//=======================================================================
// Copyright 2001 Jeremy G. Siek, Andrew Lumsdaine, Lie-Quan Lee, 
//
// 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)
//=======================================================================
#include <boost/config.hpp>
#include <iostream>
#include <fstream>
#include <stack>
#include <map>
#include <boost/lexical_cast.hpp>
#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/depth_first_search.hpp>
#include <boost/graph/graphviz.hpp>
#include <boost/graph/copy.hpp>
#include <boost/graph/reverse_graph.hpp>

using namespace boost;

template < typename OutputIterator > 
class back_edge_recorder : public default_dfs_visitor
{
public:
  back_edge_recorder(OutputIterator out):m_out(out) { }

  template < typename Edge, typename Graph >
  void back_edge(Edge e, const Graph &)
  {
    *m_out++ = e;
  }
private:
  OutputIterator m_out;
};

// object generator function
template < typename OutputIterator >
back_edge_recorder < OutputIterator >
make_back_edge_recorder(OutputIterator out)
{
  return back_edge_recorder < OutputIterator > (out);
}

template < typename Graph, typename Loops > void
find_loops(typename graph_traits < Graph >::vertex_descriptor entry, 
           const Graph & g, 
           Loops & loops)    // A container of sets of vertices
{
  function_requires < BidirectionalGraphConcept < Graph > >();
  typedef typename graph_traits < Graph >::edge_descriptor Edge;
  typedef typename graph_traits < Graph >::vertex_descriptor Vertex;
  std::vector < Edge > back_edges;
  std::vector < default_color_type > color_map(num_vertices(g));
  depth_first_visit(g, entry,
                    make_back_edge_recorder(std::back_inserter(back_edges)),
                    make_iterator_property_map(color_map.begin(),
                                               get(vertex_index, g), color_map[0]));

  for (std::vector < Edge >::size_type i = 0; i < back_edges.size(); ++i) {
    typename Loops::value_type x;
    loops.push_back(x);
    compute_loop_extent(back_edges[i], g, loops.back());
  }
}

template < typename Graph, typename Set > void
compute_loop_extent(typename graph_traits <
                    Graph >::edge_descriptor back_edge, const Graph & g,
                    Set & loop_set)
{
  function_requires < BidirectionalGraphConcept < Graph > >();
  typedef typename graph_traits < Graph >::vertex_descriptor Vertex;
  typedef color_traits < default_color_type > Color;

  Vertex loop_head, loop_tail;
  loop_tail = source(back_edge, g);
  loop_head = target(back_edge, g);

  std::vector < default_color_type >
    reachable_from_head(num_vertices(g), Color::white());
  default_color_type c;
  depth_first_visit(g, loop_head, default_dfs_visitor(),
                    make_iterator_property_map(reachable_from_head.begin(),
                                               get(vertex_index, g), c));

  std::vector < default_color_type > reachable_to_tail(num_vertices(g));
  reverse_graph < Graph > reverse_g(g);
  depth_first_visit(reverse_g, loop_tail, default_dfs_visitor(),
                    make_iterator_property_map(reachable_to_tail.begin(),
                                               get(vertex_index, g), c));

  typename graph_traits < Graph >::vertex_iterator vi, vi_end;
  for (boost::tie(vi, vi_end) = vertices(g); vi != vi_end; ++vi)
    if (reachable_from_head[*vi] != Color::white()
        && reachable_to_tail[*vi] != Color::white())
      loop_set.insert(*vi);
}


int
main(int argc, char *argv[])
{
  if (argc < 3) {
    std::cerr << "usage: loops_dfs <in-file> <out-file>" << std::endl;
    return -1;
  }
  GraphvizDigraph g_in;
  read_graphviz(argv[1], g_in);

  typedef adjacency_list < vecS, vecS, bidirectionalS,
    GraphvizVertexProperty,
    GraphvizEdgeProperty, GraphvizGraphProperty > Graph;
  typedef graph_traits < Graph >::vertex_descriptor Vertex;

  Graph g;
#if defined(BOOST_MSVC) && BOOST_MSVC <= 1300
  // VC++ has trouble with the get_property() function
  get_property(g, graph_name) = "loops";
#endif

  copy_graph(g_in, g);

  typedef std::set < Vertex > set_t;
  typedef std::list < set_t > list_of_sets_t;
  list_of_sets_t loops;
  Vertex entry = *vertices(g).first;

  find_loops(entry, g, loops);

  property_map<Graph, vertex_attribute_t>::type vattr_map = get(vertex_attribute, g);
  property_map<Graph, edge_attribute_t>::type eattr_map = get(edge_attribute, g);
  graph_traits < Graph >::edge_iterator ei, ei_end;

  for (list_of_sets_t::iterator i = loops.begin(); i != loops.end(); ++i) {
    std::vector < bool > in_loop(num_vertices(g), false);
    for (set_t::iterator j = (*i).begin(); j != (*i).end(); ++j) {
      vattr_map[*j]["color"] = "gray";
      in_loop[*j] = true;
    }
    for (boost::tie(ei, ei_end) = edges(g); ei != ei_end; ++ei)
      if (in_loop[source(*ei, g)] && in_loop[target(*ei, g)])
        eattr_map[*ei]["color"] = "gray";
  }

  std::ofstream loops_out(argv[2]);
#if defined(BOOST_MSVC) && BOOST_MSVC <= 1300
  // VC++ has trouble with the get_property() functions
  loops_out << "digraph loops {\n"
            << "size=\"3,3\"\n"
            << "ratio=\"fill\"\n"
            << "shape=\"box\"\n";
  graph_traits<Graph>::vertex_iterator vi, vi_end;
  for (boost::tie(vi, vi_end) = vertices(g); vi != vi_end; ++vi) {
    loops_out << *vi << "[";
    for (std::map<std::string,std::string>::iterator ai = vattr_map[*vi].begin();
         ai != vattr_map[*vi].end(); ++ai) {
      loops_out << ai->first << "=" << ai->second;
      if (next(ai) != vattr_map[*vi].end())
        loops_out << ", ";
    }
    loops_out<< "]";
  }

  for (boost::tie(ei, ei_end) = edges(g); ei != ei_end; ++ei) {
    loops_out << source(*ei, g) << " -> " << target(*ei, g) << "[";
    std::map<std::string,std::string>& attr_map = eattr_map[*ei];
    for (std::map<std::string,std::string>::iterator eai = attr_map.begin();
         eai != attr_map.end(); ++eai) {
      loops_out << eai->first << "=" << eai->second;
      if (next(eai) != attr_map.end())
        loops_out << ", ";
    }
    loops_out<< "]";
  }
  loops_out << "}\n";
#else
  get_property(g, graph_graph_attribute)["size"] = "3,3";
  get_property(g, graph_graph_attribute)["ratio"] = "fill";
  get_property(g, graph_vertex_attribute)["shape"] = "box";

  write_graphviz(loops_out, g,
                 make_vertex_attributes_writer(g),
                 make_edge_attributes_writer(g),
                 make_graph_attributes_writer(g));
#endif
  return 0;
}