/* -*- C++ -*-

  * src/lemon/list_graph.h - Part of LEMON, a generic C++ optimization library

  *

  * Copyright (C) 2004 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

  * (Egervary Combinatorial Optimization Research Group, 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_LIST_GRAPH_H

 #define LEMON_LIST_GRAPH_H

 ///\ingroup graphs

 ///\file

 ///\brief ListGraph, SymListGraph, NodeSet and EdgeSet classes.

 #include <lemon/erasable_graph_extender.h>

 #include <lemon/clearable_graph_extender.h>

 #include <lemon/extendable_graph_extender.h>

 #include <lemon/iterable_graph_extender.h>

 #include <lemon/alteration_observer_registry.h>

 #include <lemon/default_map.h>

 #include <list>

 namespace lemon {

   class ListGraphBase {

   protected:

     struct NodeT {

       int first_in,first_out;

       int prev, next;

     };

     struct EdgeT {

       int target, source;

       int prev_in, prev_out;

       int next_in, next_out;

     };

     std::vector<NodeT> nodes;

     int first_node;

     int first_free_node;

     std::vector<EdgeT> edges;

     int first_free_edge;

   public:

     typedef ListGraphBase Graph;

     class Node {

       friend class ListGraphBase;

     protected:

       int id;

       Node(int pid) { id = pid;}

     public:

       Node() {}

       Node (Invalid) { id = -1; }

       bool operator==(const Node& node) const {return id == node.id;}

       bool operator!=(const Node& node) const {return id != node.id;}

       bool operator<(const Node& node) const {return id < node.id;}

     };

     class Edge {

       friend class ListGraphBase;

     protected:

       int id;

       Edge(int pid) { id = pid;}

     public:

       Edge() {}

       Edge (Invalid) { id = -1; }

       bool operator==(const Edge& edge) const {return id == edge.id;}

       bool operator!=(const Edge& edge) const {return id != edge.id;}

       bool operator<(const Edge& edge) const {return id < edge.id;}

     };

     ListGraphBase()

       : nodes(), first_node(-1),

 	first_free_node(-1), edges(), first_free_edge(-1) {}

     /// Maximum node ID.

     /// Maximum node ID.

     ///\sa id(Node)

     int maxId(Node = INVALID) const { return nodes.size()-1; } 

     /// Maximum edge ID.

     /// Maximum edge ID.

     ///\sa id(Edge)

     int maxId(Edge = INVALID) const { return edges.size()-1; }

     Node source(Edge e) const { return edges[e.id].source; }

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

     void first(Node& node) const { 

       node.id = first_node;

     }

     void next(Node& node) const {

       node.id = nodes[node.id].next;

     }

     void first(Edge& e) const { 

       int n;

       for(n = first_node; 

 	  n!=-1 && nodes[n].first_in == -1; 

 	  n = nodes[n].next);

       e.id = (n == -1) ? -1 : nodes[n].first_in;

     }

     void next(Edge& edge) const {

       if (edges[edge.id].next_in != -1) {

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

       } else {

 	int n;

 	for(n = nodes[edges[edge.id].target].next;

 	  n!=-1 && nodes[n].first_in == -1; 

 	  n = nodes[n].next);

 	edge.id = (n == -1) ? -1 : nodes[n].first_in;

       }      

     }

     void firstOut(Edge &e, const Node& v) const {

       e.id = nodes[v.id].first_out;

     }

     void nextOut(Edge &e) const {

       e.id=edges[e.id].next_out;

     }

     void firstIn(Edge &e, const Node& v) const {

       e.id = nodes[v.id].first_in;

     }

     void nextIn(Edge &e) const {

       e.id=edges[e.id].next_in;

     }

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

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

     /// Adds a new node to the graph.

     /// \warning It adds the new node to the front of the list.

     /// (i.e. the lastly added node becomes the first.)

