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

  Program:   Visualization Toolkit
  Module:    vtkXMLHyperTreeGridWriter.cxx

  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
  All rights reserved.
  See Copyright.txt or http://www.kitware.com/Copyright.htm 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 "vtkXMLHyperTreeGridWriter.h"

#include "vtkAbstractArray.h"
#include "vtkBitArray.h"
#include "vtkCellData.h"
#include "vtkDoubleArray.h"
#include "vtkErrorCode.h"
#include "vtkHyperTree.h"
#include "vtkHyperTreeGrid.h"
#include "vtkHyperTreeGridNonOrientedCursor.h"
#include "vtkIdTypeArray.h"
#include "vtkInformation.h"
#include "vtkObjectFactory.h"
#include "vtkTypeInt64Array.h"
#include "vtkTypeUInt32Array.h"
#include "vtkUnsignedIntArray.h"

#define vtkXMLOffsetsManager_DoNotInclude
#include "vtkXMLOffsetsManager.h"
#undef vtkXMLOffsetsManager_DoNotInclude

#include <cassert>

vtkStandardNewMacro(vtkXMLHyperTreeGridWriter);

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

//------------------------------------------------------------------------------
vtkHyperTreeGrid* vtkXMLHyperTreeGridWriter::GetInput()
{
  return static_cast<vtkHyperTreeGrid*>(this->Superclass::GetInput());
}

//------------------------------------------------------------------------------
const char* vtkXMLHyperTreeGridWriter::GetDefaultFileExtension()
{
  return "htg";
}

//------------------------------------------------------------------------------
const char* vtkXMLHyperTreeGridWriter::GetDataSetName()
{
  return "HyperTreeGrid";
}

//------------------------------------------------------------------------------
int vtkXMLHyperTreeGridWriter::FillInputPortInformation(int, vtkInformation* info)
{
  info->Set(vtkAlgorithm::INPUT_REQUIRED_DATA_TYPE(), "vtkHyperTreeGrid");
  return 1;
}

//------------------------------------------------------------------------------
int vtkXMLHyperTreeGridWriter::WriteData()
{
  // write XML header and VTK file header and file attributes
  if (!this->StartFile())
  {
    return 0;
  }

  vtkIndent indent = vtkIndent().GetNextIndent();

  // Header attributes
  if (!this->StartPrimaryElement(indent))
  {
    return 0;
  }

  // Coordinates for grid (can be replaced by origin and scale)
  if (!this->WriteGrid(indent.GetNextIndent()))
  {
    return 0;
  }

  if (this->GetDataSetMajorVersion() == 0 && !this->WriteTrees_0(indent.GetNextIndent()))
  {
    return 0;
  }
  else if (this->GetDataSetMajorVersion() == 1 && !this->WriteTrees_1(indent.GetNextIndent()))
  {
    return 0;
  }
  else if (this->GetDataSetMajorVersion() >= 2 && !this->WriteTrees_2(indent.GetNextIndent()))
  {
    return 0;
  }

  this->WriteFieldData(indent.GetNextIndent());

  if (!this->FinishPrimaryElement(indent))
  {
    return 0;
  }

  // Write all appended data by tree using Helper function
  if (this->DataMode == vtkXMLWriter::Appended)
  {
    vtkHyperTreeGrid* input = this->GetInput();
    vtkCellData* pd = input->GetCellData();
    vtkIdType numberOfCellDataArrays = pd->GetNumberOfArrays();

    this->StartAppendedData();

    // Write the field data arrays.
    if (this->FieldDataOM->GetNumberOfElements())
    {
      vtkNew<vtkFieldData> fieldDataCopy;
      this->UpdateFieldData(fieldDataCopy);

      this->WriteFieldDataAppendedData(fieldDataCopy, this->CurrentTimeIndex, this->FieldDataOM);
      if (this->ErrorCode == vtkErrorCode::OutOfDiskSpaceError)
      {
        return 0;
      }
    }

    // Write the Coordinates arrays
    if (this->CoordsOMG->GetNumberOfElements())
    {
      assert(this->CoordsOMG->GetNumberOfElements() == 3);
      this->WriteAppendedArrayDataHelper(input->GetXCoordinates(), this->CoordsOMG->GetElement(0));
      this->WriteAppendedArrayDataHelper(input->GetYCoordinates(), this->CoordsOMG->GetElement(1));
      this->WriteAppendedArrayDataHelper(input->GetZCoordinates(), this->CoordsOMG->GetElement(2));
    }

    // Write the data for each tree
    vtkHyperTreeGrid::vtkHyperTreeGridIterator it;
    input->InitializeTreeIterator(it);
    vtkIdType inIndex;
    int treeIndx = 0;

    if (this->GetDataSetMajorVersion() == 0)
    {
      while (it.GetNextTree(inIndex))
      {
        vtkHyperTreeGridNonOrientedCursor* inCursor = input->NewNonOrientedCursor(inIndex);
        vtkHyperTree* tree = inCursor->GetTree();
        vtkIdType numberOfVertices = tree->GetNumberOfVertices();

