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

/// \ingroup galgs
/// \file
/// \brief Bfs and dfs iterators.
///
/// This file contains bfs and dfs iterator classes.
///
// /// \author Marton Makai

#include <queue>
#include <stack>
#include <utility>

#include <lemon/invalid.h>

namespace lemon {

  /// Bfs searches for the nodes wich are not marked in 
  /// \c reached_map
  /// Reached have to be a read-write bool node-map.
  /// \ingroup galgs
  template <typename Graph, /*typename OutEdgeIt,*/ 
	    typename ReachedMap/*=typename Graph::NodeMap<bool>*/ >
  class BfsIterator {
  protected:
    typedef typename Graph::Node Node;
    typedef typename Graph::Edge Edge;
    typedef typename Graph::OutEdgeIt OutEdgeIt;
    const Graph* graph;
    std::queue<Node> bfs_queue;
    ReachedMap& reached;
    bool b_node_newly_reached;
    Edge actual_edge;
    bool own_reached_map;
  public:
    /// In that constructor \c _reached have to be a reference 
    /// for a bool bode-map. The algorithm will search for the 
    /// initially \c false nodes 
    /// in a bfs order.
    BfsIterator(const Graph& _graph, ReachedMap& _reached) : 
      graph(&_graph), reached(_reached), 
      own_reached_map(false) { }
    /// The same as above, but the map storing the reached nodes 
    /// is constructed dynamically to everywhere false.
    /// \deprecated
    BfsIterator(const Graph& _graph) : 
      graph(&_graph), reached(*(new ReachedMap(*graph /*, false*/))), 
      own_reached_map(true) { }
    /// The map storing the reached nodes have to be destroyed if 
    /// it was constructed dynamically
    ~BfsIterator() { if (own_reached_map) delete &reached; }
    /// This method markes \c s reached.
    /// If the queue is empty, then \c s is pushed in the bfs queue 
    /// and the first out-edge is processed.
    /// If the queue is not empty, then \c s is simply pushed.
    BfsIterator<Graph, /*OutEdgeIt,*/ ReachedMap>& pushAndSetReached(Node s) { 
      reached.set(s, true);
      if (bfs_queue.empty()) {
	bfs_queue.push(s);
	actual_edge=OutEdgeIt(*graph, s);
	//graph->first(actual_edge, s);
	if (actual_edge!=INVALID) { 
	  Node w=graph->target(actual_edge);
	  if (!reached[w]) {
	    bfs_queue.push(w);
	    reached.set(w, true);
	    b_node_newly_reached=true;
	  } else {
	    b_node_newly_reached=false;
	  }
	} 
      } else {
	bfs_queue.push(s);
      }
      return *this;
    }
    /// As \c BfsIterator<Graph, ReachedMap> works as an edge-iterator, 
    /// its \c operator++() iterates on the edges in a bfs order.
    BfsIterator<Graph, /*OutEdgeIt,*/ ReachedMap>& 
    operator++() { 
      if (actual_edge!=INVALID) { 
	actual_edge=++OutEdgeIt(*graph, actual_edge);
	//++actual_edge;
	if (actual_edge!=INVALID) {
	  Node w=graph->target(actual_edge);
	  if (!reached[w]) {
	    bfs_queue.push(w);
	    reached.set(w, true);
	    b_node_newly_reached=true;
	  } else {
	    b_node_newly_reached=false;
	  }
	}
      } else {
	bfs_queue.pop(); 
	if (!bfs_queue.empty()) {
	  actual_edge=OutEdgeIt(*graph, bfs_queue.front());
	  //graph->first(actual_edge, bfs_queue.front());
	  if (actual_edge!=INVALID) {
	    Node w=graph->target(actual_edge);
	    if (!reached[w]) {
	      bfs_queue.push(w);
	      reached.set(w, true);
	      b_node_newly_reached=true;
	    } else {
	      b_node_newly_reached=false;
	    }
	  }
	}
      }
      return *this;
    }
    /// Returns true iff the algorithm is finished.
    bool finished() const { return bfs_queue.empty(); }
    /// The conversion operator makes for converting the bfs-iterator 
    /// to an \c out-edge-iterator.
    ///\bug Edge have to be in LEMON 0.2
    operator Edge() const { return actual_edge; }
    /// Returns if b-node has been reached just now.
    bool isBNodeNewlyReached() const { return b_node_newly_reached; }
    /// Returns if a-node is examined.
    bool isANodeExamined() const { return actual_edge==INVALID; }
    /// Returns a-node of the actual edge, so does if the edge is invalid.
    Node source() const { return bfs_queue.front(); }
    /// \pre The actual edge have to be valid.
    Node target() const { return graph->target(actual_edge); }
    /// Guess what?
    /// \deprecated 
    const ReachedMap& getReachedMap() const { return reached; }
    /// Guess what?
    /// \deprecated
    const std::queue<Node>& getBfsQueue() const { return bfs_queue; }
  };

