// SPDX-FileCopyrightText: Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
// SPDX-License-Identifier: BSD-3-Clause
#include "vtkSMPContourGrid.h"

#include "vtkCellArray.h"
#include "vtkCellData.h"
#include "vtkDataArray.h"
#include "vtkDemandDrivenPipeline.h"
#include "vtkGenericCell.h"
#include "vtkInformation.h"
#include "vtkInformationVector.h"
#include "vtkMergePoints.h"
#include "vtkMultiBlockDataSet.h"
#include "vtkMultiPieceDataSet.h"
#include "vtkNew.h"
#include "vtkNonMergingPointLocator.h"
#include "vtkObjectFactory.h"
#include "vtkPointData.h"
#include "vtkPolyData.h"
#include "vtkSMPMergePoints.h"
#include "vtkSMPMergePolyDataHelper.h"
#include "vtkSMPThreadLocal.h"
#include "vtkSMPThreadLocalObject.h"
#include "vtkSMPTools.h"
#include "vtkSmartPointer.h"
#include "vtkSpanSpace.h"
#include "vtkUnstructuredGrid.h"

#include "vtkTimerLog.h"

#include <cmath>

VTK_ABI_NAMESPACE_BEGIN
vtkStandardNewMacro(vtkSMPContourGrid);

//------------------------------------------------------------------------------
// Construct object with initial range (0,1) and single contour value
// of 0.0.
vtkSMPContourGrid::vtkSMPContourGrid()
{
  this->MergePieces = true;
}

//------------------------------------------------------------------------------
vtkSMPContourGrid::~vtkSMPContourGrid() = default;

//------------------------------------------------------------------------------
// This is to support parallel processing and potential polydata merging.
namespace
{

struct vtkLocalDataType
{
  vtkPolyData* Output;
  vtkSMPMergePoints* Locator;
  vtkIdList* VertCellOffsets;
  vtkIdList* VertConnOffsets;
  vtkIdList* LineCellOffsets;
  vtkIdList* LineConnOffsets;
  vtkIdList* PolyCellOffsets;
  vtkIdList* PolyConnOffsets;

  vtkLocalDataType()
    : Output(nullptr)
  {
  }
};

//------------------------------------------------------------------------------
// This functor uses thread local storage to create one vtkPolyData per
// thread. Each execution of the functor adds to the vtkPolyData that is
// local to the thread it is running on.
template <typename T>
class vtkContourGridFunctor
{
public:
  vtkSMPContourGrid* Filter;

  vtkUnstructuredGrid* Input;
  vtkDataArray* InScalars;

  vtkDataObject* Output;

  vtkSMPThreadLocal<vtkDataArray*> CellScalars;

  vtkSMPThreadLocalObject<vtkGenericCell> Cell;
  vtkSMPThreadLocalObject<vtkPoints> NewPts;
  vtkSMPThreadLocalObject<vtkCellArray> NewVerts;
  vtkSMPThreadLocalObject<vtkCellArray> NewLines;
  vtkSMPThreadLocalObject<vtkCellArray> NewPolys;

  vtkSMPThreadLocal<vtkLocalDataType> LocalData;

  int NumValues;
  double* Values;

  vtkContourGridFunctor(vtkSMPContourGrid* filter, vtkUnstructuredGrid* input,
    vtkDataArray* inScalars, int numValues, double* values, vtkDataObject* output)
    : Filter(filter)
    , Input(input)
    , InScalars(inScalars)
    , Output(output)
    , NumValues(numValues)
    , Values(values)
  {
  }

  virtual ~vtkContourGridFunctor()
  {
    // Cleanup all temporaries

    vtkSMPThreadLocal<vtkDataArray*>::iterator cellScalarsIter = this->CellScalars.begin();
    while (cellScalarsIter != this->CellScalars.end())
    {
      (*cellScalarsIter)->Delete();
      ++cellScalarsIter;
    }

    vtkSMPThreadLocal<vtkLocalDataType>::iterator dataIter = this->LocalData.begin();
    while (dataIter != this->LocalData.end())
    {
      (*dataIter).Output->Delete();
      (*dataIter).Locator->Delete();
      (*dataIter).VertCellOffsets->Delete();
      (*dataIter).VertConnOffsets->Delete();
      (*dataIter).LineCellOffsets->Delete();
      (*dataIter).LineConnOffsets->Delete();
      (*dataIter).PolyCellOffsets->Delete();
      (*dataIter).PolyConnOffsets->Delete();
      ++dataIter;
    }
  }

  void Initialize()
  {
    // Initialize thread local object before any processing happens.
    // This gets called once per thread.

