/* -*- 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;

       Edge(const UndirEdge &ue, bool _forward) :

         UndirEdge(ue), forward(_forward) {}

     public:

       Edge() {}

       /// 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 oppositeEdge(const Edge &e) const {

       return Edge(e,!e.forward);

     }

   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 e.forward ? Parent::source(e) : Parent::target(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 e.forward ? Parent::target(e) : Parent::source(e);

     }

     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;

     }

     /// \brief Directed edge from an undirected edge and a source node.

     ///

     /// Returns a (directed) Edge corresponding to the specified UndirEdge

     /// and source Node.

     ///

     Edge direct(const UndirEdge &ue, const Node &s) const {

       return Edge(ue, s == source(ue));

     }

     /// \brief Directed edge from an undirected edge.

     ///

     /// Returns a directed edge corresponding to the specified UndirEdge.

     /// If the given bool is true the given undirected edge and the

     /// returned edge have the same source node.

     Edge direct(const UndirEdge &ue, bool d) const {

       return Edge(ue, d);

     }

     /// 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 direction(const Edge &e) const { return e.forward; }

     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;

       }

     }

   public:

     void firstOut(Edge &e, const Node &n) const {

       Parent::firstIn(e,n);

       if( UndirEdge(e) != INVALID ) {

 	e.forward = false;

       }

       else {

 	Parent::firstOut(e,n);

 	e.forward = true;

       }

     }

     void nextOut(Edge &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);

       }

     }

     void firstIn(Edge &e, const Node &n) const {

       Parent::firstOut(e,n);

       if( UndirEdge(e) != INVALID ) {

 	e.forward = false;

       }

       else {

 	Parent::firstIn(e,n);

 	e.forward = true;

       }

     }

     void nextIn(Edge &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);

       }

     }

     void firstInc(UndirEdge &e, const Node &n) const {

       Parent::firstOut(e, n);

       if (e != INVALID) return;

       Parent::firstIn(e, n);

     }

     void nextInc(UndirEdge &e, const Node &n) const {

       if (Parent::source(e) == n) {

 	Parent::nextOut(e);

 	if (e != INVALID) return;

 	Parent::firstIn(e, n);

       } else {

 	Parent::nextIn(e);

       }

     }

     void firstInc(UndirEdge &e, bool &d, const Node &n) const {

       d = true;

       Parent::firstOut(e, n);

       if (e != INVALID) return;

       d = false;

       Parent::firstIn(e, n);

     }

     void nextInc(UndirEdge &e, bool &d) const {

       if (d) {

 	Node s = Parent::source(e);

 	Parent::nextOut(e);

 	if (e != INVALID) return;

 	d = false;

 	Parent::firstIn(e, s);

       } else {

 	Parent::nextIn(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();

     }

     Edge findEdge(Node source, Node target, Edge prev) const {

       if (prev == INVALID) {

 	UndirEdge edge = Parent::findEdge(source, target);

 	if (edge != INVALID) return direct(edge, true);

 	edge = Parent::findEdge(target, source);

 	if (edge != INVALID) return direct(edge, false);

       } else if (direction(prev)) {

 	UndirEdge edge = Parent::findEdge(source, target, prev);

 	if (edge != INVALID) return direct(edge, true);

 	edge = Parent::findEdge(target, source);

 	if (edge != INVALID) return direct(edge, false);	

       } else {

 	UndirEdge edge = Parent::findEdge(target, source, prev);

 	if (edge != INVALID) return direct(edge, false);	      

       }

       return INVALID;

     }

     UndirEdge findUndirEdge(Node source, Node target, UndirEdge prev) const {

       if (prev == INVALID) {

 	UndirEdge edge = Parent::findEdge(source, target);

 	if (edge != INVALID) return edge;

 	edge = Parent::findEdge(target, source);

 	if (edge != INVALID) return edge;

       } else if (Parent::source(prev) == source) {

 	UndirEdge edge = Parent::findEdge(source, target, prev);

 	if (edge != INVALID) return edge;

 	edge = Parent::findEdge(target, source);

 	if (edge != INVALID) return edge;	

       } else {

 	UndirEdge edge = Parent::findEdge(target, source, prev);

 	if (edge != INVALID) return edge;	      

       }

       return INVALID;

     }

   };

 }

 #endif // LEMON_UNDIR_GRAPH_EXTENDER_H