/*=========================================================================

Program:   ParaView
Module:    vtkCleanUnstructuredGrid.cxx

Copyright (c) Kitware, Inc.
All rights reserved.
See Copyright.txt or http://www.paraview.org/HTML/Copyright.html 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.

=========================================================================*/
#include "vtkCleanUnstructuredGrid.h"

#include "vtkArrayDispatch.h"
#include "vtkArrayDispatchArrayList.h"
#include "vtkBitArray.h"
#include "vtkCell.h"
#include "vtkCellData.h"
#include "vtkCellSizeFilter.h"
#include "vtkCellTypes.h"
#include "vtkCollection.h"
#include "vtkDataArrayRange.h"
#include "vtkDataSet.h"
#include "vtkDoubleArray.h"
#include "vtkIncrementalPointLocator.h"
#include "vtkInformation.h"
#include "vtkInformationVector.h"
#include "vtkIntArray.h"
#include "vtkMergePoints.h"
#include "vtkObjectFactory.h"
#include "vtkPointData.h"
#include "vtkPointSet.h"
#include "vtkPoints.h"
#include "vtkRectilinearGrid.h"
#include "vtkSMPThreadLocalObject.h"
#include "vtkSMPTools.h"
#include "vtkStringArray.h"
#include "vtkUnstructuredGrid.h"

#include <unordered_set>

namespace
{

constexpr unsigned char MAX_CELL_DIM = 3;

void AllocatePointAttributes(vtkPointData* inPD, vtkPointData* outPD, vtkIdType nPoints)
{
  for (vtkIdType iArr = 0; iArr < inPD->GetNumberOfArrays(); ++iArr)
  {
    auto inArr = inPD->GetAbstractArray(iArr);
    auto outArr = outPD->GetAbstractArray(inArr->GetName());
    if (!outArr)
    {
      vtkGenericWarningMacro(<< inArr->GetName() << " output array is nullptr");
      continue;
    }
    outArr->SetNumberOfComponents(inArr->GetNumberOfComponents());
    outArr->SetNumberOfTuples(nPoints);
  }
}

unsigned char GetTopologicalDimension(vtkDataSet* ds)
{
  vtkNew<vtkCellTypes> cTypes;
  ds->GetCellTypes(cTypes);
  unsigned char topoDim = 0;
  for (vtkIdType iC = 0; iC < cTypes->GetNumberOfTypes(); ++iC)
  {
    unsigned char dimC =
      static_cast<unsigned char>(vtkCellTypes::GetDimension(cTypes->GetCellType(iC)));
    topoDim = std::max(topoDim, dimC);
    if (topoDim >= MAX_CELL_DIM)
    {
      break;
    }
  }
  if (topoDim > MAX_CELL_DIM)
  {
    vtkErrorWithObjectMacro(
      nullptr, "Topological dimension of data set is larger than the maximal cell dimension");
    return MAX_CELL_DIM;
  }
  return topoDim;
}

struct WeighingStrategy
{
  virtual ~WeighingStrategy() = default;
  virtual vtkSmartPointer<vtkDoubleArray> ComputeWeights(
    vtkDataSet* ds, const std::vector<vtkIdType>& ptMap) = 0;
};

struct FirstPointStrategy : public WeighingStrategy
{
  vtkSmartPointer<vtkDoubleArray> ComputeWeights(
    vtkDataSet* ds, const std::vector<vtkIdType>& ptMap) override
  {
    if (ds->GetNumberOfPoints() != static_cast<vtkIdType>(ptMap.size()))
    {
      vtkGenericWarningMacro(
        "Number of points in dataset and number of entries in point map don't line up.");
      return nullptr;
    }
    vtkNew<vtkDoubleArray> weights;
    weights->SetNumberOfComponents(1);
    weights->SetNumberOfTuples(ds->GetNumberOfPoints());
    weights->Fill(0.0);

