//  (C) Copyright David Abrahams 2000.
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)

#ifndef REVERSE_GRAPH_DWA092300_H_
# define REVERSE_GRAPH_DWA092300_H_

#include <boost/graph/adjacency_iterator.hpp>
#include <boost/graph/properties.hpp>
#include <boost/iterator/transform_iterator.hpp>
#include <boost/tuple/tuple.hpp>
#include <boost/type_traits.hpp>
#include <boost/mpl/if.hpp>

namespace boost {

struct reverse_graph_tag { };

  namespace detail {

    template <typename EdgeDesc>
    class reverse_graph_edge_descriptor {
      public:
      EdgeDesc underlying_descx; // Odd name is because this needs to be public but shouldn't be exposed to users anymore

      private:
      typedef EdgeDesc base_descriptor_type;

      public:
      explicit reverse_graph_edge_descriptor(const EdgeDesc& underlying_descx = EdgeDesc())
        : underlying_descx(underlying_descx) {}

      friend bool operator==(const reverse_graph_edge_descriptor& a, const reverse_graph_edge_descriptor& b) {
        return a.underlying_descx == b.underlying_descx;
      }
      friend bool operator!=(const reverse_graph_edge_descriptor& a, const reverse_graph_edge_descriptor& b) {
        return a.underlying_descx != b.underlying_descx;
      }
      friend bool operator<(const reverse_graph_edge_descriptor& a, const reverse_graph_edge_descriptor& b) {
        return a.underlying_descx < b.underlying_descx;
      }
      friend bool operator>(const reverse_graph_edge_descriptor& a, const reverse_graph_edge_descriptor& b) {
        return a.underlying_descx > b.underlying_descx;
      }
      friend bool operator<=(const reverse_graph_edge_descriptor& a, const reverse_graph_edge_descriptor& b) {
        return a.underlying_descx <= b.underlying_descx;
      }
      friend bool operator>=(const reverse_graph_edge_descriptor& a, const reverse_graph_edge_descriptor& b) {
        return a.underlying_descx >= b.underlying_descx;
      }
    };

    template <typename EdgeDesc>
    struct reverse_graph_edge_descriptor_maker {
      typedef reverse_graph_edge_descriptor<EdgeDesc> result_type;

      reverse_graph_edge_descriptor<EdgeDesc> operator()(const EdgeDesc& ed) const {
        return reverse_graph_edge_descriptor<EdgeDesc>(ed);
      }
    };

    template <typename EdgeDesc, typename Iter>
    std::pair<transform_iterator<reverse_graph_edge_descriptor_maker<EdgeDesc>, Iter>,
              transform_iterator<reverse_graph_edge_descriptor_maker<EdgeDesc>, Iter> >
    reverse_edge_iter_pair(const std::pair<Iter, Iter>& ip) {
      return std::make_pair(make_transform_iterator(ip.first, reverse_graph_edge_descriptor_maker<EdgeDesc>()),
                            make_transform_iterator(ip.second, reverse_graph_edge_descriptor_maker<EdgeDesc>()));
    }

    // Get the underlying descriptor from a vertex or edge descriptor
    template <typename Desc>
    struct get_underlying_descriptor_from_reverse_descriptor {
      typedef Desc type;
      static Desc convert(const Desc& d) {return d;}
    };
    template <typename Desc>
    struct get_underlying_descriptor_from_reverse_descriptor<reverse_graph_edge_descriptor<Desc> > {
      typedef Desc type;
      static Desc convert(const reverse_graph_edge_descriptor<Desc>& d) {return d.underlying_descx;}
    };

    template <bool isEdgeList> struct choose_rev_edge_iter { };
    template <> struct choose_rev_edge_iter<true> {
      template <class G> struct bind_ {
        typedef transform_iterator<reverse_graph_edge_descriptor_maker<typename graph_traits<G>::edge_descriptor>, typename graph_traits<G>::edge_iterator> type;
      };
    };
    template <> struct choose_rev_edge_iter<false> {
      template <class G> struct bind_ {
        typedef void type;
      };
    };

  } // namespace detail

template <class BidirectionalGraph, class GraphRef = const BidirectionalGraph&>
class reverse_graph {
    typedef reverse_graph<BidirectionalGraph, GraphRef> Self;
    typedef graph_traits<BidirectionalGraph> Traits;
 public:
    typedef BidirectionalGraph base_type;
    typedef GraphRef base_ref_type;

