//============================================================================
//  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 2014 National Technology & Engineering Solutions of Sandia, LLC (NTESS).
//  Copyright 2014 UT-Battelle, LLC.
//  Copyright 2014 Los Alamos National Security.
//
//  Under the terms of Contract DE-NA0003525 with NTESS,
//  the U.S. Government retains certain rights in this software.
//
//  Under the terms of Contract DE-AC52-06NA25396 with Los Alamos National
//  Laboratory (LANL), the U.S. Government retains certain rights in
//  this software.
//============================================================================
#ifndef vtk_m_worklet_particleadvection_TemporalGridEvaluators_h
#define vtk_m_worklet_particleadvection_TemporalGridEvaluators_h

#include <vtkm/Types.h>
#include <vtkm/VectorAnalysis.h>
#include <vtkm/cont/ArrayHandle.h>
#include <vtkm/cont/CellSetStructured.h>
#include <vtkm/cont/DataSet.h>
#include <vtkm/cont/DeviceAdapter.h>
#include <vtkm/cont/DynamicArrayHandle.h>
#include <vtkm/worklet/particleadvection/Particles.h>

namespace vtkm
{
namespace worklet
{
namespace particleadvection
{

template <typename FieldArrayType>
class TemporalGridEvaluator : public vtkm::cont::ExecutionObjectBase
{
  using ScalarType = vtkm::worklet::particleadvection::ScalarType;

public:
  TemporalGridEvaluator() = default;

  VTKM_CONT
  TemporalGridEvaluator(const vtkm::cont::CoordinateSystem& coords1,
                        const vtkm::cont::DynamicCellSet& cellSet1,
                        const FieldArrayType& vectorField1,
                        const ScalarType datasettime1,
                        const vtkm::cont::CoordinateSystem& coords2,
                        const vtkm::cont::DynamicCellSet& cellSet2,
                        const FieldArrayType& vectorField2,
                        const ScalarType datasettime2)
    : Coords1(coords1)
    , CellSet1(cellSet1)
    , VectorField1(vectorField1)
    , DataSetTime1(datasettime1)
    , Coords2(coords2)
    , CellSet2(cellSet2)
    , VectorField2(vectorField2)
    , DataSetTime2(datasettime2)
  {
  }

public:
  template <typename DeviceAdapterTag>
  class ExecObject
  {
    using PortalType =
      typename FieldArrayType::template ExecutionTypes<DeviceAdapterTag>::PortalConst;

  public:
    /*
   * This method is intended to update the initial datasets we are going to
   * use to advect the particels.
   * The components are similar to the normal datasets except now we add times
   * for which the datasets were active to perform temporal interpolation.
   */
    VTKM_CONT
    ExecObject(const vtkm::cont::CoordinateSystem& coords1,
               const vtkm::cont::DynamicCellSet& cellSet1,
               const FieldArrayType& vectorField1,
               const ScalarType datasettime1,
               const vtkm::cont::CoordinateSystem& coords2,
               const vtkm::cont::DynamicCellSet& cellSet2,
               const FieldArrayType& vectorField2,
               const ScalarType datasettime2)

    {
      using UniformType = vtkm::cont::ArrayHandleUniformPointCoordinates;
      using StructuredType = vtkm::cont::CellSetStructured<3>;

      if (!coords1.GetData().IsType<UniformType>() || !coords2.GetData().IsType<UniformType>())
        throw vtkm::cont::ErrorInternal("Coordinates are not uniform.");
      if (!cellSet1.IsSameType(StructuredType()) || !cellSet2.IsSameType(StructuredType()))
        throw vtkm::cont::ErrorInternal("Cells are not 3D structured.");

      vectors1 = vectorField1.PrepareForInput(DeviceAdapterTag());
      vectors2 = vectorField2.PrepareForInput(DeviceAdapterTag());

      bounds1 = coords1.GetBounds();
      bounds2 = coords2.GetBounds();

      vtkm::cont::CellSetStructured<3> cells1;
      vtkm::cont::CellSetStructured<3> cells2;

      cellSet1.CopyTo(cells1);
      dims1 = cells1.GetSchedulingRange(vtkm::TopologyElementTagPoint());

      cellSet2.CopyTo(cells2);
      dims2 = cells2.GetSchedulingRange(vtkm::TopologyElementTagPoint());

      time1 = datasettime1;
      time2 = datasettime2;

