/*=========================================================================
 *
 *  Copyright NumFOCUS
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         https://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *=========================================================================*/
#ifndef itkGridImageSource_hxx
#define itkGridImageSource_hxx

#include "itkGaussianKernelFunction.h"
#include "itkImageLinearIteratorWithIndex.h"
#include "itkImageRegionIteratorWithIndex.h"
#include "itkTotalProgressReporter.h"
#include <algorithm> // For min.

namespace itk
{
template <typename TOutputImage>
GridImageSource<TOutputImage>::GridImageSource()

{
  this->m_Sigma.Fill(0.5);
  this->m_GridSpacing.Fill(4.0);
  this->m_GridOffset.Fill(0.0);
  this->m_WhichDimensions.Fill(true);

  this->m_KernelFunction = dynamic_cast<KernelFunctionType *>(GaussianKernelFunction<double>::New().GetPointer());
  this->DynamicMultiThreadingOn();
  this->ThreaderUpdateProgressOff();
}

template <typename TOutputImage>
void
GridImageSource<TOutputImage>::BeforeThreadedGenerateData()
{
  ImageType * output = this->GetOutput(0);

  this->m_PixelArrays = PixelArrayContainerType::New();
  m_PixelArrays->Initialize();

  for (unsigned int i = 0; i < ImageDimension; ++i)
  {
    this->m_GridOffset[i] = std::min(this->m_GridOffset[i], this->m_GridSpacing[i]);
    PixelArrayType pixels = m_PixelArrays->CreateElementAt(i);
    pixels.set_size(this->GetSize()[i]);
    pixels.fill(1);
    if (this->m_WhichDimensions[i])
    {
      ImageLinearIteratorWithIndex<ImageType> It(output, output->GetRequestedRegion());
      It.SetDirection(i);

      // Add two extra functions in the front and one in the back to ensure
      // coverage.
      unsigned int numberOfGaussians =
        Math::Ceil<unsigned int>(this->GetSize()[i] * output->GetSpacing()[i] / this->m_GridSpacing[i]) + 4u;
      for (It.GoToBegin(); !It.IsAtEndOfLine(); ++It)
      {
        typename ImageType::IndexType index = It.GetIndex();
        typename ImageType::PointType point;
        output->TransformIndexToPhysicalPoint(index, point);

        RealType val = 0;
        for (unsigned int j = 0; j < numberOfGaussians; ++j)
        {
          RealType num = point[i] - static_cast<RealType>(j - 2) * this->m_GridSpacing[i] - output->GetOrigin()[i] -
                         this->m_GridOffset[i];
          val += this->m_KernelFunction->Evaluate(num / this->m_Sigma[i]);
        }
        pixels[index[i]] = val;
      }
      pixels = 1.0 - pixels / pixels.max_value();
    }
    this->m_PixelArrays->SetElement(i, pixels);
  }
}

template <typename TOutputImage>
void
GridImageSource<TOutputImage>::DynamicThreadedGenerateData(const ImageRegionType & outputRegionForThread)
{
  ImageType * output = this->GetOutput(0);

  TotalProgressReporter progress(this, output->GetRequestedRegion().GetNumberOfPixels());

  for (ImageRegionIteratorWithIndex<ImageType> It(output, outputRegionForThread); !It.IsAtEnd(); ++It)
  {
    RealType                      val = 1.0;
    typename ImageType::IndexType index = It.GetIndex();
    for (unsigned int i = 0; i < ImageDimension; ++i)
    {
      val *= this->m_PixelArrays->GetElement(i)[index[i]];
    }
    It.Set(static_cast<PixelType>(m_Scale * val));
    progress.CompletedPixel();
  }
}

template <typename TOutputImage>
void
GridImageSource<TOutputImage>::PrintSelf(std::ostream & os, Indent indent) const
{
  Superclass::PrintSelf(os, indent);

  os << indent << "Output image information: " << std::endl;
  os << indent << "   Scale      : " << this->GetScale() << std::endl;

  os << indent << "Grid information: " << std::endl;
  os << indent << "   WhichDimensions : " << this->GetWhichDimensions() << std::endl;
  os << indent << "   Kernel          : " << this->GetKernelFunction() << std::endl;
  os << indent << "   Sigma           : " << this->GetSigma() << std::endl;
  os << indent << "   Grid spacing    : " << this->GetGridSpacing() << std::endl;
  os << indent << "   Grid offset     : " << this->GetGridOffset() << std::endl;

  os << indent << "Pixel arrays: " << m_PixelArrays << std::endl;
}
} // end namespace itk

#endif