    // Constructor
    reverse_graph(GraphRef g) : m_g(g) {}
    // Conversion from reverse_graph on non-const reference to one on const reference
    reverse_graph(const reverse_graph<BidirectionalGraph, BidirectionalGraph&>& o): m_g(o.m_g) {}

    // Graph requirements
    typedef typename Traits::vertex_descriptor vertex_descriptor;
    typedef detail::reverse_graph_edge_descriptor<typename Traits::edge_descriptor> edge_descriptor;
    typedef typename Traits::directed_category directed_category;
    typedef typename Traits::edge_parallel_category edge_parallel_category;
    typedef typename Traits::traversal_category traversal_category;

    // IncidenceGraph requirements
    typedef transform_iterator<detail::reverse_graph_edge_descriptor_maker<typename Traits::edge_descriptor>, typename Traits::in_edge_iterator> out_edge_iterator;
    typedef typename Traits::degree_size_type degree_size_type;

    // BidirectionalGraph requirements
    typedef transform_iterator<detail::reverse_graph_edge_descriptor_maker<typename Traits::edge_descriptor>, typename Traits::out_edge_iterator> in_edge_iterator;

    // AdjacencyGraph requirements
    typedef typename adjacency_iterator_generator<Self, vertex_descriptor, out_edge_iterator>::type adjacency_iterator;

    // VertexListGraph requirements
    typedef typename Traits::vertex_iterator vertex_iterator;

    // EdgeListGraph requirements
    enum { is_edge_list = is_convertible<traversal_category,
           edge_list_graph_tag>::value };
    typedef detail::choose_rev_edge_iter<is_edge_list> ChooseEdgeIter;
    typedef typename ChooseEdgeIter::
      template bind_<BidirectionalGraph>::type   edge_iterator;
    typedef typename Traits::vertices_size_type vertices_size_type;
    typedef typename Traits::edges_size_type edges_size_type;

    typedef reverse_graph_tag graph_tag;

#ifndef BOOST_GRAPH_NO_BUNDLED_PROPERTIES
    // Bundled properties support
    template<typename Descriptor>
    typename graph::detail::bundled_result<
               BidirectionalGraph,
               typename detail::get_underlying_descriptor_from_reverse_descriptor<Descriptor>::type
             >::type&
    operator[](Descriptor x)
    { return m_g[detail::get_underlying_descriptor_from_reverse_descriptor<Descriptor>::convert(x)]; }

    template<typename Descriptor>
    typename graph::detail::bundled_result<
               BidirectionalGraph,
               typename detail::get_underlying_descriptor_from_reverse_descriptor<Descriptor>::type
             >::type const&
    operator[](Descriptor x) const
    { return m_g[detail::get_underlying_descriptor_from_reverse_descriptor<Descriptor>::convert(x)]; }
#endif // BOOST_GRAPH_NO_BUNDLED_PROPERTIES

    static vertex_descriptor null_vertex()
    { return Traits::null_vertex(); }

    // would be private, but template friends aren't portable enough.
 // private:
    GraphRef m_g;
};


// These are separate so they are not instantiated unless used (see bug 1021)
template <class BidirectionalGraph, class GraphRef>
struct vertex_property_type<reverse_graph<BidirectionalGraph, GraphRef> > {
  typedef typename boost::vertex_property_type<BidirectionalGraph>::type type;
};

template <class BidirectionalGraph, class GraphRef>
struct edge_property_type<reverse_graph<BidirectionalGraph, GraphRef> > {
  typedef typename boost::edge_property_type<BidirectionalGraph>::type type;
};

template <class BidirectionalGraph, class GraphRef>
struct graph_property_type<reverse_graph<BidirectionalGraph, GraphRef> > {
  typedef typename boost::graph_property_type<BidirectionalGraph>::type type;
};

#ifndef BOOST_GRAPH_NO_BUNDLED_PROPERTIES
  template<typename Graph, typename GraphRef>
  struct vertex_bundle_type<reverse_graph<Graph, GraphRef> >
    : vertex_bundle_type<Graph> { };

  template<typename Graph, typename GraphRef>
  struct edge_bundle_type<reverse_graph<Graph, GraphRef> >
    : edge_bundle_type<Graph> { };

  template<typename Graph, typename GraphRef>
  struct graph_bundle_type<reverse_graph<Graph, GraphRef> >
    : graph_bundle_type<Graph> { };
#endif // BOOST_GRAPH_NO_BUNDLED_PROPERTIES

template <class BidirectionalGraph>
inline reverse_graph<BidirectionalGraph>
make_reverse_graph(const BidirectionalGraph& g)
{
    return reverse_graph<BidirectionalGraph>(g);
}

