#include <iostream>
#include "FEAdaptor.h"

#include <vtkCellData.h>
#include <vtkCellType.h>
#include <vtkCPAdaptorAPI.h>
#include <vtkCPDataDescription.h>
#include <vtkCPInputDataDescription.h>
#include <vtkCPProcessor.h>
#include <vtkCPPythonScriptPipeline.h>
#include <vtkDoubleArray.h>
#include <vtkFloatArray.h>
#include <vtkNew.h>
#include <vtkPoints.h>
#include <vtkPointData.h>
#include <vtkSmartPointer.h>
#include <vtkUnstructuredGrid.h>

namespace
{
  vtkSmartPointer<vtkUnstructuredGrid> VTKGrid;

  void BuildVTKGrid(unsigned int numberOfPoints, double* pointsData,
                    unsigned int numberOfCells, unsigned int* cellsData)
  {
    // create the points information
    vtkNew<vtkDoubleArray> pointArray;
    pointArray->SetNumberOfComponents(3);
    pointArray->SetArray(pointsData, static_cast<vtkIdType>(numberOfPoints*3), 1);
    vtkNew<vtkPoints> points;
    points->SetData(pointArray.GetPointer());
    VTKGrid->SetPoints(points.GetPointer());

    // create the cells
    VTKGrid->Allocate(static_cast<vtkIdType>(numberOfCells*9));
    for(unsigned int cell=0;cell<numberOfCells;cell++)
      {
      unsigned int* cellPoints = cellsData+8*cell;
      vtkIdType tmp[8] = {cellPoints[0], cellPoints[1], cellPoints[2], cellPoints[3],
                          cellPoints[4], cellPoints[5], cellPoints[6], cellPoints[7]};
      VTKGrid->InsertNextCell(VTK_HEXAHEDRON, 8, tmp);
      }
  }

  void UpdateVTKAttributes(unsigned int numberOfPoints, double* velocityData,
                           unsigned int numberOfCells, float* pressureData)
  {
    if(VTKGrid->GetPointData()->GetNumberOfArrays() == 0)
      {
      // velocity array
      vtkNew<vtkDoubleArray> velocity;
      velocity->SetName("velocity");
      velocity->SetNumberOfComponents(3);
      velocity->SetNumberOfTuples(static_cast<vtkIdType>(numberOfPoints));
      VTKGrid->GetPointData()->AddArray(velocity.GetPointer());
      }
    if(VTKGrid->GetCellData()->GetNumberOfArrays() == 0)
      {
      // pressure array
      vtkNew<vtkFloatArray> pressure;
      pressure->SetName("pressure");
      pressure->SetNumberOfComponents(1);
      VTKGrid->GetCellData()->AddArray(pressure.GetPointer());
      }
    vtkDoubleArray* velocity = vtkDoubleArray::SafeDownCast(
      VTKGrid->GetPointData()->GetArray("velocity"));
    // The velocity array is ordered as vx0,vx1,vx2,..,vy0,vy1,vy2,..,vz0,vz1,vz2,..
    // so we need to create a full copy of it with VTK's ordering of
    // vx0,vy0,vz0,vx1,vy1,vz1,..
    for(unsigned int i=0;i<numberOfPoints;i++)
      {
      double values[3] = {velocityData[i], velocityData[i+numberOfPoints],
                          velocityData[i+2*numberOfPoints]};
      velocity->SetTupleValue(i, values);
      }

    vtkFloatArray* pressure = vtkFloatArray::SafeDownCast(
      VTKGrid->GetCellData()->GetArray("pressure"));
    // The pressure array is a scalar array so we can reuse
    // memory as long as we ordered the points properly.
    pressure->SetArray(pressureData, static_cast<vtkIdType>(numberOfCells), 1);
  }

  void BuildVTKDataStructures(unsigned int numberOfPoints, double* points, double* velocity,
                              unsigned int numberOfCells, unsigned int* cells, float* pressure)
  {
    if(VTKGrid == NULL)
      {
      // The grid structure isn't changing so we only build it
      // the first time it's needed. If we needed the memory
      // we could delete it and rebuild as necessary.
      VTKGrid = vtkSmartPointer<vtkUnstructuredGrid>::New();
      BuildVTKGrid(numberOfPoints, points, numberOfCells, cells);
      }
    UpdateVTKAttributes(numberOfPoints, velocity, numberOfCells, pressure);
  }
}

void CatalystCoProcess(unsigned int numberOfPoints, double* pointsData,
                       unsigned int numberOfCells, unsigned int* cellsData,
                       double* velocityData, float* pressureData, double time,
                       unsigned int timeStep, int lastTimeStep)
{
  vtkCPProcessor* processor = vtkCPAdaptorAPI::GetCoProcessor();
  vtkCPDataDescription* dataDescription = vtkCPAdaptorAPI::GetCoProcessorData();
  if(processor == NULL || dataDescription == NULL)
    {
    cerr << "ERROR: Catalyst not properly initialized.\n";
    return;
    }

  dataDescription->AddInput("input");
  dataDescription->SetTimeData(time, timeStep);
  if(lastTimeStep == true)
    {
    // assume that we want to all the pipelines to execute if it
    // is the last time step.
    dataDescription->ForceOutputOn();
    }
  if(processor->RequestDataDescription(dataDescription) != 0)
    {
    BuildVTKDataStructures(numberOfPoints, pointsData, velocityData,
                           numberOfCells, cellsData, pressureData);
    dataDescription->GetInputDescriptionByName("input")->SetGrid(VTKGrid);
    processor->CoProcess(dataDescription);
    }
}

void CatalystFinalize()
{  // Used to free grid if it was used
  if(VTKGrid)
    {
    VTKGrid = NULL;
    }
}