/*=========================================================================
 *
 *  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 itkDerivativeImageFilter_hxx
#define itkDerivativeImageFilter_hxx

#include "itkNumericTraits.h"
#include "itkNeighborhoodOperatorImageFilter.h"
#include "itkDerivativeOperator.h"
#include "itkProgressAccumulator.h"

namespace itk
{
template <typename TInputImage, typename TOutputImage>
void
DerivativeImageFilter<TInputImage, TOutputImage>::GenerateInputRequestedRegion()
{
  // call the superclass' implementation of this method. this should
  // copy the output requested region to the input requested region
  Superclass::GenerateInputRequestedRegion();

  // get pointers to the input and output
  typename Superclass::InputImagePointer inputPtr = const_cast<InputImageType *>(this->GetInput());

  if (!inputPtr)
  {
    return;
  }

  // Build an operator so that we can determine the kernel size
  DerivativeOperator<OutputPixelType, ImageDimension> oper;
  oper.SetDirection(m_Direction);
  oper.SetOrder(m_Order);
  oper.CreateDirectional();

  // get a copy of the input requested region (should equal the output
  // requested region)
  typename TInputImage::RegionType inputRequestedRegion;
  inputRequestedRegion = inputPtr->GetRequestedRegion();

  // pad the input requested region by the operator radius
  inputRequestedRegion.PadByRadius(oper.GetRadius());

  // crop the input requested region at the input's largest possible region
  if (inputRequestedRegion.Crop(inputPtr->GetLargestPossibleRegion()))
  {
    inputPtr->SetRequestedRegion(inputRequestedRegion);
    return;
  }
  else
  {
    // Couldn't crop the region (requested region is outside the largest
    // possible region).  Throw an exception.

    // store what we tried to request (prior to trying to crop)
    inputPtr->SetRequestedRegion(inputRequestedRegion);

    // build an exception
    InvalidRequestedRegionError e(__FILE__, __LINE__);
    e.SetLocation(ITK_LOCATION);
    e.SetDescription("Requested region is (at least partially) outside the largest possible region.");
    e.SetDataObject(inputPtr);
    throw e;
  }
}

template <typename TInputImage, typename TOutputImage>
void
DerivativeImageFilter<TInputImage, TOutputImage>::GenerateData()
{
  ZeroFluxNeumannBoundaryCondition<TInputImage> nbc;

  // Define the operator value type so that we can filter integral
  // images and have the proper operator defined.
  using OperatorValueType = typename NumericTraits<OutputPixelType>::RealType;

  // Filter
  DerivativeOperator<OperatorValueType, ImageDimension> oper;
  oper.SetDirection(m_Direction);
  oper.SetOrder(m_Order);
  oper.CreateDirectional();
  oper.FlipAxes();

  if (m_UseImageSpacing)
  {
    if (this->GetInput()->GetSpacing()[m_Direction] == 0.0)
    {
      itkExceptionMacro("Image spacing cannot be zero.");
    }
    else
    {
      oper.ScaleCoefficients(1.0 / this->GetInput()->GetSpacing()[m_Direction]);
    }
  }

  typename NeighborhoodOperatorImageFilter<InputImageType, OutputImageType, OperatorValueType>::Pointer filter =
    NeighborhoodOperatorImageFilter<InputImageType, OutputImageType, OperatorValueType>::New();

  // Create a process accumulator for tracking the progress of this minipipeline
  auto progress = ProgressAccumulator::New();
  progress->SetMiniPipelineFilter(this);

  // Register the filter with the with progress accumulator using
  // equal weight proportion
  progress->RegisterInternalFilter(filter, 1.0f);

  filter->OverrideBoundaryCondition(&nbc);

  //
  // Set up the mini-pipeline
  //
  filter->SetOperator(oper);
  filter->SetInput(this->GetInput());

  // Graft this filter's output to the mini-pipeline.  this sets up
  // the mini-pipeline to write to this filter's output and copies
  // region ivars and meta-data
  filter->GraftOutput(this->GetOutput());

  // Execute the mini-pipeline.
  filter->Update();

  // Graft the output of the mini-pipeline back onto the filter's output,
  // this copies back the region ivars and meta-data.
  this->GraftOutput(filter->GetOutput());
}

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

  os << indent << "Order: " << m_Order << std::endl;
  os << indent << "Direction: " << m_Direction << std::endl;
  os << indent << "UseImageSpacing: " << (m_UseImageSpacing ? "On" : "Off") << std::endl;
}
} // end namespace itk

#endif