      planeSize1 = dims1[1] * dims1[1];
      rowSize1 = dims1[0];

      planeSize2 = dims2[1] * dims2[1];
      rowSize2 = dims2[0];

      scale1[0] = static_cast<ScalarType>(dims1[0] - 1) /
        static_cast<ScalarType>(bounds1.X.Max - bounds1.X.Min);
      scale1[1] = static_cast<ScalarType>(dims1[1] - 1) /
        static_cast<ScalarType>(bounds1.Y.Max - bounds1.Y.Min);
      scale1[2] = static_cast<ScalarType>(dims1[2] - 1) /
        static_cast<ScalarType>(bounds1.Z.Max - bounds1.Z.Min);

      scale2[0] = static_cast<ScalarType>(dims2[0] - 1) /
        static_cast<ScalarType>(bounds2.X.Max - bounds2.X.Min);
      scale2[1] = static_cast<ScalarType>(dims2[1] - 1) /
        static_cast<ScalarType>(bounds2.Y.Max - bounds2.Y.Min);
      scale2[2] = static_cast<ScalarType>(dims2[2] - 1) /
        static_cast<ScalarType>(bounds2.Z.Max - bounds2.Z.Min);
    }


    VTKM_EXEC_CONT
    bool IsWithinSpatialBoundary(const vtkm::Vec<ScalarType, 3>& position) const
    {
      if (!bounds1.Contains(position) || !bounds2.Contains(position))
        return false;
      return true;
    }

    VTKM_EXEC_CONT
    bool IsWithinTemporalBoundary(const ScalarType time) const
    {
      if (time < time1 || time >= time2)
        return false;
      return true;
    }

    VTKM_EXEC_CONT
    void GetSpatialBoundary(vtkm::Vec<ScalarType, 3>& dir, vtkm::Vec<ScalarType, 3>& boundary) const
    {
      // Based on the direction of the velocity we need to be able to tell where
      // the particle will exit the domain from to actually push it out of domain.
      boundary[0] = static_cast<ScalarType>(dir[0] > 0 ? bounds2.X.Max : bounds2.X.Min);
      boundary[1] = static_cast<ScalarType>(dir[1] > 0 ? bounds2.Y.Max : bounds2.Y.Min);
      boundary[2] = static_cast<ScalarType>(dir[2] > 0 ? bounds2.Z.Max : bounds2.Z.Min);
    }

    VTKM_EXEC_CONT
    void GetTemporalBoundary(ScalarType& boundary) const
    {
      // Return the time of the newest time slice
      boundary = time2;
    }

    /*
   * This method is intended to swap the initial datsets, by adding a new
   * dataset. The first dataset is replaced by the second, also the corresponding
   * times. The second dataset is replaced by a new dataset.
   */
    VTKM_CONT
    void UpdateDataSetForNewTimeSlice(const vtkm::cont::CoordinateSystem& coords,
                                      const vtkm::cont::DynamicCellSet& cellSet,
                                      const FieldArrayType& vectorField,
                                      const ScalarType time)
    {
      using UniformType = vtkm::cont::ArrayHandleUniformPointCoordinates;
      using StructuredType = vtkm::cont::CellSetStructured<3>;
      if (!coords.GetData().IsType<UniformType>())
        throw vtkm::cont::ErrorInternal("Coordinates are not uniform.");
      if (!cellSet.IsSameType(StructuredType()))
        throw vtkm::cont::ErrorInternal("Cells are not 3D structured.");
      vectors1 = vectors2;
      bounds1 = bounds2;
      dims1 = dims2;
      time1 = time2;
      planeSize1 = planeSize2;
      rowSize1 = rowSize2;
      scale1[0] = scale2[0];
      scale1[1] = scale2[1];
      scale1[2] = scale2[2];

      vectors2 = vectorField.PrepareForInput(DeviceAdapterTag());
      bounds2 = coords.GetBounds();
      vtkm::cont::CellSetStructured<3> cells;
      cellSet.CopyTo(cells);
      dims2 = cells.GetSchedulingRange(vtkm::TopologyElementTagPoint());
      time2 = time;
      planeSize2 = dims2[1] * dims2[1];
      rowSize2 = dims2[0];

      scale2[0] = static_cast<ScalarType>(dims2[0] - 1) /
        static_cast<ScalarType>(bounds2.X.Max - bounds2.X.Min);
      scale2[1] = static_cast<ScalarType>(dims2[1] - 1) /
        static_cast<ScalarType>(bounds2.Y.Max - bounds2.Y.Min);
      scale2[2] = static_cast<ScalarType>(dims2[2] - 1) /
        static_cast<ScalarType>(bounds2.Z.Max - bounds2.Z.Min);
    }

