// -*- c++ -*-

#ifndef LEMON_GRAPH_H

#define LEMON_GRAPH_H

///\file

///\brief Declaration of GraphConcept.

#include <lemon/invalid.h>

namespace lemon {

  /// @defgroup empty_graph The GraphConcept class

  /// @{

  /// An empty graph class.

  /// This class provides all the common features of a graph structure,

  /// however completely without implementations and real data structures

  /// behind the interface.

  /// All graph algorithms should compile with this class, but it will not

  /// run properly, of course.

  ///

  /// It can be used for checking the interface compatibility,

  /// or it can serve as a skeleton of a new graph structure.

  /// 

  /// Also, you will find here the full documentation of a certain graph

  /// feature, the documentation of a real graph imlementation

  /// like @ref ListGraph or

  /// @ref SmartGraph will just refer to this structure.

  class GraphConcept

  {

  public:

    /// Defalult constructor.

    GraphConcept() { }

    /// \brief Copy consructor.

    /// 

    /// \todo It is not clear, what we expect from a copy constructor.

    /// E.g. How to assign the nodes/edges to each other? What about maps?

    GraphConcept(const GraphConcept&) { }

    /// \brief The base type of the node iterators.

    ///

    /// This is the base type of each node iterators,

    /// thus each kind of node iterator will convert to this.

    /// Sometimes it is said to be a trivial iterator.

    class Node {

    public:

      /// @warning The default constructor sets the iterator

      /// to an undefined value.

      Node() { }   //FIXME

      // /// Copy constructor.

      // Node(const Node&) { }

      /// \brief Invalid constructor \& conversion.

      /// 

      /// This constructor initializes the iterator to be invalid.

      /// \sa Invalid for more details.

      Node(const Invalid&) { }

      /// Two iterators are equal if and only if they point to the

      /// same object or both are invalid.

      bool operator==(Node n) const { return true; }

      /// \sa \ref operator==(Node n)

      ///

      bool operator!=(Node n) const { return true; }

      bool operator<(Node n) const { return true; }

    };

    /// The base type of the edge iterators.

    class Edge {

    public:

      /// @warning The default constructor sets the iterator

      /// to an undefined value.

      Edge() { }   //FIXME

      // /// Copy constructor.

      // Edge(const Edge&) { }

      /// Initialize the iterator to be invalid

      Edge(const Invalid&) { }

      /// Two iterators are equal if and only if they point to the

      /// same object or both are invalid.

      bool operator==(Edge n) const { return true; }

      bool operator!=(Edge n) const { return true; }

      bool operator<(Edge n) const { return true; }

    };

    //  class SymEdgeIt : public Edge {};

    //  SymEdgeIt &first(SymEdgeIt &, Node) const { return i;}

//     Node getNext(Node) const {}

//     InEdgeIt getNext(InEdgeIt) const {}

//     OutEdgeIt getNext(OutEdgeIt) const {}

//     //SymEdgeIt getNext(SymEdgeIt) const {}

//     EdgeIt getNext(EdgeIt) const {}

    //SymEdgeIt &next(SymEdgeIt &) const {}

    /// Gives back the head node of an edge.

    Node head(const Edge&) const { return INVALID; }

    /// Gives back the tail node of an edge.

    Node tail(const Edge&) const { return INVALID; }

    //   Node aNode(SymEdgeIt) const {}

    //   Node bNode(SymEdgeIt) const {}

    /// \brief Checks if a node iterator is valid

    /// 

    /// \todo Maybe, it would be better if iterator converted to

    /// bool directly, as Jacint prefers.

    bool valid(const Node&) const { return true; }

    /// \brief Checks if an edge iterator is valid

    /// 

    /// \todo Maybe, it would be better if iterator converted to

    /// bool directly, as Jacint prefers.

    bool valid(const Edge&) const { return true; }

    /// \brief Gives back the \e id of a node.

    /// 

    /// \warning Not all graph structures provide this feature.

    ///

    int id(const Node&) const { return 0; }

    /// \brief Gives back the \e id of an edge.

    ///

    /// \warning Not all graph structures provide this feature.

    ///

    int id(const Edge&) const { return 0; }

    //void setInvalid(Node &) const {};

    //void setInvalid(Edge &) const {};

    /// \brief Add a new node to the graph.

    ///

    /// \return the new node.

    Node addNode() { return INVALID; }

    /// \brief Add a new edge to the graph.

    ///

    /// Add a new edge to the graph with tail node \c tail

    /// and head node \c head.

    /// \return the new edge.

    Edge addEdge(const Node& tail, const Node& head) { return INVALID; }

    /// \brief Resets the graph.

    /// 

    /// This function deletes all edges and nodes of the graph.

    /// It also frees the memory allocated to store them.

    /// \todo What happens with the maps?

    void clear() { }

    /// Read/write/reference map of the nodes to type \c T.

    /// Read/write/reference map of the nodes to type \c T.

