/*=========================================================================
 *
 *  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.
 *
 *=========================================================================*/
#ifndef itkImageToImageMetricv4GetValueAndDerivativeThreaderBase_hxx
#define itkImageToImageMetricv4GetValueAndDerivativeThreaderBase_hxx

#include "itkNumericTraits.h"
#include "itkMakeUniqueForOverwrite.h"

namespace itk
{

template <typename TDomainPartitioner, typename TImageToImageMetricv4>
ImageToImageMetricv4GetValueAndDerivativeThreaderBase<TDomainPartitioner, TImageToImageMetricv4>::
  ImageToImageMetricv4GetValueAndDerivativeThreaderBase()
  : m_GetValueAndDerivativePerThreadVariables(nullptr)
  , m_CachedNumberOfParameters(0)
  , m_CachedNumberOfLocalParameters(0)
{}

template <typename TDomainPartitioner, typename TImageToImageMetricv4>
void
ImageToImageMetricv4GetValueAndDerivativeThreaderBase<TDomainPartitioner,
                                                      TImageToImageMetricv4>::BeforeThreadedExecution()
{
  //---------------------------------------------------------------
  // Resize the per thread memory objects.
  //-----------------------------------------------------------------
  // Cache some values
  this->m_CachedNumberOfParameters = this->m_Associate->GetNumberOfParameters();
  this->m_CachedNumberOfLocalParameters = this->m_Associate->GetNumberOfLocalParameters();

  /* Per-thread results */
  const ThreadIdType numWorkUnitsUsed = this->GetNumberOfWorkUnitsUsed();
  this->m_GetValueAndDerivativePerThreadVariables =
    make_unique_for_overwrite<AlignedGetValueAndDerivativePerThreadStruct[]>(numWorkUnitsUsed);

  if (this->m_Associate->GetComputeDerivative())
  {
    for (ThreadIdType i = 0; i < numWorkUnitsUsed; ++i)
    {
      /* Allocate intermediary per-thread storage used to get results from
       * derived classes */
      this->m_GetValueAndDerivativePerThreadVariables[i].LocalDerivatives.SetSize(
        this->m_CachedNumberOfLocalParameters);
      this->m_GetValueAndDerivativePerThreadVariables[i].MovingTransformJacobian.SetSize(
        this->m_Associate->VirtualImageDimension, this->m_CachedNumberOfLocalParameters);
      // Not pre-allocated since it may not be used
      // this->m_GetValueAndDerivativePerThreadVariables[i].MovingTransformJacobianPositional
      if (this->m_Associate->m_MovingTransform->GetTransformCategory() ==
          MovingTransformType::TransformCategoryEnum::DisplacementField)
      {
        /* For transforms with local support, e.g. displacement field,
         * use a single derivative container that's updated by region
         * in multiple threads.
         * Initialization to zero is done in main class. */
        itkDebugMacro("ImageToImageMetricv4::Initialize: transform HAS local support\n");
        /* Set each per-thread object to point to m_DerivativeResult for efficiency. */
        this->m_GetValueAndDerivativePerThreadVariables[i].Derivatives.SetData(
          this->m_Associate->m_DerivativeResult->data_block(), this->m_Associate->m_DerivativeResult->Size(), false);
      }
      else
      {
        itkDebugMacro("ImageToImageMetricv4::Initialize: transform does NOT have local support\n");
        /* This size always comes from the moving image */
        const NumberOfParametersType globalDerivativeSize = this->m_CachedNumberOfParameters;
        /* Global transforms get a separate derivatives container for each thread
         * that holds the result over a particular image region.
         * Use a CompensatedSummation value to provide for better consistency between
         * different number of threads. */
        this->m_GetValueAndDerivativePerThreadVariables[i].CompensatedDerivatives.resize(globalDerivativeSize);
      }
    }
  }

  //---------------------------------------------------------------
  // Set initial values.
  for (ThreadIdType workUnit = 0; workUnit < numWorkUnitsUsed; ++workUnit)
  {
    this->m_GetValueAndDerivativePerThreadVariables[workUnit].NumberOfValidPoints = SizeValueType{};
    this->m_GetValueAndDerivativePerThreadVariables[workUnit].Measure = InternalComputationValueType{};
    if (this->m_Associate->GetComputeDerivative())
    {
      if (this->m_Associate->m_MovingTransform->GetTransformCategory() !=
          MovingTransformType::TransformCategoryEnum::DisplacementField)
      {
        /* Be sure to init to 0 here, because the threader may not use
         * all the threads if the region is better split into fewer
         * subregions. */
        for (NumberOfParametersType p = 0; p < this->m_CachedNumberOfParameters; ++p)
        {
          this->m_GetValueAndDerivativePerThreadVariables[workUnit].CompensatedDerivatives[p].ResetToZero();
        }
      }
    }
  }
}

