/*=========================================================================
 *
 *  Copyright Insight Software Consortium
 *
 *  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
 *
 *         http://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 "itkLandmarkDisplacementFieldSource.h"
#include "itkProgressReporter.h"
#include "itkThinPlateSplineKernelTransform.h"

namespace itk
{
/**
 * Initialize new instance
 */
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();
}

/**
 * Print out a description of self
 *
 * \todo Add details about this class
 */
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;
}

/**
 * Set the output image spacing.
 */
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);
}

/**
 * Set the output image origin.
 */
template< typename TOutputImage >
void
LandmarkDisplacementFieldSource< TOutputImage >
::SetOutputOrigin(
  const double *origin)
{
  OriginPointType p(origin);

  this->SetOutputOrigin(p);
}

/**
 * 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();

  OutputIterator outIt(outputPtr, region);

  // 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);

  outIt.GoToBegin();

  // Walk the output region
  while ( !outIt.IsAtEnd() )
    {
    // 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);
    ++outIt;
    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 )
    {
    if ( latestTime < m_KernelTransform->GetMTime() )
      {
      latestTime = m_KernelTransform->GetMTime();
      }
    }

  if ( m_SourceLandmarks )
    {
    if ( latestTime < m_SourceLandmarks->GetMTime() )
      {
      latestTime = m_SourceLandmarks->GetMTime();
      }
    }

  if ( m_TargetLandmarks )
    {
    if ( latestTime < m_TargetLandmarks->GetMTime() )
      {
      latestTime = m_TargetLandmarks->GetMTime();
      }
    }
  return latestTime;
}
} // end namespace itk

#endif
