// -*- 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