// graph-tool -- a general graph modification and manipulation thingy
//
// Copyright (C) 2006-2021 Tiago de Paula Peixoto <tiago@skewed.de>
//
// This program is free software; you can redistribute it and/or modify it under
// the terms of the GNU Lesser General Public License as published by the Free
// Software Foundation; either version 3 of the License, or (at your option) any
// later version.
//
// This program is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
// FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
// details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.

#include "graph_filtering.hh"
#include "graph.hh"
#include "graph_properties.hh"

using namespace std;
using namespace boost;
using namespace graph_tool;

// retrieves the line graph

struct get_line_graph
{
    template <class Graph, class VertexIndex, class LineGraph,
              class EdgeIndexMap, class LGVertexIndex>
    void operator()(const Graph& g, VertexIndex,
                    LineGraph& line_graph, EdgeIndexMap edge_index,
                    LGVertexIndex vmap) const
    {
        typedef typename graph_traits<LineGraph>::vertex_descriptor lg_vertex_t;
        typedef HashedDescriptorMap<EdgeIndexMap,lg_vertex_t>
            edge_to_vertex_map_t;
        edge_to_vertex_map_t edge_to_vertex_map(edge_index);

        typename LGVertexIndex::checked_t vertex_map = vmap.get_checked();

        for (auto e : edges_range(g))
        {
            auto v = add_vertex(line_graph);
            edge_to_vertex_map[e] = v;
            vertex_map[v] = edge_index[e];
        }

        if (graph_tool::is_directed(g))
        {
            for (auto v : vertices_range(g))
            {
                for (auto e1 : out_edges_range(v, g))
                {
                    for (auto e2 : out_edges_range(target(e1, g), g))
                    {
                        add_edge(edge_to_vertex_map[e1],
                                 edge_to_vertex_map[e2],
                                 line_graph);
                    }
                }
            }
        }
        else
        {
            for (auto v : vertices_range(g))
            {
                typename graph_traits<Graph>::out_edge_iterator e1, e2, e_end;
                for (tie(e1, e_end) = out_edges(v, g); e1 != e_end; ++e1)
                {
                    for (e2 = e1; e2 != e_end; ++e2)
                    {
                        if (*e1 != *e2)
                        {
                            add_edge(edge_to_vertex_map[*e1],
                                     edge_to_vertex_map[*e2],
                                     line_graph);
                        }
                    }
                }
            }
        }
    }
};

void line_graph(GraphInterface& gi, GraphInterface& lgi,
                boost::any edge_index)
{
    typedef property_map_types::apply<boost::mpl::vector<int64_t>,
                                      GraphInterface::vertex_index_map_t,
                                      boost::mpl::false_>::type
        vertex_properties;

    run_action<>()
        (gi,
         [&](auto&& graph, auto&& a2)
         {
             return get_line_graph()
                 (std::forward<decltype(graph)>(graph), gi.get_vertex_index(),
                  lgi.get_graph(), lgi.get_edge_index(),
                  std::forward<decltype(a2)>(a2));
         },
         vertex_properties())(edge_index);
}
