// -*- 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