// -*- c++ -*-

 #ifndef LEMON_ITERABLE_GRAPH_EXTENDER_H

 #define LEMON_ITERABLE_GRAPH_EXTENDER_H

 #include <lemon/invalid.h>

 #include <lemon/utility.h>

 namespace lemon {

   template <typename _Base>

   class IterableGraphExtender : public _Base {

   public:

     /// Indicates that the graph is undirected.

     ///\todo Better name?

     ///

     ///\bug Should it be here?

     typedef False UndirTag;

     typedef _Base Parent;

     typedef IterableGraphExtender<_Base> Graph;

     typedef typename Parent::Node Node;

     typedef typename Parent::Edge Edge;

     class NodeIt : public Node { 

       const Graph* graph;

     public:

       NodeIt() {}

       NodeIt(Invalid i) : Node(i) { }

       explicit NodeIt(const Graph& _graph) : graph(&_graph) {

 	_graph.first(*static_cast<Node*>(this));

       }

       NodeIt(const Graph& _graph, const Node& node) 

 	: Node(node), graph(&_graph) {}

       NodeIt& operator++() { 

 	graph->next(*this);

 	return *this; 

       }

     };

     class EdgeIt : public Edge { 

       const Graph* graph;

     public:

       EdgeIt() { }

       EdgeIt(Invalid i) : Edge(i) { }

       explicit EdgeIt(const Graph& _graph) : graph(&_graph) {

 	_graph.first(*static_cast<Edge*>(this));

       }

       EdgeIt(const Graph& _graph, const Edge& e) : 

 	Edge(e), graph(&_graph) { }

       EdgeIt& operator++() { 

 	graph->next(*this);

 	return *this; 

       }

     };

     class OutEdgeIt : public Edge { 

       const Graph* graph;

     public:

       OutEdgeIt() { }

       OutEdgeIt(Invalid i) : Edge(i) { }

       OutEdgeIt(const Graph& _graph, const Node& node) 

 	: graph(&_graph) {

 	_graph.firstOut(*this, node);

       }

       OutEdgeIt(const Graph& _graph, const Edge& edge) 

 	: Edge(edge), graph(&_graph) {}

       OutEdgeIt& operator++() { 

 	graph->nextOut(*this);

 	return *this; 

       }

     };

     class InEdgeIt : public Edge { 

       const Graph* graph;

     public:

       InEdgeIt() { }

       InEdgeIt(Invalid i) : Edge(i) { }

       InEdgeIt(const Graph& _graph, const Node& node) 

 	: graph(&_graph) {

 	_graph.firstIn(*this, node);

       }

       InEdgeIt(const Graph& _graph, const Edge& edge) : 

 	Edge(edge), graph(&_graph) {}

       InEdgeIt& operator++() { 

 	graph->nextIn(*this);

 	return *this; 

       }

     };

     /// Base node of the iterator

     ///

     /// Returns the base node (ie. the source in this case) of the iterator

     ///

     /// \todo Document in the concept!

     Node baseNode(const OutEdgeIt &e) const {

       return source(e);

     }

     /// Running node of the iterator

     ///

     /// Returns the running node (ie. the target in this case) of the

     /// iterator

     ///

     /// \todo Document in the concept!

     Node runningNode(const OutEdgeIt &e) const {

       return target(e);

     }

     /// Base node of the iterator

     ///

     /// Returns the base node (ie. the target in this case) of the iterator

     ///

     /// \todo Document in the concept!

     Node baseNode(const InEdgeIt &e) const {

       return target(e);

     }

     /// Running node of the iterator

     ///

     /// Returns the running node (ie. the source in this case) of the

     /// iterator

     ///

     /// \todo Document in the concept!

     Node runningNode(const InEdgeIt &e) const {

       return source(e);

     }

     using Parent::first;

   private:

     // /// \todo When (and if) we change the iterators concept to use operator*,

     // /// then the following shadowed methods will become superfluous.

     // /// But for now these are important safety measures.

     // void first(NodeIt &) const;

     // void first(EdgeIt &) const;

     // void first(OutEdgeIt &) const;

     // void first(InEdgeIt &) const;

   };

   template <typename _Base>

   class IterableUndirGraphExtender : public IterableGraphExtender<_Base> {

   public:

     /// Indicates that the graph is undirected.

     ///\todo Better name?

     ///

     ///\bug Should it be here?

     ///\bug Should be tested in the concept checker whether it is defined

     ///correctly.

     typedef True UndirTag;

     typedef IterableGraphExtender<_Base> Parent;

     typedef IterableUndirGraphExtender<_Base> Graph;

     typedef typename Parent::Node Node;

     typedef typename Parent::UndirEdge UndirEdge;

     class UndirEdgeIt : public Parent::UndirEdge { 

       const Graph* graph;

     public:

       UndirEdgeIt() { }

       UndirEdgeIt(Invalid i) : UndirEdge(i) { }

       explicit UndirEdgeIt(const Graph& _graph) : graph(&_graph) {

 	_graph.first(*static_cast<UndirEdge*>(this));

       }

       UndirEdgeIt(const Graph& _graph, const UndirEdge& e) : 

 	UndirEdge(e), graph(&_graph) { }

       UndirEdgeIt& operator++() { 

 	graph->next(*this);

 	return *this; 

       }

     };

     class IncEdgeIt : public Parent::UndirEdge { 

       const Graph* graph;

       bool forward;

       friend class IterableUndirGraphExtender;

       template <typename G>

       friend class UndirGraphExtender;

     public:

       IncEdgeIt() { }

       IncEdgeIt(Invalid i) : UndirEdge(i), forward(false) { }

       IncEdgeIt(const Graph& _graph, const Node &n)

 	: graph(&_graph)

       {

 	_graph._dirFirstOut(*this, n);

       }

       IncEdgeIt(const Graph& _graph, const UndirEdge &ue, const Node &n)

 	: graph(&_graph), UndirEdge(ue)

       {

 	forward = (_graph.source(ue) == n);

       }

       IncEdgeIt& operator++() {

 	graph->_dirNextOut(*this);

 	return *this; 

       }

     };

     using Parent::baseNode;

     using Parent::runningNode;

     /// Base node of the iterator

     ///

     /// Returns the base node of the iterator

     Node baseNode(const IncEdgeIt &e) const {

       return _dirSource(e);

     }

     /// Running node of the iterator

     ///

     /// Returns the running node of the iterator

     Node runningNode(const IncEdgeIt &e) const {

       return _dirTarget(e);

     }

   };

 }

 #endif // LEMON_GRAPH_EXTENDER_H