/*=========================================================================
 *
 *  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 itkFEMElement3DStrain_hxx
#define itkFEMElement3DStrain_hxx


namespace itk
{
namespace fem
{
template <typename TBaseClass>
Element3DStrain<TBaseClass>::Element3DStrain()
  : Superclass()
{}

// ////////////////////////////////////////////////////////////////////////
/**
 * Methods related to the physics of the problem.
 */

template <typename TBaseClass>
void
Element3DStrain<TBaseClass>::GetStrainDisplacementMatrix(MatrixType & B, const MatrixType & shapeDgl) const
{
  unsigned int p;
  unsigned int Nn = 3 * this->GetNumberOfNodes();

  B.set_size(6, Nn);

  // Initialize the B matrix to zero - subsequently, only the nonzero
  // terms will be filled in
  B.fill(0.0);

  // Copy the shape function derivatives wrt global coordinates
  // in right position in B matrix.
  for (unsigned int i = 0; i < Nn; ++i)
  {
    p = i / 3;

    switch (i % 3)
    {
        // case 0:  /** Columns 1, 4, 7, ..., 22 */
        //   B[0][i] = shapeDgl[0][p];
        //   B[3][i] = shapeDgl[1][p];
        //   B[5][i] = shapeDgl[2][p];
        //   break;

        // case 1:  /** Columns 2, 5, 8, ..., 23 */
        //   B[1][i] = shapeDgl[1][p];
        //   B[3][i] = shapeDgl[0][p];
        //   B[4][i] = shapeDgl[2][p];
        //   break;

        // case 2:  /** Columns 3, 6, 9, ..., 24 */
        //   B[2][i] = shapeDgl[2][p];
        //   B[4][i] = shapeDgl[1][p];
        //   B[5][i] = shapeDgl[0][p];
        //   break;

      case 0: /** Columns 1, 4, 7, ..., 22 */
        B[0][i] = shapeDgl[0][p];
        B[4][i] = shapeDgl[2][p];
        B[5][i] = shapeDgl[1][p];
        break;

      case 1: /** Columns 2, 5, 8, ..., 23 */
        B[1][i] = shapeDgl[1][p];
        B[3][i] = shapeDgl[2][p];
        B[5][i] = shapeDgl[0][p];
        break;

      case 2: /** Columns 3, 6, 9, ..., 24 */
        B[2][i] = shapeDgl[2][p];
        B[3][i] = shapeDgl[1][p];
        B[4][i] = shapeDgl[0][p];
        break;
    }
  }
}

template <typename TBaseClass>
void
Element3DStrain<TBaseClass>::GetMaterialMatrix(MatrixType & D) const
{
  D.set_size(6, 6);
  D.fill(0.0);

  /* Material properties matrix */
  Float fac = (m_mat->GetThickness() * m_mat->GetYoungsModulus()) /
              ((1 + m_mat->GetPoissonsRatio()) * (1 - 2 * m_mat->GetPoissonsRatio()));
  /** Set the elements in the top left quadrant */
  for (int j = 0; j < 3; ++j)
  {
    for (int k = 0; k < 3; ++k)
    {
      D[j][k] = m_mat->GetPoissonsRatio();
    }
  }
  /** Set the diagonal elements */
  for (int k = 0; k < 3; ++k)
  {
    D[k][k] = 1 - m_mat->GetPoissonsRatio();
  }
  for (int k = 3; k < 6; ++k)
  {
    D[k][k] = (1 - (2 * m_mat->GetPoissonsRatio())) * 0.5;
  }

  /** Multiply by the factor */
  D = D * fac;
}

template <typename TBaseClass>
void
Element3DStrain<TBaseClass>::PrintSelf(std::ostream & os, Indent indent) const
{
  Superclass::PrintSelf(os, indent);
  os << indent << "Materials: " << this->m_mat << std::endl;
}

} // end namespace fem
} // end namespace itk

#endif