/*=========================================================================
 *
 *  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 "itkImageFileReader.h"
#include "itkImageFileWriter.h"
#include "itkDiscreteHessianGaussianImageFunction.h"
#include "itkMath.h"
#include "itkRescaleIntensityImageFilter.h"
#include "itkTestingMacros.h"


template <int VDimension>
int
itkDiscreteHessianGaussianImageFunctionTestND(int argc, char * argv[])
{
  const unsigned int Dimension = VDimension;

  using PixelType = float;
  using ImageType = itk::Image<PixelType, Dimension>;

  // Read input
  using ReaderType = itk::ImageFileReader<ImageType>;
  auto reader = ReaderType::New();
  reader->SetFileName(argv[1]);

  ITK_TRY_EXPECT_NO_EXCEPTION(reader->Update());


  // Create the itk::DiscreteHessianGaussianImageFunction
  using HessianGaussianImageFunctionType = itk::DiscreteHessianGaussianImageFunction<ImageType, PixelType>;
  typename HessianGaussianImageFunctionType::TensorType                       hessian;
  typename HessianGaussianImageFunctionType::TensorType::EigenValuesArrayType eigenValues;

  auto function = HessianGaussianImageFunctionType::New();


  function->SetInputImage(reader->GetOutput());


  // Set up operator parameters
  double sigma = std::stod(argv[3]);

  double       maxError = 0.001;
  unsigned int maxKernelWidth = 100;
  if (argc > 4)
  {
    maxError = std::stod(argv[4]);
  }
  if (argc > 5)
  {
    maxKernelWidth = std::stoi(argv[5]);
  }

  double                                                       varianceValue = sigma * sigma;
  typename HessianGaussianImageFunctionType::VarianceArrayType varianceArray;
  varianceArray.Fill(varianceValue);

  function->SetVariance(varianceArray);
  ITK_TEST_SET_GET_VALUE(varianceArray, function->GetVariance());

  // Increase code coverage calling other variations of the SetVariance method
  function->SetVariance(varianceValue);
  ITK_TEST_SET_GET_VALUE(varianceArray, function->GetVariance());

  // Test itkSetVectorMacro
  double varianceVector[HessianGaussianImageFunctionType::VarianceArrayType::Length];
  for (unsigned int i = 0; i < HessianGaussianImageFunctionType::VarianceArrayType::Length; ++i)
  {
    varianceVector[i] = varianceValue;
  }
  function->SetVariance(varianceVector);
  ITK_TEST_SET_GET_VALUE(varianceArray, function->GetVariance());


  function->SetMaximumError(maxError);
  ITK_TEST_SET_GET_VALUE(maxError, function->GetMaximumError());

  function->SetMaximumKernelWidth(maxKernelWidth);
  ITK_TEST_SET_GET_VALUE(maxKernelWidth, function->GetMaximumKernelWidth());

  bool normalizeAcrossScale = true;
  ITK_TEST_SET_GET_BOOLEAN(function, NormalizeAcrossScale, normalizeAcrossScale);

  bool useImageSpacing = true;
  ITK_TEST_SET_GET_BOOLEAN(function, UseImageSpacing, useImageSpacing);

  typename HessianGaussianImageFunctionType::InterpolationModeEnum interpolationMode =
    HessianGaussianImageFunctionType::InterpolationModeEnum::NearestNeighbourInterpolation;

  function->SetInterpolationMode(interpolationMode);
  ITK_TEST_SET_GET_VALUE(interpolationMode, function->GetInterpolationMode());


  function->Initialize();


  // Create image for storing result
  using ImageTypePointer = typename ImageType::Pointer;

  ImageTypePointer output = ImageType::New();
  output->SetSpacing(reader->GetOutput()->GetSpacing());
  output->SetOrigin(reader->GetOutput()->GetOrigin());
  output->SetDirection(reader->GetOutput()->GetDirection());
  output->SetLargestPossibleRegion(reader->GetOutput()->GetLargestPossibleRegion());
  output->SetRequestedRegion(reader->GetOutput()->GetRequestedRegion());
  output->SetBufferedRegion(reader->GetOutput()->GetBufferedRegion());
  output->Allocate();
  output->FillBuffer(itk::NumericTraits<PixelType>::ZeroValue());


  // Step over input and output images
  using ConstIteratorType = itk::ImageRegionConstIterator<ImageType>;
  using IteratorType = itk::ImageRegionIterator<ImageType>;

  ConstIteratorType it(reader->GetOutput(), reader->GetOutput()->GetRequestedRegion());
  it.GoToBegin();
  IteratorType outIter(output, output->GetRequestedRegion());

  using PointType = typename HessianGaussianImageFunctionType::PointType;
  PointType point;
  using ContinuousIndexType = typename HessianGaussianImageFunctionType::ContinuousIndexType;
  const unsigned long nop = reader->GetOutput()->GetRequestedRegion().GetNumberOfPixels();
  unsigned long       pixelNumber = 0;
  while (!it.IsAtEnd())
  {
    if (pixelNumber < nop / 3)
    {
      hessian = function->EvaluateAtIndex(it.GetIndex());
    }
    else if (pixelNumber < nop * 2 / 3)
    {
      reader->GetOutput()->TransformIndexToPhysicalPoint(it.GetIndex(), point);
      hessian = function->Evaluate(point);
    }
    else
    {
      using ContinuousIndexValueType = typename ContinuousIndexType::ValueType;

      reader->GetOutput()->TransformIndexToPhysicalPoint(it.GetIndex(), point);
      const ContinuousIndexType cindex =
        reader->GetOutput()->template TransformPhysicalPointToContinuousIndex<ContinuousIndexValueType>(point);
      hessian = function->EvaluateAtContinuousIndex(cindex);
    }

    hessian.ComputeEigenValues(eigenValues);