    vtkPointLocator* locator;
    vtkPolyData* output;
    vtkIdList* vertCellOffsets;
    vtkIdList* vertConnOffsets;
    vtkIdList* lineCellOffsets;
    vtkIdList* lineConnOffsets;
    vtkIdList* polyCellOffsets;
    vtkIdList* polyConnOffsets;

    vtkLocalDataType& localData = this->LocalData.Local();

    localData.Output = vtkPolyData::New();
    output = localData.Output;

    localData.Locator = vtkSMPMergePoints::New();
    locator = localData.Locator;

    localData.VertCellOffsets = vtkIdList::New();
    vertCellOffsets = localData.VertCellOffsets;
    localData.VertConnOffsets = vtkIdList::New();
    vertConnOffsets = localData.VertConnOffsets;

    localData.LineCellOffsets = vtkIdList::New();
    lineCellOffsets = localData.LineCellOffsets;
    localData.LineConnOffsets = vtkIdList::New();
    lineConnOffsets = localData.LineConnOffsets;

    localData.PolyCellOffsets = vtkIdList::New();
    polyCellOffsets = localData.PolyCellOffsets;
    localData.PolyConnOffsets = vtkIdList::New();
    polyConnOffsets = localData.PolyConnOffsets;

    vtkPoints*& newPts = this->NewPts.Local();

    // set precision for the points in the output
    if (this->Filter->GetOutputPointsPrecision() == vtkAlgorithm::DEFAULT_PRECISION)
    {
      newPts->SetDataType(this->Input->GetPoints()->GetDataType());
    }
    else if (this->Filter->GetOutputPointsPrecision() == vtkAlgorithm::SINGLE_PRECISION)
    {
      newPts->SetDataType(VTK_FLOAT);
    }
    else if (this->Filter->GetOutputPointsPrecision() == vtkAlgorithm::DOUBLE_PRECISION)
    {
      newPts->SetDataType(VTK_DOUBLE);
    }

    output->SetPoints(newPts);

    vtkIdType numCells = this->Input->GetNumberOfCells();

    vtkIdType estimatedSize = static_cast<vtkIdType>(pow(static_cast<double>(numCells), .75));
    estimatedSize = estimatedSize / 1024 * 1024; // multiple of 1024
    estimatedSize = std::max<vtkIdType>(estimatedSize, 1024);

    newPts->Allocate(estimatedSize, estimatedSize);

    vertCellOffsets->Allocate(estimatedSize);
    vertConnOffsets->Allocate(estimatedSize);
    lineCellOffsets->Allocate(estimatedSize);
    lineConnOffsets->Allocate(estimatedSize);
    polyCellOffsets->Allocate(estimatedSize);
    polyConnOffsets->Allocate(estimatedSize);

    // locator->SetPoints(newPts);
    locator->InitPointInsertion(newPts, this->Input->GetBounds(), this->Input->GetNumberOfPoints());

    vtkCellArray*& newVerts = this->NewVerts.Local();
    newVerts->AllocateExact(estimatedSize, estimatedSize);
    output->SetVerts(newVerts);

    vtkCellArray*& newLines = this->NewLines.Local();
    newLines->AllocateExact(estimatedSize, estimatedSize);
    output->SetLines(newLines);

    vtkCellArray*& newPolys = this->NewPolys.Local();
    newPolys->AllocateExact(estimatedSize, estimatedSize);
    output->SetPolys(newPolys);

