/*=========================================================================
 *
 *  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.
 *
 *=========================================================================*/

#include "itkNaryAddImageFilter.h"
#include "itkImageRegionIterator.h"
#include "itkMath.h"
#include "itkTestingMacros.h"

#include <iostream>


// Function for image initialization
template <typename ImageType>
void
InitializeImage(ImageType * image, const typename ImageType::PixelType & value)
{
  typename ImageType::Pointer inputImage(image);

  // Define their size, and start index
  typename ImageType::SizeType size;
  size.Fill(2);

  typename ImageType::IndexType start;
  start.Fill(0);

  typename ImageType::RegionType region{ start, size };

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

  inputImage->FillBuffer(value);
}


int
itkNaryAddImageFilterTest(int, char *[])
{
  bool testStatus = true;

  // Define the dimension of the images
  constexpr unsigned int Dimension3D = 3;

  // Declare the pixel types of the images
  using PixelType = float;

  // Declare the types of the images
  using InputImageType = itk::Image<PixelType, Dimension3D>;
  using OutputImageType = itk::Image<PixelType, Dimension3D>;

  // Create some images
  auto inputImageA = InputImageType::New();
  auto inputImageB = InputImageType::New();
  auto inputImageC = InputImageType::New();


  constexpr InputImageType::PixelType valueA = 12;
  InitializeImage<InputImageType>(inputImageA, valueA);
  constexpr InputImageType::PixelType valueB = 17;
  InitializeImage<InputImageType>(inputImageB, valueB);
  const InputImageType::PixelType valueC = -4;
  InitializeImage<InputImageType>(inputImageC, valueC);


  // Declare the type for the itk::NaryAddImageFilter
  using FilterType = itk::NaryAddImageFilter<InputImageType, OutputImageType>;

  // Create the filter
  auto filter = FilterType::New();

  ITK_EXERCISE_BASIC_OBJECT_METHODS(filter, NaryAddImageFilter, NaryFunctorImageFilter);

  // Set the input images
  filter->SetInput(0, inputImageA);
  filter->SetInput(1, inputImageB);
  filter->SetInput(2, inputImageC);

  filter->SetFunctor(filter->GetFunctor());

  // Execute the filter
  ITK_TRY_EXPECT_NO_EXCEPTION(filter->Update());


  // Get the filter output
  OutputImageType::Pointer outputImage = filter->GetOutput();

  // Test the validity of the output
  using InputImageIteratorType = itk::ImageRegionConstIterator<InputImageType>;
  using OutputImageIteratorType = itk::ImageRegionConstIterator<OutputImageType>;

  InputImageIteratorType  iterA(inputImageA, inputImageA->GetRequestedRegion());
  InputImageIteratorType  iterB(inputImageB, inputImageA->GetRequestedRegion());
  InputImageIteratorType  iterC(inputImageC, inputImageA->GetRequestedRegion());
  OutputImageIteratorType oIt(outputImage, inputImageA->GetRequestedRegion());

  const OutputImageType::PixelType epsilon = 1e-9;
  unsigned int                     failures = 0;
  while (!oIt.IsAtEnd())
  {
    auto expectedValue = static_cast<OutputImageType::PixelType>(iterA.Get() + iterB.Get() + iterC.Get());
    if (!itk::Math::FloatAlmostEqual(oIt.Get(), expectedValue, 10, epsilon))
    {
      ++failures;
    }
    ++iterA;
    ++iterB;
    ++iterC;
    ++oIt;
  }

  if (failures > 0)
  {
    std::cout << "Test failed!" << std::endl;
    std::cout << "Got " << failures << " different pixels." << std::endl;
    testStatus = false;
  }


  // Execute the filter in place
  filter->InPlaceOn();

  ITK_TRY_EXPECT_NO_EXCEPTION(filter->Update());