    /// \sa MemoryMapConcept

    /// \todo We may need copy constructor

    /// \todo We may need conversion from other nodetype

    /// \todo We may need operator=

    /// \warning Making maps that can handle bool type (NodeMap<bool>)

    /// needs extra attention!

    template<class T> class NodeMap

    {

    public:

      typedef T ValueType;

      typedef Node KeyType;

      NodeMap(const GraphConcept& g) { }

      NodeMap(const GraphConcept& g, T t) { }

      template<typename TT> NodeMap(const NodeMap<TT>& m) { }

      /// Sets the value of a node.

      /// Sets the value associated with node \c i to the value \c t.

      ///

      void set(Node i, T t) {}

      /// Gets the value of a node.

      T get(Node i) const {return *(T*)0;}  //FIXME: Is it necessary

      T &operator[](Node i) {return *(T*)0;}

      const T &operator[](Node i) const {return *(T*)0;}

      /// Updates the map if the graph has been changed

      /// \todo Do we need this?

      ///

      void update() { }

      //void update(T a) { }   //FIXME: Is it necessary

    };

    ///Read/write/reference map of the edges to type \c T.

    /// Read/write/reference map of the edges to type \c T.

    /// It behaves exactly in the same way as \ref NodeMap.

    /// \sa NodeMap

    /// \sa MemoryMapConcept

    /// \todo We may need copy constructor

    /// \todo We may need conversion from other edgetype

    /// \todo We may need operator=

    template<class T> class EdgeMap

    {

    public:

      typedef T ValueType;

      typedef Edge KeyType;

      EdgeMap(const GraphConcept& g) {}

      EdgeMap(const GraphConcept& g, T t) {}

      void set(Edge i, T t) {}

      T get(Edge i) const {return *(T*)0;}

      T &operator[](Edge i) {return *(T*)0;}

      void update() { }

      //void update(T a) { }   //FIXME: Is it necessary

    };

  };

  /// \brief Node-iterable graph concept.

  ///

  /// A graph class which provides functions to 

  /// iterate on its nodes.

  class NodeIterableGraphConcept : virtual public GraphConcept

  {

  public:

    /// \brief This iterator goes trough the nodes of the graph.

    ///

    /// This iterator goes trough the \e nodes of the graph.

    /// Its usage is quite simple, for example you can count the number

    /// of nodes in graph \c g of type \c Graph as follows.

    /// \code

    /// int count=0;

    /// for(Graph::NodeIt n(g); g.valid(n); g.next(n)) ++count;

    /// \endcode

    class NodeIt : public Node {

    public:

      /// @warning The default constructor sets the iterator.

      /// to an undefined value.

      NodeIt() { }

      // /// Copy constructor

      //NodeIt(const NodeIt& n) { }

      /// Initialize the iterator to be invalid.

      NodeIt(const Invalid&) { }

      /// \brief This constructor sets the iterator to first node.

      ///

      /// This constructor set the iterator to the first 

      /// node of the graph \c g.

      ///

      ///@param g the graph

      NodeIt(const GraphConcept& g) { }

    };

    /// The first node.

    NodeIt &first(NodeIt &i) const { return i; }

    /// Go to the next node.

    NodeIt &next(NodeIt &i) const { return i; }

  };

  /// \brief Edge-iterable graph concept.

  ///

  /// A graph class which provides functions to 

  /// iterate on its edges.

  class EdgeIterableGraphConcept : virtual public GraphConcept

  {

  public:

    /// \brief This iterator goes trough the edges of the graph.

    ///

    /// This iterator goes trough the \e edges of the graph.

    /// Its usage is quite simple, for example you can count the number

    /// of edges in graph \c g of type \c Graph as follows.

    /// \code

    /// int count=0;

    /// for(Graph::EdgeIt e(g); g.valid(e); g.next(e)) ++count;

    /// \endcode

    class EdgeIt : public Edge {

    public:

      /// @warning The default constructor sets the iterator.

      /// to an undefined value.

      EdgeIt() { }

      // /// Copy constructor

      // EdgeIt(const EdgeIt&) { }

      /// Initialize the iterator to be invalid.

      EdgeIt(const Invalid&) { }

      /// \brief This constructor sets the iterator to first edge.

      ///

      /// This constructor set the iterator to the first 

      /// edge of the graph \c g.

      ///

      ///@param g the graph

      EdgeIt(const GraphConcept& g) { }

    };

    /// The first edge.

    EdgeIt &first(EdgeIt &i) const { return i; }

    /// Go to the next edge.

    EdgeIt &next(EdgeIt &i) const { return i; }

  };

  /// \brief Out-edge-iterable graph concept.

  ///

  /// A graph class which provides functions to 

  /// iterate on out-edges of any node.

  class OutEdgeIterableGraphConcept : virtual public GraphConcept

  {

  public:

    /// \brief This iterator goes trough the outgoing edges of a node.

    ///

    /// This iterator goes trough the \e outgoing edges of a certain node

    /// of a graph.

    /// Its usage is quite simple, for example you can count the number

    /// of outgoing edges of a node \c n

    /// in graph \c g of type \c Graph as follows.

    /// \code

    /// int count=0;

    /// for(Graph::OutEdgeIt e(g, n); g.valid(e); g.next(e)) ++count;

    /// \endcode

    class OutEdgeIt : public Edge {

    public:

      /// @warning The default constructor sets the iterator.