    vtkDataArray*& cellScalars = this->CellScalars.Local();
    cellScalars = this->InScalars->NewInstance();
    cellScalars->SetNumberOfComponents(this->InScalars->GetNumberOfComponents());
    cellScalars->Allocate(VTK_CELL_SIZE * this->InScalars->GetNumberOfComponents());

    vtkPointData* outPd = output->GetPointData();
    vtkCellData* outCd = output->GetCellData();
    vtkPointData* inPd = this->Input->GetPointData();
    vtkCellData* inCd = this->Input->GetCellData();
    outPd->InterpolateAllocate(inPd, estimatedSize, estimatedSize);
    outCd->CopyAllocate(inCd, estimatedSize, estimatedSize);
  }

  void operator()(vtkIdType begin, vtkIdType end)
  {
    // Actual computation.
    // Note the usage of thread local objects. These objects
    // persist for each thread across multiple execution of the
    // functor.

    vtkLocalDataType& localData = this->LocalData.Local();

    vtkGenericCell* cell = this->Cell.Local();
    vtkDataArray* cs = this->CellScalars.Local();
    vtkPointData* inPd = this->Input->GetPointData();
    vtkCellData* inCd = this->Input->GetCellData();

    vtkPolyData* output = localData.Output;
    vtkPointData* outPd = output->GetPointData();
    vtkCellData* outCd = output->GetCellData();

    vtkCellArray* vrts = this->NewVerts.Local();
    vtkCellArray* lines = this->NewLines.Local();
    vtkCellArray* polys = this->NewPolys.Local();

    vtkPointLocator* loc = localData.Locator;

    vtkIdList* vertCellOffsets = localData.VertCellOffsets;
    vtkIdList* vertConnOffsets = localData.VertConnOffsets;
    vtkIdList* lineCellOffsets = localData.LineCellOffsets;
    vtkIdList* lineConnOffsets = localData.LineConnOffsets;
    vtkIdList* polyCellOffsets = localData.PolyCellOffsets;
    vtkIdList* polyConnOffsets = localData.PolyConnOffsets;

    const double* values = this->Values;
    int numValues = this->NumValues;

    vtkNew<vtkIdList> pids;
    T range[2];
    vtkIdType cellid;
    bool isFirst = vtkSMPTools::GetSingleThread();
    vtkIdType checkAbortInterval = std::min((end - begin) / 10 + 1, (vtkIdType)1000);

    // If UseScalarTree is enabled at this point, we assume that a scalar
    // tree has been computed and thus the way cells are traversed changes.
    if (!this->Filter->GetUseScalarTree())
    {
      // This code assumes no scalar tree, thus it checks scalar range prior
      // to invoking contour.
      for (cellid = begin; cellid < end; cellid++)
      {
        if (cellid % checkAbortInterval == 0)
        {
          if (isFirst)
          {
            this->Filter->CheckAbort();
          }
          if (this->Filter->GetAbortOutput())
          {
            break;
          }
        }

        this->Input->GetCellPoints(cellid, pids);
        cs->SetNumberOfTuples(pids->GetNumberOfIds());
        this->InScalars->GetTuples(pids, cs);
        int numCellScalars = cs->GetNumberOfComponents() * cs->GetNumberOfTuples();
        T* cellScalarPtr = static_cast<T*>(cs->GetVoidPointer(0));

        // find min and max values in scalar data
        range[0] = range[1] = cellScalarPtr[0];

        for (T *it = cellScalarPtr + 1, *itEnd = cellScalarPtr + numCellScalars; it != itEnd; ++it)
        {
          if (*it < range[0])
          {
            range[0] = *it;
          } // if scalar <= min range value
          if (*it > range[1])
          {
            range[1] = *it;
          } // if scalar >= max range value
        }   // for all cellScalars

        bool needCell = false;
        for (int i = 0; i < numValues; i++)
        {
          if ((values[i] >= range[0]) && (values[i] <= range[1]))
          {
            needCell = true;
          } // if contour value in range for this cell
        }   // end for numContours

