/*=========================================================================
 *
 *  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 "itkMultipleValuedNonLinearVnlOptimizer.h"

namespace itk
{
/**
 * Constructor
 */
MultipleValuedNonLinearVnlOptimizer::MultipleValuedNonLinearVnlOptimizer()
  : m_CostFunctionAdaptor(nullptr)
  , m_UseGradient(true)
{
  m_Command = CommandType::New();
  m_Command->SetCallbackFunction(this, &MultipleValuedNonLinearVnlOptimizer::IterationReport);
  m_CachedValue.Fill(0);
  m_CachedCurrentPosition.Fill(0);
  m_CachedDerivative.Fill(0);
}

/**
 * Destructor
 */
MultipleValuedNonLinearVnlOptimizer::~MultipleValuedNonLinearVnlOptimizer() = default;

void
MultipleValuedNonLinearVnlOptimizer::SetCostFunctionAdaptor(CostFunctionAdaptorType * adaptor)
{
  if (m_CostFunctionAdaptor.get() == adaptor)
  {
    return;
  }

  m_CostFunctionAdaptor.reset(adaptor);

  this->SetUseCostFunctionGradient(m_UseGradient);

  m_CostFunctionAdaptor->AddObserver(IterationEvent(), m_Command);
}

const MultipleValuedNonLinearVnlOptimizer::CostFunctionAdaptorType *
MultipleValuedNonLinearVnlOptimizer::GetCostFunctionAdaptor() const
{
  return m_CostFunctionAdaptor.get();
}

MultipleValuedNonLinearVnlOptimizer::CostFunctionAdaptorType *
MultipleValuedNonLinearVnlOptimizer::GetCostFunctionAdaptor()
{
  return m_CostFunctionAdaptor.get();
}

/** The purpose of this method is to get around the lack of const
 * correctness in vnl cost_functions and optimizers */
MultipleValuedNonLinearVnlOptimizer::CostFunctionAdaptorType *
MultipleValuedNonLinearVnlOptimizer::GetNonConstCostFunctionAdaptor() const
{
  return m_CostFunctionAdaptor.get();
}

void
MultipleValuedNonLinearVnlOptimizer::SetUseCostFunctionGradient(bool useGradient)
{
  if (m_CostFunctionAdaptor)
  {
    m_CostFunctionAdaptor->SetUseGradient(useGradient);
  }
  else
  {
    m_UseGradient = useGradient;
  }
}

bool
MultipleValuedNonLinearVnlOptimizer::GetUseCostFunctionGradient() const
{
  if (m_CostFunctionAdaptor)
  {
    return m_CostFunctionAdaptor->GetUseGradient();
  }

  return m_UseGradient;
}

/** The purpose of this method is to get around the lack of iteration reporting
 * in VNL optimizers. By interfacing directly with the ITK cost function
 * adaptor we are generating here Iteration Events. Note the iteration events
 * here are produce PER EVALUATION of the metric, not per real iteration of the
 * vnl optimizer. Optimizers that evaluate the metric multiple times at each
 * iteration will generate a lot more of Iteration events here. */
void
MultipleValuedNonLinearVnlOptimizer::IterationReport(const EventObject & event)
{
  const CostFunctionAdaptorType * adaptor = this->GetCostFunctionAdaptor();

  m_CachedValue = adaptor->GetCachedValue();
  m_CachedDerivative = adaptor->GetCachedDerivative();
  m_CachedCurrentPosition = adaptor->GetCachedCurrentParameters();
  this->InvokeEvent(event);
}

/**
 * PrintSelf
 */
void
MultipleValuedNonLinearVnlOptimizer::PrintSelf(std::ostream & os, Indent indent) const
{
  Superclass::PrintSelf(os, indent);
  os << indent << "Cached Value: " << m_CachedValue << std::endl;
  os << indent << "Cached Derivative: " << m_CachedDerivative << std::endl;
  os << indent << "Cached current positiion: " << m_CachedCurrentPosition << std::endl;
  os << indent << "Command observer " << m_Command.GetPointer() << std::endl;
  os << indent << "Cost Function adaptor" << m_CostFunctionAdaptor.get() << std::endl;
}
} // end namespace itk