    VTKM_EXEC
    bool Interpolate(const vtkm::Vec<ScalarType, 3>& position,
                     vtkm::Vec<ScalarType, 3>& velocity,
                     const PortalType& vectors,
                     const vtkm::Bounds& bounds,
                     const vtkm::Id3 dims,
                     const vtkm::Id& planeSize,
                     const vtkm::Id& rowSize,
                     const vtkm::Vec<ScalarType, 3>& scale) const
    {
      if (!bounds.Contains(position))
        return false;
      //Set the indices for the interpolation.
      vtkm::Id3 idx000, idx001, idx010, idx011, idx100, idx101, idx110, idx111;

      vtkm::Vec<ScalarType, 3> normalized =
        vtkm::Vec<ScalarType, 3>((position[0] - static_cast<ScalarType>(bounds.X.Min)) * scale[0],
                                 (position[1] - static_cast<ScalarType>(bounds.Y.Min)) * scale[1],
                                 (position[2] - static_cast<ScalarType>(bounds.Z.Min)) * scale[2]);

      idx000[0] = static_cast<vtkm::IdComponent>(floor(normalized[0]));
      idx000[1] = static_cast<vtkm::IdComponent>(floor(normalized[1]));
      idx000[2] = static_cast<vtkm::IdComponent>(floor(normalized[2]));

      idx001 = idx000;
      idx001[0] = (idx001[0] + 1) <= dims[0] - 1 ? idx001[0] + 1 : dims[0] - 1;
      idx010 = idx000;
      idx010[1] = (idx010[1] + 1) <= dims[1] - 1 ? idx010[1] + 1 : dims[1] - 1;
      idx011 = idx010;
      idx011[0] = (idx011[0] + 1) <= dims[0] - 1 ? idx011[0] + 1 : dims[0] - 1;
      idx100 = idx000;
      idx100[2] = (idx100[2] + 1) <= dims[2] - 1 ? idx100[2] + 1 : dims[2] - 1;
      idx101 = idx100;
      idx101[0] = (idx101[0] + 1) <= dims[0] - 1 ? idx101[0] + 1 : dims[0] - 1;
      idx110 = idx100;
      idx110[1] = (idx110[1] + 1) <= dims[1] - 1 ? idx110[1] + 1 : dims[1] - 1;
      idx111 = idx110;
      idx111[0] = (idx111[0] + 1) <= dims[0] - 1 ? idx111[0] + 1 : dims[0] - 1;

      // Get the vecdata at the eight corners
      vtkm::Vec<ScalarType, 3> v000, v001, v010, v011, v100, v101, v110, v111;
      v000 = vectors.Get(idx000[2] * planeSize + idx000[1] * rowSize + idx000[0]);
      v001 = vectors.Get(idx001[2] * planeSize + idx001[1] * rowSize + idx001[0]);
      v010 = vectors.Get(idx010[2] * planeSize + idx010[1] * rowSize + idx010[0]);
      v011 = vectors.Get(idx011[2] * planeSize + idx011[1] * rowSize + idx011[0]);
      v100 = vectors.Get(idx100[2] * planeSize + idx100[1] * rowSize + idx100[0]);
      v101 = vectors.Get(idx101[2] * planeSize + idx101[1] * rowSize + idx101[0]);
      v110 = vectors.Get(idx110[2] * planeSize + idx110[1] * rowSize + idx110[0]);
      v111 = vectors.Get(idx111[2] * planeSize + idx111[1] * rowSize + idx111[0]);