        // Tree Descriptor
        this->WriteAppendedArrayDataHelper(
          this->Descriptors[treeIndx], this->DescriptorOMG->GetElement(treeIndx));
        if (input->GetMask())
        {
          // Tree Mask
          this->WriteAppendedArrayDataHelper(
            this->Masks[treeIndx], this->MaskOMG->GetElement(treeIndx));
        }
        // Point Data
        for (int i = 0; i < pd->GetNumberOfArrays(); ++i)
        {
          vtkAbstractArray* array = pd->GetAbstractArray(i);
          vtkIdType pdIndx = treeIndx * numberOfCellDataArrays + i;
          this->WriteCellDataAppendedArrayDataHelper(
            array, numberOfVertices, this->CellDataOMG->GetElement(pdIndx), tree);
        }
        ++treeIndx;
        inCursor->Delete();
      }
    }
    else if (this->GetDataSetMajorVersion() == 1)
    {
      while (it.GetNextTree(inIndex))
      {
        // Tree Descriptor
        this->WriteAppendedArrayDataHelper(
          this->Descriptors[treeIndx], this->DescriptorOMG->GetElement(treeIndx));
        // Tree NbVerticesByLevels
        this->WriteAppendedArrayDataHelper(
          this->NbVerticesByLevels[treeIndx], this->NbVerticesByLevelOMG->GetElement(treeIndx));
        if (input->GetMask())
        {
          // Tree Mask
          this->WriteAppendedArrayDataHelper(
            this->Masks[treeIndx], this->MaskOMG->GetElement(treeIndx));
        }
        // Point Data
        vtkIdList* ids = this->Ids[treeIndx];
        vtkIdType numberOfVertices = ids->GetNumberOfIds();
        for (int i = 0; i < pd->GetNumberOfArrays(); ++i)
        {
          vtkAbstractArray* a = pd->GetAbstractArray(i);
          vtkAbstractArray* b = a->NewInstance();
          int numberOfComponents = a->GetNumberOfComponents();
          b->SetNumberOfTuples(numberOfVertices);
          b->SetNumberOfComponents(numberOfComponents);
          b->SetNumberOfValues(numberOfComponents * numberOfVertices);
          // BitArray processed
          auto* aBit = vtkArrayDownCast<vtkBitArray>(a);
          if (aBit)
          {
            auto* bBit = vtkArrayDownCast<vtkBitArray>(b);
            aBit->GetTuples(ids, bBit);
          } // DataArray processed
          else
          {
            a->GetTuples(ids, b);
          }
          // Write the data or XML description for appended data
          vtkIdType pdIndx = treeIndx * numberOfCellDataArrays + i;
          this->WriteAppendedArrayDataHelper(b, this->CellDataOMG->GetElement(pdIndx));
          b->Delete();
        }
        ++treeIndx;
      }
    }
    else if (this->GetDataSetMajorVersion() == 2)
    {
      auto& metaData = this->MetaDataForVersion2;
      vtkIdType numberOfVertices = metaData.BreadthFirstIdMap->GetNumberOfIds();
      this->WriteAppendedArrayDataHelper(metaData.Descriptors, this->DescriptorOMG->GetElement(0));
      this->WriteAppendedArrayDataHelper(
        metaData.NumberOfVerticesPerDepth, this->NbVerticesByLevelOMG->GetElement(0));
      this->WriteAppendedArrayDataHelper(metaData.TreeIds, this->TreeIdsOMG->GetElement(0));
      this->WriteAppendedArrayDataHelper(
        metaData.DepthPerTree, this->DepthPerTreeOMG->GetElement(0));
      if (input->GetMask())
      {
        vtkBitArray* breadthFirstReorderedMask = input->GetMask()->NewInstance();
        breadthFirstReorderedMask->SetNumberOfComponents(1);
        breadthFirstReorderedMask->SetNumberOfValues(numberOfVertices);
        input->GetMask()->GetTuples(metaData.BreadthFirstIdMap, breadthFirstReorderedMask);
        this->WriteAppendedArrayDataHelper(breadthFirstReorderedMask, this->MaskOMG->GetElement(0));
        breadthFirstReorderedMask->Delete();
      }
      for (int i = 0; i < pd->GetNumberOfArrays(); ++i)
      {
        // We remap the input array to a breadth first ordering
        vtkAbstractArray* array = pd->GetAbstractArray(i);
        vtkAbstractArray* breadthFirstReorderedArray = array->NewInstance();
        int numberOfComponents = array->GetNumberOfComponents();
        breadthFirstReorderedArray->SetNumberOfComponents(numberOfComponents);
        breadthFirstReorderedArray->SetNumberOfValues(numberOfVertices * numberOfComponents);
        array->GetTuples(metaData.BreadthFirstIdMap, breadthFirstReorderedArray);
        this->WriteAppendedArrayDataHelper(
          breadthFirstReorderedArray, this->CellDataOMG->GetElement(i));
        breadthFirstReorderedArray->Delete();
      }
    }
    this->EndAppendedData();
  }
  this->Descriptors.clear();
  this->NbVerticesByLevels.clear();
  this->Masks.clear();
  this->Ids.clear();
  this->MetaDataForVersion2.Initialize();
  if (!this->EndFile())
  {
    return 0;
  }
  return 1;
}

