/*=========================================================================
 *
 *  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 itkFEMLoadLandmark_h
#define itkFEMLoadLandmark_h

#include "itkFEMLoadElementBase.h"
#include "ITKFEMExport.h"

#include "vnl/vnl_vector.h"

namespace itk
{
namespace fem
{
/**
 * \class LoadLandmark
 * \brief This load is derived from the motion of a specific landmark
 *
 * This load depends on the motion of a point from an undeformed
 * configuration to a deformed configuration.
 * \ingroup ITKFEM
 */
class ITKFEM_EXPORT LoadLandmark : public LoadElement
{
public:
  /** Standard class type aliases. */
  using Self = LoadLandmark;
  using Superclass = LoadElement;
  using Pointer = SmartPointer<Self>;
  using ConstPointer = SmartPointer<const Self>;

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

  /** \see LightObject::GetNameOfClass() */
  itkOverrideGetNameOfClassMacro(LoadLandmark);

  /** CreateAnother method will clone the existing instance of this type,
   * including its internal member variables. */
  itk::LightObject::Pointer
  CreateAnother() const override;

  /**
   * Methods to access the most recent solution vector
   */
  void
  SetSolution(Solution::ConstPointer ptr) override
  {
    m_Solution = ptr;
  }
  Solution::ConstPointer
  GetSolution() override
  {
    return m_Solution;
  }
  Float
  GetSolution(unsigned int i, unsigned int v = 0)
  {
    return m_Solution->GetSolutionValue(i, v);
  }

  /**
   * Access the location of the point load
   */
  Element::VectorType &
  GetPoint()
  {
    return m_Point;
  }

  /**
   * Set the force vector
   */
  void
  SetPoint(const vnl_vector<Float> & pt)
  {
    m_Point = pt;
  }

  /**
   * Access the location of the point load
   */
  Element::VectorType &
  GetSource()
  {
    return m_Source;
  }

  const Element::VectorType &
  GetSource() const
  {
    return m_Source;
  }

  /**
   * Get the force vector
   */
  Element::VectorType &
  GetForce()
  {
    return m_Force;
  }

  const Element::VectorType &
  GetForce() const
  {
    return m_Force;
  }

  /**
   * Set the force vector
   */
  void
  SetForce(const vnl_vector<Float> & force)
  {
    if (m_Force.size() != force.size())
    {
      m_Force.set_size(force.size());
    }
    for (unsigned int i = 0; i < force.size(); ++i)
    {
      m_Force[i] = force[i];
    }
  }

  /**
   * Set the force vector
   */
  void
  SetSource(const vnl_vector<Float> & source)
  {
    if (m_Source.size() != source.size())
    {
      m_Source.set_size(source.size());
    }
    for (unsigned int i = 0; i < source.size(); ++i)
    {
      m_Source[i] = source[i];
    }
  }

  /**
   * Access the location of the point load
   */
  Element::VectorType &
  GetTarget()
  {
    return m_Target;
  }
  const Element::VectorType &
  GetTarget() const
  {
    return m_Target;
  }

  /**
   * Set the force vector
   */
  void
  SetTarget(const vnl_vector<Float> & target)
  {
    if (m_Target.size() != target.size())
    {
      m_Target.set_size(target.size());
    }
    for (unsigned int i = 0; i < target.size(); ++i)
    {
      m_Target[i] = target[i];
    }
  }

  void
  ScalePointAndForce(double * spacing, double fwt)
  {
    for (unsigned int i = 0; i < m_Target.size(); ++i)
    {
      m_Target[i] /= spacing[i];
      m_Source[i] /= spacing[i];
      this->m_Eta *= fwt;
    }
  }

  /**
   * Set the element containing the landmark
   */
  void
  SetContainedElement(const Element * e)
  {
    this->m_Element[0] = e;
  }

  /**
   * Get the element containing the landmark
   */
  const Element *
  GetContainedElement() const
  {
    return this->m_Element[0];
  }

  /**
   * Assign the LoadLandmark to an element
   */
  virtual bool
  AssignToElement(Element::ArrayType::Pointer elements);

  virtual bool
  AssignToElement(Element::ArrayType1::Pointer elements);

  virtual Element::ConstPointer
  GetAssignedElement(Element::ArrayType1::Pointer elements);

  /**
   * Default constructors
   */
  LoadLandmark()
    : m_Target(0)
    , m_Source(0)
    , m_Force(0)
  {}

  /** Get/Set the eta parameter, square root of the variance, for the load */
  void
  SetEta(double e);

  double
  GetEta() const;

  /** Apply the load to the specified element */
  void
  ApplyLoad(Element::ConstPointer element, Element::VectorType & Fe) override;

protected:
  void
  PrintSelf(std::ostream & os, Indent indent) const override;

  /**
   * Square root of the variance (eta)
   */
  double m_Eta{ 0 };

  /**
   * Point in __local coordinates__ in the undeformed configuration
   */
  vnl_vector<Float> m_Point{};

  /**
   * Point in __global coordinates__ in the deformed configuration
   */
  vnl_vector<Float> m_Target{};

  vnl_vector<Float> m_Source{};

  vnl_vector<Float> m_Force{};

  /**
   * Pointer to the element which contains the undeformed
   * configuration of the landmark
   */
  // Element::ConstPointer m_element;

  /**
   * Pointer to the solution object
   */
  Solution::ConstPointer m_Solution{ nullptr };
};

} // namespace fem
} // namespace itk

#endif // itkFEMLoadLandmark_h