// -*- c++ -*-

#ifndef LEMON_ITERABLE_GRAPH_EXTENDER_H

#define LEMON_ITERABLE_GRAPH_EXTENDER_H

#include <lemon/invalid.h>

namespace lemon {

  template <typename _Base>

  class IterableGraphExtender : public _Base {

  public:

    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; 

      }

    };

    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:

    typedef IterableGraphExtender<_Base> Parent;

    typedef IterableUndirGraphExtender<_Base> Graph;

    typedef typename Parent::Node Node;

    typedef typename Parent::UndirEdge UndirEdge;

    class UndirEdgeIt : public 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 UndirEdge { 

      const Graph* graph;

      bool forward;

      friend class IterableUndirGraphExtender;

      template <typename G>

      friend class UndirGraphExtender;

    public:

      IncEdgeIt() { }

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

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

	: graph(&_graph)

      {

	_graph._dirFirstOut(*this, n);

      }

      // FIXME: Do we need this type of constructor here?

      // IncEdgeIt(const Graph& _graph, const Edge& e) : 

      //   UndirEdge(e), graph(&_graph), forward(_graph.forward(e)) { }

      // or

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

      //    Const UndirEdge &e) ... ?

      IncEdgeIt& operator++() {

	graph->_dirNextOut(*this);

	return *this; 

      }

    };

    Node source(const IncEdgeIt &e) const {

      return _dirSource(e);

    }

    /// \todo Shouldn't the "source" of an undirected edge be called "aNode"

    /// or something???

    using Parent::source;

    /// Target of the given Edge.

    Node target(const IncEdgeIt &e) const {

      return _dirTarget(e);

    }

    /// \todo Shouldn't the "target" of an undirected edge be called "bNode"

    /// or something???

    using Parent::target;

  };

}

#endif // LEMON_GRAPH_EXTENDER_H