    std::unordered_set<vtkIdType> firstPoints;
    for (vtkIdType iP = 0; iP < ds->GetNumberOfPoints(); ++iP)
    {
      if (firstPoints.find(ptMap[iP]) != firstPoints.end())
      {
        continue;
      }
      firstPoints.insert(ptMap[iP]);
      weights->SetValue(iP, 1.0);
    }
    return weights;
  }
};

struct AveragingStrategy : public WeighingStrategy
{
  vtkSmartPointer<vtkDoubleArray> ComputeWeights(
    vtkDataSet* ds, const std::vector<vtkIdType>& ptMap) override
  {
    if (ds->GetNumberOfPoints() != static_cast<vtkIdType>(ptMap.size()))
    {
      vtkGenericWarningMacro(
        "Number of points in dataset and number of entries in point map don't line up.");
      return nullptr;
    }
    std::vector<double> counts(ds->GetNumberOfPoints(), 0.0);
    for (vtkIdType iP = 0; iP < ds->GetNumberOfPoints(); ++iP)
    {
      if (ptMap[iP] < 0)
      {
        continue;
      }
      counts[ptMap[iP]] += 1.0;
    }

    vtkNew<vtkDoubleArray> weights;
    weights->SetNumberOfComponents(1);
    weights->SetNumberOfTuples(ds->GetNumberOfPoints());
    weights->Fill(0.0);

    auto wRange = vtk::DataArrayValueRange<1>(weights);
    for (vtkIdType iP = 0; iP < ds->GetNumberOfPoints(); ++iP)
    {
      if (ptMap[iP] < 0)
      {
        continue;
      }
      wRange[iP] = (counts[ptMap[iP]] ? 1.0 / counts[ptMap[iP]] : 0.0);
    }

    return weights;
  }
};

struct SpatialDensityStrategy : public WeighingStrategy
{
  vtkSmartPointer<vtkDoubleArray> ComputeWeights(
    vtkDataSet* ds, const std::vector<vtkIdType>& ptMap) override
  {
    if (ds->GetNumberOfPoints() != static_cast<vtkIdType>(ptMap.size()))
    {
      vtkGenericWarningMacro(
        "Number of points in dataset and number of entries in point map don't line up.");
      return nullptr;
    }
    // Get topological dimension of data set
    auto topoDim = GetTopologicalDimension(ds);
    // Calculate cell measures
    vtkSmartPointer<vtkDataArray> measures;
    {
      // this scope is so that any extra memory related to the cell size filter gets released when
      // no longer needed
      vtkNew<vtkCellSizeFilter> cellSizeFilter;
      cellSizeFilter->SetInputData(ds);
      cellSizeFilter->Update();
      auto output = vtkDataSet::SafeDownCast(cellSizeFilter->GetOutputDataObject(0));
      auto cData = output->GetCellData();
      if (!cData || !cData->HasArray("VertexCount") || !cData->HasArray("Length") ||
        !cData->HasArray("Area") || !cData->HasArray("Volume"))
      {
        vtkErrorWithObjectMacro(
          nullptr, "Could not find correct cell data in output of cell size filter");
        return nullptr;
      }
      switch (topoDim)
      {
        case 0:
          measures = cData->GetArray("VertexCount");
          break;
        case 1:
          measures = cData->GetArray("Length");
          break;
        case 2:
          measures = cData->GetArray("Area");
          break;
        case 3:
          measures = cData->GetArray("Volume");
          break;
        default:
          vtkErrorWithObjectMacro(
            nullptr, "Topological dimension of data set is higher than 3. Cannot deal with that.");
          return nullptr;
      }
    }
    // Distribute spatial density to points
    vtkNew<vtkDoubleArray> density;
    density->SetNumberOfComponents(1);
    density->SetNumberOfTuples(ds->GetNumberOfPoints());
    density->Fill(0.0);
    auto dRange = vtk::DataArrayValueRange<1>(density);
    auto mRange = vtk::DataArrayValueRange<1>(measures);
    if (ds->GetNumberOfCells() > 0)
    {
      vtkNew<vtkIdList> pointIdList;
      ds->GetCellPoints(0, pointIdList);
    }
    vtkSMPThreadLocalObject<vtkIdList> localPointIds;
    auto distribute = [&](vtkIdType begin, vtkIdType end) {
      for (vtkIdType iC = begin; iC < end; ++iC)
      {
        ds->GetCellPoints(iC, localPointIds.Local());
        double participation = mRange[iC] / localPointIds.Local()->GetNumberOfIds();
        for (vtkIdType iP = 0; iP < localPointIds.Local()->GetNumberOfIds(); ++iP)
        {
          dRange[localPointIds.Local()->GetId(iP)] += participation;
        }
      }
    };
    // For thread safety
    if (ds->GetNumberOfCells() > 0)
    {
      vtkNew<vtkIdList> buffer;
      ds->GetCellPoints(0, buffer);
    }
    distribute(0, ds->GetNumberOfCells());
    // Merits a dedicated struct with a reduce operation
    // collisions occuring in the += operation
    // vtkSMPTools::For(0, ds->GetNumberOfCells(), distribute);
    // Normalize spatial densities with respect to point map
    {
      std::vector<double> masses(*std::max_element(ptMap.begin(), ptMap.end()) + 1, 0);
      auto computeMasses = [&dRange, &masses, &ptMap](vtkIdType begin, vtkIdType end) {
        for (vtkIdType iP = begin; iP < end; ++iP)
        {
          if (ptMap[iP] < 0)
          {
            dRange[iP] = 0.0;
            continue;
          }
          masses[ptMap[iP]] += dRange[iP];
        }
      };
      computeMasses(0, ds->GetNumberOfPoints());
      // Merits a dedicated struct with a reduce operation
      // collisions occuring in the += operation
      // vtkSMPTools::For(0, ds->GetNumberOfPoints(), computeMasses);
      vtkSMPTools::For(
        0, ds->GetNumberOfPoints(), [&dRange, &masses, &ptMap](vtkIdType begin, vtkIdType end) {
          for (vtkIdType iP = begin; iP < end; ++iP)
          {
            if (ptMap[iP] < 0)
            {
              continue;
            }
            dRange[iP] = (masses[ptMap[iP]] != 0 ? dRange[iP] / masses[ptMap[iP]] : 0.0);
          }
        });
    }
    return density;
  }
};

