// -*- c++ -*-

#ifndef HUGO_SKELETON_GRAPH_H

#define HUGO_SKELETON_GRAPH_H

///\ingroup skeletons

///\file

///\brief Declaration of GraphSkeleton.

#include <hugo/invalid.h>

#include <hugo/skeletons/maps.h>

/// The namespace of HugoLib

namespace hugo {

  namespace skeleton {

    /// \addtogroup skeletons

    /// @{

    /// An empty static 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 StaticGraphSkeleton

    {

    public:

      /// Defalult constructor.

      /// Defalult constructor.

      ///

      StaticGraphSkeleton() { }

      ///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?

//       StaticGraphSkeleton(const StaticGraphSkeleton& g) { }

      /// The base type of node iterators, 

      /// or in other words, the trivial node iterator.

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

      /// thus each kind of node iterator converts to this.

      /// More precisely each kind of node iterator should be inherited 

      /// from the trivial node iterator.

      class Node {

      public:

	/// Default constructor

	/// @warning The default constructor sets the iterator

	/// to an undefined value.

	Node() { }

	/// Copy constructor.

	/// Copy constructor.

	///

	Node(const Node&) { }

	/// Invalid constructor \& conversion.

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

	/// \sa Invalid for more details.

	Node(Invalid) { }

	/// Equality operator

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

	/// same object or both are invalid.

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

	/// Inequality operator

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

	///

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

 	///Comparison operator.

	///This is a strict ordering between the nodes.

	///

	///This ordering can be different from the order in which NodeIt

	///goes through the nodes.

	///\todo Possibly we don't need it.

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

      };

      /// This iterator goes through each node.

      /// This iterator goes through each node.

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

      /// of nodes in graph \c g of type \c Graph like this:

      /// \code

      /// int count=0;

      /// for (Graph::NodeIt n(g); n!=INVALID; ++n) ++count;

      /// \endcode

      class NodeIt : public Node {

      public:

	/// Default constructor

	/// @warning The default constructor sets the iterator

	/// to an undefined value.

	NodeIt() { }

	/// Copy constructor.

	/// Copy constructor.

	///

	NodeIt(const NodeIt&) { }

	/// Invalid constructor \& conversion.

	/// Initialize the iterator to be invalid.

	/// \sa Invalid for more details.

	NodeIt(Invalid) { }

	/// Sets the iterator to the first node.

	/// Sets the iterator to the first node of \c g.

	///

	NodeIt(const StaticGraphSkeleton& g) { }

	/// Node -> NodeIt conversion.

	/// Sets the iterator to the node of \c g pointed by the trivial 

	/// iterator n.

	/// This feature necessitates that each time we 

	/// iterate the edge-set, the iteration order is the same.

	NodeIt(const StaticGraphSkeleton& g, const Node& n) { }

	/// Next node.

	/// Assign the iterator to the next node.

	///

	NodeIt& operator++() { return *this; }

      };

      /// The base type of the edge iterators.

      /// The base type of the edge iterators.

      ///

      class Edge {

      public:

	/// Default constructor

	/// @warning The default constructor sets the iterator

	/// to an undefined value.

	Edge() { }

	/// Copy constructor.

	/// Copy constructor.

	///

	Edge(const Edge&) { }

	/// Initialize the iterator to be invalid.

	/// Initialize the iterator to be invalid.

	///

	Edge(Invalid) { }

	/// Equality operator

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

	/// same object or both are invalid.

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

	/// Inequality operator

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

	///

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

 	///Comparison operator.

	///This is a strict ordering between the nodes.

	///

	///This ordering can be different from the order in which NodeIt

	///goes through the nodes.

	///\todo Possibly we don't need it.

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

      };

      /// 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); e!=INVALID; ++e) ++count;

      /// \endcode

      class OutEdgeIt : public Edge {

      public:

	/// Default constructor

	/// @warning The default constructor sets the iterator

	/// to an undefined value.

	OutEdgeIt() { }

	/// Copy constructor.

	/// Copy constructor.

	///

	OutEdgeIt(const OutEdgeIt&) { }

	/// Initialize the iterator to be invalid.

	/// Initialize the iterator to be invalid.

	///

	OutEdgeIt(Invalid) { }

	/// 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 StaticGraphSkeleton& g, const Node& n) { }

	/// Edge -> OutEdgeIt conversion

	/// Sets the iterator to the value of the trivial iterator \c e.

	/// This feature necessitates that each time we 

	/// iterate the edge-set, the iteration order is the same.

	OutEdgeIt(const StaticGraphSkeleton& g, const Edge& e) { }

	///Next outgoing edge

	/// Assign the iterator to the next 

	/// outgoing edge of the corresponding node.

	OutEdgeIt& operator++() { return *this; }

      };

      /// 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 outgoing 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); e!=INVALID; ++e) ++count;

      /// \endcode

      class InEdgeIt : public Edge {

      public:

	/// Default constructor

	/// @warning The default constructor sets the iterator

	/// to an undefined value.

	InEdgeIt() { }

	/// Copy constructor.

	/// Copy constructor.

	///

	InEdgeIt(const InEdgeIt&) { }

	/// Initialize the iterator to be invalid.

	/// Initialize the iterator to be invalid.

