/*=========================================================================
 *
 *  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 "itkMeanSampleFilter.h"
#include "itkListSample.h"
#include "itkSubsample.h"

int
itkSubsampleTest3(int, char *[])
{
  std::cout << "MeanSampleFilter test \n \n";

  constexpr unsigned int MeasurementVectorSize = 2;
  constexpr unsigned int numberOfMeasurementVectors = 5;
  unsigned int           counter;

  using MeasurementVectorType = itk::FixedArray<float, MeasurementVectorSize>;
  using SampleType = itk::Statistics::ListSample<MeasurementVectorType>;

  auto sample = SampleType::New();

  sample->SetMeasurementVectorSize(MeasurementVectorSize);

  MeasurementVectorType measure;

  // reset counter
  counter = 0;

  while (counter < numberOfMeasurementVectors)
  {
    for (unsigned int i = 0; i < MeasurementVectorSize; ++i)
    {
      measure[i] = counter;
    }
    sample->PushBack(measure);
    counter++;
  }

  using SubsampleType = itk::Statistics::Subsample<SampleType>;

  auto subsample = SubsampleType::New();

  subsample->SetSample(sample);

  // Initialize the subsample with all the samples
  subsample->InitializeWithAllInstances();

  using FilterType = itk::Statistics::MeanSampleFilter<SubsampleType>;

  auto filter = FilterType::New();

  filter->SetInput(subsample);

  try
  {
    filter->Update();
  }
  catch (const itk::ExceptionObject & excp)
  {
    std::cerr << "Exception caught: " << excp << std::endl;
  }

  const FilterType::MeasurementVectorDecoratedType * decorator = filter->GetOutput();
  FilterType::MeasurementVectorType                  meanOutput = decorator->Get();

  FilterType::MeasurementVectorType mean;

  mean[0] = 2.0;
  mean[1] = 2.0;

  std::cout << meanOutput[0] << ' ' << mean[0] << ' ' << meanOutput[1] << ' ' << mean[1] << ' ' << std::endl;

  FilterType::MeasurementVectorType::ValueType epsilon = 1e-6;

  if ((itk::Math::abs(meanOutput[0] - mean[0]) > epsilon) || (itk::Math::abs(meanOutput[1] - mean[1]) > epsilon))
  {
    std::cerr << "The result is not what is expected" << std::endl;
    return EXIT_FAILURE;
  }

  // Clear and  repopulate the subsample container
  subsample->Clear();

  // add only the first half of instances of the sample
  for (SampleType::InstanceIdentifier id = 0; id < static_cast<SampleType::InstanceIdentifier>(sample->Size() / 2);
       id++)
  {
    subsample->AddInstance(id);
  }

  std::cout << "Subsample size: " << subsample->Size() << std::endl;

  try
  {
    filter->Update();
  }
  catch (const itk::ExceptionObject & excp)
  {
    std::cerr << "Exception caught: " << excp << std::endl;
  }

  decorator = filter->GetOutput();
  meanOutput = decorator->Get();

  mean[0] = 0.5;
  mean[1] = 0.5;

  std::cout << meanOutput[0] << ' ' << mean[0] << ' ' << meanOutput[1] << ' ' << mean[1] << ' ' << std::endl;

  if ((itk::Math::abs(meanOutput[0] - mean[0]) > epsilon) || (itk::Math::abs(meanOutput[1] - mean[1]) > epsilon))
  {
    std::cerr << "The result is not what is expected" << std::endl;
    return EXIT_FAILURE;
  }

  return EXIT_SUCCESS;
}