//============================================================================
//  The contents of this file are covered by the Viskores license. See
//  LICENSE.txt for details.
//
//  By contributing to this file, all contributors agree to the Developer
//  Certificate of Origin Version 1.1 (DCO 1.1) as stated in DCO.txt.
//============================================================================

//============================================================================
//  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,
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// 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 viskores_worklet_contourtree_distributed_hierarchical_hyper_sweeper_transfer_weights_update_lhe_worklet_h
#define viskores_worklet_contourtree_distributed_hierarchical_hyper_sweeper_transfer_weights_update_lhe_worklet_h

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

namespace viskores
{
namespace worklet
{
namespace contourtree_distributed
{
namespace hierarchical_hyper_sweeper
{

/// Worklet used in HierarchicalHyperSweeper.TransferWeights(...) to implement
/// step 7b. Now find the LHE of each group and subtract out the prior weight
class TransferWeightsUpdateLHEWorklet : public viskores::worklet::WorkletMapField
{
public:
  using ControlSignature = void(FieldIn sortedTransferTargetPortal,
                                FieldIn sortedTransferTargetShiftedView,
                                FieldIn valuePrefixSumShiftedView,
                                WholeArrayInOut dependentValuesPortal);
  using ExecutionSignature = void(_1, _2, _3, _4);

  template <typename InOutPortalType>
  VISKORES_EXEC void operator()(const viskores::Id& sortedTransferTargetValue,
                                const viskores::Id& sortedTransferTargetPreviousValue,
                                const viskores::Id& valuePrefixSumPreviousValue,
                                InOutPortalType& dependentValuesPortal) const
  {
    // per supernode
    // ignore any that point at NO_SUCH_ELEMENT
    if (viskores::worklet::contourtree_augmented::NoSuchElement(sortedTransferTargetValue))
    {
      return;
    }

    // we need to separate out the flag for attachment points
    bool superarcTransfer =
      viskores::worklet::contourtree_augmented::TransferToSuperarc(sortedTransferTargetValue);
    viskores::Id superarcOrNodeId =
      viskores::worklet::contourtree_augmented::MaskedIndex(sortedTransferTargetValue);

    // ignore the transfers for attachment points
    if (superarcTransfer)
    {
      return;
    }

    // the LHE at 0 is special - it subtracts zero.  In practice, since NO_SUCH_ELEMENT will sort low, this will never
    // occur, but let's keep the logic strict
    auto originalValue = dependentValuesPortal.Get(superarcOrNodeId);
    // Outside the worklet, we have excluded the condition where supernode == firstSupernode using shift
    if (sortedTransferTargetValue != sortedTransferTargetPreviousValue)
    { // LHE not 0
      dependentValuesPortal.Set(superarcOrNodeId, originalValue - valuePrefixSumPreviousValue);
    }
  } // operator()()
};  // TransferWeightsUpdateLHEWorklet

} // namespace hierarchical_hyper_sweeper
} // namespace contourtree_distributed
} // namespace worklet
} // namespace viskores

#endif