struct WeighingStrategyFactory
{
  std::shared_ptr<WeighingStrategy> operator()(vtkCleanUnstructuredGrid::DataWeighingType dwt)
  {
    switch (dwt)
    {
      case vtkCleanUnstructuredGrid::FIRST_POINT:
        return std::make_shared<FirstPointStrategy>();
      case vtkCleanUnstructuredGrid::AVERAGING:
        return std::make_shared<AveragingStrategy>();
      case vtkCleanUnstructuredGrid::SPATIAL_DENSITY:
        return std::make_shared<SpatialDensityStrategy>();
      default:
        vtkGenericWarningMacro(
          "Incorrect weighing strategy type passed to factory. defaulting to FIRST_POINT.");
        return std::make_shared<FirstPointStrategy>();
    }
  }
};

struct WeighingWorklet
{
  template <typename ArrayTypeIn, typename ArrayTypeOut>
  void operator()(ArrayTypeIn* inArray, ArrayTypeOut* outArray, vtkDoubleArray* weights,
    const std::vector<vtkIdType>& ptMap)
  {
    outArray->Fill(0);
    auto inRange = vtk::DataArrayTupleRange(inArray);
    auto outRange = vtk::DataArrayTupleRange(outArray);
    auto wRange = vtk::DataArrayValueRange<1>(weights);
    auto weighing = [&](vtkIdType begin, vtkIdType end) {
      for (vtkIdType iP = begin; iP < end; ++iP)
      {
        if (ptMap[iP] < 0)
        {
          continue;
        }
        auto inT = inRange[iP];
        auto outT = outRange[ptMap[iP]];
        for (vtkIdType iT = 0; iT < inArray->GetNumberOfComponents(); ++iT)
        {
          outT[iT] += wRange[iP] * inT[iT];
        }
      }
    };
    weighing(0, inArray->GetNumberOfTuples());
    // Merits a dedicated struct with a reduce operation
    // collisions occuring in the += operation
    // vtkSMPTools::For(0, inArray->GetNumberOfTuples(), weighing);
  }
};

