/*=========================================================================
 *
 *  Copyright UMC Utrecht and contributors
 *
 *  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
 *
 *        http://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 "itkBSplineInterpolationWeightFunction.h"
#include "itkBSplineInterpolationWeightFunction2.h"

#include <ctime>
#include <iomanip>

#include <itkMath.h>

//-------------------------------------------------------------------------------------
// This test tests the itkBSplineInterpolationWeightFunction2 and compares
// it with the ITK implementation. It should give equal results and comparable
// performance. The test is performed in 2D and 3D, with spline order 3.
// Also the PrintSelf()-functions are called.

int
main()
{
  /** Some basic type definitions. */
  const unsigned int SplineOrder = 3;
  using CoordinateRepresentationType = float;
  const double distance = 1e-3;             // the allowable distance
  const double allowedTimeDifference = 0.2; // 20% is considered within limits
  /** The number of calls to Evaluate() in 2D. This number gives reasonably
   * fast test results in Release mode. In 3D half of this number calls are
   * made.
   */
  auto N = static_cast<unsigned int>(1e6);

  /** Other typedefs. */
  using WeightFunctionType2D = itk::BSplineInterpolationWeightFunction<CoordinateRepresentationType, 2, SplineOrder>;
  using WeightFunction2Type2D = itk::BSplineInterpolationWeightFunction2<CoordinateRepresentationType, 2, SplineOrder>;
  using WeightFunctionType3D = itk::BSplineInterpolationWeightFunction<CoordinateRepresentationType, 3, SplineOrder>;
  using WeightFunction2Type3D = itk::BSplineInterpolationWeightFunction2<CoordinateRepresentationType, 3, SplineOrder>;
  using ContinuousIndexType2D = WeightFunctionType2D::ContinuousIndexType;
  using WeightsType2D = WeightFunctionType2D::WeightsType;
  using ContinuousIndexType3D = WeightFunctionType3D::ContinuousIndexType;
  using WeightsType3D = WeightFunctionType3D::WeightsType;

  /**
   * *********** 2D TESTING ***********************************************
   */

  std::cerr << "2D TESTING:\n" << std::endl;

  /** Construct several weight functions. */
  auto weightFunction2D = WeightFunctionType2D::New();
  auto weight2Function2D = WeightFunction2Type2D::New();

  /** Create and fill a continuous index. */
  auto cindex = itk::MakeFilled<ContinuousIndexType2D>(0.1f);

  /** Run evaluate for the original ITK implementation. */
  WeightsType2D weights2D = weightFunction2D->Evaluate(cindex);
  // std::cerr << "weights (ITK) " << weights2D << std::endl;
  unsigned int weightsSize = weights2D.Size();
  std::cerr << "weights (ITK): [" << weights2D[0] << ", " << weights2D[1] << ", ..., " << weights2D[weightsSize - 2]
            << ", " << weights2D[weightsSize - 1] << "]" << std::endl;

  /** Run evaluate for our modified implementation. */
  WeightsType2D weights2_2D = weight2Function2D->Evaluate(cindex);
  // std::cerr << "weights (our) " << weights2_2D << std::endl;
  std::cerr << "weights (our): [" << weights2_2D[0] << ", " << weights2_2D[1] << ", ..., "
            << weights2_2D[weightsSize - 2] << ", " << weights2_2D[weightsSize - 1] << "]" << std::endl;

  /** Compute the distance between the two vectors. */
  double error = 0.0;
  for (unsigned int i = 0; i < weights2D.Size(); ++i)
  {
    error += vnl_math::sqr(weights2D[i] - weights2_2D[i]);
  }
  error = std::sqrt(error);

  /** TEST: Compare the two qualitatively. */
  if (error > distance)
  {
    std::cerr << "ERROR: the ITK implementation differs from our implementation with more than "
              << static_cast<unsigned int>(distance * 100.0) << "%." << std::endl;
    return EXIT_FAILURE;
  }
  std::cerr << std::showpoint;
  std::cerr << std::scientific;
  std::cerr << std::setprecision(4);
  std::cerr << "The distance is: " << error << std::endl;

  /** Time the ITK implementation. */
  clock_t startClock = clock();
  for (unsigned int i = 0; i < N; ++i)
  {
    weightFunction2D->Evaluate(cindex);
  }
  clock_t endClock = clock();
  clock_t clockITK = endClock - startClock;
  std::cerr << "The elapsed time for the ITK implementation is: " << clockITK << std::endl;

  /** Time our own implementation, which is essentially the same, but created
   * a little more general, so that higher order derivatives are also easily
   * implemented.
   */
  startClock = clock();
  for (unsigned int i = 0; i < N; ++i)
  {
    weight2Function2D->Evaluate(cindex);
  }
  endClock = clock();
  clock_t clockOur = endClock - startClock;
  std::cerr << "The elapsed time for our own implementation is: " << clockOur << std::endl;

  /** TEST: Compare the two performance wise. */
  double timeDifference = static_cast<double>(clockITK) / static_cast<double>(clockOur);
  std::cerr << std::fixed;
  std::cerr << std::setprecision(1);
  std::cerr << "The time difference is " << (timeDifference - 1.0) * 100.0 << "% in favor of "
            << (timeDifference > 1.0 ? "our " : "the ITK ") << "implementation." << std::endl;
  if (timeDifference < (1.0 - allowedTimeDifference))
  {
    std::cerr << "ERROR: the ITK implementation is more than "
              << static_cast<unsigned int>(allowedTimeDifference * 100.0) << "% faster than our implementation."
              << std::endl;
#if _ELASTIX_TEST_TIMING
    return EXIT_FAILURE;
#endif
  }

