//============================================================================
//  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
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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 vtkm_worklet_contourtree_augmented_process_contourtree_inc_euler_tour_list_h
#define vtkm_worklet_contourtree_augmented_process_contourtree_inc_euler_tour_list_h

#include <vtkm/cont/Algorithm.h>
#include <vtkm/worklet/WorkletMapField.h>
#include <vtkm/worklet/contourtree_augmented/Types.h>

/*
* This code is written by Petar Hristov in 09.2019
*
* This worklet performs the second step in computing an Euler tour.
* That is computing the adjacency list of the euler edge tour.
* See https://en.wikipedia.org/wiki/Euler_tour_technique for details
*
*/
namespace vtkm
{
namespace worklet
{
namespace contourtree_augmented
{
namespace process_contourtree_inc
{
class ComputeEulerTourList : public vtkm::worklet::WorkletMapField
{
public:
  typedef void ControlSignature(WholeArrayIn next,
                                WholeArrayIn first,
                                WholeArrayIn edges,
                                WholeArrayOut succ);

  typedef void ExecutionSignature(InputIndex, _1, _2, _3, _4);
  using InputDomain = _1;

  template <typename NextArrayPortalType,
            typename FirstArrayPortalType,
            typename EdgesArrayPortalType,
            typename OutputArrayPortalType>
  VTKM_EXEC void operator()(const vtkm::Id i,
                            const NextArrayPortalType& next,
                            const FirstArrayPortalType& first,
                            const EdgesArrayPortalType& edges,
                            const OutputArrayPortalType& succ) const
  {
    // For edge (a, b) find the opposite edge (b, a) in the sorted list of edges
    // This relies on the fact that in the contour tree nodes have bounded degree.
    // This comes from the fact that vertices in a 2D/3D mesh have a bounded degree.
    auto currentEdge = edges.Get(i);
    auto oppositeIndex = first.Get(currentEdge[1]);

    while (oppositeIndex < edges.GetNumberOfValues() &&
           currentEdge[1] == edges.Get(oppositeIndex)[0])
    {
      if (currentEdge[0] == edges.Get(oppositeIndex)[1])
      {
        break;
      }

      oppositeIndex++;
    }

    if (NO_SUCH_ELEMENT == next.Get(oppositeIndex))
    {
      succ.Set(i, first.Get(edges.Get(i)[1]));
    }
    else
    {
      succ.Set(i, next.Get(oppositeIndex));
    }
  }
}; // ComputeEulerTourList
} // process_contourtree_inc
} // namespace contourtree_augmented
} // namespace worklet
} // namespace vtkm


#endif