template <>
void WeighingWorklet::operator()(vtkBitArray* inArray, vtkBitArray* outArray,
  vtkDoubleArray* vtkNotUsed(weights), const std::vector<vtkIdType>& ptMap)
{
  outArray->Fill(0);
  for (vtkIdType iP = 0; iP < inArray->GetNumberOfValues(); ++iP)
  {
    if (ptMap[iP] < 0)
    {
      continue;
    }
    outArray->SetValue(ptMap[iP], inArray->GetValue(iP));
  }
}

template <>
void WeighingWorklet::operator()(vtkStringArray* inArray, vtkStringArray* outArray,
  vtkDoubleArray* vtkNotUsed(weights), const std::vector<vtkIdType>& ptMap)
{
  for (vtkIdType iP = 0; iP < inArray->GetNumberOfValues(); ++iP)
  {
    if (ptMap[iP] < 0)
    {
      continue;
    }
    outArray->SetValue(ptMap[iP], inArray->GetValue(iP));
  }
}

template <>
void WeighingWorklet::operator()(vtkAbstractArray* inArray, vtkAbstractArray* outArray,
  vtkDoubleArray* vtkNotUsed(weights), const std::vector<vtkIdType>& ptMap)
{
  for (vtkIdType iP = 0; iP < inArray->GetNumberOfTuples(); ++iP)
  {
    if (ptMap[iP] < 0)
    {
      continue;
    }
    outArray->InsertTuple(ptMap[iP], iP, inArray);
  }
}

void WeightAttributes(vtkPointData* inPD, vtkPointData* outPD, vtkDoubleArray* weights,
  const std::vector<vtkIdType>& ptMap)
{
  // better here to use a Dispatch2BySameArrayType, but that doesn't exist
  using Dispatcher = vtkArrayDispatch::Dispatch2BySameValueType<vtkArrayDispatch::AllTypes>;
  WeighingWorklet worker;
  for (vtkIdType iArr = 0; iArr < inPD->GetNumberOfArrays(); ++iArr)
  {
    auto inArr = inPD->GetArray(iArr);
    // if not data array check for abstract
    if (!inArr)
    {
      auto inAbsArr = inPD->GetAbstractArray(iArr);
      if (!inAbsArr)
      {
        vtkGenericWarningMacro("One of the arrays in the point data is nullptr.");
        continue;
      }
      auto outAbsArr = outPD->GetAbstractArray(inAbsArr->GetName());
      if (!outAbsArr)
      {
        vtkGenericWarningMacro("Output array " << inAbsArr->GetName() << " is nullptr.");
        continue;
      }
      // if string array go to dedicated path
      auto inStrArr = vtkStringArray::SafeDownCast(inAbsArr);
      if (inStrArr)
      {
        auto outStrArr = vtkStringArray::SafeDownCast(outAbsArr);
        if (!outStrArr)
        {
          vtkGenericWarningMacro("Output array " << inStrArr->GetName()
                                                 << " is not the same type as input string array.");
          continue;
        }
        worker(inStrArr, outStrArr, weights, ptMap);
        continue;
      }
      worker(inAbsArr, outAbsArr, weights, ptMap);
      continue;
    }
    auto outArr = outPD->GetArray(inArr->GetName());
    if (!outArr)
    {
      vtkGenericWarningMacro(
        "Output array " << inArr->GetName() << " is nullptr or not a vtkDataArray.");
      continue;
    }
    if (!Dispatcher::Execute(inArr, outArr, worker, weights, ptMap))
    {
      auto inBitArr = vtkBitArray::SafeDownCast(inArr);
      auto outBitArr = vtkBitArray::SafeDownCast(outArr);
      if (inBitArr && outBitArr)
      {
        worker(inBitArr, outBitArr, weights, ptMap);
      }
      worker(inArr, outArr, weights, ptMap);
    }
  }
}

