/* -*- C++ -*-

  *

  * This file is a part of LEMON, a generic C++ optimization library

  *

  * Copyright (C) 2003-2006

  * 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_BITS_BASE_EXTENDER_H

 #define LEMON_BITS_BASE_EXTENDER_H

 #include <lemon/bits/invalid.h>

 #include <lemon/error.h>

 #include <lemon/bits/map_extender.h>

 #include <lemon/bits/default_map.h>

 #include <lemon/concept_check.h>

 #include <lemon/concept/maps.h>

 ///\ingroup graphbits

 ///\file

 ///\brief Extenders for the graph types

 namespace lemon {

   /// \ingroup graphbits

   ///

   /// \brief BaseExtender for the UGraphs

   template <typename Base>

   class UndirGraphExtender : public Base {

   public:

     typedef Base Parent;

     typedef typename Parent::Edge UEdge;

     typedef typename Parent::Node Node;

     typedef True UndirectedTag;

     class Edge : public UEdge {

       friend class UndirGraphExtender;

     protected:

       bool forward;

       Edge(const UEdge &ue, bool _forward) :

         UEdge(ue), forward(_forward) {}

     public:

       Edge() {}

       /// Invalid edge constructor

       Edge(Invalid i) : UEdge(i), forward(true) {}

       bool operator==(const Edge &that) const {

 	return forward==that.forward && UEdge(*this)==UEdge(that);

       }

       bool operator!=(const Edge &that) const {

 	return forward!=that.forward || UEdge(*this)!=UEdge(that);

       }

       bool operator<(const Edge &that) const {

 	return forward<that.forward ||

 	  (!(that.forward<forward) && UEdge(*this)<UEdge(that));

       }

     };

     using Parent::source;

     /// Source of the given Edge.

     Node source(const Edge &e) const {

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

     }

     using Parent::target;

     /// Target of the given Edge.

     Node target(const Edge &e) const {

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

     }

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

     ///

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

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

     /// returned edge have the same source node.

     static Edge direct(const UEdge &ue, bool d) {

       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?"

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

     using Parent::first;

     using Parent::next;

     void first(Edge &e) const {

       Parent::first(e);

       e.forward=true;

     }

     void next(Edge &e) const {

       if( e.forward ) {

 	e.forward = false;

       }

       else {

 	Parent::next(e);

 	e.forward = true;

       }

     }

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

       Parent::firstIn(e,n);

       if( UEdge(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( UEdge(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( UEdge(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( UEdge(e) == INVALID ) {

 	  Parent::firstIn(e, n);

 	  e.forward = true;

 	}

       }

       else {

 	Parent::nextIn(e);

       }

     }

     void firstInc(UEdge &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(UEdge &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);

       }

     }

     Node nodeFromId(int id) const {

       return Parent::nodeFromId(id);

     }

     Edge edgeFromId(int id) const {

       return direct(Parent::edgeFromId(id >> 1), bool(id & 1));

     }

     UEdge uEdgeFromId(int id) const {

       return Parent::edgeFromId(id);

     }

     int id(const Node &n) const {

       return Parent::id(n);

     }

     int id(const UEdge &e) const {

       return Parent::id(e);

     }

     int id(const Edge &e) const {

       return 2 * Parent::id(e) + int(e.forward);

     }

     int maxNodeId() const {

       return Parent::maxNodeId();

     }

     int maxEdgeId() const {

       return 2 * Parent::maxEdgeId() + 1;

     }

     int maxUEdgeId() const {

       return Parent::maxEdgeId();

     }

     int edgeNum() const {

       return 2 * Parent::edgeNum();

     }

     int uEdgeNum() const {

       return Parent::edgeNum();

     }

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

       if (prev == INVALID) {

 	UEdge 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)) {

 	UEdge 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 {

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

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

       }

       return INVALID;

     }

     UEdge findUEdge(Node source, Node target, UEdge prev) const {

       if (prev == INVALID) {

 	UEdge 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) {

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

 	if (edge != INVALID) return edge;

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

 	if (edge != INVALID) return edge;	

       } else {

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

 	if (edge != INVALID) return edge;	      

       }

       return INVALID;

     }

   };

 }

 #endif