//=======================================================================
// Copyright 1997, 1998, 1999, 2000 University of Notre Dame.
// Copyright 2006 The Trustees of Indiana University.
// Copyright (C) 2001 Vladimir Prus <ghost@cs.msu.su>
// Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek, Douglas Gregor
//
// 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)
//=======================================================================

// The mutating functions (add_edge, etc.) were added by Vladimir Prus.

#ifndef BOOST_VECTOR_AS_GRAPH_HPP
#define BOOST_VECTOR_AS_GRAPH_HPP

#include <cassert>
#include <utility>
#include <vector>
#include <cstddef>
#include <boost/iterator.hpp>
#include <boost/iterator/counting_iterator.hpp>
#include <boost/range/irange.hpp>
#include <boost/graph/graph_traits.hpp>
#include <boost/property_map/property_map.hpp>
#include <boost/graph/properties.hpp>
#include <algorithm>

/*
  This module implements the VertexListGraph concept using a
  std::vector as the "back-bone" of the graph (the vector *is* the
  graph object). The edge-lists type of the graph is templated, so the
  user can choose any STL container, so long as the value_type of the
  container is convertible to the size_type of the vector. For now any
  graph properties must be stored seperately.

  This module requires the C++ compiler to support partial
  specialization for the graph_traits class, so this is not portable
  to VC++.

*/


namespace boost {
  namespace detail {
    template <class EdgeList> struct val_out_edge_ret;
    template <class EdgeList> struct val_out_edge_iter;
    template <class EdgeList> struct val_edge;
  }
}

namespace boost {

  struct vector_as_graph_traversal_tag
    : public vertex_list_graph_tag,
      public adjacency_graph_tag,
      public incidence_graph_tag { };

  template <class EdgeList>
  struct graph_traits< std::vector<EdgeList> >
  {
    typedef typename EdgeList::value_type V;
    typedef V vertex_descriptor;
    typedef typename detail::val_edge<EdgeList>::type edge_descriptor;
    typedef typename EdgeList::const_iterator adjacency_iterator;
    typedef typename detail::val_out_edge_iter<EdgeList>::type
      out_edge_iterator;
    typedef void in_edge_iterator;
    typedef void edge_iterator;
    typedef counting_iterator<V> vertex_iterator;
    typedef directed_tag directed_category;
    typedef allow_parallel_edge_tag edge_parallel_category;
    typedef vector_as_graph_traversal_tag traversal_category;
    typedef typename std::vector<EdgeList>::size_type vertices_size_type;
    typedef void edges_size_type;
    typedef typename EdgeList::size_type degree_size_type;
    static V null_vertex() {return V(-1);}
  };
  template <class EdgeList>
  struct edge_property_type< std::vector<EdgeList> >
  {
    typedef void type;
  };
  template <class EdgeList>
  struct vertex_property_type< std::vector<EdgeList> >
  {
    typedef void type;
  };
  template <class EdgeList>
  struct graph_property_type< std::vector<EdgeList> >
  {
    typedef void type;
  };
}

namespace boost {

  namespace detail {

    // "val" is short for Vector Adjacency List

    template <class EdgeList>
    struct val_edge
    {
      typedef typename EdgeList::value_type V;
      typedef std::pair<V,V> type;
    };

    // need rewrite this using boost::iterator_adaptor
    template <class V, class Iter>
    class val_out_edge_iterator
      : public boost::iterator<std::input_iterator_tag, std::pair<V,V>,
         std::ptrdiff_t, std::pair<V,V>*, const std::pair<V,V> >
    {
      typedef val_out_edge_iterator self;
      typedef std::pair<V,V> Edge;
    public:
      val_out_edge_iterator() { }
      val_out_edge_iterator(V s, Iter i) : _source(s), _iter(i) { }
      Edge operator*() const { return Edge(_source, *_iter); }
      self& operator++() { ++_iter; return *this; }
      self operator++(int) { self t = *this; ++_iter; return t; }
      bool operator==(const self& x) const { return _iter == x._iter; }
      bool operator!=(const self& x) const { return _iter != x._iter; }
    protected:
      V _source;
      Iter _iter;
    };

    template <class EdgeList>
    struct val_out_edge_iter
    {
      typedef typename EdgeList::value_type V;
      typedef typename EdgeList::const_iterator Iter;
      typedef val_out_edge_iterator<V,Iter> type;
    };

    template <class EdgeList>
    struct val_out_edge_ret
    {
      typedef typename val_out_edge_iter<EdgeList>::type IncIter;
      typedef std::pair<IncIter,IncIter> type;
    };

  } // namesapce detail

  template <class EdgeList, class Alloc>
  typename detail::val_out_edge_ret<EdgeList>::type
  out_edges(typename EdgeList::value_type v,
            const std::vector<EdgeList, Alloc>& g)
  {
    typedef typename detail::val_out_edge_iter<EdgeList>::type Iter;
    typedef typename detail::val_out_edge_ret<EdgeList>::type return_type;
    return return_type(Iter(v, g[v].begin()), Iter(v, g[v].end()));
  }

  template <class EdgeList, class Alloc>
  typename EdgeList::size_type
  out_degree(typename EdgeList::value_type v,
             const std::vector<EdgeList, Alloc>& g)
  {
    return g[v].size();
  }

  template <class EdgeList, class Alloc>
  std::pair<typename EdgeList::const_iterator,
            typename EdgeList::const_iterator>
  adjacent_vertices(typename EdgeList::value_type v,
                    const std::vector<EdgeList, Alloc>& g)
  {
    return std::make_pair(g[v].begin(), g[v].end());
  }

