/*=========================================================================
 *
 *  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 itkImageRegistrationMethodImageSource_h
#define itkImageRegistrationMethodImageSource_h
#include "itkImage.h"
#include "itkImageRegionIteratorWithIndex.h"
#include "itkCommandIterationUpdate.h"
#include "itkOptimizerParameters.h"

/**
 *  This class generates two 2D-Gaussians (standard deviation RegionSize/2)
 *  One is shifted by 7,3 pixels from the other.
 *
 *  These two images are provided to the registration methods in this
 *  directory in order to obtain a uniform test input data.
 *
 *  Therefore the solution of the registration is |-7 -3|
 */
namespace itk
{

namespace testhelper
{

template <typename TFixedPixelType, typename TMovingPixelType, unsigned int VDimension>
class ImageRegistrationMethodImageSource : public itk::Object
{
public:
  using Self = ImageRegistrationMethodImageSource;
  using Superclass = Object;
  using Pointer = SmartPointer<Self>;
  using ConstPointer = SmartPointer<const Self>;
  using ParametersType = OptimizerParameters<double>;

  /** Method for creation through the object factory. */
  itkNewMacro(Self);

  /** \see LightObject::GetNameOfClass() */
  itkOverrideGetNameOfClassMacro(ImageRegistrationMethodImageSource);


  using MovingImageType = itk::Image<TMovingPixelType, VDimension>;
  using FixedImageType = itk::Image<TFixedPixelType, VDimension>;

  const MovingImageType *
  GetMovingImage() const
  {
    return m_MovingImage.GetPointer();
  }

  const FixedImageType *
  GetFixedImage() const
  {
    return m_FixedImage.GetPointer();
  }

  const ParametersType &
  GetActualParameters() const
  {
    return m_Parameters;
  }


  void
  GenerateImages(const typename MovingImageType::SizeType & size)
  {
    const typename MovingImageType::RegionType region(size);

    m_MovingImage->SetRegions(region);
    m_MovingImage->Allocate();

    m_FixedImage->SetRegions(region);
    m_FixedImage->Allocate();

    /* Fill images with a 2D gaussian*/
    using MovingImageIteratorType = itk::ImageRegionIteratorWithIndex<MovingImageType>;

    using FixedImageIteratorType = itk::ImageRegionIteratorWithIndex<FixedImageType>;


    itk::Point<double, 2> center;
    center[0] = static_cast<double>(region.GetSize()[0]) / 2.0;
    center[1] = static_cast<double>(region.GetSize()[1]) / 2.0;

    const double s = static_cast<double>(region.GetSize()[0]) / 2.0;

    itk::Point<double, 2>  p;
    itk::Vector<double, 2> d;

    /* Set the displacement */
    itk::Vector<double, 2> displacement;
    displacement[0] = m_Parameters[0];
    displacement[1] = m_Parameters[1];


    MovingImageIteratorType ri(m_MovingImage, region);
    FixedImageIteratorType  ti(m_FixedImage, region);
    while (!ri.IsAtEnd())
    {
      p[0] = ri.GetIndex()[0];
      p[1] = ri.GetIndex()[1];
      d = p - center;
      d += displacement;
      const double x = d[0];
      const double y = d[1];
      const double value = 200.0 * std::exp(-(x * x + y * y) / (s * s));
      ri.Set(static_cast<typename MovingImageType::PixelType>(value));
      ++ri;
    }


    while (!ti.IsAtEnd())
    {
      p[0] = ti.GetIndex()[0];
      p[1] = ti.GetIndex()[1];
      d = p - center;
      const double x = d[0];
      const double y = d[1];
      const double value = 200.0 * std::exp(-(x * x + y * y) / (s * s));
      ti.Set(static_cast<typename FixedImageType::PixelType>(value));
      ++ti;
    }
  }

protected:
  ImageRegistrationMethodImageSource()
  {
    m_MovingImage = MovingImageType::New();
    m_FixedImage = FixedImageType::New();
    m_Parameters = ParametersType(2);
    m_Parameters[0] = 7.0;
    m_Parameters[1] = 3.0;
  }

private:
  typename FixedImageType::Pointer  m_FixedImage{};
  typename MovingImageType::Pointer m_MovingImage{};

  ParametersType m_Parameters{};
};

} // end namespace testhelper

} // end namespace itk
#endif
