/*=========================================================================
 *
 *  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 "itkScalarImageToHistogramGenerator.h"
#include "itkMinimumMaximumImageFilter.h"
#include "itkImageFileReader.h"
#include "itkTestingMacros.h"

int
itkScalarImageToHistogramGeneratorTest(int argc, char * argv[])
{

  if (argc < 3)
  {
    std::cerr << "Missing parameters." << std::endl;
    std::cerr << "Usage: " << itkNameOfTestExecutableMacro(argv);
    std::cerr << " inputScalarImageFileName outputHistogramFile.txt" << std::endl;
    return EXIT_FAILURE;
  }


  constexpr unsigned int Dimension{ 2 };
  using PixelComponentType = unsigned char;
  using ScalarImageType = itk::Image<PixelComponentType, Dimension>;
  using ReaderType = itk::ImageFileReader<ScalarImageType>;

  auto reader = ReaderType::New();
  reader->SetFileName(argv[1]);

  ITK_TRY_EXPECT_NO_EXCEPTION(reader->Update());


  const itk::MinimumMaximumImageFilter<ScalarImageType>::Pointer minmaxFilter =
    itk::MinimumMaximumImageFilter<ScalarImageType>::New();
  minmaxFilter->SetInput(reader->GetOutput());
  minmaxFilter->Update();
  const ScalarImageType::PixelType imageMin = minmaxFilter->GetMinimum();
  const ScalarImageType::PixelType imageMax = minmaxFilter->GetMaximum();


  using HistogramGeneratorType = itk::Statistics::ScalarImageToHistogramGenerator<ScalarImageType>;
  auto histogramGenerator = HistogramGeneratorType::New();

  ITK_EXERCISE_BASIC_OBJECT_METHODS(histogramGenerator, ScalarImageToHistogramGenerator, Object);


  histogramGenerator->SetInput(reader->GetOutput());

  const int NumberOfBins = static_cast<unsigned int>(imageMax - imageMin + 1);
  histogramGenerator->SetNumberOfBins(NumberOfBins);
  histogramGenerator->SetMarginalScale(1.0);
  // BUG revealed.  Solution is located at:
  // https://public.kitware.com/Bug/view.php?id=10025
  histogramGenerator->SetHistogramMin(imageMin);
  histogramGenerator->SetHistogramMax(imageMax);
  histogramGenerator->Compute();


  using HistogramType = HistogramGeneratorType::HistogramType;
  const HistogramType * histogram = histogramGenerator->GetOutput();

  std::ofstream outputFile;
  outputFile.open(argv[2]);

  const unsigned int histogramSize = histogram->Size();
  outputFile << "Histogram size " << histogramSize << std::endl;

  constexpr unsigned int channel{ 0 }; // red channel
  outputFile << "Histogram of the scalar component" << std::endl;
  for (unsigned int bin = 0; bin < histogramSize; ++bin)
  {
    outputFile << "bin = " << bin << " frequency = ";
    outputFile << histogram->GetFrequency(bin, channel) << std::endl;
  }
  outputFile.close();
  return EXIT_SUCCESS;
}
