/*=========================================================================
 *
 *  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 "itkAtan2ImageFilter.h"
#include "itkImageRegionIteratorWithIndex.h"
#include "itkMath.h"
#include "itkTestingMacros.h"


int
itkAtan2ImageFilterTest(int, char *[])
{

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

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

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

  // Declare appropriate Iterator types for each image
  using InputIteratorType = itk::ImageRegionIteratorWithIndex<InputImageType>;

  using OutputIteratorType = itk::ImageRegionIteratorWithIndex<OutputImageType>;

  // Declare the type of the index to access images
  using IndexType = itk::Index<ImageDimension>;

  // Declare the type of the size
  using SizeType = itk::Size<ImageDimension>;

  // Declare the type of the Region
  using RegionType = itk::ImageRegion<ImageDimension>;

  // Create two images
  auto sinImage = InputImageType::New();
  auto cosImage = InputImageType::New();

  // Define their size, and start index
  SizeType size;
  size[0] = 2;
  size[1] = 2;
  size[2] = 2;

  IndexType start;
  start[0] = 0;
  start[1] = 0;
  start[2] = 0;

  RegionType region;
  region.SetIndex(start);
  region.SetSize(size);

  // Initialize Sinus Image
  sinImage->SetRegions(region);
  sinImage->Allocate();

  // Initialize Cosinus Image
  cosImage->SetRegions(region);
  cosImage->Allocate();

  // Create one iterator for the Input Image (this is a light object)
  InputIteratorType it1(sinImage, sinImage->GetBufferedRegion());

  // Initialize the content of Image A
  const double sinValue = std::sin(itk::Math::pi / 6.0);
  it1.GoToBegin();
  while (!it1.IsAtEnd())
  {
    it1.Set(sinValue);
    ++it1;
  }

  // Create one iterator for the Input Image (this is a light object)
  InputIteratorType it2(cosImage, cosImage->GetBufferedRegion());

  // Initialize the content of Image A
  const double cosValue = std::cos(itk::Math::pi / 6.0);
  it2.GoToBegin();
  while (!it2.IsAtEnd())
  {
    it2.Set(cosValue);
    ++it2;
  }

  // Declare the type for the Atan filter
  using FilterType = itk::Atan2ImageFilter<InputImageType, InputImageType, OutputImageType>;

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

  ITK_EXERCISE_BASIC_OBJECT_METHODS(filter, Atan2ImageFilter, BinaryGeneratorImageFilter);

  // Set the input images
  filter->SetInput1(sinImage);
  filter->SetInput2(cosImage);

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

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

  // Create an iterator for going through the image output
  OutputIteratorType ot(outputImage, outputImage->GetRequestedRegion());

  // Check the content of the result image
  const OutputImageType::PixelType epsilon = 1e-6;
  ot.GoToBegin();

  it1.GoToBegin();
  it2.GoToBegin();

  while (!ot.IsAtEnd())
  {
    const InputImageType::PixelType  input1 = it1.Get();
    const InputImageType::PixelType  input2 = it2.Get();
    const OutputImageType::PixelType output = ot.Get();
    const OutputImageType::PixelType atan2 = std::atan2(input1, input2);
    if (!itk::Math::FloatAlmostEqual(atan2, output, 10, epsilon))
    {
      std::cerr.precision(static_cast<int>(itk::Math::abs(std::log10(epsilon))));
      std::cerr << "Error " << std::endl;
      std::cerr << " std::atan2( " << input1 << ", " << input2 << ") = " << atan2 << std::endl;
      std::cerr << " differs from " << output;
      std::cerr << " by more than " << epsilon << std::endl;
      return EXIT_FAILURE;
    }
    ++ot;
    ++it1;
  }

  return EXIT_SUCCESS;
}