        if (needCell)
        {
          this->Input->GetCell(cellid, cell);

          for (int i = 0; i < numValues; i++)
          {
            if ((values[i] >= range[0]) && (values[i] <= range[1]))
            {
              vtkIdType begVertCellSize = vrts->GetNumberOfCells();
              vtkIdType begVertConnSize = vrts->GetNumberOfConnectivityIds();
              vtkIdType begLineCellSize = lines->GetNumberOfCells();
              vtkIdType begLineConnSize = lines->GetNumberOfConnectivityIds();
              vtkIdType begPolyCellSize = polys->GetNumberOfCells();
              vtkIdType begPolyConnSize = polys->GetNumberOfConnectivityIds();
              cell->Contour(
                values[i], cs, loc, vrts, lines, polys, inPd, outPd, inCd, cellid, outCd);
              // We keep track of the insertion point of verts, lines and polys.
              // This is later used when merging these data structures in parallel.
              // The reason this is needed is that vtkCellArray is not normally
              // random access with makes processing it in parallel very difficult.
              // So we create a semi-random-access structures in parallel. This
              // is only useful for merging since each of these indices can point
              // to multiple cells.
              if (vrts->GetNumberOfCells() > begVertCellSize)
              {
                vertCellOffsets->InsertNextId(begVertCellSize);
              }
              if (vrts->GetNumberOfConnectivityIds() > begVertConnSize)
              {
                vertConnOffsets->InsertNextId(begVertConnSize);
              }
              if (lines->GetNumberOfCells() > begLineCellSize)
              {
                lineCellOffsets->InsertNextId(begLineCellSize);
              }
              if (lines->GetNumberOfConnectivityIds() > begLineConnSize)
              {
                lineConnOffsets->InsertNextId(begLineConnSize);
              }
              if (polys->GetNumberOfCells() > begPolyCellSize)
              {
                polyCellOffsets->InsertNextId(begPolyCellSize);
              }
              if (polys->GetNumberOfConnectivityIds() > begPolyConnSize)
              {
                polyConnOffsets->InsertNextId(begPolyConnSize);
              }
            }
          }
        } // if cell need be contoured
      }   // for all cells
    }     // if no scalar tree requested
    else
    { // scalar tree provided
      // The begin / end parameters to this function represent batches of candidate
      // cells.
      vtkScalarTree* scalarTree = this->Filter->GetScalarTree();
      const vtkIdType* cellIds;
      vtkIdType numCells;
      for (vtkIdType batchNum = begin; batchNum < end; ++batchNum)
      {
        if (isFirst)
        {
          this->Filter->CheckAbort();
        }
        if (this->Filter->GetAbortOutput())
        {
          break;
        }
        cellIds = scalarTree->GetCellBatch(batchNum, numCells);
        for (vtkIdType idx = 0; idx < numCells; ++idx)
        {
          cellid = cellIds[idx];
          this->Input->GetCellPoints(cellid, pids);
          cs->SetNumberOfTuples(pids->GetNumberOfIds());
          this->InScalars->GetTuples(pids, cs);

