//============================================================================
//  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_filter_scalar_topology_worklet_select_top_volume_branches_UpdateInfoByBranchDirectionWorklet_h
#define vtk_m_filter_scalar_topology_worklet_select_top_volume_branches_UpdateInfoByBranchDirectionWorklet_h

#include <vtkm/worklet/WorkletMapField.h>

namespace vtkm
{
namespace worklet
{
namespace scalar_topology
{
namespace select_top_volume_branches
{

/// <summary>
///  1. Get the saddle end isovalue
///  2. Get Epsilon direction near the branch saddle end
///  If main branch, epsilon is 0.
///  Otherwise, -1 if the branch is the lower leaf branch, or 1 if upper leaf branch.
/// </summary>
template <typename ValueType>
class UpdateInfoByBranchDirectionWorklet : public vtkm::worklet::WorkletMapField
{
public:
  using ControlSignature = void(
    FieldIn isLowerLeaf,    // (input) bool, whether the lower end is a leaf
    FieldIn isUpperLeaf,    // (input) bool, whether the upper end is a leaf
    FieldIn upperEndValue,  // (input) value type, the branch upper end value
    FieldIn lowerEndValue,  // (input) value type, the branch lower end value
    FieldOut saddleEpsilon, // (output) vtkm::Id, epsilon direction around the saddle isovalue
    FieldOut saddleValue    // (output) value type, the saddle isovalue
  );
  using ExecutionSignature = void(_1, _2, _3, _4, _5, _6);
  using InputDomain = _1;

  /// Constructor
  VTKM_EXEC_CONT
  UpdateInfoByBranchDirectionWorklet()
  { // constructor
  } // constructor

  /// The functor returns the isovalue and the epsilon direction around the saddle end of the branch
  VTKM_EXEC void operator()(const bool isLowerLeaf,
                            const bool isUpperLeaf,
                            const ValueType upperEndValue,
                            const ValueType lowerEndValue,
                            vtkm::Id& saddleEpsilon,
                            ValueType& saddleValue) const
  {
    // NOTE: for the main branch, the saddle value is undefined,
    // because both upper and lower ends are leaf nodes.
    // Let's use upperEndValue here to make the output not random.
    if (isLowerLeaf && isUpperLeaf)
    {
      saddleEpsilon = 0;
      saddleValue = upperEndValue;
    }
    else
    {
      saddleEpsilon = isLowerLeaf ? -1 : 1;
      saddleValue = isLowerLeaf ? upperEndValue : lowerEndValue;
    }
  }
}; // EpsilonFromBranchDirection


} // namespace select_top_volume_branches
} // namespace scalar_topology
} // namespace worklet
} // namespace vtkm

#endif