template <class BidirectionalGraph>
inline reverse_graph<BidirectionalGraph, BidirectionalGraph&>
make_reverse_graph(BidirectionalGraph& g)
{
    return reverse_graph<BidirectionalGraph, BidirectionalGraph&>(g);
}

template <class BidirectionalGraph, class GRef>
std::pair<typename reverse_graph<BidirectionalGraph>::vertex_iterator,
          typename reverse_graph<BidirectionalGraph>::vertex_iterator>
vertices(const reverse_graph<BidirectionalGraph,GRef>& g)
{
    return vertices(g.m_g);
}

template <class BidirectionalGraph, class GRef>
std::pair<typename reverse_graph<BidirectionalGraph>::edge_iterator,
          typename reverse_graph<BidirectionalGraph>::edge_iterator>
edges(const reverse_graph<BidirectionalGraph,GRef>& g)
{
    return detail::reverse_edge_iter_pair<typename graph_traits<BidirectionalGraph>::edge_descriptor>(edges(g.m_g));
}

template <class BidirectionalGraph, class GRef>
inline std::pair<typename reverse_graph<BidirectionalGraph>::out_edge_iterator,
                 typename reverse_graph<BidirectionalGraph>::out_edge_iterator>
out_edges(const typename graph_traits<BidirectionalGraph>::vertex_descriptor u,
          const reverse_graph<BidirectionalGraph,GRef>& g)
{
    return detail::reverse_edge_iter_pair<typename graph_traits<BidirectionalGraph>::edge_descriptor>(in_edges(u, g.m_g));
}

template <class BidirectionalGraph, class GRef>
inline typename graph_traits<BidirectionalGraph>::vertices_size_type
num_vertices(const reverse_graph<BidirectionalGraph,GRef>& g)
{
    return num_vertices(g.m_g);
}

template <class BidirectionalGraph, class GRef>
inline typename reverse_graph<BidirectionalGraph>::edges_size_type
num_edges(const reverse_graph<BidirectionalGraph,GRef>& g)
{
    return num_edges(g.m_g);
}

template <class BidirectionalGraph, class GRef>
inline typename graph_traits<BidirectionalGraph>::degree_size_type
out_degree(const typename graph_traits<BidirectionalGraph>::vertex_descriptor u,
           const reverse_graph<BidirectionalGraph,GRef>& g)
{
    return in_degree(u, g.m_g);
}

template <class BidirectionalGraph, class GRef>
inline typename graph_traits<BidirectionalGraph>::vertex_descriptor
vertex(const typename graph_traits<BidirectionalGraph>::vertices_size_type v,
       const reverse_graph<BidirectionalGraph,GRef>& g)
{
    return vertex(v, g.m_g);
}

template <class BidirectionalGraph, class GRef>
inline std::pair< typename graph_traits<reverse_graph<BidirectionalGraph,GRef> >::edge_descriptor,
                  bool>
edge(const typename graph_traits<BidirectionalGraph>::vertex_descriptor u,
     const typename graph_traits<BidirectionalGraph>::vertex_descriptor v,
     const reverse_graph<BidirectionalGraph,GRef>& g)
{
    typedef typename graph_traits<BidirectionalGraph>::edge_descriptor underlying_edge_descriptor;
    std::pair<underlying_edge_descriptor, bool> e = edge(v, u, g.m_g);
    return std::make_pair(detail::reverse_graph_edge_descriptor<underlying_edge_descriptor>(e.first), e.second);
}

template <class BidirectionalGraph, class GRef>
inline std::pair<typename reverse_graph<BidirectionalGraph>::in_edge_iterator,
                 typename reverse_graph<BidirectionalGraph>::in_edge_iterator>
in_edges(const typename graph_traits<BidirectionalGraph>::vertex_descriptor u,
         const reverse_graph<BidirectionalGraph,GRef>& g)
{
    return detail::reverse_edge_iter_pair<typename graph_traits<BidirectionalGraph>::edge_descriptor>(out_edges(u, g.m_g));
}

template <class BidirectionalGraph, class GRef>
inline std::pair<typename reverse_graph<BidirectionalGraph,GRef>::adjacency_iterator,
    typename reverse_graph<BidirectionalGraph,GRef>::adjacency_iterator>
adjacent_vertices(typename graph_traits<BidirectionalGraph>::vertex_descriptor u,
                  const reverse_graph<BidirectionalGraph,GRef>& g)
{
    typedef reverse_graph<BidirectionalGraph,GRef> Graph;
    typename graph_traits<Graph>::out_edge_iterator first, last;
    boost::tie(first, last) = out_edges(u, g);
    typedef typename graph_traits<Graph>::adjacency_iterator adjacency_iterator;
    return std::make_pair(adjacency_iterator(first, const_cast<Graph*>(&g)),
                          adjacency_iterator(last, const_cast<Graph*>(&g)));
}