  /**
   * *********** 3D TESTING ***********************************************
   */

  std::cerr << "\n--------------------------------------------------------";
  std::cerr << "\n3D TESTING:\n" << std::endl;

  /** Construct several weight functions. */
  auto weightFunction3D = WeightFunctionType3D::New();
  auto weight2Function3D = WeightFunction2Type3D::New();

  /** Create and fill a continuous index. */
  auto cindex3D = itk::MakeFilled<ContinuousIndexType3D>(0.1f);

  /** Run evaluate for the original ITK implementation. */
  WeightsType3D weights3D = weightFunction3D->Evaluate(cindex3D);
  std::cerr << std::setprecision(6);
  // std::cerr << "weights (ITK) " << weights3D << std::endl;
  weightsSize = weights3D.Size();
  std::cerr << "weights (ITK): [" << weights3D[0] << ", " << weights3D[1] << ", ..., " << weights3D[weightsSize - 2]
            << ", " << weights3D[weightsSize - 1] << "]" << std::endl;

  /** Run evaluate for our modified implementation. */
  WeightsType3D weights2_3D = weight2Function3D->Evaluate(cindex3D);
  // std::cerr << "weights (our) " << weights2_3D << std::endl;
  std::cerr << "weights (our): [" << weights2_3D[0] << ", " << weights2_3D[1] << ", ..., "
            << weights2_3D[weightsSize - 2] << ", " << weights2_3D[weightsSize - 1] << "]" << std::endl;

  /** Compute the distance between the two vectors. */
  error = 0.0;
  for (unsigned int i = 0; i < weights3D.Size(); ++i)
  {
    error += vnl_math::sqr(weights3D[i] - weights2_3D[i]);
  }
  error = std::sqrt(error);

  /** TEST: Compare the two qualitatively. */
  if (error > distance)
  {
    std::cerr << "ERROR: the ITK implementation differs from our implementation with more than "
              << static_cast<unsigned int>(distance * 100.0) << "%." << std::endl;
    return EXIT_FAILURE;
  }
  std::cerr << std::scientific;
  std::cerr << std::setprecision(4);
  std::cerr << "The distance is: " << error << std::endl;

  /** TEST: Compare the two performance wise. */
  N /= 2;

  /** Time the ITK implementation. */
  startClock = clock();
  for (unsigned int i = 0; i < N; ++i)
  {
    weightFunction3D->Evaluate(cindex3D);
  }
  endClock = clock();
  clockITK = endClock - startClock;
  std::cerr << "The elapsed time for the ITK implementation is: " << clockITK << std::endl;

  /** Time our own implementation, which is essentially the same, but created
   * a little more general, so that higher order derivatives are also easily
   * implemented.
   */
  startClock = clock();
  for (unsigned int i = 0; i < N; ++i)
  {
    weight2Function3D->Evaluate(cindex3D);
  }
  endClock = clock();
  clockOur = endClock - startClock;
  std::cerr << "The elapsed time for our own implementation is: " << clockOur << std::endl;

  /** TEST: Compare the two performance wise. */
  timeDifference = static_cast<double>(clockITK) / static_cast<double>(clockOur);
  std::cerr << std::fixed;
  std::cerr << std::setprecision(1);
  std::cerr << "The time difference is " << (timeDifference - 1.0) * 100.0 << "% in favor of "
            << (timeDifference > 1.0 ? "our " : "the ITK ") << "implementation." << std::endl;
  if (timeDifference < (1.0 - allowedTimeDifference))
  {
    std::cerr << "ERROR: the ITK implementation is more than "
              << static_cast<unsigned int>(allowedTimeDifference * 100.0) << "% faster than our implementation."
              << std::endl;
#if _ELASTIX_TEST_TIMING
    return EXIT_FAILURE;
#endif
  }

  /**
   * *********** Function TESTING ****************************************
   */

  std::cerr << "\n--------------------------------------------------------";
  std::cerr << "\nFunction TESTING:\n" << std::endl;

  /** Just call all available public functions. */
  auto                                   trueStartIndex = WeightFunction2Type2D::IndexType::Filled(-1);
  const WeightFunction2Type2D::IndexType startIndex = WeightFunction2Type2D::ComputeStartIndex(cindex);
  if (startIndex != trueStartIndex)
  {
    std::cerr << "ERROR: wrong start index was computed." << std::endl;
    return EXIT_FAILURE;
  }

  auto trueSize = WeightFunction2Type2D::SizeType::Filled(SplineOrder + 1);
  if (WeightFunction2Type2D::SupportSize != trueSize)
  {
    std::cerr << "ERROR: wrong support size was computed." << std::endl;
    return EXIT_FAILURE;
  }

  if (WeightFunction2Type2D::NumberOfWeights != itk::Math::sqr(SplineOrder + 1))
  {
    std::cerr << "ERROR: wrong number of weights was computed." << std::endl;
    return EXIT_FAILURE;
  }

  std::cerr << "All public functions returned valid output." << std::endl;

  /**
   * *********** PrintSelf TESTING ****************************************
   */

  std::cerr << "\n--------------------------------------------------------";
  std::cerr << "\nPrintSelf() TESTING:\n" << std::endl;

  weightFunction2D->Print(std::cerr, 0);
  std::cerr << "\n--------------------------------------------------------\n";
  weight2Function2D->Print(std::cerr, 0);
  std::cerr << "\n--------------------------------------------------------\n";
  weightFunction3D->Print(std::cerr, 0);
  std::cerr << "\n--------------------------------------------------------\n";
  weight2Function3D->Print(std::cerr, 0);

  /** Return a value. */
  return EXIT_SUCCESS;

} // end main
