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#ifndef PCL_REGISTRATION_TRANSFORMATION_ESTIMATION_2D_HPP_
#define PCL_REGISTRATION_TRANSFORMATION_ESTIMATION_2D_HPP_

namespace pcl {

namespace registration {

template <typename PointSource, typename PointTarget, typename Scalar>
inline void
TransformationEstimation2D<PointSource, PointTarget, Scalar>::
    estimateRigidTransformation(const pcl::PointCloud<PointSource>& cloud_src,
                                const pcl::PointCloud<PointTarget>& cloud_tgt,
                                Matrix4& transformation_matrix) const
{
  const auto nr_points = cloud_src.size();
  if (cloud_tgt.size() != nr_points) {
    PCL_ERROR("[pcl::TransformationEstimation2D::estimateRigidTransformation] Number "
              "or points in source (%zu) differs than target (%zu)!\n",
              static_cast<std::size_t>(nr_points),
              static_cast<std::size_t>(cloud_tgt.size()));
    return;
  }

  ConstCloudIterator<PointSource> source_it(cloud_src);
  ConstCloudIterator<PointTarget> target_it(cloud_tgt);
  estimateRigidTransformation(source_it, target_it, transformation_matrix);
}

template <typename PointSource, typename PointTarget, typename Scalar>
void
TransformationEstimation2D<PointSource, PointTarget, Scalar>::
    estimateRigidTransformation(const pcl::PointCloud<PointSource>& cloud_src,
                                const pcl::Indices& indices_src,
                                const pcl::PointCloud<PointTarget>& cloud_tgt,
                                Matrix4& transformation_matrix) const
{
  if (indices_src.size() != cloud_tgt.size()) {
    PCL_ERROR("[pcl::Transformation2D::estimateRigidTransformation] Number or points "
              "in source (%zu) differs than target (%zu)!\n",
              indices_src.size(),
              static_cast<std::size_t>(cloud_tgt.size()));
    return;
  }

  ConstCloudIterator<PointSource> source_it(cloud_src, indices_src);
  ConstCloudIterator<PointTarget> target_it(cloud_tgt);
  estimateRigidTransformation(source_it, target_it, transformation_matrix);
}

template <typename PointSource, typename PointTarget, typename Scalar>
inline void
TransformationEstimation2D<PointSource, PointTarget, Scalar>::
    estimateRigidTransformation(const pcl::PointCloud<PointSource>& cloud_src,
                                const pcl::Indices& indices_src,
                                const pcl::PointCloud<PointTarget>& cloud_tgt,
                                const pcl::Indices& indices_tgt,
                                Matrix4& transformation_matrix) const
{
  if (indices_src.size() != indices_tgt.size()) {
    PCL_ERROR("[pcl::TransformationEstimation2D::estimateRigidTransformation] Number "
              "or points in source (%lu) differs than target (%lu)!\n",
              indices_src.size(),
              indices_tgt.size());
    return;
  }

  ConstCloudIterator<PointSource> source_it(cloud_src, indices_src);
  ConstCloudIterator<PointTarget> target_it(cloud_tgt, indices_tgt);
  estimateRigidTransformation(source_it, target_it, transformation_matrix);
}

template <typename PointSource, typename PointTarget, typename Scalar>
void
TransformationEstimation2D<PointSource, PointTarget, Scalar>::
    estimateRigidTransformation(const pcl::PointCloud<PointSource>& cloud_src,
                                const pcl::PointCloud<PointTarget>& cloud_tgt,
                                const pcl::Correspondences& correspondences,
                                Matrix4& transformation_matrix) const
{
  ConstCloudIterator<PointSource> source_it(cloud_src, correspondences, true);
  ConstCloudIterator<PointTarget> target_it(cloud_tgt, correspondences, false);
  estimateRigidTransformation(source_it, target_it, transformation_matrix);
}

template <typename PointSource, typename PointTarget, typename Scalar>
inline void
TransformationEstimation2D<PointSource, PointTarget, Scalar>::
    estimateRigidTransformation(ConstCloudIterator<PointSource>& source_it,
                                ConstCloudIterator<PointTarget>& target_it,
                                Matrix4& transformation_matrix) const
{
  source_it.reset();
  target_it.reset();

  Eigen::Matrix<Scalar, 4, 1> centroid_src, centroid_tgt;
  // Estimate the centroids of source, target
  compute3DCentroid(source_it, centroid_src);
  compute3DCentroid(target_it, centroid_tgt);
  source_it.reset();
  target_it.reset();

  // ignore z component
  centroid_src[2] = 0.0f;
  centroid_tgt[2] = 0.0f;
  // Subtract the centroids from source, target
  Eigen::Matrix<Scalar, Eigen::Dynamic, Eigen::Dynamic> cloud_src_demean,
      cloud_tgt_demean;
  demeanPointCloud(source_it, centroid_src, cloud_src_demean);
  demeanPointCloud(target_it, centroid_tgt, cloud_tgt_demean);

  getTransformationFromCorrelation(cloud_src_demean,
                                   centroid_src,
                                   cloud_tgt_demean,
                                   centroid_tgt,
                                   transformation_matrix);
}

template <typename PointSource, typename PointTarget, typename Scalar>
void
TransformationEstimation2D<PointSource, PointTarget, Scalar>::
    getTransformationFromCorrelation(
        const Eigen::Matrix<Scalar, Eigen::Dynamic, Eigen::Dynamic>& cloud_src_demean,
        const Eigen::Matrix<Scalar, 4, 1>& centroid_src,
        const Eigen::Matrix<Scalar, Eigen::Dynamic, Eigen::Dynamic>& cloud_tgt_demean,
        const Eigen::Matrix<Scalar, 4, 1>& centroid_tgt,
        Matrix4& transformation_matrix) const
{
  transformation_matrix.setIdentity();

  // Assemble the correlation matrix H = source * target'
  Eigen::Matrix<Scalar, 3, 3> H =
      (cloud_src_demean * cloud_tgt_demean.transpose()).topLeftCorner(3, 3);

  float angle = std::atan2((H(0, 1) - H(1, 0)), (H(0, 0) + H(1, 1)));

  Eigen::Matrix<Scalar, 3, 3> R(Eigen::Matrix<Scalar, 3, 3>::Identity());
  R(0, 0) = R(1, 1) = std::cos(angle);
  R(0, 1) = -std::sin(angle);
  R(1, 0) = std::sin(angle);

  // Return the correct transformation
  transformation_matrix.topLeftCorner(3, 3).matrix() = R;
  const Eigen::Matrix<Scalar, 3, 1> Rc(R * centroid_src.head(3).matrix());
  transformation_matrix.block(0, 3, 3, 1).matrix() = centroid_tgt.head(3) - Rc;
}

} // namespace registration
} // namespace pcl

#endif // PCL_REGISTRATION_TRANSFORMATION_ESTIMATION_2D_HPP_