//------------------------------------------------------------------------------
int vtkXMLHyperTreeGridWriter::StartPrimaryElement(vtkIndent indent)
{
  ostream& os = *(this->Stream);

  return (!this->WritePrimaryElement(os, indent)) ? 0 : 1;
}

//------------------------------------------------------------------------------
void vtkXMLHyperTreeGridWriter::WritePrimaryElementAttributes(ostream& os, vtkIndent indent)
{
  this->Superclass::WritePrimaryElementAttributes(os, indent);
  vtkHyperTreeGrid* input = this->GetInput();

  int extent[6];
  input->GetExtent(extent);

  if (this->GetDataSetMajorVersion() < 1) // Major version < 1
  {
    this->WriteScalarAttribute("Dimension", (int)input->GetDimension());
    this->WriteScalarAttribute("Orientation", (int)input->GetOrientation());
  }

  this->WriteScalarAttribute("BranchFactor", (int)input->GetBranchFactor());
  this->WriteScalarAttribute("TransposedRootIndexing", (bool)input->GetTransposedRootIndexing());
  this->WriteVectorAttribute(
    "Dimensions", 3, (int*)const_cast<unsigned int*>(input->GetDimensions()));
  if (input->GetHasInterface())
  {
    this->WriteStringAttribute("InterfaceNormalsName", input->GetInterfaceNormalsName());
  }
  if (input->GetHasInterface())
  {
    this->WriteStringAttribute("InterfaceInterceptsName", input->GetInterfaceInterceptsName());
  }

  if (this->GetDataSetMajorVersion() < 1)
  {
    this->WriteScalarAttribute("NumberOfVertices", input->GetNumberOfCells());
  }
}

//------------------------------------------------------------------------------
int vtkXMLHyperTreeGridWriter::WriteGrid(vtkIndent indent)
{
  vtkHyperTreeGrid* input = this->GetInput();
  ostream& os = *(this->Stream);
  os << indent << "<Grid>\n";

  if (this->DataMode == Appended)
  {
    // Coordinates of the grid
    this->CoordsOMG->Allocate(3, this->NumberOfTimeSteps);
    this->WriteArrayAppended(input->GetXCoordinates(), indent.GetNextIndent(),
      this->CoordsOMG->GetElement(0), "XCoordinates",
      input->GetXCoordinates()->GetNumberOfTuples());
    this->WriteArrayAppended(input->GetYCoordinates(), indent.GetNextIndent(),
      this->CoordsOMG->GetElement(1), "YCoordinates",
      input->GetYCoordinates()->GetNumberOfTuples());
    this->WriteArrayAppended(input->GetZCoordinates(), indent.GetNextIndent(),
      this->CoordsOMG->GetElement(2), "ZCoordinates",
      input->GetZCoordinates()->GetNumberOfTuples());
  }
  else
  {
    // Coordinates of the grid
    this->WriteArrayInline(input->GetXCoordinates(), indent.GetNextIndent(), "XCoordinates",
      input->GetXCoordinates()->GetNumberOfValues());
    this->WriteArrayInline(input->GetYCoordinates(), indent.GetNextIndent(), "YCoordinates",
      input->GetYCoordinates()->GetNumberOfValues());
    this->WriteArrayInline(input->GetZCoordinates(), indent.GetNextIndent(), "ZCoordinates",
      input->GetZCoordinates()->GetNumberOfValues());
  }

  os << indent << "</Grid>\n";
  os.flush();
  if (os.fail())
  {
    this->SetErrorCode(vtkErrorCode::OutOfDiskSpaceError);
    return 0;
  }
  return 1;
}

//------------------------------------------------------------------------------
vtkXMLHyperTreeGridWriter::vtkXMLHyperTreeGridWriter()
  : CoordsOMG(new OffsetsManagerGroup)
  , DescriptorOMG(new OffsetsManagerGroup)
  , NbVerticesByLevelOMG(new OffsetsManagerGroup)
  , MaskOMG(new OffsetsManagerGroup)
  , CellDataOMG(new OffsetsManagerGroup)
  , TreeIdsOMG(new OffsetsManagerGroup)
  , DepthPerTreeOMG(new OffsetsManagerGroup)
  , NumberOfTrees(0)
  , DataSetMajorVersion(2)
  , DataSetMinorVersion(0)
{
}

//------------------------------------------------------------------------------
vtkXMLHyperTreeGridWriter::~vtkXMLHyperTreeGridWriter()
{
  delete this->CoordsOMG;
  delete this->DescriptorOMG;
  delete this->NbVerticesByLevelOMG;
  delete this->MaskOMG;
  delete this->CellDataOMG;
  delete this->TreeIdsOMG;
  delete this->DepthPerTreeOMG;
}