  /// Bfs searches for the nodes wich are not marked in 
  /// \c reached_map
  /// Reached have to work as a read-write bool Node-map, 
  /// Pred is a write edge node-map and
  /// Dist is a read-write node-map of integral value, have to be. 
  /// \ingroup galgs
  template <typename Graph, 
	    typename ReachedMap=typename Graph::template NodeMap<bool>, 
	    typename PredMap
	    =typename Graph::template NodeMap<typename Graph::Edge>, 
	    typename DistMap=typename Graph::template NodeMap<int> > 
  class Bfs : public BfsIterator<Graph, ReachedMap> {
    typedef BfsIterator<Graph, ReachedMap> Parent;
  protected:
    typedef typename Parent::Node Node;
    PredMap& pred;
    DistMap& dist;
  public:
    /// The algorithm will search in a bfs order for 
    /// the nodes which are \c false initially. 
    /// The constructor makes no initial changes on the maps.
    Bfs<Graph, ReachedMap, PredMap, DistMap>(const Graph& _graph, ReachedMap& _reached, PredMap& _pred, DistMap& _dist) : 
      BfsIterator<Graph, ReachedMap>(_graph, _reached), 
      pred(_pred), dist(_dist) { }
    /// \c s is marked to be reached and pushed in the bfs queue.
    /// If the queue is empty, then the first out-edge is processed.
    /// If \c s was not marked previously, then 
    /// in addition its pred is set to be \c INVALID, and dist to \c 0. 
    /// if \c s was marked previuosly, then it is simply pushed.
    Bfs<Graph, ReachedMap, PredMap, DistMap>& push(Node s) { 
      if (this->reached[s]) {
	Parent::pushAndSetReached(s);
      } else {
	Parent::pushAndSetReached(s);
	pred.set(s, INVALID);
	dist.set(s, 0);
      }
      return *this;
    }
    /// A bfs is processed from \c s.
    Bfs<Graph, ReachedMap, PredMap, DistMap>& run(Node s) {
      push(s);
      while (!this->finished()) this->operator++();
      return *this;
    }
    /// Beside the bfs iteration, \c pred and \dist are saved in a 
    /// newly reached node. 
    Bfs<Graph, ReachedMap, PredMap, DistMap>& operator++() {
      Parent::operator++();
      if (this->graph->valid(this->actual_edge) && this->b_node_newly_reached) 
      {
	pred.set(this->target(), this->actual_edge);
	dist.set(this->target(), dist[this->source()]);
      }
      return *this;
    }
    /// Guess what?
    /// \deprecated 
    const PredMap& getPredMap() const { return pred; }
    /// Guess what?
    /// \deprecated
    const DistMap& getDistMap() const { return dist; }
  };

