#ifndef MARCI_BFS_HH

#define MARCI_BFS_HH

#include <queue>

#include <marci_graph_traits.hh>

#include <marci_property_vector.hh>

namespace marci {

  template <typename graph_type>

  struct bfs {

    typedef typename graph_traits<graph_type>::node_iterator node_iterator;

    typedef typename graph_traits<graph_type>::edge_iterator edge_iterator;

    typedef typename graph_traits<graph_type>::each_node_iterator each_node_iterator;

    typedef typename graph_traits<graph_type>::out_edge_iterator out_edge_iterator;

    graph_type& G;

    node_iterator s;

    node_property_vector<graph_type, bool> reached;

    node_property_vector<graph_type, edge_iterator> pred;

    node_property_vector<graph_type, int> dist;

    std::queue<node_iterator> bfs_queue;

    bfs(graph_type& _G, node_iterator _s) : G(_G), s(_s), reached(_G), pred(_G), dist(_G) { 

      bfs_queue.push(s); 

      for(each_node_iterator i=G.first_node(); i.is_valid(); ++i) 

	reached.put(i, false);

      reached.put(s, true);

      dist.put(s, 0); 

    }

    void run() {

      while (!bfs_queue.empty()) {

	node_iterator v=bfs_queue.front();

	out_edge_iterator e=G.first_out_edge(v);

	bfs_queue.pop();

	for( ; e.is_valid(); ++e) {

	  node_iterator w=G.head(e);

	  std::cout << "scan node " << G.id(w) << " from node " << G.id(v) << std::endl;

	  if (!reached.get(w)) {

	    std::cout << G.id(w) << " is newly reached :-)" << std::endl;

	    bfs_queue.push(w);

	    dist.put(w, dist.get(v)+1);

	    pred.put(w, e);

	    reached.put(w, true);

	  } else {

	    std::cout << G.id(w) << " is already reached" << std::endl;

	  }

	}

      }

    }

  };

  template <typename graph_type> 

  struct bfs_visitor {

    typedef typename graph_traits<graph_type>::node_iterator node_iterator;

    typedef typename graph_traits<graph_type>::edge_iterator edge_iterator;

    typedef typename graph_traits<graph_type>::each_node_iterator each_node_iterator;

    typedef typename graph_traits<graph_type>::out_edge_iterator out_edge_iterator;

    graph_type& G;

    bfs_visitor(graph_type& _G) : G(_G) { }

    void at_previously_reached(out_edge_iterator& e) { 

      //node_iterator v=G.tail(e);

      node_iterator w=G.head(e);

      std::cout << G.id(w) << " is already reached" << std::endl;

   }

    void at_newly_reached(out_edge_iterator& e) { 

      //node_iterator v=G.tail(e);

      node_iterator w=G.head(e);

      std::cout << G.id(w) << " is newly reached :-)" << std::endl;

    }

  };

  template <typename graph_type, typename reached_type, typename visitor_type>

  struct bfs_iterator {

    typedef typename graph_traits<graph_type>::node_iterator node_iterator;

    typedef typename graph_traits<graph_type>::edge_iterator edge_iterator;

    typedef typename graph_traits<graph_type>::each_node_iterator each_node_iterator;

    typedef typename graph_traits<graph_type>::out_edge_iterator out_edge_iterator;

    graph_type& G;

    std::queue<out_edge_iterator>& bfs_queue;

    reached_type& reached;

    visitor_type& visitor;

    void process() {

      while ( !bfs_queue.empty() && !bfs_queue.front().is_valid() ) { bfs_queue.pop(); } 

      if (bfs_queue.empty()) return;

      out_edge_iterator e=bfs_queue.front();

      //node_iterator v=G.tail(e);

      node_iterator w=G.head(e);

      if (!reached.get(w)) {

	visitor.at_newly_reached(e);

	bfs_queue.push(G.first_out_edge(w));

	reached.put(w, true);

      } else {

	visitor.at_previously_reached(e);

      }

    }

    bfs_iterator(graph_type& _G, std::queue<out_edge_iterator>& _bfs_queue, reached_type& _reached, visitor_type& _visitor) : G(_G), bfs_queue(_bfs_queue), reached(_reached), visitor(_visitor) { 

      //while ( !bfs_queue.empty() && !bfs_queue.front().is_valid() ) { bfs_queue.pop(); } 

      is_valid();

    }

    bfs_iterator<graph_type, reached_type, visitor_type>& operator++() { 

      //while ( !bfs_queue.empty() && !bfs_queue.front().is_valid() ) { bfs_queue.pop(); } 

      //if (bfs_queue.empty()) return *this;

      if (!is_valid()) return *this;

      ++(bfs_queue.front());

      //while ( !bfs_queue.empty() && !bfs_queue.front().is_valid() ) { bfs_queue.pop(); } 

      is_valid();

      return *this;

    }

    //void next() { 

    //  while ( !bfs_queue.empty() && !bfs_queue.front().is_valid() ) { bfs_queue.pop(); } 

    //  if (bfs_queue.empty()) return;

    //  ++(bfs_queue.front());

    //  while ( !bfs_queue.empty() && !bfs_queue.front().is_valid() ) { bfs_queue.pop(); } 

    //}

    bool is_valid() { 

      while ( !bfs_queue.empty() && !bfs_queue.front().is_valid() ) { bfs_queue.pop(); } 

      if (bfs_queue.empty()) return false; else return true;

    }

    //bool finished() { 

    //  while ( !bfs_queue.empty() && !bfs_queue.front().is_valid() ) { bfs_queue.pop(); } 

    //  if (bfs_queue.empty()) return true; else return false;

    //}

    operator edge_iterator () { return bfs_queue.front(); }

  };

} // namespace marci

#endif //MARCI_BFS_HH