/* -*- C++ -*-
 *
 * src/lemon/undir_graph_extender.h - Part of LEMON, a generic C++
 * optimization library
 *
 * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi
 * Kutatocsoport (Egervary Combinatorial Optimization Research Group,
 * EGRES).
 *
 * Permission to use, modify and distribute this software is granted
 * provided that this copyright notice appears in all copies. For
 * precise terms see the accompanying LICENSE file.
 *
 * This software is provided "AS IS" with no warranty of any kind,
 * express or implied, and with no claim as to its suitability for any
 * purpose.
 *
 */

#ifndef LEMON_UNDIR_GRAPH_EXTENDER_H
#define LEMON_UNDIR_GRAPH_EXTENDER_H

#include <lemon/invalid.h>

namespace lemon {

  template <typename _Base>
  class UndirGraphExtender : public _Base {
    typedef _Base Parent;
    typedef UndirGraphExtender Graph;

  public:

    typedef typename Parent::Edge UndirEdge;
    typedef typename Parent::Node Node;

    class Edge : public UndirEdge {
      friend class UndirGraphExtender;

    protected:
      // FIXME: Marci use opposite logic in his graph wrappers. It would
      // be reasonable to syncronize...
      bool forward;

    public:
      Edge() {}

      /// \brief Directed edge from undirected edge and a direction.
      ///
      /// This constructor is not a part of the concept interface of
      /// undirected graph, so please avoid using it if possible!
      Edge(const UndirEdge &ue, bool _forward) :
        UndirEdge(ue), forward(_forward) {}

      /// \brief Directed edge from undirected edge and a source node.
      ///
      /// Constructs a directed edge from undirected edge and a source node.
      ///
      /// \note You have to specify the graph for this constructor.
      Edge(const Graph &g, const UndirEdge &ue, const Node &n) :
	UndirEdge(ue) { forward = (g.source(ue) == n); }

      /// Invalid edge constructor
      Edge(Invalid i) : UndirEdge(i), forward(true) {}

      bool operator==(const Edge &that) const {
	return forward==that.forward && UndirEdge(*this)==UndirEdge(that);
      }
      bool operator!=(const Edge &that) const {
	return forward!=that.forward || UndirEdge(*this)!=UndirEdge(that);
      }
      bool operator<(const Edge &that) const {
	return forward<that.forward ||
	  (!(that.forward<forward) && UndirEdge(*this)<UndirEdge(that));
      }
    };


    /// \brief Edge of opposite direction.
    ///
    /// Returns the Edge of opposite direction.
    Edge opposite(const Edge &e) const {
      return Edge(e,!e.forward);
    }

  protected:

    template <typename E>
    Node _dirSource(const E &e) const {
      return e.forward ? Parent::source(e) : Parent::target(e);
    }

    template <typename E>
    Node _dirTarget(const E &e) const {
      return e.forward ? Parent::target(e) : Parent::source(e);
    }

  public:
    /// \todo Shouldn't the "source" of an undirected edge be called "aNode"
    /// or something???
    using Parent::source;

    /// Source of the given Edge.
    Node source(const Edge &e) const {
      return _dirSource(e);
    }

    /// \todo Shouldn't the "target" of an undirected edge be called "bNode"
    /// or something???
    using Parent::target;

    /// Target of the given Edge.
    Node target(const Edge &e) const {
      return _dirTarget(e);
    }

    /// Returns whether the given directed edge is same orientation as the
    /// corresponding undirected edge.
    ///
    /// \todo reference to the corresponding point of the undirected graph
    /// concept. "What does the direction of an undirected edge mean?"
    bool forward(const Edge &e) const { return e.forward; }

    Node oppositeNode(const Node &n, const UndirEdge &e) const {
      if( n == Parent::source(e))
	return Parent::target(e);
      else if( n == Parent::target(e))
	return Parent::source(e);
      else
	return INVALID;
    }

    /// Directed edge from an undirected edge and a source node.
    ///
    /// Returns a (directed) Edge corresponding to the specified UndirEdge
    /// and source Node.
    ///
    ///\todo Do we need this?
    ///
    ///\todo Better name...
    Edge edgeWithSource(const UndirEdge &ue, const Node &s) const {
      return Edge(*this, ue, s);
    }

    using Parent::first;
    void first(Edge &e) const {
      Parent::first(e);
      e.forward=true;
    }

    using Parent::next;
    void next(Edge &e) const {
      if( e.forward ) {
	e.forward = false;
      }
      else {
	Parent::next(e);
	e.forward = true;
      }
    }

    
  protected:

    template <typename E>
    void _dirFirstOut(E &e, const Node &n) const {
      Parent::firstIn(e,n);
      if( UndirEdge(e) != INVALID ) {
	e.forward = false;
      }
      else {
	Parent::firstOut(e,n);
	e.forward = true;
      }
    }
    template <typename E>
    void _dirFirstIn(E &e, const Node &n) const {
      Parent::firstOut(e,n);
      if( UndirEdge(e) != INVALID ) {
	e.forward = false;
      }
      else {
	Parent::firstIn(e,n);
	e.forward = true;
      }
    }

    template <typename E>
    void _dirNextOut(E &e) const {
      if( ! e.forward ) {
	Node n = Parent::target(e);
	Parent::nextIn(e);
	if( UndirEdge(e) == INVALID ) {
	  Parent::firstOut(e, n);
	  e.forward = true;
	}
      }
      else {
	Parent::nextOut(e);
      }
    }
    template <typename E>
    void _dirNextIn(E &e) const {
      if( ! e.forward ) {
	Node n = Parent::source(e);
	Parent::nextOut(e);
	if( UndirEdge(e) == INVALID ) {
	  Parent::firstIn(e, n);
	  e.forward = true;
	}
      }
      else {
	Parent::nextIn(e);
      }
    }

  public:

    void firstOut(Edge &e, const Node &n) const {
      _dirFirstOut(e, n);
    }
    void firstIn(Edge &e, const Node &n) const {
      _dirFirstIn(e, n);
    }

    void nextOut(Edge &e) const {
      _dirNextOut(e);
    }
    void nextIn(Edge &e) const {
      _dirNextIn(e);
    }

    // Miscellaneous stuff:

    /// \todo these methods (id, maxEdgeId) should be moved into separate
    /// Extender

    // using Parent::id;
    // Using "using" is not a good idea, cause it could be that there is
    // no "id" in Parent...

    int id(const Node &n) const {
      return Parent::id(n);
    }

    int id(const UndirEdge &e) const {
      return Parent::id(e);
    }

    int id(const Edge &e) const {
      return 2 * Parent::id(e) + int(e.forward);
    }


    int maxId(Node) const {
      return Parent::maxId(Node());
    }

    int maxId(Edge) const {
      return 2 * Parent::maxId(typename Parent::Edge()) + 1;
    }
    int maxId(UndirEdge) const {
      return Parent::maxId(typename Parent::Edge());
    }


    int edgeNum() const {
      return 2 * Parent::edgeNum();
    }
    int undirEdgeNum() const {
      return Parent::edgeNum();
    }

  };

}

#endif // LEMON_UNDIR_GRAPH_EXTENDER_H