}

vtkStandardNewMacro(vtkCleanUnstructuredGrid);
vtkCxxSetSmartPointerMacro(vtkCleanUnstructuredGrid, Locator, vtkIncrementalPointLocator);

//----------------------------------------------------------------------------
vtkCleanUnstructuredGrid::vtkCleanUnstructuredGrid() = default;

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

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

  if (this->Locator)
  {
    os << indent << "Locator: ";
    this->Locator->PrintSelf(os, indent.GetNextIndent());
  }
  else
  {
    os << indent << "Locator: none\n";
  }
  os << indent << "ToleranceIsAbsolute: " << (this->ToleranceIsAbsolute ? "On\n" : "Off\n");
  os << indent << "Tolerance: " << this->Tolerance << std::endl;
  os << indent << "AbsoluteTolerance: " << this->AbsoluteTolerance << std::endl;
  os << indent
     << "RemovePointsWithoutCells: " << (this->RemovePointsWithoutCells ? "On\n" : "Off\n");
  os << indent << "OutputPointsPrecision: " << this->OutputPointsPrecision << std::endl;
}

//----------------------------------------------------------------------------
int vtkCleanUnstructuredGrid::RequestData(vtkInformation* vtkNotUsed(request),
  vtkInformationVector** inputVector, vtkInformationVector* outputVector)
{
  vtkInformation* inInfo = inputVector[0]->GetInformationObject(0);
  vtkInformation* outInfo = outputVector->GetInformationObject(0);

  vtkDataSet* input = vtkDataSet::SafeDownCast(inInfo->Get(vtkDataObject::DATA_OBJECT()));
  vtkUnstructuredGrid* output =
    vtkUnstructuredGrid::SafeDownCast(outInfo->Get(vtkDataObject::DATA_OBJECT()));

  if (input->GetNumberOfCells() == 0)
  {
    // set up a ugrid with same data arrays as input, but
    // no points, cells or data.
    output->Allocate(1);
    output->GetPointData()->CopyAllocate(input->GetPointData(), VTK_CELL_SIZE);
    output->GetCellData()->CopyAllocate(input->GetCellData(), 1);
    vtkNew<vtkPoints> pts;
    output->SetPoints(pts);
    return 1;
  }

  output->GetPointData()->CopyAllocate(input->GetPointData());
  output->GetCellData()->PassData(input->GetCellData());

  // First, create a new points array that eliminate duplicate points.
  // Also create a mapping from the old point id to the new.
  vtkNew<vtkPoints> newPts;

  // Set the desired precision for the points in the output.
  if (this->OutputPointsPrecision == vtkAlgorithm::DEFAULT_PRECISION)
  {
    // The logical behaviour would be to use the data type from the input.
    // However, input is a vtkDataSet, which has no point data type; only the
    // derived class vtkPointSet has a vtkPoints attribute, so only for that
    // the logical practice can be applied, while for others (currently
    // vtkImageData and vtkRectilinearGrid) the data type is the default
    // for vtkPoints - which is VTK_FLOAT.
    vtkPointSet* ps = vtkPointSet::SafeDownCast(input);
    if (ps)
    {
      newPts->SetDataType(ps->GetPoints()->GetDataType());
    }
  }
  else if (this->OutputPointsPrecision == vtkAlgorithm::SINGLE_PRECISION)
  {
    newPts->SetDataType(VTK_FLOAT);
  }
  else if (this->OutputPointsPrecision == vtkAlgorithm::DOUBLE_PRECISION)
  {
    newPts->SetDataType(VTK_DOUBLE);
  }

  vtkIdType num = input->GetNumberOfPoints();
  vtkIdType id;
  vtkIdType newId;
  std::vector<vtkIdType> ptMap(num);
  double pt[3];

  this->CreateDefaultLocator(input);
  if (this->ToleranceIsAbsolute)
  {
    this->Locator->SetTolerance(this->AbsoluteTolerance);
  }
  else
  {
    this->Locator->SetTolerance(this->Tolerance * input->GetLength());
  }
  double bounds[6];
  input->GetBounds(bounds);
  this->Locator->InitPointInsertion(newPts, bounds);

