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#ifndef PCL_REGISTRATION_IMPL_ELCH_H_
#define PCL_REGISTRATION_IMPL_ELCH_H_

#include <pcl/common/transforms.h>
#include <pcl/registration/registration.h>

#include <boost/graph/dijkstra_shortest_paths.hpp> // for dijkstra_shortest_paths

#include <algorithm>
#include <list>
#include <tuple>

//////////////////////////////////////////////////////////////////////////////////////////////
template <typename PointT>
void
pcl::registration::ELCH<PointT>::loopOptimizerAlgorithm(LOAGraph& g, double* weights)
{
  std::list<int> crossings, branches;
  crossings.push_back(static_cast<int>(loop_start_));
  crossings.push_back(static_cast<int>(loop_end_));
  weights[loop_start_] = 0;
  weights[loop_end_] = 1;

  int* p = new int[num_vertices(g)];
  int* p_min = new int[num_vertices(g)];
  double* d = new double[num_vertices(g)];
  double* d_min = new double[num_vertices(g)];
  bool do_swap = false;
  std::list<int>::iterator start_min, end_min;

  // process all junctions
  while (!crossings.empty()) {
    double dist = -1;
    // find shortest crossing for all vertices on the loop
    for (auto crossings_it = crossings.begin(); crossings_it != crossings.end();) {
      dijkstra_shortest_paths(g,
                              *crossings_it,
                              predecessor_map(boost::make_iterator_property_map(
                                                  p, get(boost::vertex_index, g)))
                                  .distance_map(boost::make_iterator_property_map(
                                      d, get(boost::vertex_index, g))));

      auto end_it = crossings_it;
      end_it++;
      // find shortest crossing for one vertex
      for (; end_it != crossings.end(); end_it++) {
        if (*end_it != p[*end_it] && (dist < 0 || d[*end_it] < dist)) {
          dist = d[*end_it];
          start_min = crossings_it;
          end_min = end_it;
          do_swap = true;
        }
      }
      if (do_swap) {
        std::swap(p, p_min);
        std::swap(d, d_min);
        do_swap = false;
      }
      // vertex starts a branch
      if (dist < 0) {
        branches.push_back(static_cast<int>(*crossings_it));
        crossings_it = crossings.erase(crossings_it);
      }
      else
        crossings_it++;
    }

    if (dist > -1) {
      remove_edge(*end_min, p_min[*end_min], g);
      for (int i = p_min[*end_min]; i != *start_min; i = p_min[i]) {
        // even right with weights[*start_min] > weights[*end_min]! (math works)
        weights[i] = weights[*start_min] + (weights[*end_min] - weights[*start_min]) *
                                               d_min[i] / d_min[*end_min];
        remove_edge(i, p_min[i], g);
        if (degree(i, g) > 0) {
          crossings.push_back(i);
        }
      }

      if (degree(*start_min, g) == 0)
        crossings.erase(start_min);

      if (degree(*end_min, g) == 0)
        crossings.erase(end_min);
    }
  }

  delete[] p;
  delete[] p_min;
  delete[] d;
  delete[] d_min;

  boost::graph_traits<LOAGraph>::adjacency_iterator adjacent_it, adjacent_it_end;

  // error propagation
  while (!branches.empty()) {
    int s = branches.front();
    branches.pop_front();

    for (std::tie(adjacent_it, adjacent_it_end) = adjacent_vertices(s, g);
         adjacent_it != adjacent_it_end;
         ++adjacent_it) {
      weights[*adjacent_it] = weights[s];
      if (degree(*adjacent_it, g) > 1)
        branches.push_back(static_cast<int>(*adjacent_it));
    }
    clear_vertex(s, g);
  }
}

//////////////////////////////////////////////////////////////////////////////////////////////
template <typename PointT>
bool
pcl::registration::ELCH<PointT>::initCompute()
{
  /*if (!PCLBase<PointT>::initCompute ())
  {
    PCL_ERROR ("[pcl::registration:ELCH::initCompute] Init failed.\n");
    return (false);
  }*/ //TODO

  if (loop_end_ == 0) {
    PCL_ERROR("[pcl::registration::ELCH::initCompute] no end of loop defined!\n");
    deinitCompute();
    return (false);
  }