//------------------------------------------------------------------------------
namespace
{
//
// Depth first recursion to walk the tree in child order
// Used to create the breadth first BitArray descriptor appending
// node and leaf indicator by level
//
void BuildDescriptor(vtkHyperTreeGridNonOrientedCursor* inCursor, int level, bool hasMask,
  unsigned int numChildren, std::vector<std::string>& descriptor, std::vector<std::string>& mask)
{
  // Append to mask string
  if (hasMask)
  {
    if (inCursor->IsMasked())
      mask[level] += '1';
    else
      mask[level] += '0';
  }

  // Append to descriptor string
  if (!inCursor->IsLeaf())
  {
    descriptor[level] += 'R';

    // If input cursor is not a leaf, recurse to all children
    for (unsigned int child = 0; child < numChildren; ++child)
    {
      // Move cursor to child
      inCursor->ToChild(child);

      // Recurse
      BuildDescriptor(inCursor, level + 1, hasMask, numChildren, descriptor, mask);

      // Move cursor back to parent
      inCursor->ToParent();
    } // child
  }
  else
  {
    descriptor[level] += '.';
  }
}
}

//------------------------------------------------------------------------------
int vtkXMLHyperTreeGridWriter::WriteTrees_0(vtkIndent indent)
{
  vtkHyperTreeGrid* input = this->GetInput();
  vtkIdType maxLevels = input->GetNumberOfLevels();
  vtkCellData* pd = input->GetCellData();
  vtkIdType numberOfCellDataArrays = pd->GetNumberOfArrays();

  // Count the actual number of hypertrees represented in this hypertree grid
  vtkHyperTreeGrid::vtkHyperTreeGridIterator it;
  input->InitializeTreeIterator(it);
  this->NumberOfTrees = 0;
  vtkIdType inIndex;
  while (it.GetNextTree(inIndex))
  {
    ++this->NumberOfTrees;
  }

  // Allocate offsets managers for appended data
  if (this->DataMode == Appended && this->NumberOfTrees > 0)
  {
    this->DescriptorOMG->Allocate(this->NumberOfTrees, this->NumberOfTimeSteps);
    this->MaskOMG->Allocate(this->NumberOfTrees, this->NumberOfTimeSteps);
    this->CellDataOMG->Allocate(
      this->NumberOfTrees * numberOfCellDataArrays, this->NumberOfTimeSteps);
  }

  ostream& os = *(this->Stream);
  os << indent << "<Trees>\n";
  vtkIndent treeIndent = indent.GetNextIndent();

  // Collect description by processing depth first and writing breadth first
  input->InitializeTreeIterator(it);
  int treeIndx = 0;
  vtkIdType globalOffset = 0;
  while (it.GetNextTree(inIndex))
  {
    // Initialize new grid cursor at root of current input tree
    vtkHyperTreeGridNonOrientedCursor* inCursor = input->NewNonOrientedCursor(inIndex);
    vtkHyperTree* tree = inCursor->GetTree();
    vtkIdType numberOfVertices = tree->GetNumberOfVertices();

    os << treeIndent << "<Tree";
    this->WriteScalarAttribute("Index", inIndex);
    this->WriteScalarAttribute("GlobalOffset", globalOffset);
    this->WriteScalarAttribute("NumberOfVertices", numberOfVertices);
    os << ">\n";

    // Recursively compute descriptor for this tree, appending any
    // entries for each of the levels in descByLevel for output.
    // Collect the masked indicator at the same time
    std::vector<std::string> descByLevel(maxLevels);
    std::vector<std::string> maskByLevel(maxLevels);
    BuildDescriptor(
      inCursor, 0, input->HasMask(), input->GetNumberOfChildren(), descByLevel, maskByLevel);

    // Clean up
    inCursor->Delete();

    // Descriptor BitArray
    vtkBitArray* descriptor = vtkBitArray::New();
    std::string::const_iterator liter;
    for (int l = 0; l < maxLevels; ++l)
    {
      for (liter = descByLevel[l].begin(); liter != descByLevel[l].end(); ++liter)
      {
        switch (*liter)
        {
          case 'R': //  Refined cell
            descriptor->InsertNextValue(1);
            break;
          case '.': // Leaf cell
            descriptor->InsertNextValue(0);
            break;
          default:
            vtkErrorMacro(<< "Unrecognized character: " << *liter << " in string "
                          << descByLevel[l]);
            return 0;
        }
      }
    }
    descriptor->Squeeze();
    this->Descriptors.emplace_back(vtkSmartPointer<vtkBitArray>::Take(descriptor));
    auto& desc = this->Descriptors.back();

    // Mask BitAarray
    vtkBitArray* mask = input->GetMask() ? vtkBitArray::New() : nullptr;
    if (input->GetMask())
    {
      for (int l = 0; l < maxLevels; ++l)
      {
        for (liter = maskByLevel[l].begin(); liter != maskByLevel[l].end(); ++liter)
        {
          switch (*liter)
          {
            case '0': // Not masked
              mask->InsertNextValue(0);
              break;
            case '1': // Masked
              mask->InsertNextValue(1);
              break;
            default:
              vtkErrorMacro(<< "Unrecognized character: " << *liter << " in string "
                            << maskByLevel[l]);
              return 0;
          }
        }
      }
      mask->Squeeze();
      this->Masks.emplace_back(vtkSmartPointer<vtkBitArray>::Take(mask));
    }

    vtkIndent infoIndent = treeIndent.GetNextIndent();

