// -*- mode:C++ -*-

 #ifndef HUGO_SMART_GRAPH_H

 #define HUGO_SMART_GRAPH_H

 ///\ingroup graphs

 ///\file

 ///\brief SmartGraph and SymSmartGraph classes.

 #include <vector>

 #include <climits>

 #include <hugo/invalid.h>

 #include <hugo/default_map.h>

 #include <hugo/sym_map.h>

 #include <hugo/map_registry.h>

 #include <hugo/map_defines.h>

 namespace hugo {

 /// \addtogroup graphs

 /// @{

 //  class SymSmartGraph;

   ///A smart graph class.

   ///This is a simple and fast graph implementation.

   ///It is also quite memory efficient, but at the price

   ///that <b> it does not support node and edge deletion</b>.

   ///It conforms to 

   ///the \ref skeleton::ExtendableGraph "ExtendableGraph" concept.

   ///\sa skeleton::ExtendableGraph.

   ///

   ///\todo Some member functions could be \c static.

   ///

   ///\todo A possibly useful functionality: a function saveState() would

   ///give back a data sturcture X and then the function restoreState(X)

   ///would remove the nodes and edges added after the call of saveState().

   ///Of course it should be used as a stack. (Maybe X is not necessary.)

   ///

   ///\author Alpar Juttner

   class SmartGraph {

     struct NodeT 

     {

       int first_in,first_out;      

       NodeT() : first_in(-1), first_out(-1) {}

     };

     struct EdgeT 

     {

       int head, tail, next_in, next_out;      

       //FIXME: is this necessary?

       EdgeT() : next_in(-1), next_out(-1) {}  

     };

     std::vector<NodeT> nodes;

     std::vector<EdgeT> edges;

   public:

     typedef SmartGraph Graph;

     class Node;

     class Edge;

     class NodeIt;

     class EdgeIt;

     class OutEdgeIt;

     class InEdgeIt;

     /// Creating map registries.

     CREATE_MAP_REGISTRIES;

     /// Creating node and edge maps.

     CREATE_MAPS(DefaultMap);

   public:

     SmartGraph() : nodes(), edges() { }

     SmartGraph(const SmartGraph &_g) : nodes(_g.nodes), edges(_g.edges) { }

     ///Number of nodes.

     int nodeNum() const { return nodes.size(); }

     ///Number of edges.

     int edgeNum() const { return edges.size(); }

     /// Maximum node ID.

     /// Maximum node ID.

     ///\sa id(Node)

     int maxNodeId() const { return nodes.size()-1; }

     /// Maximum edge ID.

     /// Maximum edge ID.

     ///\sa id(Edge)

     int maxEdgeId() const { return edges.size()-1; }

     Node tail(Edge e) const { return edges[e.n].tail; }

     Node head(Edge e) const { return edges[e.n].head; }

     NodeIt& first(NodeIt& v) const { 

       v=NodeIt(*this); return v; }

     EdgeIt& first(EdgeIt& e) const { 

       e=EdgeIt(*this); return e; }

     OutEdgeIt& first(OutEdgeIt& e, const Node v) const { 

       e=OutEdgeIt(*this,v); return e; }

     InEdgeIt& first(InEdgeIt& e, const Node v) const { 

       e=InEdgeIt(*this,v); return e; }

     /// Node ID.

     /// The ID of a valid Node is a nonnegative integer not greater than

     /// \ref maxNodeId(). The range of the ID's is not surely continuous

     /// and the greatest node ID can be actually less then \ref maxNodeId().

     ///

     /// The ID of the \ref INVALID node is -1.

     ///\return The ID of the node \c v. 

     static int id(Node v) { return v.n; }

     /// Edge ID.

     /// The ID of a valid Edge is a nonnegative integer not greater than

     /// \ref maxEdgeId(). The range of the ID's is not surely continuous

     /// and the greatest edge ID can be actually less then \ref maxEdgeId().

     ///

     /// The ID of the \ref INVALID edge is -1.

     ///\return The ID of the edge \c e. 

     static int id(Edge e) { return e.n; }

     Node addNode() {

       Node n; n.n=nodes.size();

       nodes.push_back(NodeT()); //FIXME: Hmmm...

       node_maps.add(n);

       return n;

     }

     Edge addEdge(Node u, Node v) {

       Edge e; e.n=edges.size(); edges.push_back(EdgeT()); //FIXME: Hmmm...

       edges[e.n].tail=u.n; edges[e.n].head=v.n;

       edges[e.n].next_out=nodes[u.n].first_out;

       edges[e.n].next_in=nodes[v.n].first_in;

       nodes[u.n].first_out=nodes[v.n].first_in=e.n;

       edge_maps.add(e);

       return e;

     }

     /// Finds an edge between two nodes.

     /// Finds an edge from node \c u to node \c v.

     ///

     /// If \c prev is \ref INVALID (this is the default value), then

     /// It finds the first edge from \c u to \c v. Otherwise it looks for

     /// the next edge from \c u to \c v after \c prev.

     /// \return The found edge or INVALID if there is no such an edge.