  vtkIdType progressStep = num / 100;
  if (progressStep == 0)
  {
    progressStep = 1;
  }

  vtkNew<vtkIdList> pointCells;
  for (id = 0; id < num; ++id)
  {
    if (id % progressStep == 0)
    {
      this->UpdateProgress(0.8 * ((float)id / num));
    }

    bool insert = true;
    if (this->RemovePointsWithoutCells)
    {
      input->GetPointCells(id, pointCells);
      if (pointCells->GetNumberOfIds() == 0)
      {
        insert = false;
      }
    }

    if (insert)
    {
      input->GetPoint(id, pt);
      this->Locator->InsertUniquePoint(pt, newId);
      ptMap[id] = newId;
    }
    else
    {
      // Strictly speaking, this is not needed
      // as this is never accessed, but better not let
      // an id undefined.
      ptMap[id] = -1;
    }
  }
  output->SetPoints(newPts);

  ::WeighingStrategyFactory factory;
  auto strategy = factory(static_cast<DataWeighingType>(this->PointDataWeighingStrategy));
  auto weights = strategy->ComputeWeights(input, ptMap);
  auto inPD = input->GetPointData();
  auto outPD = output->GetPointData();
  ::AllocatePointAttributes(inPD, outPD, output->GetNumberOfPoints());
  ::WeightAttributes(inPD, outPD, weights, ptMap);

  // Now copy the cells.
  vtkNew<vtkIdList> cellPoints;
  num = input->GetNumberOfCells();
  output->Allocate(num);
  for (id = 0; id < num; ++id)
  {
    if (id % progressStep == 0)
    {
      this->UpdateProgress(0.8 + 0.2 * (static_cast<float>(id) / num));
    }
    // special handling for polyhedron cells
    if (vtkUnstructuredGrid::SafeDownCast(input) && input->GetCellType(id) == VTK_POLYHEDRON)
    {
      vtkUnstructuredGrid::SafeDownCast(input)->GetFaceStream(id, cellPoints);
      vtkUnstructuredGrid::ConvertFaceStreamPointIds(cellPoints, ptMap.data());
    }
    else
    {
      input->GetCellPoints(id, cellPoints);
      for (int i = 0; i < cellPoints->GetNumberOfIds(); i++)
      {
        int cellPtId = cellPoints->GetId(i);
        newId = ptMap[cellPtId];
        cellPoints->SetId(i, newId);
      }
    }
    output->InsertNextCell(input->GetCellType(id), cellPoints);
  }

  output->Squeeze();
  return 1;
}

//----------------------------------------------------------------------------
int vtkCleanUnstructuredGrid::FillInputPortInformation(int vtkNotUsed(port), vtkInformation* info)
{
  info->Set(vtkAlgorithm::INPUT_REQUIRED_DATA_TYPE(), "vtkDataSet");
  return 1;
}

//------------------------------------------------------------------------------
vtkIncrementalPointLocator* vtkCleanUnstructuredGrid::GetLocator()
{
  return this->Locator;
}

//----------------------------------------------------------------------------
void vtkCleanUnstructuredGrid::CreateDefaultLocator(vtkDataSet* input)
{
  double tol;
  if (this->ToleranceIsAbsolute)
  {
    tol = this->AbsoluteTolerance;
  }
  else
  {
    if (input)
    {
      tol = this->Tolerance * input->GetLength();
    }
    else
    {
      tol = this->Tolerance;
    }
  }

  if (this->Locator.Get() == nullptr)
  {
    if (tol == 0.0)
    {
      this->Locator = vtkSmartPointer<vtkMergePoints>::New();
    }
    else
    {
      this->Locator = vtkSmartPointer<vtkPointLocator>::New();
    }
  }
  else
  {
    // check that the tolerance wasn't changed from zero to non-zero
    if ((tol > 0.0) && (this->GetLocator()->GetTolerance() == 0.0))
    {
      this->Locator = vtkSmartPointer<vtkPointLocator>::New();
    }
  }
}