    // Write the descriptor and mask BitArrays
    if (this->DataMode == Appended)
    {
      this->WriteArrayAppended(desc, infoIndent, this->DescriptorOMG->GetElement(treeIndx),
        "Descriptor", desc->GetNumberOfValues());
      if (input->GetMask())
      {
        this->WriteArrayAppended(
          mask, infoIndent, this->MaskOMG->GetElement(treeIndx), "Mask", mask->GetNumberOfValues());
      }
    }
    else
    {
      this->WriteArrayInline(desc, infoIndent, "Descriptor", desc->GetNumberOfValues());
      if (input->GetMask())
      {
        this->WriteArrayInline(mask, infoIndent, "Mask", mask->GetNumberOfValues());
      }
    }

    // Write the point data
    os << infoIndent << "<CellData>\n";
    for (int i = 0; i < pd->GetNumberOfArrays(); ++i)
    {
      vtkAbstractArray* a = pd->GetAbstractArray(i);
      vtkAbstractArray* b = a->NewInstance();
      int numberOfComponents = a->GetNumberOfComponents();
      b->SetNumberOfTuples(numberOfVertices);
      b->SetNumberOfComponents(numberOfComponents);
      for (int e = 0; e < numberOfVertices; ++e)
      {
        // note - we unravel the array contents which may be interleaved in input array.
        // The reader expect that each grid's data will be contiguous and uses "GlobalOffset"
        // to assemble a big array on the other side.
        // The in memory order of elements then isn't necessarily the same but HTG handles that.
        vtkIdType aDataOffset = tree->GetGlobalIndexFromLocal(e) * numberOfComponents;
        int bDataOffset = e * numberOfComponents;
        for (int c = 0; c < numberOfComponents; ++c)
        {
          b->SetVariantValue(bDataOffset + c, a->GetVariantValue(aDataOffset + c));
        }
      }

      // Write the data or XML description for appended data
      if (this->DataMode == Appended)
      {
        this->WriteArrayAppended(b, infoIndent.GetNextIndent(),
          this->CellDataOMG->GetElement(treeIndx * numberOfCellDataArrays + i), a->GetName(),
          numberOfVertices * numberOfComponents);
      }
      else
      {
        this->WriteArrayInline(
          b, infoIndent.GetNextIndent(), a->GetName(), numberOfVertices * numberOfComponents);
      }
      b->Delete();
    }
    ++treeIndx;

    // Increment to next tree with CellData
    os << infoIndent << "</CellData>\n";
    os << treeIndent << "</Tree>\n";
    globalOffset += numberOfVertices;
  }
  os << indent << "</Trees>\n";

  os.flush();
  if (os.fail())
  {
    this->SetErrorCode(vtkErrorCode::OutOfDiskSpaceError);
    return 0;
  }
  return 1;
}

//------------------------------------------------------------------------------
int vtkXMLHyperTreeGridWriter::WriteTrees_1(vtkIndent indent)
{
  vtkHyperTreeGrid* input = this->GetInput();
  vtkCellData* pd = input->GetCellData();
  vtkIdType numberOfCellDataArrays = pd->GetNumberOfArrays();

  // Count the actual number of hypertrees represented in this hypertree grid
  vtkHyperTreeGrid::vtkHyperTreeGridIterator it;
  input->InitializeTreeIterator(it);
  this->NumberOfTrees = 0;
  vtkIdType inIndex;
  while (it.GetNextTree(inIndex))
  {
    ++this->NumberOfTrees;
  }

  // Allocate offsets managers for appended data
  if (this->DataMode == Appended && this->NumberOfTrees > 0)
  {
    this->DescriptorOMG->Allocate(this->NumberOfTrees, this->NumberOfTimeSteps);
    this->NbVerticesByLevelOMG->Allocate(this->NumberOfTrees, this->NumberOfTimeSteps);
    this->MaskOMG->Allocate(this->NumberOfTrees, this->NumberOfTimeSteps);
    this->CellDataOMG->Allocate(
      this->NumberOfTrees * numberOfCellDataArrays, this->NumberOfTimeSteps);
  }

  ostream& os = *(this->Stream);
  os << indent << "<Trees>\n";
  vtkIndent treeIndent = indent.GetNextIndent();

  // Collect description by processing depth first and writing breadth first
  input->InitializeTreeIterator(it);
  int treeIndx = 0;
  while (it.GetNextTree(inIndex))
  {
    os << treeIndent << "<Tree";
    this->WriteScalarAttribute("Index", inIndex);
    vtkHyperTree* tree = input->GetTree(inIndex);
    const int numberOfLevels = static_cast<int>(tree->GetNumberOfLevels());
    this->WriteScalarAttribute("NumberOfLevels", numberOfLevels);

    vtkTypeInt64Array* nbVerticesByLevel = vtkTypeInt64Array::New();
    vtkBitArray* descriptor = vtkBitArray::New();
    vtkIdList* ids = vtkIdList::New();
    tree->ComputeBreadthFirstOrderDescriptor(input->GetMask(), nbVerticesByLevel, descriptor, ids);