      /// to an undefined value.

      OutEdgeIt() { }

      /// Initialize the iterator to be invalid.

      OutEdgeIt(const Invalid&) { }

      /// \brief This constructor sets the iterator to first outgoing edge.

      ///

      /// This constructor set the iterator to the first outgoing edge of

      /// node

      ///@param n the node

      ///@param g the graph

      OutEdgeIt(const GraphConcept& g, const Node& n) { }

    };

    /// The first outgoing edge.

    OutEdgeIt &first(OutEdgeIt &i, const Node& n) const { return i; }

    /// Go to the next outgoing edge.

    OutEdgeIt &next(OutEdgeIt &i) const { return i; }

    Node aNode(const OutEdgeIt&) const { return Node(); }

    Node bNode(const OutEdgeIt&) const { return Node(); }

  };

  /// \brief In-edge-iterable graph concept.

  ///

  /// A Graph class which provides a function to 

  /// iterate on in-edges of any node.

  class InEdgeIterableGraphConcept : virtual public GraphConcept

  {

  public:

    /// \brief This iterator goes trough the incoming edges of a node.

    /// 

    /// This iterator goes trough the \e incoming edges of a certain node

    /// of a graph.

    /// Its usage is quite simple, for example you can count the number

    /// of incoming edges of a node \c n

    /// in graph \c g of type \c Graph as follows.

    /// \code

    /// int count=0;

    /// for(Graph::InEdgeIt e(g, n); g.valid(e); g.next(e)) ++count;

    /// \endcode

    class InEdgeIt : public Edge {

    public:

      /// @warning The default constructor sets the iterator

      /// to an undefined value.

      InEdgeIt() { }

      /// Initialize the iterator to be invalid

      InEdgeIt(const Invalid&) { }

      /// \brief This constructor sets the iterator to first incomig edge.

      /// 

      /// This constructor set the iterator to the first incomig edge of

      /// node

      ///@param n the node

      ///@param g the graph

      InEdgeIt(const GraphConcept& g, const Node& n) { }

    };

    /// The first incoming edge.

    InEdgeIt &first(InEdgeIt &i, const Node& n) const { return i; }

    /// Go to the next incoming edge.

    InEdgeIt &next(InEdgeIt &i) const { return i; }

    Node aNode(const InEdgeIt&) const { return Node(); }

    Node bNode(const InEdgeIt&) const { return Node(); }

  };

  /// \brief Node-erasable graph concept.

  ///

  /// A graph class which provides a function to 

  /// delete any of its nodes.

  class NodeErasableGraphConcept : virtual public GraphConcept

  {

  public:

    /// Deletes a node.

    void erase(const Node& n) { }

  };

  /// \brief Edge-erasable graph concept.

  /// 

  /// A graph class which provides a function to delete any 

  /// of its edges.

  class EdgeErasableGraphConcept : virtual public GraphConcept

  {

  public:

    /// Deletes a node.

    void erase(const Edge& n) { }

  };

  /// \brief An empty graph class which provides a function to 

  /// get the number of its nodes.

  /// 

  /// This graph class provides a function for getting the number of its 

  /// nodes. 

  /// Clearly, for physical graph structures it can be expected to have such a 

  /// function. For wrappers or graphs which are given in an implicit way, 

  /// the implementation can be circumstantial, that is why this composes a 

  /// separate concept.

  class NodeCountingGraphConcept : virtual public GraphConcept

  {

  public:

    /// Returns the number of nodes.

    int nodeNum() const { return 0; }

  };

  /// \brief An empty graph class which provides a function to 

  /// get the number of its edges.

  /// 

  /// This graph class provides a function for getting the number of its 

  /// edges. 

  /// Clearly, for physical graph structures it can be expected to have such a 

  /// function. For wrappers or graphs which are given in an implicit way, 

  /// the implementation can be circumstantial, that is why this composes a 

  /// separate concept.

  class EdgeCountingGraphConcept : virtual public GraphConcept

  {

  public:

    /// Returns the number of edges.

    int edgeNum() const { return 0; }

  };

  class FullFeatureGraphConcept : virtual public NodeIterableGraphConcept,

				  virtual public EdgeIterableGraphConcept, 

				  virtual public OutEdgeIterableGraphConcept, 

				  virtual public InEdgeIterableGraphConcept, 

				  virtual public NodeCountingGraphConcept {

  public:

    FullFeatureGraphConcept() { }

    using EdgeIterableGraphConcept::next;

    using NodeIterableGraphConcept::next;

    using OutEdgeIterableGraphConcept::next;    

    using InEdgeIterableGraphConcept::next;

  };

  /// @}

} //namespace lemon

// class EmptyBipGraph : public Graph Concept

// {

//   class ANode {};

//   class BNode {};

//   ANode &next(ANode &) {}

//   BNode &next(BNode &) {}

//   ANode &getFirst(ANode &) const {}

//   BNode &getFirst(BNode &) const {}

//   enum NodeClass { A = 0, B = 1 };

//   NodeClass getClass(Node n) {}

// }

#endif // LEMON_GRAPH_H