  /// Dfs searches for the nodes wich are not marked in 
  /// \c reached_map
  /// Reached have to be a read-write bool Node-map.
  /// \ingroup galgs
  template <typename Graph, /*typename OutEdgeIt,*/ 
	    typename ReachedMap/*=typename Graph::NodeMap<bool>*/ >
  class DfsIterator {
  protected:
    typedef typename Graph::Node Node;
    typedef typename Graph::Edge Edge;
    typedef typename Graph::OutEdgeIt OutEdgeIt;
    const Graph* graph;
    std::stack<OutEdgeIt> dfs_stack;
    bool b_node_newly_reached;
    Edge actual_edge;
    Node actual_node;
    ReachedMap& reached;
    bool own_reached_map;
  public:
    /// In that constructor \c _reached have to be a reference 
    /// for a bool node-map. The algorithm will search in a dfs order for 
    /// the nodes which are \c false initially
    DfsIterator(const Graph& _graph, ReachedMap& _reached) : 
      graph(&_graph), reached(_reached), 
      own_reached_map(false) { }
    /// The same as above, but the map of reached nodes is 
    /// constructed dynamically 
    /// to everywhere false.
    DfsIterator(const Graph& _graph) : 
      graph(&_graph), reached(*(new ReachedMap(*graph /*, false*/))), 
      own_reached_map(true) { }
    ~DfsIterator() { if (own_reached_map) delete &reached; }
    /// This method markes s reached and first out-edge is processed.
    DfsIterator<Graph, /*OutEdgeIt,*/ ReachedMap>& pushAndSetReached(Node s) { 
      actual_node=s;
      reached.set(s, true);
      OutEdgeIt e(*graph, s);
      //graph->first(e, s);
      dfs_stack.push(e); 
      return *this;
    }
    /// As \c DfsIterator<Graph, ReachedMap> works as an edge-iterator, 
    /// its \c operator++() iterates on the edges in a dfs order.
    DfsIterator<Graph, /*OutEdgeIt,*/ ReachedMap>& 
    operator++() { 
      actual_edge=dfs_stack.top();
      if (actual_edge!=INVALID/*.valid()*/) { 
	Node w=graph->target(actual_edge);
	actual_node=w;
	if (!reached[w]) {
	  OutEdgeIt e(*graph, w);
	  //graph->first(e, w);
	  dfs_stack.push(e);
	  reached.set(w, true);
	  b_node_newly_reached=true;
	} else {
	  actual_node=graph->source(actual_edge);
	  ++dfs_stack.top();
	  b_node_newly_reached=false;
	}
      } else {
	//actual_node=G.aNode(dfs_stack.top());
	dfs_stack.pop();
      }
      return *this;
    }
    /// Returns true iff the algorithm is finished.
    bool finished() const { return dfs_stack.empty(); }
    /// The conversion operator makes for converting the bfs-iterator 
    /// to an \c out-edge-iterator.
    ///\bug Edge have to be in LEMON 0.2
    operator Edge() const { return actual_edge; }
    /// Returns if b-node has been reached just now.
    bool isBNodeNewlyReached() const { return b_node_newly_reached; }
    /// Returns if a-node is examined.
    bool isANodeExamined() const { return actual_edge==INVALID; }
    /// Returns a-node of the actual edge, so does if the edge is invalid.
    Node source() const { return actual_node; /*FIXME*/}
    /// Returns b-node of the actual edge. 
    /// \pre The actual edge have to be valid.
    Node target() const { return graph->target(actual_edge); }
    /// Guess what?
    /// \deprecated
    const ReachedMap& getReachedMap() const { return reached; }
    /// Guess what?
    /// \deprecated
    const std::stack<OutEdgeIt>& getDfsStack() const { return dfs_stack; }
  };

  /// Dfs searches for the nodes wich are not marked in 
  /// \c reached_map
  /// Reached is a read-write bool node-map, 
  /// Pred is a write node-map, have to be.
  /// \ingroup galgs
  template <typename Graph, 
	    typename ReachedMap=typename Graph::template NodeMap<bool>, 
	    typename PredMap
	    =typename Graph::template NodeMap<typename Graph::Edge> > 
  class Dfs : public DfsIterator<Graph, ReachedMap> {
    typedef DfsIterator<Graph, ReachedMap> Parent;
  protected:
    typedef typename Parent::Node Node;
    PredMap& pred;
  public:
    /// The algorithm will search in a dfs order for 
    /// the nodes which are \c false initially. 
    /// The constructor makes no initial changes on the maps.
    Dfs<Graph, ReachedMap, PredMap>(const Graph& _graph, ReachedMap& _reached, PredMap& _pred) : DfsIterator<Graph, ReachedMap>(_graph, _reached), pred(_pred) { }
    /// \c s is marked to be reached and pushed in the bfs queue.
    /// If the queue is empty, then the first out-edge is processed.
    /// If \c s was not marked previously, then 
    /// in addition its pred is set to be \c INVALID. 
    /// if \c s was marked previuosly, then it is simply pushed.
    Dfs<Graph, ReachedMap, PredMap>& push(Node s) { 
      if (this->reached[s]) {
	Parent::pushAndSetReached(s);
      } else {
	Parent::pushAndSetReached(s);
	pred.set(s, INVALID);
      }
      return *this;
    }
    /// A bfs is processed from \c s.
    Dfs<Graph, ReachedMap, PredMap>& run(Node s) {
      push(s);
      while (!this->finished()) this->operator++();
      return *this;
    }
    /// Beside the dfs iteration, \c pred is saved in a 
    /// newly reached node. 
    Dfs<Graph, ReachedMap, PredMap>& operator++() {
      Parent::operator++();
      if (this->graph->valid(this->actual_edge) && this->b_node_newly_reached) 
      {
	pred.set(this->target(), this->actual_edge);
      }
      return *this;
    }
    /// Guess what?
    /// \deprecated
    const PredMap& getPredMap() const { return pred; }
  };


} // namespace lemon

#endif //LEMON_BFS_DFS_H