  // Test the validity of the output
  OutputImageIteratorType oIt2(outputImage, inputImageA->GetRequestedRegion());
  failures = 0;
  while (!oIt2.IsAtEnd())
  {
    // Here we cannot test using the input iterators anymore since
    // inputImageA should have been overwritten
    auto expectedValue = static_cast<OutputImageType::PixelType>(valueA + valueB + valueC);
    if (!itk::Math::FloatAlmostEqual(oIt2.Get(), expectedValue, 10, epsilon))
    {
      ++failures;
    }
    ++oIt2;
  }

  if (failures > 0)
  {
    std::cout << "Test failed!" << std::endl;
    std::cout << "Got " << failures << " different pixels." << std::endl;
    testStatus = false;
  }


  // Testing with vector Images
  //

  // Define the dimension of the images
  constexpr unsigned int Dimension2D = 2;

  // Declare the pixel types of the images
  using ElementPixelType = int;

  using VectorPixelType = itk::Vector<ElementPixelType, Dimension2D>;
  using VectorImageType = itk::Image<VectorPixelType, Dimension2D>;

  auto vectorImageA = VectorImageType::New();
  auto vectorImageB = VectorImageType::New();
  auto vectorImageC = VectorImageType::New();

  VectorPixelType vectorImageValueA, vectorImageValueB, vectorImageValueC;

  constexpr VectorImageType::PixelType::ValueType vectorValueA = 12;
  vectorImageValueA.Fill(vectorValueA);
  vectorImageValueA[0] = 5;

  constexpr VectorImageType::PixelType::ValueType vectorValueB = 17;
  vectorImageValueB.Fill(vectorValueB);
  vectorImageValueB[0] = 9;

  const VectorImageType::PixelType::ValueType vectorValueC = -4;
  vectorImageValueC.Fill(vectorValueC);
  vectorImageValueC[0] = -80;

  InitializeImage<VectorImageType>(vectorImageA, vectorImageValueA);
  InitializeImage<VectorImageType>(vectorImageB, vectorImageValueB);
  InitializeImage<VectorImageType>(vectorImageC, vectorImageValueC);


  // Create an ADD Filter
  using VectorAdderType = itk::NaryAddImageFilter<VectorImageType, VectorImageType>;

  auto vectorFilter = VectorAdderType::New();

  ITK_EXERCISE_BASIC_OBJECT_METHODS(vectorFilter, NaryAddImageFilter, NaryFunctorImageFilter);


  // Set the input images
  vectorFilter->SetInput(0, vectorImageA);
  vectorFilter->SetInput(1, vectorImageB);
  vectorFilter->SetInput(2, vectorImageC);

  // Get the filter output
  VectorImageType::Pointer vectorOutputImage = vectorFilter->GetOutput();


  // Execute the filter
  ITK_TRY_EXPECT_NO_EXCEPTION(vectorFilter->Update());


  // Test the validity of the output
  using VectorIteratorType = itk::ImageRegionConstIterator<VectorImageType>;

  VectorIteratorType vIterA(vectorImageA, vectorImageA->GetRequestedRegion());
  VectorIteratorType vIterB(vectorImageB, vectorImageA->GetRequestedRegion());
  VectorIteratorType vIterC(vectorImageC, vectorImageA->GetRequestedRegion());
  VectorIteratorType vOutIter(vectorOutputImage, vectorImageA->GetRequestedRegion());

  failures = 0;
  while (!vOutIter.IsAtEnd())
  {
    VectorImageType::PixelType expectedValue =
      static_cast<VectorImageType::PixelType>(vIterA.Get() + vIterB.Get() + vIterC.Get());
    for (unsigned int i = 0; i < vOutIter.GetImageIteratorDimension(); ++i)
    {
      if (!itk::Math::ExactlyEquals(vOutIter.Get()[i], expectedValue[i]))
      {
        ++failures;
      }
    }
    ++vIterA;
    ++vIterB;
    ++vIterC;
    ++vOutIter;
  }

  if (failures > 0)
  {
    std::cout << "Test failed!" << std::endl;
    std::cout << "Got " << failures << " different pixels." << std::endl;
    testStatus = false;
  }

  if (!testStatus)
  {
    return EXIT_FAILURE;
  }

  // All objects should be automatically destroyed at this point
  std::cout << "Test finished." << std::endl;
  return EXIT_SUCCESS;
}