	///

	InEdgeIt(Invalid) { }

	/// This constructor sets the iterator to first incoming edge.

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

	/// node

	///@param n the node

	///@param g the graph

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

	/// Edge -> InEdgeIt conversion

	/// Sets the iterator to the value of the trivial iterator \c e.

	/// This feature necessitates that each time we 

	/// iterate the edge-set, the iteration order is the same.

	InEdgeIt(const StaticGraphSkeleton& g, const Edge& n) { }

	/// Next incoming edge

	/// Assign the iterator to the next inedge of the corresponding node.

	///

	InEdgeIt& operator++() { return *this; }

      };

      /// This iterator goes through each edge.

      /// This iterator goes through each edge of a graph.

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

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

      /// \code

      /// int count=0;

      /// for(Graph::EdgeIt e(g); e!=INVALID; ++e) ++count;

      /// \endcode

      class EdgeIt : public Edge {

      public:

	/// Default constructor

	/// @warning The default constructor sets the iterator

	/// to an undefined value.

	EdgeIt() { }

	/// Copy constructor.

	/// Copy constructor.

	///

	EdgeIt(const EdgeIt&) { }

	/// Initialize the iterator to be invalid.

	/// Initialize the iterator to be invalid.

	///

	EdgeIt(Invalid) { }

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

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

	/// node

	///@param g the graph

	EdgeIt(const StaticGraphSkeleton& g) { }

	/// Edge -> EdgeIt conversion

	/// Sets the iterator to the value of the trivial iterator \c e.

	/// This feature necessitates that each time we 

	/// iterate the edge-set, the iteration order is the same.

	EdgeIt(const StaticGraphSkeleton&, const Edge&) { } 

    	///Next edge

	/// Assign the iterator to the next 

	/// edge of the corresponding node.

	EdgeIt& operator++() { return *this; }

      };

      /// First node of the graph.

      /// \retval i the first node.

      /// \return the first node.

      ///

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

      /// The first incoming edge.

      /// The first incoming edge.

      ///

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

      /// The first outgoing edge.

      /// The first outgoing edge.

      ///

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

      /// The first edge of the Graph.

      /// The first edge of the Graph.

      ///

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

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

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

      ///

      Node head(Edge) const { return INVALID; }

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

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

      ///

      Node tail(Edge) const { return INVALID; }

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

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

      ///

      ///\todo Should each graph provide \c id?

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

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

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

      ///

      ///\todo Should each graph provide \c id?

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

      /// .

      ///\todo What is this?

      ///

      int nodeNum() const { return 0; }

      /// .

      ///\todo What is this?

      ///

      int edgeNum() const { return 0; }

      ///Reference map of the nodes to type \c T.

      ///Reference map of the nodes to type \c T.

      /// \sa ReferenceSkeleton

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

      /// needs some extra attention!

      template<class T> class NodeMap: public ReferenceMap< Node, T >

      {

      public:

	/// .

	NodeMap(const StaticGraphSkeleton&) { }

	/// .

	NodeMap(const StaticGraphSkeleton&, T) { }

	///Copy constructor

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

	///Assignment operator

	template<typename TT> NodeMap& operator=(const NodeMap<TT>&)

	{ return *this; }

      };

      ///Reference map of the edges to type \c T.

      ///Reference map of the edges to type \c T.

      /// \sa ReferenceSkeleton

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

      /// needs some extra attention!

      template<class T> class EdgeMap

	: public ReferenceMap<Edge,T>

      {

      public:

	/// .

	EdgeMap(const StaticGraphSkeleton&) { }

	/// .

	EdgeMap(const StaticGraphSkeleton&, T) { }

	///Copy constructor

	template<typename TT> EdgeMap(const EdgeMap<TT>&) { }

	///Assignment operator

	template<typename TT> EdgeMap &operator=(const EdgeMap<TT>&)

	{ return *this; }

      };

    };

    /// An empty non-static graph class.

    /// This class provides everything that \c StaticGraphSkeleton

    /// with additional functionality which enables to build a

    /// graph from scratch.

    class ExtendableGraphSkeleton : public StaticGraphSkeleton

    {

    public:

      /// Defalult constructor.

      /// Defalult constructor.

      ///

      ExtendableGraphSkeleton() { }

      ///Add a new node to the graph.

      /// \return the new node.

      ///

      Node addNode() { return INVALID; }

      ///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(Node, Node) { return INVALID; }

      /// Resets the graph.

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

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

      /// \todo It might belong to \c ErasableGraphSkeleton.

      void clear() { }

    };

    /// An empty erasable graph class.

    /// This class is an extension of \c GraphSkeleton. It also makes it

    /// possible to erase edges or nodes.

    class ErasableGraphSkeleton : public ExtendableGraphSkeleton

    {

    public:

      /// Defalult constructor.

      /// Defalult constructor.

      ///

      ErasableGraphSkeleton() { }

      /// Deletes a node.

      /// Deletes node \c n node.

      ///

      void erase(Node n) { }

      /// Deletes an edge.

      /// Deletes edge \c e edge.

      ///

      void erase(Edge e) { }

    };

    // @}

  } //namespace skeleton  

} //namespace hugo

#endif // HUGO_SKELETON_GRAPH_H