    // squeezing last zeros of last row out of descriptor
    if (vtkIdType lastNonZeroId = descriptor->GetNumberOfValues())
    {
      while (lastNonZeroId && !descriptor->GetValue(--lastNonZeroId))
        ;

      descriptor->SetNumberOfValues(lastNonZeroId + 1);
    }

    if (input->GetMask())
    {
      this->Masks.emplace_back(vtkSmartPointer<vtkBitArray>::New());
      auto& mask = this->Masks.back();
      mask->SetNumberOfComponents(1);
      mask->SetNumberOfValues(ids->GetNumberOfIds());
      input->GetMask()->GetTuples(ids, mask);
      // squeezing last zeros of last row out of mask
      if (vtkIdType lastNonZeroId = mask->GetNumberOfValues())
      {
        while (lastNonZeroId && !mask->GetValue(--lastNonZeroId))
          ;

        mask->SetNumberOfValues(lastNonZeroId + 1);
      }
    }

    this->NbVerticesByLevels.emplace_back(
      vtkSmartPointer<vtkTypeInt64Array>::Take(nbVerticesByLevel));
    this->Descriptors.emplace_back(vtkSmartPointer<vtkBitArray>::Take(descriptor));
    this->Ids.emplace_back(vtkSmartPointer<vtkIdList>::Take(ids));

    vtkIndent infoIndent = treeIndent.GetNextIndent();

    const vtkIdType numberOfVertices = ids->GetNumberOfIds();
    // Because non describe last False values...
    assert(numberOfVertices >= descriptor->GetNumberOfTuples());
    this->WriteScalarAttribute("NumberOfVertices", numberOfVertices);
    os << ">\n";

    // Write the descriptor and mask BitArrays
    if (this->DataMode == Appended)
    {
      this->WriteArrayAppended(descriptor, infoIndent, this->DescriptorOMG->GetElement(treeIndx),
        "Descriptor", descriptor->GetNumberOfValues());
      this->WriteArrayAppended(nbVerticesByLevel, infoIndent,
        this->NbVerticesByLevelOMG->GetElement(treeIndx), "NbVerticesByLevel",
        nbVerticesByLevel->GetNumberOfValues());
      if (input->GetMask())
      {
        this->WriteArrayAppended(this->Masks.back(), infoIndent,
          this->MaskOMG->GetElement(treeIndx), "Mask",
          input->GetMask() ? this->Masks.back()->GetNumberOfValues() : 0);
      }
    }
    else
    {
      this->WriteArrayInline(descriptor, infoIndent, "Descriptor", descriptor->GetNumberOfValues());
      this->WriteArrayInline(
        nbVerticesByLevel, infoIndent, "NbVerticesByLevel", nbVerticesByLevel->GetNumberOfValues());
      if (input->GetMask())
      {
        this->WriteArrayInline(
          this->Masks.back(), infoIndent, "Mask", this->Masks.back()->GetNumberOfValues());
      }
    }

    // Write the point data
    os << infoIndent << "<CellData>\n";

    for (int i = 0; i < pd->GetNumberOfArrays(); ++i)
    {
      vtkAbstractArray* a = pd->GetAbstractArray(i);

      // Write the data or XML description for appended data
      if (this->DataMode == Appended)
      {
        this->WriteArrayAppended(a, infoIndent.GetNextIndent(),
          this->CellDataOMG->GetElement(treeIndx * numberOfCellDataArrays + i), a->GetName(), 0);
        // Last parameter will eventually become the size of the stored arrays.
        // When this modification is done, 0 should be replaced by:
        // numberOfVertices * a->GetNumberOfComponents());
      }
      else
      {
        vtkAbstractArray* b = a->NewInstance();
        const int numberOfComponents = a->GetNumberOfComponents();
        b->SetNumberOfTuples(numberOfVertices);
        b->SetNumberOfComponents(numberOfComponents);
        b->SetNumberOfValues(numberOfComponents * numberOfVertices);
        // BitArray processed
        auto* aBit = vtkArrayDownCast<vtkBitArray>(a);
        if (aBit)
        {
          auto* bBit = vtkArrayDownCast<vtkBitArray>(b);
          aBit->GetTuples(ids, bBit);
        } // DataArray processed
        else
        {
          a->GetTuples(ids, b);
        }
        this->WriteArrayInline(
          b, infoIndent.GetNextIndent(), a->GetName(), b->GetNumberOfTuples() * numberOfComponents);
        b->Delete();
      }
    }
    ++treeIndx;

    // Increment to next tree with CellData
    os << infoIndent << "</CellData>\n";
    os << treeIndent << "</Tree>\n";
  }
  os << indent << "</Trees>\n";

  os.flush();
  if (os.fail())
  {
    this->SetErrorCode(vtkErrorCode::OutOfDiskSpaceError);
    return 0;
  }
  return 1;
}

