//============================================================================
//  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,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
// 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_augmented_contourtree_maker_inc_compress_trees_step_h
#define vtk_m_worklet_contourtree_augmented_contourtree_maker_inc_compress_trees_step_h

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

namespace vtkm
{
namespace worklet
{
namespace contourtree_augmented
{
namespace contourtree_maker_inc
{

// Worklet implementing a single step in the ContourTreeMaker::CompressTrees function
class CompressTrees_Step : public vtkm::worklet::WorkletMapField
{
public:
  typedef void ControlSignature(FieldIn activeSupernodes,               // (input)
                                WholeArrayIn contourTreeSuperarcs,      // (input)
                                WholeArrayInOut augmentedJoinSuperarcs, // (input/output)
                                WholeArrayInOut augmentedSplitSuperarcs // (input/output)
  );
  typedef void ExecutionSignature(_1, InputIndex, _2, _3, _4);
  using InputDomain = _1;


  // Default Constructor
  VTKM_EXEC_CONT
  CompressTrees_Step() {}

  template <typename InFieldPortalType, typename InOutFieldPortalType>
  VTKM_EXEC void operator()(const vtkm::Id& superID,
                            const vtkm::Id /*activeID*/, // FIXME: Remove unused parameter?
                            const InFieldPortalType& contourTreeSuperarcsPortal,
                            const InOutFieldPortalType& augmentedJoinSuperarcsPortal,
                            const InOutFieldPortalType& augmentedSplitSuperarcsPortal) const
  {
    // per active suoper node
    //      retrieve it's join neighbour j
    vtkm::Id joinNeighbour = augmentedJoinSuperarcsPortal.Get(superID);

    //      if j actually exists (not infinite root) and j has a contour superarc set
    if (!NoSuchElement(joinNeighbour))
    { // not pointing to infinite root
      // if the superarc is already set, then we jump past it to the next one
      if (!NoSuchElement(contourTreeSuperarcsPortal.Get(MaskedIndex(joinNeighbour))))
      {
        // reset the vertex' join neighbour
        augmentedJoinSuperarcsPortal.Set(
          superID, augmentedJoinSuperarcsPortal.Get(MaskedIndex(joinNeighbour)));
      }
    } // not pointing to infinite root

    //      retrieve it's split neighbour s
    vtkm::Id splitNeighbour = augmentedSplitSuperarcsPortal.Get(superID);

    //      if s actually exists (not infinite root) and s has a contour superarc set
    if (!NoSuchElement(splitNeighbour))
    { // not pointing to infinite root
      // if the superarc is already set, then we jump past it to the next one
      if (!NoSuchElement(contourTreeSuperarcsPortal.Get(MaskedIndex(splitNeighbour))))
      {
        // reset the vertex' join neighbour
        augmentedSplitSuperarcsPortal.Set(
          superID, augmentedSplitSuperarcsPortal.Get(MaskedIndex(splitNeighbour)));
      }
    } // not pointing to infinite root

    // In serial this worklet implements the following operation
    /*
      for (vtkm::Id activeID = 0; activeID < activeSupernodes.size(); activeID++)
          { // per active supernode
            // retrieve the supernode ID
            vtkm::Id superID = activeSupernodes[activeID];

            //      retrieve it's join neighbour j
            vtkm::Id joinNeighbour = augmentedJoinSuperarcs[superID];

            //      if j actually exists (not infinite root) and j has a contour superarc set
            if (!NoSuchElement(joinNeighbour))
              { // not pointing to infinite root
                // if the superarc is already set, then we jump past it to the next one
                if (!NoSuchElement(contourTree.superarcs[MaskedIndex(joinNeighbour)]))
                  // reset the vertex' join neighbour
                  augmentedJoinSuperarcs[superID] = augmentedJoinSuperarcs[MaskedIndex(joinNeighbour)];
              } // not pointing to infinite root

            //      retrieve it's split neighbour s
            vtkm::Id splitNeighbour = augmentedSplitSuperarcs[superID];

            //      if s actually exists (not infinite root) and s has a contour superarc set
            if (!NoSuchElement(splitNeighbour))
              { // not pointing to infinite root
                // if the superarc is already set, then we jump past it to the next one
                if (!NoSuchElement(contourTree.superarcs[MaskedIndex(splitNeighbour)]))
                        // reset the vertex' join neighbour
                        augmentedSplitSuperarcs[superID] = augmentedSplitSuperarcs[MaskedIndex(splitNeighbour)];
              } // not pointing to infinite root
          } // per active supernode

      */
  }

}; // CompressTrees_Step

} // namespace contourtree_maker_inc
} // namespace contourtree_augmented
} // namespace worklet
} // namespace vtkm

#endif