      // Interpolation in X
      vtkm::Vec<ScalarType, 3> v00, v01, v10, v11;
      ScalarType a = normalized[0] - static_cast<ScalarType>(floor(normalized[0]));
      v00[0] = (1.0f - a) * v000[0] + a * v001[0];
      v00[1] = (1.0f - a) * v000[1] + a * v001[1];
      v00[2] = (1.0f - a) * v000[2] + a * v001[2];

      v01[0] = (1.0f - a) * v010[0] + a * v011[0];
      v01[1] = (1.0f - a) * v010[1] + a * v011[1];
      v01[2] = (1.0f - a) * v010[2] + a * v011[2];

      v10[0] = (1.0f - a) * v100[0] + a * v101[0];
      v10[1] = (1.0f - a) * v100[1] + a * v101[1];
      v10[2] = (1.0f - a) * v100[2] + a * v101[2];

      v11[0] = (1.0f - a) * v110[0] + a * v111[0];
      v11[1] = (1.0f - a) * v110[1] + a * v111[1];
      v11[2] = (1.0f - a) * v110[2] + a * v111[2];

      // Interpolation in Y
      vtkm::Vec<ScalarType, 3> v0, v1;
      a = normalized[1] - static_cast<ScalarType>(floor(normalized[1]));
      v0[0] = (1.0f - a) * v00[0] + a * v01[0];
      v0[1] = (1.0f - a) * v00[1] + a * v01[1];
      v0[2] = (1.0f - a) * v00[2] + a * v01[2];

      v1[0] = (1.0f - a) * v10[0] + a * v11[0];
      v1[1] = (1.0f - a) * v10[1] + a * v11[1];
      v1[2] = (1.0f - a) * v10[2] + a * v11[2];

      a = normalized[2] - static_cast<ScalarType>(floor(normalized[2]));
      velocity[0] = (1.0f - a) * v0[0] + a * v1[0];
      velocity[1] = (1.0f - a) * v0[1] + a * v1[1];
      velocity[2] = (1.0f - a) * v0[2] + a * v1[2];
      return true;
    }

    VTKM_EXEC
    bool Evaluate(const vtkm::Vec<ScalarType, 3>& position,
                  const ScalarType particleTime,
                  vtkm::Vec<ScalarType, 3>& velocity) const
    {
      vtkm::Vec<ScalarType, 3> velocity1;
      bool result;
      result =
        Interpolate(position, velocity1, vectors1, bounds1, dims1, planeSize1, rowSize1, scale1);
      if (!result)
        return false;

      vtkm::Vec<ScalarType, 3> velocity2;
      result =
        Interpolate(position, velocity2, vectors2, bounds2, dims2, planeSize1, rowSize1, scale2);
      if (!result)
        return false;

      ScalarType proportion = (particleTime - time1) / (time2 - time1);

      velocity[0] = (1.0f - proportion) * velocity1[0] + proportion * velocity2[0];
      velocity[1] = (1.0f - proportion) * velocity1[1] + proportion * velocity2[1];
      velocity[2] = (1.0f - proportion) * velocity1[2] + proportion * velocity2[2];
      return true;
    }

  private:
    ScalarType time1, time2;
    vtkm::Vec<ScalarType, 3> scale1, scale2;
    /*
   * Currently only adding functionality to work with unifrom grids.
   * Reason being they are easy to work with.
   */
    vtkm::Bounds bounds1;
    vtkm::Bounds bounds2;
    vtkm::Id3 dims1;
    vtkm::Id3 dims2;
    /*
   * The resolution of the different slices of data may be
   * different, but needs to be uniform.
   */
    vtkm::Id planeSize1, planeSize2;
    vtkm::Id rowSize1, rowSize2;
    /*
   * These are the portals that contain the actual data for the interpolation.
   */
    PortalType vectors1;
    PortalType vectors2;
  };

  template <typename DeviceAdapter>
  VTKM_CONT ExecObject<DeviceAdapter> PrepareForExecution(DeviceAdapter) const
  {
    return ExecObject<DeviceAdapter>(this->Coords1,
                                     this->CellSet1,
                                     this->VectorField1,
                                     this->DataSetTime1,
                                     this->Coords2,
                                     this->CellSet2,
                                     this->VectorField2,
                                     this->DataSetTime2);
  }

private:
  vtkm::cont::CoordinateSystem Coords1;
  vtkm::cont::DynamicCellSet CellSet1;
  FieldArrayType VectorField1;
  ScalarType DataSetTime1;
  vtkm::cont::CoordinateSystem Coords2;
  vtkm::cont::DynamicCellSet CellSet2;
  FieldArrayType VectorField2;
  ScalarType DataSetTime2;
};

} //namespace particleadvection
} //namespace worklet
} //namespace vtkm

#endif //vtk_m_worklet_particleadvection_TemporalGridEvaluators_h
