#ifndef LEMON_CHRISTOFIDES_TSP_H

#define LEMON_CHRISTOFIDES_TSP_H

#include <lemon/full_graph.h>

#include <lemon/smart_graph.h>

#include <lemon/path.h>

#include <lemon/kruskal.h>

#include <lemon/matching.h>

#include <lemon/adaptors.h>

#include <lemon/maps.h>

#include <lemon/euler.h>

namespace lemon {

  namespace christofides_helper {

    template <class L>

    L vectorConvert(const std::vector<FullGraph::Node> &_path) {

      return L(_path.begin(), _path.end());

    }

    template <>

    std::vector<FullGraph::Node> vectorConvert(const std::vector<FullGraph::Node> &_path) {

      return _path;

    }

  }

  template <typename CM>

  class ChristofidesTsp {

    private:

      GRAPH_TYPEDEFS(SmartGraph);

    public:

      typedef typename CM::Value Cost;

      typedef SmartGraph::EdgeMap<Cost> CostMap;

      ChristofidesTsp(const FullGraph &gr, const CM &cost) : _cost(_gr), fullg(gr), fullcost(cost), nr(_gr) {

        graphCopy(gr, _gr).nodeCrossRef(nr).edgeMap(cost, _cost).run();

      }

      Cost run() {

        _path.clear();

        SmartGraph::EdgeMap<bool> tree(_gr);

        kruskal(_gr, _cost, tree);

        FilterEdges<SmartGraph> treefiltered(_gr, tree);

        InDegMap<FilterEdges<SmartGraph> > deg(treefiltered);

        SmartGraph::NodeMap<bool> oddfilter(_gr, false);

        FilterNodes<SmartGraph> oddNodes(_gr, oddfilter);

        for (NodeIt n(_gr); n!=INVALID; ++n) {

          if (deg[n]%2 == 1) {

            oddNodes.enable(n);

          }

        }

        NegMap<CostMap> negmap(_cost);

        MaxWeightedPerfectMatching<FilterNodes<SmartGraph>,

                  NegMap<CostMap> > perfmatch(oddNodes, negmap);

        perfmatch.run();

        for (FilterNodes<SmartGraph>::EdgeIt e(oddNodes); e!=INVALID; ++e) {

          if (perfmatch.matching(e)) {

            treefiltered.enable(_gr.addEdge(_gr.u(e), _gr.v(e)));

          }

        }

        FilterEdges<SmartGraph>::NodeMap<bool> seen(treefiltered, false);

        for (EulerIt<FilterEdges<SmartGraph> > e(treefiltered); e!=INVALID; ++e) {

          if (seen[treefiltered.target(e)]==false) {

            _path.push_back(nr[treefiltered.target(e)]);

            seen[treefiltered.target(e)] = true;

          }

        }

        _sum = fullcost[ fullg.edge(_path.back(), _path.front()) ];

        for (unsigned int i=0; i<_path.size()-1; ++i)

          _sum += fullcost[ fullg.edge(_path[i], _path[i+1]) ];

        return _sum;

      }

      template <typename L>

      void tourNodes(L &container) {

        container(christofides_helper::vectorConvert<L>(_path));

      }

      template <template <typename> class L>

      L<FullGraph::Node> tourNodes() {

        return christofides_helper::vectorConvert<L<FullGraph::Node> >(_path);

      }

      const std::vector<Node>& tourNodes() {

        return _path;

      }

      Path<FullGraph> tour() {

        Path<FullGraph> p;

        if (_path.size()<2)

          return p;

        for (unsigned int i=0; i<_path.size()-1; ++i) {

          p.addBack(fullg.arc(_path[i], _path[i+1]));

        }

        p.addBack(fullg.arc(_path.back(), _path.front()));

        return p;

      }

      Cost tourCost() {

        return _sum;

      }

  private:

    SmartGraph _gr;

    CostMap _cost;

    Cost _sum;

    const FullGraph &fullg;

    const CM &fullcost;

    std::vector<FullGraph::Node> _path;

    SmartGraph::NodeMap<FullGraph::Node> nr;

  };

}; // namespace lemon

#endif