/* -*- C++ -*-

  *

  * This file is a part of LEMON, a generic C++ optimization library

  *

  * Copyright (C) 2003-2006

  * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

  * (Egervary Research Group on Combinatorial Optimization, EGRES).

  *

  * Permission to use, modify and distribute this software is granted

  * provided that this copyright notice appears in all copies. For

  * precise terms see the accompanying LICENSE file.

  *

  * This software is provided "AS IS" with no warranty of any kind,

  * express or implied, and with no claim as to its suitability for any

  * purpose.

  *

  */

 #ifndef LEMON_SMART_GRAPH_H

 #define LEMON_SMART_GRAPH_H

 ///\ingroup graphs

 ///\file

 ///\brief SmartGraph class.

 #include <vector>

 #include <lemon/bits/invalid.h>

 #include <lemon/bits/graph_extender.h>

 #include <lemon/bits/utility.h>

 #include <lemon/bits/graph_extender.h>

 namespace lemon {

   class SmartGraph;

   ///Base of SmartGraph

   ///Base of SmartGraph

   ///

   class SmartGraphBase {

     friend class SmatGraph;

   protected:

     struct NodeT 

     {

       int first_in,first_out;      

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

     };

     struct EdgeT 

     {

       int target, source, 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 SmartGraphBase Graph;

     class Node;

     class Edge;

   public:

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

     SmartGraphBase(const SmartGraphBase &_g) 

       : nodes(_g.nodes), edges(_g.edges) { }

     typedef True NodeNumTag;

     typedef True EdgeNumTag;

     ///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 source(Edge e) const { return edges[e.n].source; }

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

     /// 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; }

     /// \brief Returns the node from its \c id.

     ///

     /// Returns the node from its \c id. If there is not node

     /// with the given id the effect of the function is undefinied.

     static Node nodeFromId(int id) { return Node(id);}

     /// \brief Returns the edge from its \c id.

     ///

     /// Returns the edge from its \c id. If there is not edge

     /// with the given id the effect of the function is undefinied.

     static Edge edgeFromId(int id) { return Edge(id);}

     Node addNode() {

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

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

       return n;

     }

     Edge addEdge(Node u, Node v) {

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

       edges[e.n].source=u.n; edges[e.n].target=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;

       return e;

     }

     void clear() {

       edges.clear();

       nodes.clear();

     }

     class Node {

       friend class SmartGraphBase;

       friend class SmartGraph;

     protected:

       int n;

       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;}

     };

     class Edge {

       friend class SmartGraphBase;

       friend class SmartGraph;

     protected:

       int n;

       Edge(int nn) {n=nn;}

     public:

       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;}

     };

     void first(Node& node) const {

       node.n = nodes.size() - 1;

     }

     static void next(Node& node) {

       --node.n;

     }

     void first(Edge& edge) const {

       edge.n = edges.size() - 1;

     }

     static void next(Edge& edge) {

       --edge.n;

     }

     void firstOut(Edge& edge, const Node& node) const {

       edge.n = nodes[node.n].first_out;

     }

     void nextOut(Edge& edge) const {

       edge.n = edges[edge.n].next_out;

     }

     void firstIn(Edge& edge, const Node& node) const {

       edge.n = nodes[node.n].first_in;

     }

     void nextIn(Edge& edge) const {

       edge.n = edges[edge.n].next_in;

     }

     Node _split(Node n, bool connect = true)

     {

       Node b = addNode();

       nodes[b.n].first_out=nodes[n.n].first_out;

       nodes[n.n].first_out=-1;

       for(int i=nodes[b.n].first_out;i!=-1;i++) edges[i].source=b.n;

       if(connect) addEdge(n,b);

       return b;

     }

   };

   typedef GraphExtender<SmartGraphBase> ExtendedSmartGraphBase;

   /// \ingroup graphs

   ///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 support only limited (only stack-like)

   ///node and edge deletions</b>.

   ///It conforms to 

   ///the \ref concept::Graph "Graph" concept.

   ///\sa concept::Graph.

   ///

   ///\author Alpar Juttner

   class SmartGraph : public ExtendedSmartGraphBase {

   public:

     typedef ExtendedSmartGraphBase Parent;

     class Snapshot;

     friend class Snapshot;

   protected:

     void restoreSnapshot(const Snapshot &s)

     {

       while(s.edge_num<edges.size()) {

 	Parent::getNotifier(Edge()).erase(Edge(edges.size()-1));

 	nodes[edges.back().target].first_in=edges.back().next_in;

 	nodes[edges.back().source].first_out=edges.back().next_out;

 	edges.pop_back();

       }

       //nodes.resize(s.nodes_num);

       while(s.node_num<nodes.size()) {

 	Parent::getNotifier(Node()).erase(Node(nodes.size()-1));

 	nodes.pop_back();

       }

     }    

   public:

     ///Split a node.

     ///This function splits a node. First a new node is added to the graph,

     ///then the source of each outgoing edge of \c n is moved to this new node.

     ///If \c connect is \c true (this is the default value), then a new edge

     ///from \c n to the newly created node is also added.

     ///\return The newly created node.

     ///

     ///\note The <tt>Edge</tt>s

     ///referencing a moved edge remain

     ///valid. However <tt>InEdge</tt>'s and <tt>OutEdge</tt>'s

     ///may be invalidated.

     ///\warning This functionality cannot be used together with the Snapshot

     ///feature.

     ///\todo It could be implemented in a bit faster way.

     Node split(Node n, bool connect = true) 

     {

       Node b = _split(n,connect);

       return b;

     }

     ///Class to make a snapshot of the graph and to restrore to it later.

     ///Class to make a snapshot of the graph and to restrore to it later.

     ///

     ///The newly added nodes and edges can be removed using the

     ///restore() function.

     ///\note After you restore a state, you cannot restore

     ///a later state, in other word you cannot add again the edges deleted

     ///by restore() using another Snapshot instance.

     ///

     class Snapshot 

     {

       SmartGraph *g;

     protected:

       friend class SmartGraph;

       unsigned int node_num;

       unsigned int edge_num;

     public:

       ///Default constructor.

       ///Default constructor.

       ///To actually make a snapshot you must call save().

       ///

       Snapshot() : g(0) {}

       ///Constructor that immediately makes a snapshot

       ///This constructor immediately makes a snapshot of the graph.

       ///\param _g The graph we make a snapshot of.

       Snapshot(SmartGraph &_g) :g(&_g) {

 	node_num=g->nodes.size();

 	edge_num=g->edges.size();

       }

       ///Make a snapshot.

       ///Make a snapshot of the graph.

       ///

       ///This function can be called more than once. In case of a repeated

       ///call, the previous snapshot gets lost.

       ///\param _g The graph we make the snapshot of.

       void save(SmartGraph &_g) 

       {

 	g=&_g;

 	node_num=g->nodes.size();

 	edge_num=g->edges.size();

       }

       ///Undo the changes until a snapshot.

       ///Undo the changes until a snapshot created by save().

       ///

       ///\note After you restored a state, you cannot restore

       ///a later state, in other word you cannot add again the edges deleted

       ///by restore().

       ///

       ///\todo This function might be called undo().

       void restore()

       {

 	g->restoreSnapshot(*this);

       }

     };

   };

 } //namespace lemon

 #endif //LEMON_SMART_GRAPH_H