/*=========================================================================
 *
 * 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 itkFEMElement3DC0LinearTriangularLaplaceBeltrami_h
#define itkFEMElement3DC0LinearTriangularLaplaceBeltrami_h

#include "itkFEMElement3DC0LinearTriangular.h"
#include "itkFEMElement3DMembrane.h"
#include "itkFEMElement3DMembrane1DOF.h"
#include "ITKFEMExport.h"

namespace itk
{
namespace fem
{
/**
 * \class Element3DC0LinearTriangularLaplaceBeltrami
 * \brief 3-noded finite element class in 3D space for surface LaplaceBeltrami problem.
 *
 * * This class combines the geometry of the FE problem defined in
 * \link Element3DC0LinearTriangular\endlink
 * and the physics of the problem defined in
 * \link Element3DMembrane1DOF\endlink
 *
 * \ingroup ITKFEM
 */
class ITKFEM_EXPORT Element3DC0LinearTriangularLaplaceBeltrami
  : public Element3DMembrane1DOF<Element3DC0LinearTriangular>
{
public:
  /** Standard class type aliases. */
  using Self = Element3DC0LinearTriangularLaplaceBeltrami;
  using Superclass = Element3DMembrane1DOF<Element3DC0LinearTriangular>;
  using Pointer = SmartPointer<Self>;
  using ConstPointer = SmartPointer<const Self>;

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

  /** \see LightObject::GetNameOfClass() */
  itkOverrideGetNameOfClassMacro(Element3DC0LinearTriangularLaplaceBeltrami);

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

  /**
   * Default constructor only clears the internal storage
   */
  Element3DC0LinearTriangularLaplaceBeltrami();

  /**
   * Construct an element by specifying pointers to
   * 3 points and a material.
   */
  Element3DC0LinearTriangularLaplaceBeltrami(NodeIDType n1_, NodeIDType n2_, NodeIDType n3_, Material::ConstPointer p_);

  /** Get the degrees of freedom for each node */
  unsigned int
  GetNumberOfDegreesOfFreedomPerNode() const override
  {
    return 1;
  }

  /** Get the Stiffness matrix */
  void
  GetStiffnessMatrix(MatrixType & Ke) const override;

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

}; // class Element3DC0LinearTriangularLaplaceBeltrami
} // end namespace fem
} // end namespace itk

#endif // itkFEMElement3DC0LinearTriangularLaplaceBeltrami_h