//------------------------------------------------------------------------------
int vtkXMLHyperTreeGridWriter::WriteTrees_2(vtkIndent indent)
{
  vtkHyperTreeGrid* input = this->GetInput();
  vtkCellData* cd = input->GetCellData();
  vtkIdType numberOfCellDataArrays = cd->GetNumberOfArrays();

  // Count the actual number of hypertrees represented in this hypertree grid
  vtkHyperTreeGrid::vtkHyperTreeGridIterator it;
  input->InitializeTreeIterator(it);
  this->NumberOfTrees = 0;
  vtkIdType inIndex;
  while (it.GetNextTree(inIndex))
  {
    ++this->NumberOfTrees;
  }

  // Allocate offsets managers for appended data
  if (this->DataMode == Appended)
  {
    this->DescriptorOMG->Allocate(1, this->NumberOfTimeSteps);
    this->NbVerticesByLevelOMG->Allocate(1, this->NumberOfTimeSteps);
    this->TreeIdsOMG->Allocate(1, this->NumberOfTimeSteps);
    this->DepthPerTreeOMG->Allocate(1, this->NumberOfTimeSteps);
    this->CellDataOMG->Allocate(numberOfCellDataArrays, this->NumberOfTimeSteps);
    if (input->GetMask())
    {
      this->MaskOMG->Allocate(1, this->NumberOfTimeSteps);
    }
  }

  // Collect description by processing depth first and writing breadth first
  input->InitializeTreeIterator(it);

  auto& metaData = this->MetaDataForVersion2;

  metaData.Descriptors = vtkSmartPointer<vtkBitArray>::New();
  metaData.TreeIds = vtkSmartPointer<vtkTypeInt64Array>::New();
  metaData.NumberOfVerticesPerDepth = vtkSmartPointer<vtkTypeInt64Array>::New();
  metaData.DepthPerTree = vtkSmartPointer<vtkTypeUInt32Array>::New();
  metaData.BreadthFirstIdMap = vtkSmartPointer<vtkIdList>::New();

  metaData.TreeIds->SetNumberOfValues(input->GetNumberOfNonEmptyTrees());
  metaData.DepthPerTree->SetNumberOfValues(input->GetNumberOfNonEmptyTrees());

  vtkIdType currentId = 0;

  while (it.GetNextTree(inIndex))
  {
    vtkHyperTree* tree = input->GetTree(inIndex);
    metaData.TreeIds->SetValue(currentId, inIndex);

    vtkIdType previousSize = metaData.NumberOfVerticesPerDepth->GetNumberOfValues();
    tree->ComputeBreadthFirstOrderDescriptor(input->GetMask(), metaData.NumberOfVerticesPerDepth,
      metaData.Descriptors, metaData.BreadthFirstIdMap);
    metaData.DepthPerTree->SetValue(
      currentId++, metaData.NumberOfVerticesPerDepth->GetNumberOfValues() - previousSize);
  }

  ostream& os = *(this->Stream);
  os << indent << "<Trees>\n";
  vtkIndent treeIndent = indent.GetNextIndent();
  vtkIndent infoIndent = treeIndent.GetNextIndent();

  if (this->DataMode == Appended)
  {
    this->WriteArrayAppended(metaData.Descriptors, infoIndent, this->DescriptorOMG->GetElement(0),
      "Descriptors", metaData.Descriptors->GetNumberOfValues());
    this->WriteArrayAppended(metaData.NumberOfVerticesPerDepth, infoIndent,
      this->NbVerticesByLevelOMG->GetElement(0), "NumberOfVerticesPerDepth",
      metaData.NumberOfVerticesPerDepth->GetNumberOfValues());
    this->WriteArrayAppended(metaData.TreeIds, infoIndent, this->TreeIdsOMG->GetElement(0),
      "TreeIds", metaData.TreeIds->GetNumberOfValues());
    this->WriteArrayAppended(metaData.DepthPerTree, infoIndent,
      this->DepthPerTreeOMG->GetElement(0), "DepthPerTree",
      metaData.DepthPerTree->GetNumberOfValues());
    if (input->GetMask())
    {
      this->WriteArrayAppended(input->GetMask(), infoIndent, this->MaskOMG->GetElement(0), "Mask",
        metaData.BreadthFirstIdMap->GetNumberOfIds());
    }
  }
  else
  {
    this->WriteArrayInline(
      metaData.Descriptors, infoIndent, "Descriptors", metaData.Descriptors->GetNumberOfValues());
    this->WriteArrayInline(metaData.NumberOfVerticesPerDepth, infoIndent,
      "NumberOfVerticesPerDepth", metaData.NumberOfVerticesPerDepth->GetNumberOfValues());
    this->WriteArrayInline(
      metaData.TreeIds, infoIndent, "TreeIds", metaData.TreeIds->GetNumberOfValues());
    this->WriteArrayInline(metaData.DepthPerTree, infoIndent, "DepthPerTree",
      metaData.DepthPerTree->GetNumberOfValues());
    if (input->GetMask())
    {
      vtkBitArray* breadthFirstReorderedMask = input->GetMask()->NewInstance();
      breadthFirstReorderedMask->SetNumberOfComponents(1);
      breadthFirstReorderedMask->SetNumberOfValues(metaData.BreadthFirstIdMap->GetNumberOfIds());
      input->GetMask()->GetTuples(metaData.BreadthFirstIdMap, breadthFirstReorderedMask);
      this->WriteArrayInline(breadthFirstReorderedMask, infoIndent, "Mask",
        metaData.BreadthFirstIdMap->GetNumberOfIds());
      breadthFirstReorderedMask->Delete();
    }
  }

  os << indent << "</Trees>\n";