  // compute transformation if it's not given
  if (compute_loop_) {
    PointCloudPtr meta_start(new PointCloud);
    PointCloudPtr meta_end(new PointCloud);
    *meta_start = *(*loop_graph_)[loop_start_].cloud;
    *meta_end = *(*loop_graph_)[loop_end_].cloud;

    typename boost::graph_traits<LoopGraph>::adjacency_iterator si, si_end;
    for (std::tie(si, si_end) = adjacent_vertices(loop_start_, *loop_graph_);
         si != si_end;
         si++)
      *meta_start += *(*loop_graph_)[*si].cloud;

    for (std::tie(si, si_end) = adjacent_vertices(loop_end_, *loop_graph_);
         si != si_end;
         si++)
      *meta_end += *(*loop_graph_)[*si].cloud;

    // TODO use real pose instead of centroid
    // Eigen::Vector4f pose_start;
    // pcl::compute3DCentroid (*(*loop_graph_)[loop_start_].cloud, pose_start);

    // Eigen::Vector4f pose_end;
    // pcl::compute3DCentroid (*(*loop_graph_)[loop_end_].cloud, pose_end);

    PointCloudPtr tmp(new PointCloud);
    // Eigen::Vector4f diff = pose_start - pose_end;
    // Eigen::Translation3f translation (diff.head (3));
    // Eigen::Affine3f trans = translation * Eigen::Quaternionf::Identity ();
    // pcl::transformPointCloud (*(*loop_graph_)[loop_end_].cloud, *tmp, trans);

    reg_->setInputTarget(meta_start);

    reg_->setInputSource(meta_end);

    reg_->align(*tmp);

    loop_transform_ = reg_->getFinalTransformation();
    // TODO hack
    // loop_transform_ *= trans.matrix ();
  }

  return (true);
}

//////////////////////////////////////////////////////////////////////////////////////////////
template <typename PointT>
void
pcl::registration::ELCH<PointT>::compute()
{
  if (!initCompute()) {
    return;
  }

  LOAGraph grb[4];

  typename boost::graph_traits<LoopGraph>::edge_iterator edge_it, edge_it_end;
  for (std::tie(edge_it, edge_it_end) = edges(*loop_graph_); edge_it != edge_it_end;
       edge_it++) {
    for (auto& j : grb)
      add_edge(source(*edge_it, *loop_graph_),
               target(*edge_it, *loop_graph_),
               1,
               j); // TODO add variance
  }

  double* weights[4];
  for (int i = 0; i < 4; i++) {
    weights[i] = new double[num_vertices(*loop_graph_)];
    loopOptimizerAlgorithm(grb[i], weights[i]);
  }

  // TODO use pose
  // Eigen::Vector4f cend;
  // pcl::compute3DCentroid (*((*loop_graph_)[loop_end_].cloud), cend);
  // Eigen::Translation3f tend (cend.head (3));
  // Eigen::Affine3f aend (tend);
  // Eigen::Affine3f aendI = aend.inverse ();

  // TODO iterate ovr loop_graph_
  // typename boost::graph_traits<LoopGraph>::vertex_iterator vertex_it, vertex_it_end;
  // for (std::tie (vertex_it, vertex_it_end) = vertices (*loop_graph_); vertex_it !=
  // vertex_it_end; vertex_it++)
  for (std::size_t i = 0; i < num_vertices(*loop_graph_); i++) {
    Eigen::Vector3f t2;
    t2[0] = loop_transform_(0, 3) * static_cast<float>(weights[0][i]);
    t2[1] = loop_transform_(1, 3) * static_cast<float>(weights[1][i]);
    t2[2] = loop_transform_(2, 3) * static_cast<float>(weights[2][i]);

    Eigen::Affine3f bl(loop_transform_);
    Eigen::Quaternionf q(bl.rotation());
    Eigen::Quaternionf q2;
    q2 = Eigen::Quaternionf::Identity().slerp(static_cast<float>(weights[3][i]), q);

    // TODO use rotation from branch start
    Eigen::Translation3f t3(t2);
    Eigen::Affine3f a(t3 * q2);
    // a = aend * a * aendI;

    pcl::transformPointCloud(*(*loop_graph_)[i].cloud, *(*loop_graph_)[i].cloud, a);
    (*loop_graph_)[i].transform = a;
  }

  add_edge(loop_start_, loop_end_, *loop_graph_);

  deinitCompute();
}

#endif // PCL_REGISTRATION_IMPL_ELCH_H_
