// -*- c++ -*-
#ifndef HUGO_BFS_DFS_MISC_H
#define HUGO_BFS_DFS_MISC_H

#include <bfs_iterator.h>
#include <for_each_macros.h>

namespace hugo {

  /// This function eat a read-write \c BoolMap& bool_map, 
  /// which have to work well up 
  /// to its \c set and \c operator[]() method. Thus we have to deal 
  /// very carefully with an uninitialized \c IterableBoolMap.
  template<typename Graph, typename BoolMap> 
  bool isBipartite(const Graph& g, BoolMap& bool_map) {
    typedef typename Graph::template NodeMap<bool> ReachedMap;
    ReachedMap reached(g/*, false*/);
    BfsIterator<Graph, ReachedMap> bfs(g, reached);
    FOR_EACH_LOC(typename Graph::NodeIt, n, g) {
      if (!reached[n]) {
	bfs.pushAndSetReached(n);
	bool_map.set(n, false);
	while (!bfs.finished()) {
	  if (bfs.isBNodeNewlyReached()) {
	    bool_map.set(bfs.bNode())=!bfs.aNode();
	  } else {
	    if (bool_map[bfs.bNode()]==bool_map[bfs.aNode()]) {
	      return false;
	    }
	  }
	  ++bfs;
	}
      }
    }
    
    return true;
  }

  /// experimental topsort, 
  /// I think the final version will work as an iterator
  /// if the graph is not a acyclic, the na pre-topological order is obtained 
  /// (see Schrijver's book).
  /// PredMap have to be a writtable node-map.
  /// If the graph is directed and not acyclic, 
  /// then going back from the returned node via the pred information, a 
  /// cycle is obtained.
  template<typename Graph, typename PredMap> 
  typename Graph::Node 
  topSort(const Graph& g, std::list<typename Graph::Node>& l, 
	       PredMap& pred) {
    l.clear();
    typedef typename Graph::template NodeMap<bool> ReachedMap;
    typedef typename Graph::template NodeMap<bool> ExaminedMap;    
    ReachedMap reached(g/*, false*/);
    ExaminedMap examined(g/*, false*/);
    DfsIterator<Graph, ReachedMap> dfs(g, reached);
    FOR_EACH_LOC(typename Graph::NodeIt, n, g) {
      if (!reached[n]) {
	dfs.pushAndSetReached(n);
	pred.set(n, INVALID);
	while (!dfs.finished()) {
	  ++dfs;
	  if (dfs.isBNodeNewlyReached()) {
	    ///\bug hugo 0.2-ben Edge kell
	    pred.set(dfs.aNode(), typename Graph::OutEdgeIt(dfs));
	  } else {
	    ///\bug ugyanaz
	    if (g.valid(typename Graph::OutEdgeIt(dfs)) && 
		!examined[dfs.bNode()]) {
	      ///\bug hugo 0.2-ben Edge kell
	      pred.set(dfs.bNode(), typename Graph::OutEdgeIt(dfs));
	      return dfs.aNode();
	    }
	  }
	  if (dfs.isANodeExamined()) {
	    l.push_back(dfs.aNode());
	    examined.set(dfs.aNode(), true);
	  }
	}
      }
    }
    return INVALID;
  }
} //namespace hugo

#endif //HUGO_BFS_DFS_MISC_H