template <class BidirectionalGraph, class GRef>
inline typename graph_traits<BidirectionalGraph>::degree_size_type
in_degree(const typename graph_traits<BidirectionalGraph>::vertex_descriptor u,
          const reverse_graph<BidirectionalGraph,GRef>& g)
{
    return out_degree(u, g.m_g);
}

template <class Edge, class BidirectionalGraph, class GRef>
inline typename graph_traits<BidirectionalGraph>::vertex_descriptor
source(const detail::reverse_graph_edge_descriptor<Edge>& e, const reverse_graph<BidirectionalGraph,GRef>& g)
{
    return target(e.underlying_descx, g.m_g);
}

template <class Edge, class BidirectionalGraph, class GRef>
inline typename graph_traits<BidirectionalGraph>::vertex_descriptor
target(const detail::reverse_graph_edge_descriptor<Edge>& e, const reverse_graph<BidirectionalGraph,GRef>& g)
{
    return source(e.underlying_descx, g.m_g);
}

template <class BidirectionalGraph, class GRef>
inline typename graph_traits<BidirectionalGraph>::degree_size_type
degree(const typename graph_traits<BidirectionalGraph>::vertex_descriptor u,
          const reverse_graph<BidirectionalGraph,GRef>& g)
{
    return degree(u, g.m_g);
}

namespace detail {

  template <typename PM>
  struct reverse_graph_edge_property_map {
    private:
    PM underlying_pm;

    public:
    typedef reverse_graph_edge_descriptor<typename property_traits<PM>::key_type> key_type;
    typedef typename property_traits<PM>::value_type value_type;
    typedef typename property_traits<PM>::reference reference;
    typedef typename property_traits<PM>::category category;

    explicit reverse_graph_edge_property_map(const PM& pm): underlying_pm(pm) {}

    friend reference
    get(const reverse_graph_edge_property_map& m,
        const key_type& e) {
      return get(m.underlying_pm, e.underlying_descx);
    }

    friend void
    put(const reverse_graph_edge_property_map& m,
        const key_type& e,
        const value_type& v) {
      put(m.underlying_pm, e.underlying_descx, v);
    }

    reference operator[](const key_type& k) const {
      return (this->underlying_pm)[k.underlying_descx];
    }
  };

} // namespace detail

template <class BidirGraph, class GRef, class Property>
struct property_map<reverse_graph<BidirGraph, GRef>, Property> {
  typedef boost::is_same<typename detail::property_kind_from_graph<BidirGraph, Property>::type, edge_property_tag> is_edge_prop;
  typedef boost::is_const<typename boost::remove_reference<GRef>::type> is_ref_const;
  typedef typename boost::mpl::if_<
                     is_ref_const,
                     typename property_map<BidirGraph, Property>::const_type,
                     typename property_map<BidirGraph, Property>::type>::type
    orig_type;
  typedef typename property_map<BidirGraph, Property>::const_type orig_const_type;
  typedef typename boost::mpl::if_<is_edge_prop, detail::reverse_graph_edge_property_map<orig_type>, orig_type>::type type;
  typedef typename boost::mpl::if_<is_edge_prop, detail::reverse_graph_edge_property_map<orig_const_type>, orig_const_type>::type const_type;
};

template <class BidirGraph, class GRef, class Property>
struct property_map<const reverse_graph<BidirGraph, GRef>, Property> {
  typedef boost::is_same<typename detail::property_kind_from_graph<BidirGraph, Property>::type, edge_property_tag> is_edge_prop;
  typedef typename property_map<BidirGraph, Property>::const_type orig_const_type;
  typedef typename boost::mpl::if_<is_edge_prop, detail::reverse_graph_edge_property_map<orig_const_type>, orig_const_type>::type const_type;
  typedef const_type type;
};

template <class BidirGraph, class GRef, class Property>
typename disable_if<
  is_same<Property, edge_underlying_t>,
  typename property_map<reverse_graph<BidirGraph,GRef>, Property>::type>::type
get(Property p, reverse_graph<BidirGraph,GRef>& g)
{
  return typename property_map<reverse_graph<BidirGraph,GRef>, Property>::type(get(p, g.m_g));
}

