//============================================================================
//  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_active_graph_build_chains_worklet_h
#define vtkm_worklet_contourtree_augmented_active_graph_build_chains_worklet_h

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

namespace vtkm
{
namespace worklet
{
namespace contourtree_augmented
{
namespace active_graph_inc
{

// Worklet for computing the sort indices from the sort order
class BuildChainsWorklet : public vtkm::worklet::WorkletMapField
{
public:
  typedef void ControlSignature(FieldIn activeVertices,      // (input) activeVertices
                                WholeArrayInOut hyperacrcs); // (input/output) hyperarcs
  typedef void ExecutionSignature(_1, InputIndex, _2);
  using InputDomain = _1;

  // Default Constructor
  VTKM_EXEC_CONT
  BuildChainsWorklet() {}

  template <typename InOutFieldPortalType>
  VTKM_EXEC void operator()(const vtkm::Id& vertexId,
                            const vtkm::Id /*vertex*/, // FIXME: Remove unused parameter?
                            const InOutFieldPortalType& hyperarcsPortal) const
  {
    // retrieve neighbour's ID
    vtkm::Id neighbour = hyperarcsPortal.Get(vertexId);
    // test for terminal vertex
    if (isTerminalElement(neighbour))
    {
      return;
    }
    // retrieve supernode flags
    vtkm::Id supernodeFlag = neighbour & (IS_SUPERNODE | IS_HYPERNODE);
    // remove the mask to get a raw index
    neighbour = maskedIndex(neighbour);
    // otherwise, retrieve the double neighbour
    vtkm::Id doubleNeighbour = hyperarcsPortal.Get(neighbour);
    // remove it's supernode & hypernode flags, but preserve the terminal flag
    doubleNeighbour = doubleNeighbour & (TERMINAL_ELEMENT | INDEX_MASK);
    // and add our own supernode flag in
    hyperarcsPortal.Set(vertexId, doubleNeighbour | supernodeFlag);

    // In serial this worklet implements the following operation
    /*
      for (indexType vertex = 0; vertex < activeVertices.size(); vertex++)
        { // per vertex
          // convert to vertex ID
          indexType vertexID = activeVertices[vertex];
          // retrieve neighbour's ID
          indexType neighbour = hyperarcs[vertexID];
          // test for terminal vertex
          if (isTerminalElement(neighbour))
            continue;
          // retrieve supernode flags
          indexType supernodeFlag = neighbour & (IS_SUPERNODE | IS_HYPERNODE);
          // remove the mask to get a raw index
          neighbour = maskedIndex(neighbour);
          // otherwise, retrieve the double neighbour
          indexType doubleNeighbour = hyperarcs[neighbour];
          // remove it's supernode & hypernode flags, but preserve the terminal flag
          doubleNeighbour = doubleNeighbour & (TERMINAL_ELEMENT | INDEX_MASK);
          // and add our own supernode flag in
          hyperarcs[vertexID] = doubleNeighbour | supernodeFlag;
        } // per vertex

      */
  }

}; // BuildChainsWorklet

} // namespace active_graph_inc
} // namespace contourtree_augmented
} // namespace worklet
} // namespace vtkm

#endif
