulate in multiple passes
      if (hyperarcTarget != nextHyperarcTarget)
      { // no match
        supernodeTransferBoundaryCountPortal.Set(
          hyperarcTarget,
          supernodeTransferBoundaryCountPortal.Get(hyperarcTarget) +
            accumulatedBoundaryCountPortal.Get(hyperarc));
      } // no match
    }   // not last hyperarc

    // In serial this worklet implements the following operation
    /*
    for (vtkm::Id hyperarc = 0; hyperarc < hyperarcTargetSortPermutation.size(); hyperarc++)
    {   // per hyperarc
        // retrieve the hypertarget
        vtkm::Id hyperarcTarget = contourTree->hyperarcs[hyperarcTargetSortPermutation[hyperarc]];

        // in the last loop, no transfer is needed
        if (noSuchElement(hyperarcTarget))
            continue;

        // now mask out the flag
        hyperarcTarget = maskedIndex(hyperarcTarget);

        // the last one of all has a different rule
        if (hyperarc == hyperarcTargetSortPermutation.size() - 1)
            { // last hyperarc
            supernodeTransferBoundaryCount[hyperarcTarget] += accumulatedBoundaryCount[hyperarc];
            } // last hyperarc
        // the others compute a delta
        else
            { // not last hyperarc
            vtkm::Id nextHyperarcTarget = maskedIndex(contourTree->hyperarcs[hyperarcTargetSortPermutation[hyperarc+1]]);
            // only write for the last one in the cluster
            // note that this is an addition because a target may accumulate in multiple passes
            if (hyperarcTarget != nextHyperarcTarget)
                { // no match
                supernodeTransferBoundaryCount[hyperarcTarget] += accumulatedBoundaryCount[hyperarc];
                } // no match
            } // not last hyperarc
    } // per hyperarc
    */
  }
}; // PropagateBoundaryCountsTransferCumulativeCountsWorklet


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

#endif