          // Okay let's grab the cell and contour it
          this->Input->GetCell(cellid, cell);
          vtkIdType begVertCellSize = vrts->GetNumberOfCells();
          vtkIdType begVertConnSize = vrts->GetNumberOfConnectivityIds();
          vtkIdType begLineCellSize = lines->GetNumberOfCells();
          vtkIdType begLineConnSize = lines->GetNumberOfConnectivityIds();
          vtkIdType begPolyCellSize = polys->GetNumberOfCells();
          vtkIdType begPolyConnSize = polys->GetNumberOfConnectivityIds();
          cell->Contour(scalarTree->GetScalarValue(), cs, loc, vrts, lines, polys, inPd, outPd,
            inCd, cellid, outCd);
          // We keep track of the insertion point of verts, lines and polys.
          // This is later used when merging these data structures in parallel.
          // The reason this is needed is that vtkCellArray is not normally
          // random access with makes processing it in parallel very difficult.
          // So we create a semi-random-access structures in parallel. This
          // is only useful for merging since each of these indices can point
          // to multiple cells.
          if (vrts->GetNumberOfCells() > begVertCellSize)
          {
            vertCellOffsets->InsertNextId(begVertCellSize);
          }
          if (vrts->GetNumberOfConnectivityIds() > begVertConnSize)
          {
            vertConnOffsets->InsertNextId(begVertConnSize);
          }
          if (lines->GetNumberOfCells() > begLineCellSize)
          {
            lineCellOffsets->InsertNextId(begLineCellSize);
          }
          if (lines->GetNumberOfConnectivityIds() > begLineConnSize)
          {
            lineConnOffsets->InsertNextId(begLineConnSize);
          }
          if (polys->GetNumberOfCells() > begPolyCellSize)
          {
            polyCellOffsets->InsertNextId(begPolyCellSize);
          }
          if (polys->GetNumberOfConnectivityIds() > begPolyConnSize)
          {
            polyConnOffsets->InsertNextId(begPolyConnSize);
          }
        } // for all cells in this batch
      }   // for this batch of cells
    }     // using scalar tree

  } // operator()

  void Reduce()
  {
    // Create the final multi-block dataset

    vtkNew<vtkMultiPieceDataSet> mp;
    int count = 0;

    vtkSMPThreadLocal<vtkLocalDataType>::iterator outIter = this->LocalData.begin();
    while (outIter != this->LocalData.end())
    {
      vtkPolyData* output = (*outIter).Output;

      if (output->GetVerts()->GetNumberOfCells() == 0)
      {
        output->SetVerts(nullptr);
      }

      if (output->GetLines()->GetNumberOfCells() == 0)
      {
        output->SetLines(nullptr);
      }

      if (output->GetPolys()->GetNumberOfCells() == 0)
      {
        output->SetPolys(nullptr);
      }

      output->Squeeze();

      mp->SetPiece(count++, output);

      ++outIter;
    }

    vtkMultiBlockDataSet* output = vtkMultiBlockDataSet::SafeDownCast(this->Output);
    // If the output is a vtkPolyData (no merging), we throw away the multi-piece
    // dataset.
    if (output)
    {
      output->SetBlock(0, mp);
    }
  }
};

//------------------------------------------------------------------------------
template <typename T>
void DoContour(vtkSMPContourGrid* filter, vtkUnstructuredGrid* input, vtkIdType numCells,
  vtkDataArray* inScalars, int numContours, double* values, vtkDataObject* output)
{
  // Contour in parallel; create the processing functor
  vtkContourGridFunctor<T> functor(filter, input, inScalars, numContours, values, output);

  // If a scalar tree is used, then the way in which cells are iterated over changes.
  // With a scalar tree, batches of candidate cells are provided. Without one, then all
  // cells are iterated over one by one.
  if (filter->GetUseScalarTree())
  { // process in threaded using scalar tree
    vtkScalarTree* scalarTree = filter->GetScalarTree();
    vtkIdType numBatches;
    for (int i = 0; i < numContours; ++i)
    {
      numBatches = scalarTree->GetNumberOfCellBatches(values[i]);
      if (numBatches > 0)
      {
        vtkSMPTools::For(0, numBatches, functor);
      }
    }
  }
  else
  { // process all cells in parallel manner
    vtkSMPTools::For(0, numCells, functor);
  }

  // Now process the output from the separate threads. Merging may or may not be
  // required.
  if (output->IsA("vtkPolyData"))
  {
    // Do the merging.
    vtkSMPThreadLocal<vtkLocalDataType>::iterator itr = functor.LocalData.begin();
    vtkSMPThreadLocal<vtkLocalDataType>::iterator end = functor.LocalData.end();

    std::vector<vtkSMPMergePolyDataHelper::InputData> mpData;
    while (itr != end)
    {
      mpData.emplace_back((*itr).Output, (*itr).Locator, (*itr).VertCellOffsets,
        (*itr).VertConnOffsets, (*itr).LineCellOffsets, (*itr).LineConnOffsets,
        (*itr).PolyCellOffsets, (*itr).PolyConnOffsets);
      ++itr;
    }

    vtkPolyData* moutput = vtkSMPMergePolyDataHelper::MergePolyData(mpData);
    output->ShallowCopy(moutput);
    moutput->Delete();
  }
}