  // Write the vertices data
  os << indent << "<CellData>\n";

  for (int i = 0; i < cd->GetNumberOfArrays(); ++i)
  {
    vtkAbstractArray* array = cd->GetAbstractArray(i);

    // Write the data or XML description for appended data
    if (this->DataMode == Appended)
    {
      this->WriteArrayAppended(array, infoIndent, this->CellDataOMG->GetElement(0),
        array->GetName(),
        metaData.BreadthFirstIdMap->GetNumberOfIds() * array->GetNumberOfComponents());
    }
    else
    {
      // We remap the input array to a breadth first ordering
      vtkAbstractArray* breadthFirstReorderedArray = array->NewInstance();
      int numberOfComponents = array->GetNumberOfComponents();
      breadthFirstReorderedArray->SetNumberOfComponents(numberOfComponents);
      breadthFirstReorderedArray->SetNumberOfValues(
        metaData.BreadthFirstIdMap->GetNumberOfIds() * numberOfComponents);
      array->GetTuples(metaData.BreadthFirstIdMap, breadthFirstReorderedArray);
      this->WriteArrayInline(breadthFirstReorderedArray, infoIndent, array->GetName(),
        breadthFirstReorderedArray->GetNumberOfValues());
      breadthFirstReorderedArray->Delete();
    }
  }

  // Increment to next tree with CellData
  os << indent << "</CellData>\n";

  os.flush();
  if (os.fail())
  {
    this->SetErrorCode(vtkErrorCode::OutOfDiskSpaceError);
    return 0;
  }
  return 1;
}

//------------------------------------------------------------------------------
int vtkXMLHyperTreeGridWriter::FinishPrimaryElement(vtkIndent indent)
{
  ostream& os = *(this->Stream);

  // End the primary element.
  os << indent << "</" << this->GetDataSetName() << ">\n";

  os.flush();
  if (os.fail())
  {
    this->SetErrorCode(vtkErrorCode::OutOfDiskSpaceError);
    return 0;
  }
  return 1;
}

//------------------------------------------------------------------------------
void vtkXMLHyperTreeGridWriter::WriteAppendedArrayDataHelper(
  vtkAbstractArray* array, OffsetsManager& offsets)
{
  this->WriteArrayAppendedData(array, offsets.GetPosition(this->CurrentTimeIndex),
    offsets.GetOffsetValue(this->CurrentTimeIndex));

  auto* dArray = vtkArrayDownCast<vtkDataArray>(array);
  if (dArray)
  {
    double* range = dArray->GetRange(-1);
    this->ForwardAppendedDataDouble(
      offsets.GetRangeMinPosition(this->CurrentTimeIndex), range[0], "RangeMin");
    this->ForwardAppendedDataDouble(
      offsets.GetRangeMaxPosition(this->CurrentTimeIndex), range[1], "RangeMax");
  }
}

//------------------------------------------------------------------------------
void vtkXMLHyperTreeGridWriter::WriteCellDataAppendedArrayDataHelper(
  vtkAbstractArray* a, vtkIdType numberOfVertices, OffsetsManager& offsets, vtkHyperTree* tree)
{
  vtkAbstractArray* b = a->NewInstance();
  int numberOfComponents = a->GetNumberOfComponents();

  b->SetNumberOfComponents(numberOfComponents);
  b->SetNumberOfTuples(numberOfVertices);
  for (int e = 0; e < numberOfComponents * numberOfVertices; ++e)
  {
    b->SetVariantValue(e, a->GetVariantValue(tree->GetGlobalIndexFromLocal(e)));
  }

  this->WriteArrayAppendedData(
    b, offsets.GetPosition(this->CurrentTimeIndex), offsets.GetOffsetValue(this->CurrentTimeIndex));

  auto* dArray = vtkArrayDownCast<vtkDataArray>(a);
  if (dArray)
  {
    double* range = dArray->GetRange(-1);
    this->ForwardAppendedDataDouble(
      offsets.GetRangeMinPosition(this->CurrentTimeIndex), range[0], "RangeMin");
    this->ForwardAppendedDataDouble(
      offsets.GetRangeMaxPosition(this->CurrentTimeIndex), range[1], "RangeMax");
  }
  b->Delete();
}

//------------------------------------------------------------------------------
void vtkXMLHyperTreeGridWriter::HyperTreeGridMetaDataForVersion2::Initialize()
{
  this->Descriptors = nullptr;
  this->TreeIds = nullptr;
  this->NumberOfVerticesPerDepth = nullptr;
  this->DepthPerTree = nullptr;
  this->BreadthFirstIdMap = nullptr;
}