/*=========================================================================
 *
 *  Copyright Insight Software Consortium
 *
 *  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.
 *
 *=========================================================================*/
#ifndef itkCommandVnlIterationUpdate_h
#define itkCommandVnlIterationUpdate_h

#include "itkCommand.h"
#include "itkWeakPointer.h"

namespace itk {

/**
 *  Implementation of the Command Pattern to be invoked every iteration
 * \class CommandVnlIterationUpdate
 * \ingroup ITKRegistrationCommon
 */
template < typename TOptimizer >
class CommandVnlIterationUpdate : public Command
{
public:
  /**
   * Standard "Self" typedef.
   */
  using Self = CommandVnlIterationUpdate;


  /**
   * Standard "Superclass" typedef.
   */
  using Superclass = itk::Command;


  /**
   * Smart pointer type alias support
   */
  using Pointer = itk::SmartPointer<Self>;

  /**
   * ConstSmart pointer type alias support
   */
  using ConstPointer = itk::SmartPointer<const Self>;

  /**
   * Execute method will print data at each iteration
   */
  void Execute(itk::Object *caller, const itk::EventObject & event) override
  {
    Execute( (const itk::Object *)caller, event);
  }

  void Execute(const itk::Object * itkNotUsed(caller), const itk::EventObject & event) override
  {
    if( typeid( event ) == typeid( itk::StartEvent ) )
      {
      std::cout << std::endl << "Position              Value";
      std::cout << std::endl << std::endl;
      }
    else if( itk::IterationEvent().CheckEvent( &event ) )
      {
      std::cout << m_Optimizer->GetCurrentIteration() << " = ";
      std::cout << m_Optimizer->GetCurrentPosition() << std::endl;
      }
    else if( typeid( event ) == typeid( itk::EndEvent ) )
      {
      std::cout << std::endl << std::endl;
      std::cout << "After " << m_Optimizer->GetCurrentIteration();
      std::cout << "  iterations " << std::endl;
      std::cout << "Solution is    = " << m_Optimizer->GetCurrentPosition();
      std::cout << std::endl;
      std::cout << "vnl report = " << std::endl;
      m_Optimizer->GetOptimizer()->diagnose_outcome( std::cout );
      }

  }


  /**
   * Run-time type information (and related methods).
   */
  itkTypeMacro( CommandVnlIterationUpdate, ::itk::Command );


  /**
   * Method for creation through the object factory.
   */
  itkNewMacro( Self );


  /**
   * Type defining the optimizer
   */
  using OptimizerType = TOptimizer;


  /**
   * Set Optimizer
   */
  void SetOptimizer( OptimizerType * optimizer )
    {
    m_Optimizer = optimizer;
    m_Optimizer->AddObserver( itk::IterationEvent(), this );
    }

protected:

  /**
   * Constructor
   */
  CommandVnlIterationUpdate() = default;

private:

  /**
   *  WeakPointer to the Optimizer
   */
  WeakPointer<OptimizerType>   m_Optimizer;
};


} // end namespace itk


#endif