template <typename TDomainPartitioner, typename TImageToImageMetricv4>
void
ImageToImageMetricv4GetValueAndDerivativeThreaderBase<TDomainPartitioner,
                                                      TImageToImageMetricv4>::AfterThreadedExecution()
{
  const ThreadIdType numWorkUnitsUsed = this->GetNumberOfWorkUnitsUsed();
  /* Store the number of valid points the enclosing class \c
   * m_NumberOfValidPoints by collecting the valid points per thread. */
  this->m_Associate->m_NumberOfValidPoints = SizeValueType{};
  for (ThreadIdType i = 0; i < numWorkUnitsUsed; ++i)
  {
    this->m_Associate->m_NumberOfValidPoints += this->m_GetValueAndDerivativePerThreadVariables[i].NumberOfValidPoints;
  }
  itkDebugMacro("ImageToImageMetricv4: NumberOfValidPoints: " << this->m_Associate->m_NumberOfValidPoints);

  /* For global transforms, sum the derivatives from each region. */
  if (this->m_Associate->GetComputeDerivative())
  {
    if (this->m_Associate->m_MovingTransform->GetTransformCategory() !=
        MovingTransformType::TransformCategoryEnum::DisplacementField)
    {
      for (NumberOfParametersType p = 0; p < this->m_Associate->GetNumberOfParameters(); ++p)
      {
        /* Use a compensated sum to be ready for when there is a very large number of threads */
        CompensatedDerivativeValueType sum;
        sum.ResetToZero();
        for (ThreadIdType i = 0; i < numWorkUnitsUsed; ++i)
        {
          sum += this->m_GetValueAndDerivativePerThreadVariables[i].CompensatedDerivatives[p].GetSum();
        }
        (*(this->m_Associate->m_DerivativeResult))[p] += sum.GetSum();
      }
    }
  }

  /* Check the number of valid points. If there aren't enough,
   * m_Value and m_DerivativeResult will get appropriate values assigned,
   * and a warning will be output. */
  if (this->m_Associate->VerifyNumberOfValidPoints(this->m_Associate->m_Value,
                                                   *(this->m_Associate->m_DerivativeResult)))
  {
    this->m_Associate->m_Value = MeasureType{};
    /* Accumulate the metric value from threads and store the average. */
    for (ThreadIdType threadId = 0; threadId < numWorkUnitsUsed; ++threadId)
    {
      this->m_Associate->m_Value += this->m_GetValueAndDerivativePerThreadVariables[threadId].Measure;
    }
    this->m_Associate->m_Value /= this->m_Associate->m_NumberOfValidPoints;

    /* For global transforms, calculate the average values */
    if (this->m_Associate->GetComputeDerivative())
    {
      if (this->m_Associate->m_MovingTransform->GetTransformCategory() !=
          MovingTransformType::TransformCategoryEnum::DisplacementField)
      {
        *(this->m_Associate->m_DerivativeResult) /= this->m_Associate->m_NumberOfValidPoints;
      }
    }
  }
}

template <typename TDomainPartitioner, typename TImageToImageMetricv4>
bool
ImageToImageMetricv4GetValueAndDerivativeThreaderBase<TDomainPartitioner, TImageToImageMetricv4>::ProcessVirtualPoint(
  const VirtualIndexType & virtualIndex,
  const VirtualPointType & virtualPoint,
  const ThreadIdType       threadId)
{
  FixedImagePointType     mappedFixedPoint;
  FixedImagePixelType     mappedFixedPixelValue;
  FixedImageGradientType  mappedFixedImageGradient;
  MovingImagePointType    mappedMovingPoint;
  MovingImagePixelType    mappedMovingPixelValue;
  MovingImageGradientType mappedMovingImageGradient;
  bool                    pointIsValid = false;
  MeasureType             metricValueResult;

  /* Transform the point into fixed and moving spaces, and evaluate.
   * Do this in a try block to catch exceptions and print more useful info
   * then we otherwise get when exceptions are caught in MultiThreaderBase. */
  try
  {
    pointIsValid =
      this->m_Associate->TransformAndEvaluateFixedPoint(virtualPoint, mappedFixedPoint, mappedFixedPixelValue);
    if (pointIsValid && this->m_Associate->GetComputeDerivative() &&
        this->m_Associate->GetGradientSourceIncludesFixed())
    {
      this->m_Associate->ComputeFixedImageGradientAtPoint(mappedFixedPoint, mappedFixedImageGradient);
    }
  }
  catch (const ExceptionObject & exc)
  {
    // NOTE: there must be a cleaner way to do this:
    std::string msg("Caught exception: \n");
    msg += exc.what();
    ExceptionObject err(__FILE__, __LINE__, msg);
    throw err;
  }
  if (!pointIsValid)
  {
    return pointIsValid;
  }

  try
  {
    pointIsValid =
      this->m_Associate->TransformAndEvaluateMovingPoint(virtualPoint, mappedMovingPoint, mappedMovingPixelValue);
    if (pointIsValid && this->m_Associate->GetComputeDerivative() &&
        this->m_Associate->GetGradientSourceIncludesMoving())
    {
      this->m_Associate->ComputeMovingImageGradientAtPoint(mappedMovingPoint, mappedMovingImageGradient);
    }
  }
  catch (const ExceptionObject & exc)
  {
    std::string msg("Caught exception: \n");
    msg += exc.what();
    ExceptionObject err(__FILE__, __LINE__, msg);
    throw err;
  }
  if (!pointIsValid)
  {
    return pointIsValid;
  }

