/* -*- C++ -*-

 *

 * lemon/undir_graph_extender.h - Part of LEMON, a generic C++

 * optimization library

 *

 * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi

 * Kutatocsoport (Egervary Research Group on Combinatorial Optimization,

 * 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 adaptors. 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