    PixelType maxEigen = eigenValues[0];
    for (unsigned int i = 1; i < Dimension; ++i)
    {
      maxEigen = std::max(eigenValues[i], maxEigen);
    }

    outIter.Set(maxEigen);
    ++outIter;

    ++it;
    ++pixelNumber;
  }

  // Write the output image
  using WriterType = itk::ImageFileWriter<ImageType>;
  auto writer = WriterType::New();
  writer->SetFileName(argv[2]);
  writer->SetInput(output);

  ITK_TRY_EXPECT_NO_EXCEPTION(writer->Update());


  // Check that VarianceArrayType can be changed
  using VarianceArrayType = typename HessianGaussianImageFunctionType::VarianceArrayType;
  VarianceArrayType varReturned = function->GetVariance();

  VarianceArrayType varChanged = varReturned;
  for (unsigned int i = 0; i < varChanged.Size(); ++i)
  {
    varChanged[i] *= 2.0;
  }
  function->SetVariance(varChanged);
  varReturned = function->GetVariance();
  for (unsigned int i = 0; i < Dimension; ++i)
  {
    if (varReturned[i] != varChanged[i])
    {
      std::cout << "Test failed!" << std::endl;
      std::cout << "Error in GetVariance() at index [" << i << ']' << std::endl;
      std::cout << "Expected: " << varChanged[i] << ", but got: " << varReturned[i] << std::endl;
      return EXIT_FAILURE;
    }
  }


  double piValues[Dimension];
  for (unsigned int i = 0; i < Dimension; ++i)
  {
    piValues[i] = itk::Math::pi;
  }
  function->SetVariance(piValues);
  varReturned = function->GetVariance();
  for (unsigned int i = 0; i < Dimension; ++i)
  {
    if (itk::Math::NotAlmostEquals(varReturned[i], itk::Math::pi))
    {
      std::cout << "Test failed!" << std::endl;
      std::cout << "Error in GetVariance() at index [" << i << ']' << std::endl;
      std::cout << "Expected: " << itk::Math::pi << ", but got: " << varReturned[i] << std::endl;
      return EXIT_FAILURE;
    }
  }


  // Exercise another interpolation mode: LinearInterpolation
  {
    function->SetInterpolationMode(HessianGaussianImageFunctionType::InterpolationModeEnum::LinearInterpolation);
    const ImageType *              inputImage = reader->GetOutput();
    typename ImageType::RegionType region = inputImage->GetBufferedRegion();
    typename ImageType::SizeType   size = region.GetSize();
    typename ImageType::IndexType  index = region.GetIndex();
    // Aim for the pixel at the center of the image
    for (unsigned int i = 0; i < Dimension; ++i)
    {
      index[i] += size[i] / 2;
    }

    hessian = function->EvaluateAtIndex(index);
    inputImage->TransformIndexToPhysicalPoint(index, point);
    hessian = function->Evaluate(point);

    ContinuousIndexType cindex;

    // Exercise the fractional computation of the linear interpolator
    for (unsigned int i = 0; i < Dimension; ++i)
    {
      cindex[i] = static_cast<double>(index[i]) + 0.5;
    }

    hessian = function->EvaluateAtContinuousIndex(cindex);
  }


  std::cout << "Test finished." << std::endl;
  return EXIT_SUCCESS;
}

int
itkDiscreteHessianGaussianImageFunctionTest(int argc, char * argv[])
{
  if (argc < 4)
  {
    std::cerr << "Missing parameters." << std::endl;
    std::cerr << "Usage: " << itkNameOfTestExecutableMacro(argv);
    std::cerr << "inputFileName"
                 " outputFileName"
                 " sigma"
                 " [maximumError]"
                 " [maximumKernelWidth]"
              << std::endl;
    return EXIT_FAILURE;
  }


  // Exercise basic object methods
  // Done outside the helper function in the test because GCC is limited
  // when calling overloaded base class functions.
  constexpr unsigned int Dimension = 3;

  using PixelType = float;
  using ImageType = itk::Image<PixelType, Dimension>;


  using HessianGaussianImageFunctionType = itk::DiscreteHessianGaussianImageFunction<ImageType, PixelType>;
  auto function = HessianGaussianImageFunctionType::New();

  ITK_EXERCISE_BASIC_OBJECT_METHODS(function, DiscreteHessianGaussianImageFunction, ImageFunction);


  return itkDiscreteHessianGaussianImageFunctionTestND<Dimension>(argc, argv);
}
