//============================================================================
//  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 vtkm_worklet_contourtree_augmented_contourtree_maker_inc_transfer_leaf_chains_collapse_past_regular_h
#define vtkm_worklet_contourtree_augmented_contourtree_maker_inc_transfer_leaf_chains_collapse_past_regular_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 to collapse past regular vertices by updating inbound and outbound as part
// loop to find the now-regular vertices and collapse past them without altering
// the existing join & split arcs
class TransferLeafChains_CollapsePastRegular : public vtkm::worklet::WorkletMapField
{
public:
  typedef void ControlSignature(FieldIn activeSupernodes, // (input)
                                WholeArrayInOut outbound, // (output)
                                WholeArrayInOut inbound   // (output)
                                );
  typedef void ExecutionSignature(_1, InputIndex, _2, _3);
  using InputDomain = _1;


  // Default Constructor
  VTKM_EXEC_CONT
  TransferLeafChains_CollapsePastRegular() {}

  template <typename InOutFieldPortalType>
  VTKM_EXEC void operator()(const vtkm::Id& superID,
                            const vtkm::Id /*activeID*/, // FIXME: Remove unused parameter?
                            const InOutFieldPortalType& outboundPortal,
                            const InOutFieldPortalType& inboundPortal) const
  {
    vtkm::Id outNeighbour = outboundPortal.Get(superID);
    vtkm::Id inNeighbour = inboundPortal.Get(superID);

    // if the outbound is terminal, we're done, otherwise update
    if (!isTerminalElement(outNeighbour))
      outboundPortal.Set(superID, outboundPortal.Get(outNeighbour));

    // if the inNeighbour is not terminal, update
    if (!isTerminalElement(inNeighbour))
      inboundPortal.Set(superID, inboundPortal.Get(inNeighbour));

    // In serial this worklet implements the following operation
    /*
        for (vtkm::Id activeID = 0; activeID < activeSupernodes.GetNumberOfValues(); activeID++)
          { // per active vertex
            vtkm::Id superID = activeSupernodes[activeID];
            vtkm::Id outNeighbour = outbound[superID];
            vtkm::Id inNeighbour = inbound[superID];

            // if the outbound is terminal, we're done, otherwise update
            if (!isTerminalElement(outNeighbour))
                    outbound[superID] = outbound[outNeighbour];

            // if the inNeighbour is not terminal, update
            if (!isTerminalElement(inNeighbour))
                    inbound[superID] = inbound[inNeighbour];
          } // per active vertex

      */
  }

}; // TransferLeafChains_CollapsePastRegular

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

#endif