} // end namespace

//------------------------------------------------------------------------------
int vtkSMPContourGrid::RequestDataObject(
  vtkInformation* vtkNotUsed(request), vtkInformationVector**, vtkInformationVector* outputVector)
{
  vtkInformation* info = outputVector->GetInformationObject(0);
  if (this->MergePieces)
  {
    vtkPolyData* output = vtkPolyData::GetData(info);
    if (!output)
    {
      vtkPolyData* newOutput = vtkPolyData::New();
      info->Set(vtkDataObject::DATA_OBJECT(), newOutput);
      newOutput->Delete();
    }
  }
  else
  {
    vtkMultiBlockDataSet* output = vtkMultiBlockDataSet::GetData(info);
    if (!output)
    {
      vtkMultiBlockDataSet* newOutput = vtkMultiBlockDataSet::New();
      info->Set(vtkDataObject::DATA_OBJECT(), newOutput);
      newOutput->Delete();
    }
  }
  return 1;
}

//------------------------------------------------------------------------------
int vtkSMPContourGrid::RequestData(vtkInformation* vtkNotUsed(request),
  vtkInformationVector** inputVector, vtkInformationVector* outputVector)
{
  // get the input and output
  vtkUnstructuredGrid* input = vtkUnstructuredGrid::GetData(inputVector[0]);
  vtkDataObject* output = vtkDataObject::GetData(outputVector);

  if (input->GetNumberOfCells() == 0)
  {
    return 1;
  }

  vtkDataArray* inScalars = this->GetInputArrayToProcess(0, inputVector);
  if (!inScalars)
  {
    return 1;
  }

  // Not thread safe so calculate first.
  input->GetBounds();

  vtkIdType numContours = this->GetNumberOfContours();
  if (numContours < 1)
  {
    return 1;
  }

  double* values = this->GetValues();

  vtkIdType numCells = input->GetNumberOfCells();

  // Create scalar tree if necessary and if requested
  int useScalarTree = this->GetUseScalarTree();
  if (useScalarTree)
  {
    if (this->ScalarTree == nullptr)
    {
      this->ScalarTree = vtkSpanSpace::New();
    }
    this->ScalarTree->SetDataSet(input);
    this->ScalarTree->SetScalars(inScalars);
  }

  // Actually execute the contouring operation
  if (inScalars->GetDataType() == VTK_FLOAT)
  {
    DoContour<float>(this, input, numCells, inScalars, numContours, values, output);
  }
  else if (inScalars->GetDataType() == VTK_DOUBLE)
  {
    DoContour<double>(this, input, numCells, inScalars, numContours, values, output);
  }

  return 1;
}

//------------------------------------------------------------------------------
int vtkSMPContourGrid::FillOutputPortInformation(int vtkNotUsed(port), vtkInformation* info)
{
  info->Set(vtkDataObject::DATA_TYPE_NAME(), "vtkDataObject");
  return 1;
}

//------------------------------------------------------------------------------
vtkTypeBool vtkSMPContourGrid::ProcessRequest(
  vtkInformation* request, vtkInformationVector** inputVector, vtkInformationVector* outputVector)
{
  // generate the data
  if (request->Has(vtkDemandDrivenPipeline::REQUEST_DATA_OBJECT()))
  {
    return this->RequestDataObject(request, inputVector, outputVector);
  }

  return this->Superclass::ProcessRequest(request, inputVector, outputVector);
}

//------------------------------------------------------------------------------
void vtkSMPContourGrid::PrintSelf(ostream& os, vtkIndent indent)
{
  this->Superclass::PrintSelf(os, indent);

  os << indent << "Merge Pieces: " << (this->MergePieces ? "On\n" : "Off\n");
}
VTK_ABI_NAMESPACE_END