/*=========================================================================
 *
 *  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 itkLandmarkDisplacementFieldSource_hxx
#define itkLandmarkDisplacementFieldSource_hxx

#include "itkProgressReporter.h"
#include "itkThinPlateSplineKernelTransform.h"
#include <algorithm> // For max.

namespace itk
{

template <typename TOutputImage>
LandmarkDisplacementFieldSource<TOutputImage>::LandmarkDisplacementFieldSource()
{
  m_OutputSpacing.Fill(1.0);
  m_OutputOrigin.Fill(0.0);
  m_OutputDirection.SetIdentity();

  using DefaultTransformType = ThinPlateSplineKernelTransform<double, Self::ImageDimension>;

  m_KernelTransform = DefaultTransformType::New();
}

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

  os << indent << "OutputRegion: " << m_OutputRegion << std::endl;
  os << indent << "OutputSpacing: " << m_OutputSpacing << std::endl;
  os << indent << "OutputOrigin: " << m_OutputOrigin << std::endl;
  os << indent << "OutputDirection: " << m_OutputDirection << std::endl;
  os << indent << "KernelTransform: " << m_KernelTransform.GetPointer() << std::endl;
  os << indent << "Source Landmarks: " << m_SourceLandmarks.GetPointer() << std::endl;
  os << indent << "Target Landmarks: " << m_TargetLandmarks.GetPointer() << std::endl;
}

template <typename TOutputImage>
void
LandmarkDisplacementFieldSource<TOutputImage>::SetOutputSpacing(const double * spacing)
{
  SpacingType s;
  for (unsigned int i = 0; i < TOutputImage::ImageDimension; ++i)
  {
    s[i] = static_cast<typename SpacingType::ValueType>(spacing[i]);
  }

  this->SetOutputSpacing(s);
}

template <typename TOutputImage>
void
LandmarkDisplacementFieldSource<TOutputImage>::SetOutputOrigin(const double * origin)
{
  this->SetOutputOrigin(OriginPointType(origin));
}

/**
 * Sub-sample the input displacement field and prepare the KernelBase
 * BSpline
 */
template <typename TOutputImage>
void
LandmarkDisplacementFieldSource<TOutputImage>::PrepareKernelBaseSpline()
{
  // Shameful violation of const-correctness due to the
  // lack of constness in the PointSet. That is, the point
  // set is actually allowed to modify its points containers.

  auto * sources = const_cast<LandmarkContainer *>(m_SourceLandmarks.GetPointer());
  auto * targets = const_cast<LandmarkContainer *>(m_TargetLandmarks.GetPointer());

  m_KernelTransform->GetModifiableTargetLandmarks()->SetPoints(targets);
  m_KernelTransform->GetModifiableSourceLandmarks()->SetPoints(sources);

  itkDebugMacro("Before ComputeWMatrix() ");

  m_KernelTransform->ComputeWMatrix();

  itkDebugMacro("After ComputeWMatrix() ");
}

/**
 * GenerateData
 */
template <typename TOutputImage>
void
LandmarkDisplacementFieldSource<TOutputImage>::GenerateData()
{
  // First subsample the input displacement field in order to create
  // the KernelBased spline.
  this->PrepareKernelBaseSpline();

  itkDebugMacro("Actually executing");

  // Get the output pointers
  OutputImageType * outputPtr = this->GetOutput();

  outputPtr->SetBufferedRegion(outputPtr->GetRequestedRegion());
  outputPtr->Allocate();

  // Create an iterator that will walk the output region for this thread.
  using OutputIterator = ImageRegionIteratorWithIndex<TOutputImage>;

  OutputImageRegionType region = outputPtr->GetRequestedRegion();

  // Define a few indices that will be used to translate from an input pixel
  // to an output pixel
  OutputIndexType outputIndex; // Index to current output pixel

  using InputPointType = typename KernelTransformType::InputPointType;
  using OutputPointType = typename KernelTransformType::OutputPointType;

  InputPointType outputPoint; // Coordinates of current output pixel

  // Support for progress methods/callbacks
  ProgressReporter progress(this, 0, region.GetNumberOfPixels(), 10);

  // Walk the output region
  for (OutputIterator outIt(outputPtr, region); !outIt.IsAtEnd(); ++outIt)
  {
    // Determine the index of the current output pixel
    outputIndex = outIt.GetIndex();
    outputPtr->TransformIndexToPhysicalPoint(outputIndex, outputPoint);

    // Compute corresponding inverse displacement vector
    OutputPointType interpolatedDisplacement = m_KernelTransform->TransformPoint(outputPoint);

    OutputPixelType displacement;
    for (unsigned int i = 0; i < ImageDimension; ++i)
    {
      displacement[i] = interpolatedDisplacement[i] - outputPoint[i];
    }

    outIt.Set(displacement);
    progress.CompletedPixel();
  }
}

/**
 * Inform pipeline of required output region
 */
template <typename TOutputImage>
void
LandmarkDisplacementFieldSource<TOutputImage>::GenerateOutputInformation()
{
  // call the superclass' implementation of this method
  Superclass::GenerateOutputInformation();

  // get pointers to the input and output
  OutputImagePointer outputPtr = this->GetOutput();
  if (!outputPtr)
  {
    return;
  }

  // Set the size of the output region
  outputPtr->SetLargestPossibleRegion(m_OutputRegion);

  // Set spacing and origin
  outputPtr->SetSpacing(m_OutputSpacing);
  outputPtr->SetOrigin(m_OutputOrigin);
  outputPtr->SetDirection(m_OutputDirection);
}

/**
 * Verify if any of the components has been modified.
 */
template <typename TOutputImage>
ModifiedTimeType
LandmarkDisplacementFieldSource<TOutputImage>::GetMTime() const
{
  ModifiedTimeType latestTime = Object::GetMTime();

  if (m_KernelTransform)
  {
    latestTime = std::max(latestTime, m_KernelTransform->GetMTime());
  }

  if (m_SourceLandmarks)
  {
    latestTime = std::max(latestTime, m_SourceLandmarks->GetMTime());
  }

  if (m_TargetLandmarks)
  {
    latestTime = std::max(latestTime, m_TargetLandmarks->GetMTime());
  }
  return latestTime;
}

} // end namespace itk

#endif