  /* Call the user method in derived classes to do the specific
   * calculations for value and derivative. */
  try
  {
    pointIsValid = this->ProcessPoint(virtualIndex,
                                      virtualPoint,
                                      mappedFixedPoint,
                                      mappedFixedPixelValue,
                                      mappedFixedImageGradient,
                                      mappedMovingPoint,
                                      mappedMovingPixelValue,
                                      mappedMovingImageGradient,
                                      metricValueResult,
                                      this->m_GetValueAndDerivativePerThreadVariables[threadId].LocalDerivatives,
                                      threadId);
  }
  catch (const ExceptionObject & exc)
  {
    // NOTE: there must be a cleaner way to do this:
    std::string msg("Exception in GetValueAndDerivativeProcessPoint:\n");
    msg += exc.what();
    ExceptionObject err(__FILE__, __LINE__, msg);
    throw err;
  }
  if (pointIsValid)
  {
    this->m_GetValueAndDerivativePerThreadVariables[threadId].NumberOfValidPoints++;
    this->m_GetValueAndDerivativePerThreadVariables[threadId].Measure += metricValueResult;
    if (this->m_Associate->GetComputeDerivative())
    {
      this->StorePointDerivativeResult(virtualIndex, threadId);
    }
  }

  return pointIsValid;
}

template <typename TDomainPartitioner, typename TImageToImageMetricv4>
void
ImageToImageMetricv4GetValueAndDerivativeThreaderBase<TDomainPartitioner, TImageToImageMetricv4>::
  StorePointDerivativeResult(const VirtualIndexType & virtualIndex, const ThreadIdType threadId)
{
  if (this->m_Associate->m_MovingTransform->GetTransformCategory() !=
      MovingTransformType::TransformCategoryEnum::DisplacementField)
  {
    /* Global support */
    if (this->m_Associate->GetUseFloatingPointCorrection())
    {
      DerivativeValueType correctionResolution = this->m_Associate->GetFloatingPointCorrectionResolution();
      for (NumberOfParametersType p = 0; p < this->m_CachedNumberOfParameters; ++p)
      {
        auto test = static_cast<intmax_t>(
          this->m_GetValueAndDerivativePerThreadVariables[threadId].LocalDerivatives[p] * correctionResolution);
        this->m_GetValueAndDerivativePerThreadVariables[threadId].LocalDerivatives[p] =
          static_cast<DerivativeValueType>(test / correctionResolution);
      }
    }
    for (NumberOfParametersType p = 0; p < this->m_CachedNumberOfParameters; ++p)
    {
      this->m_GetValueAndDerivativePerThreadVariables[threadId].CompensatedDerivatives[p] +=
        this->m_GetValueAndDerivativePerThreadVariables[threadId].LocalDerivatives[p];
    }
  }
  else
  {
    // Update derivative at some index
    // this requires the moving image displacement field to be
    // same size as virtual image, and that VirtualImage PixelType
    // is scalar (which is verified during Metric initialization).
    try
    {
      OffsetValueType offset =
        this->m_Associate->ComputeParameterOffsetFromVirtualIndex(virtualIndex, this->m_CachedNumberOfLocalParameters);
      for (NumberOfParametersType i = 0; i < this->m_CachedNumberOfLocalParameters; ++i)
      {
        /* Be sure to *add* here and not assign. Required for proper behavior
         * with multi-variate metric. */
        this->m_GetValueAndDerivativePerThreadVariables[threadId].Derivatives[offset + i] +=
          this->m_GetValueAndDerivativePerThreadVariables[threadId].LocalDerivatives[i];
      }
    }
    catch (const ExceptionObject & exc)
    {
      std::string msg("Caught exception: \n");
      msg += exc.what();
      ExceptionObject err(__FILE__, __LINE__, msg);
      throw err;
    }
  }
}

template <typename TDomainPartitioner, typename TImageToImageMetricv4>
bool
ImageToImageMetricv4GetValueAndDerivativeThreaderBase<TDomainPartitioner, TImageToImageMetricv4>::GetComputeDerivative()
  const
{
  return this->m_Associate->GetComputeDerivative();
}

} // end namespace itk

#endif