  // source() and target() already provided for pairs in graph_traits.hpp

  template <class EdgeList, class Alloc>
  std::pair<boost::counting_iterator<typename EdgeList::value_type>,
            boost::counting_iterator<typename EdgeList::value_type> >
  vertices(const std::vector<EdgeList, Alloc>& v)
  {
    typedef boost::counting_iterator<typename EdgeList::value_type> Iter;
    return std::make_pair(Iter(0), Iter(v.size()));
  }

  template <class EdgeList, class Alloc>
  typename std::vector<EdgeList, Alloc>::size_type
  num_vertices(const std::vector<EdgeList, Alloc>& v)
  {
    return v.size();
  }

  template<class EdgeList, class Allocator>
  typename std::pair<typename detail::val_edge<EdgeList>::type, bool>
  add_edge(typename EdgeList::value_type u, typename EdgeList::value_type v,
           std::vector<EdgeList, Allocator>& g)
  {
    typedef typename detail::val_edge<EdgeList>::type edge_type;
    g[u].insert(g[u].end(), v);
    return std::make_pair(edge_type(u, v), true);
  }

  template<class EdgeList, class Allocator>
  typename std::pair<typename detail::val_edge<EdgeList>::type, bool>
  edge(typename EdgeList::value_type u, typename EdgeList::value_type v,
       std::vector<EdgeList, Allocator>& g)
  {
    typedef typename detail::val_edge<EdgeList>::type edge_type;
    typename EdgeList::iterator i = g[u].begin(), end = g[u].end();
    for (; i != end; ++i)
      if (*i == v)
        return std::make_pair(edge_type(u, v), true);
    return std::make_pair(edge_type(), false);
  }

  template<class EdgeList, class Allocator>
  void
  remove_edge(typename EdgeList::value_type u, typename EdgeList::value_type v,
              std::vector<EdgeList, Allocator>& g)
  {
    typename EdgeList::iterator i = std::remove(g[u].begin(), g[u].end(), v);
    if (i != g[u].end())
      g[u].erase(i, g[u].end());
  }

  template<class EdgeList, class Allocator>
  void
  remove_edge(typename detail::val_edge<EdgeList>::type e,
              std::vector<EdgeList, Allocator>& g)
  {
    typename EdgeList::value_type u, v;
    u = e.first;
    v = e.second;
    // FIXME: edge type does not fully specify the edge to be deleted
    typename EdgeList::iterator i = std::remove(g[u].begin(), g[u].end(), v);
    if (i != g[u].end())
      g[u].erase(i, g[u].end());
  }

  template<class EdgeList, class Allocator, class Predicate>
  void
  remove_edge_if(Predicate p,
                 std::vector<EdgeList, Allocator>& g)
  {
      for (std::size_t u = 0; u < g.size(); ++u) {
          // Oops! gcc gets internal compiler error on compose_.......

          typedef typename EdgeList::iterator iterator;
          iterator b = g[u].begin(), e = g[u].end();

          if (!g[u].empty()) {

              for(; b != e;) {
                  if (p(std::make_pair(u, *b))) {
                      --e;
                      if (b == e)
                          break;
                      else
                          iter_swap(b, e);
                  } else {
                      ++b;
                  }
              }
          }

          if (e != g[u].end())
              g[u].erase(e, g[u].end());
      }
  }

  template<class EdgeList, class Allocator>
  typename EdgeList::value_type
  add_vertex(std::vector<EdgeList, Allocator>& g)
  {
    g.resize(g.size()+1);
    return g.size()-1;
  }

  template<class EdgeList, class Allocator>
  void
  clear_vertex(typename EdgeList::value_type u,
               std::vector<EdgeList, Allocator>& g)
  {
    g[u].clear();
    for (std::size_t i = 0; i < g.size(); ++i)
      remove_edge(i, u, g);
  }

  template<class EdgeList, class Allocator>
  void
  remove_vertex(typename EdgeList::value_type u,
                std::vector<EdgeList, Allocator>& g)
  {
    typedef typename EdgeList::iterator iterator;
    clear_vertex(u, g);
    g.erase(g.begin() + u);
    for (std::size_t i = 0; i < g.size(); ++i)
      for ( iterator it = g[i].begin(); it != g[i].end(); ++it )
        // after clear_vertex *it is never equal to u
        if ( *it > u )
          --*it;
  }

  template<typename EdgeList, typename Allocator>
  struct property_map<std::vector<EdgeList, Allocator>, vertex_index_t>
  {
    typedef identity_property_map type;
    typedef type const_type;
  };

  template<typename EdgeList, typename Allocator>
  identity_property_map
  get(vertex_index_t, const std::vector<EdgeList, Allocator>&)
  {
    return identity_property_map();
  }

  template<typename EdgeList, typename Allocator>
  identity_property_map
  get(vertex_index_t, std::vector<EdgeList, Allocator>&)
  {
    return identity_property_map();
  }
} // namespace boost

#endif // BOOST_VECTOR_AS_GRAPH_HPP