template <class BidirGraph, class GRef, class Property>
typename disable_if<
  is_same<Property, edge_underlying_t>,
  typename property_map<reverse_graph<BidirGraph,GRef>, Property>::const_type>::type
get(Property p, const reverse_graph<BidirGraph,GRef>& g)
{
  const BidirGraph& gref = g.m_g; // in case GRef is non-const
  return typename property_map<reverse_graph<BidirGraph,GRef>, Property>::const_type(get(p, gref));
}

template <class BidirectionalGraph, class GRef, class Property, class Key>
typename disable_if<
  is_same<Property, edge_underlying_t>,
  typename property_traits<
    typename property_map<reverse_graph<BidirectionalGraph, GRef>, Property>::const_type
  >::value_type>::type
get(Property p, const reverse_graph<BidirectionalGraph,GRef>& g, const Key& k)
{
  return get(get(p, g), k);
}

template <class BidirectionalGraph, class GRef, class Property, class Key, class Value>
void
put(Property p, reverse_graph<BidirectionalGraph,GRef>& g, const Key& k,
    const Value& val)
{
  put(get(p, g), k, val);
}

// Get the underlying descriptor from a reverse_graph's wrapped edge descriptor

namespace detail {
  template <class E>
  struct underlying_edge_desc_map_type {
    E operator[](const reverse_graph_edge_descriptor<E>& k) const {
      return k.underlying_descx;
    }
  };

  template <class E>
  E
  get(underlying_edge_desc_map_type<E> m,
      const reverse_graph_edge_descriptor<E>& k)
  {
    return m[k];
  }
}

template <class E>
struct property_traits<detail::underlying_edge_desc_map_type<E> > {
  typedef detail::reverse_graph_edge_descriptor<E> key_type;
  typedef E value_type;
  typedef const E& reference;
  typedef readable_property_map_tag category;
};

template <class Graph, class GRef>
struct property_map<reverse_graph<Graph, GRef>, edge_underlying_t> {
  private:
  typedef typename graph_traits<Graph>::edge_descriptor ed;

  public:
  typedef detail::underlying_edge_desc_map_type<ed> type;
  typedef detail::underlying_edge_desc_map_type<ed> const_type;
};

template <typename T> struct is_reverse_graph: boost::mpl::false_ {};
template <typename G, typename R> struct is_reverse_graph<reverse_graph<G, R> >: boost::mpl::true_ {};

template <class G>
typename enable_if<is_reverse_graph<G>,
  detail::underlying_edge_desc_map_type<typename graph_traits<typename G::base_type>::edge_descriptor> >::type
get(edge_underlying_t,
    G&)
{
  return detail::underlying_edge_desc_map_type<typename graph_traits<typename G::base_type>::edge_descriptor>();
}

template <class G>
typename enable_if<is_reverse_graph<G>, typename graph_traits<typename G::base_type>::edge_descriptor>::type
get(edge_underlying_t,
    G&,
    const typename graph_traits<G>::edge_descriptor& k)
{
  return k.underlying_descx;
}

template <class G>
typename enable_if<is_reverse_graph<G>, detail::underlying_edge_desc_map_type<typename graph_traits<typename G::base_type>::edge_descriptor> >::type
get(edge_underlying_t,
    const G&)
{
  return detail::underlying_edge_desc_map_type<typename graph_traits<typename G::base_type>::edge_descriptor>();
}

template <class G>
typename enable_if<is_reverse_graph<G>, typename graph_traits<typename G::base_type>::edge_descriptor>::type
get(edge_underlying_t,
    const G&,
    const typename graph_traits<G>::edge_descriptor& k)
{
  return k.underlying_descx;
}

// Access to wrapped graph's graph properties

template<typename BidirectionalGraph, typename GRef, typename Tag,
         typename Value>
inline void
set_property(const reverse_graph<BidirectionalGraph,GRef>& g, Tag tag,
             const Value& value)
{
  set_property(g.m_g, tag, value);
}

template<typename BidirectionalGraph, typename GRef, typename Tag>
inline
typename boost::mpl::if_<
           boost::is_const<typename boost::remove_reference<GRef>::type>,
           const typename graph_property<BidirectionalGraph, Tag>::type&,
           typename graph_property<BidirectionalGraph, Tag>::type& >::type
get_property(const reverse_graph<BidirectionalGraph,GRef>& g, Tag tag)
{
  return get_property(g.m_g, tag);
}

} // namespace boost

#endif