     Edge findEdge(Node u,Node v, Edge prev = INVALID) 

     {

       int e = (prev.n==-1)? nodes[u.n].first_out : edges[prev.n].next_out;

       while(e!=-1 && edges[e].tail!=v.n) e = edges[e].next_out;

       prev.n=e;

       return prev;

     }

     void clear() {

       edge_maps.clear();

       edges.clear();

       node_maps.clear();

       nodes.clear();

     }

     class Node {

       friend class SmartGraph;

       template <typename T> friend class NodeMap;

       friend class Edge;

       friend class OutEdgeIt;

       friend class InEdgeIt;

       friend class SymEdge;

     protected:

       int n;

       friend int SmartGraph::id(Node v); 

       Node(int nn) {n=nn;}

     public:

       Node() {}

       Node (Invalid) { n=-1; }

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

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

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

       //      ///Validity check

       //      operator bool() { return n!=-1; }

     };

     class NodeIt : public Node {

       const SmartGraph *G;

       friend class SmartGraph;

     public:

       NodeIt() : Node() { }

       NodeIt(const SmartGraph& _G,Node n) : Node(n), G(&_G) { }

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

       NodeIt(const SmartGraph& _G) : Node(_G.nodes.size()?0:-1), G(&_G) { }

       NodeIt &operator++() {

 	n=(n+2)%(G->nodes.size()+1)-1; 

 	return *this; 

       }

 //       ///Validity check

 //       operator bool() { return Node::operator bool(); }      

     };

     class Edge {

       friend class SmartGraph;

       template <typename T> friend class EdgeMap;

       //template <typename T> friend class SymSmartGraph::SymEdgeMap;      

       //friend Edge SymSmartGraph::opposite(Edge) const;

       friend class Node;

       friend class NodeIt;

     protected:

       int n;

       friend int SmartGraph::id(Edge e);

     public:

       /// An Edge with id \c n.

       /// \bug It should be

       /// obtained by a member function of the Graph.

       Edge(int nn) {n=nn;}

       Edge() { }

       Edge (Invalid) { n=-1; }

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

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

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

       ///\bug This is a workaround until somebody tells me how to

       ///make class \c SymSmartGraph::SymEdgeMap friend of Edge

       int &idref() {return n;}

       const int &idref() const {return n;} 

 //       ///Validity check

 //       operator bool() { return n!=-1; }

    };

     class EdgeIt : public Edge {

       const SmartGraph *G;

       friend class SmartGraph;

     public:

       EdgeIt(const SmartGraph& _G) : Edge(_G.edges.size()-1), G(&_G) { }

       EdgeIt(const SmartGraph& _G, Edge e) : Edge(e), G(&_G) { }

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

       EdgeIt() : Edge() { }

       ///\bug This is a workaround until somebody tells me how to

       ///make class \c SymSmartGraph::SymEdgeMap friend of Edge

       int &idref() {return n;}

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

 //       ///Validity check

 //       operator bool() { return Edge::operator bool(); }      

     };

     class OutEdgeIt : public Edge {

       const SmartGraph *G;

       friend class SmartGraph;

     public: 

       OutEdgeIt() : Edge() { }

       OutEdgeIt(const SmartGraph& _G, Edge e) : Edge(e), G(&_G) { }

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

       OutEdgeIt(const SmartGraph& _G,const Node v)

 	: Edge(_G.nodes[v.n].first_out), G(&_G) {}

       OutEdgeIt &operator++() { n=G->edges[n].next_out; return *this; }

 //       ///Validity check

 //       operator bool() { return Edge::operator bool(); }      

     };

     class InEdgeIt : public Edge {

       const SmartGraph *G;

       friend class SmartGraph;

     public: 

       InEdgeIt() : Edge() { }

       InEdgeIt(const SmartGraph& _G, Edge e) : Edge(e), G(&_G) { }

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

       InEdgeIt(const SmartGraph& _G,Node v)

 	: Edge(_G.nodes[v.n].first_in), G(&_G) { }

       InEdgeIt &operator++() { n=G->edges[n].next_in; return *this; }

 //       ///Validity check

 //       operator bool() { return Edge::operator bool(); }      

     };

   };

   ///Graph for bidirectional edges.

   ///The purpose of this graph structure is to handle graphs

   ///having bidirectional edges. Here the function \c addEdge(u,v) adds a pair

   ///of oppositely directed edges.

   ///There is a new edge map type called

   ///\ref SymSmartGraph::SymEdgeMap "SymEdgeMap"

   ///that complements this

   ///feature by

   ///storing shared values for the edge pairs. The usual

   ///\ref Graph::EdgeMap "EdgeMap"

   ///can be used

   ///as well.

   ///

   ///The oppositely directed edge can also be obtained easily

   ///using \ref opposite.

   ///\warning It shares the similarity with \ref SmartGraph that

   ///it is not possible to delete edges or nodes from the graph.

   //\sa SmartGraph.

   class SymSmartGraph : public SmartGraph

   {

   public:

     typedef SymSmartGraph Graph;

     /// Importing maps from the base class ListGraph.

     KEEP_MAPS(SmartGraph, SymSmartGraph);

     /// Creating symmetric map registry.

     CREATE_SYM_EDGE_MAP_REGISTRY;

     /// Creating symmetric edge map.

     CREATE_SYM_EDGE_MAP(DefaultMap);

     SymSmartGraph() : SmartGraph() { }

     SymSmartGraph(const SmartGraph &_g) : SmartGraph(_g) { }

     ///Adds a pair of oppositely directed edges to the graph.

     Edge addEdge(Node u, Node v)

     {

       Edge e = SmartGraph::addEdge(u,v);

       Edge f = SmartGraph::addEdge(v,u);

       sym_edge_maps.add(e);

       sym_edge_maps.add(f);

       return e;

     }

     ///The oppositely directed edge.

     ///Returns the oppositely directed

     ///pair of the edge \c e.

     static Edge opposite(Edge e)

     {

       Edge f;

       f.idref() = e.idref() - 2*(e.idref()%2) + 1;

       return f;

     }

   };

   /// @}  

 } //namespace hugo

 #endif //HUGO_SMART_GRAPH_H