     Node addNode() {     

       int n;

       if(first_free_node==-1) {

 	n = nodes.size();

 	nodes.push_back(NodeT());

       } else {

 	n = first_free_node;

 	first_free_node = nodes[n].next;

       }

       nodes[n].next = first_node;

       if(first_node != -1) nodes[first_node].prev = n;

       first_node = n;

       nodes[n].prev = -1;

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

       return Node(n);

     }

     Edge addEdge(Node u, Node v) {

       int n;      

       if (first_free_edge == -1) {

 	n = edges.size();

 	edges.push_back(EdgeT());

       } else {

 	n = first_free_edge;

 	first_free_edge = edges[n].next_in;

       }

       edges[n].source = u.id; 

       edges[n].target = v.id;

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

       if(nodes[u.id].first_out != -1) {

 	edges[nodes[u.id].first_out].prev_out = n;

       }

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

       if(nodes[v.id].first_in != -1) {

 	edges[nodes[v.id].first_in].prev_in = n;

       }

       edges[n].prev_in = edges[n].prev_out = -1;

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

       return Edge(n);

     }

     void erase(const Node& node) {

       int n = node.id;

       if(nodes[n].next != -1) {

 	nodes[nodes[n].next].prev = nodes[n].prev;

       }

       if(nodes[n].prev != -1) {

 	nodes[nodes[n].prev].next = nodes[n].next;

       } else {

 	first_node = nodes[n].next;

       }

       nodes[n].next = first_free_node;

       first_free_node = n;

     }

     void erase(const Edge& edge) {

       int n = edge.id;

       if(edges[n].next_in!=-1) {

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

       }

       if(edges[n].prev_in!=-1) {

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

       } else {

 	nodes[edges[n].target].first_in = edges[n].next_in;

       }

       if(edges[n].next_out!=-1) {

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

       } 

       if(edges[n].prev_out!=-1) {

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

       } else {

 	nodes[edges[n].source].first_out = edges[n].next_out;

       }

       edges[n].next_in = first_free_edge;

       first_free_edge = n;      

     }

     void clear() {

       edges.clear();

       nodes.clear();

       first_node = first_free_node = first_free_edge = -1;

     }

   protected:

     void _moveTarget(Edge e, Node n) 

     {

       if(edges[e.id].next_in != -1)

 	edges[edges[e.id].next_in].prev_in = edges[e.id].prev_in;

       if(edges[e.id].prev_in != -1)

 	edges[edges[e.id].prev_in].next_in = edges[e.id].next_in;

       else nodes[edges[e.id].target].first_in = edges[e.id].next_in;

       edges[e.id].target = n.id;

       edges[e.id].prev_in = -1;

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

       nodes[n.id].first_in = e.id;

     }

     void _moveSource(Edge e, Node n) 

     {

       if(edges[e.id].next_out != -1)

 	edges[edges[e.id].next_out].prev_out = edges[e.id].prev_out;

       if(edges[e.id].prev_out != -1)

 	edges[edges[e.id].prev_out].next_out = edges[e.id].next_out;

       else nodes[edges[e.id].source].first_out = edges[e.id].next_out;

       edges[e.id].source = n.id;

       edges[e.id].prev_out = -1;

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

       nodes[n.id].first_out = e.id;

     }

   };

   typedef AlterableGraphExtender<ListGraphBase> AlterableListGraphBase;

   typedef IterableGraphExtender<AlterableListGraphBase> IterableListGraphBase;

   typedef DefaultMappableGraphExtender<IterableListGraphBase> MappableListGraphBase;

   typedef ExtendableGraphExtender<MappableListGraphBase> ExtendableListGraphBase;

   typedef ClearableGraphExtender<ExtendableListGraphBase> ClearableListGraphBase;

   typedef ErasableGraphExtender<ClearableListGraphBase> ErasableListGraphBase;

 /// \addtogroup graphs

 /// @{

   ///A list graph class.

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

   ///

   ///It addition that it conforms to the

   ///\ref concept::ErasableGraph "ErasableGraph" concept,

   ///it also provides several additional useful extra functionalities.

   ///\sa concept::ErasableGraph.

   class ListGraph : public ErasableListGraphBase 

   {

   public:

     /// Moves the target of \c e to \c n

     /// Moves the target of \c e to \c n

     ///

     ///\note The <tt>Edge</tt>'s and <tt>OutEdge</tt>'s

     ///referencing the moved edge remain

     ///valid. However <tt>InEdge</tt>'s are invalidated.

     void moveTarget(Edge e, Node n) { _moveTarget(e,n); }

     /// Moves the source of \c e to \c n

     /// Moves the source of \c e to \c n

     ///

     ///\note The <tt>Edge</tt>'s and <tt>InEdge</tt>'s

     ///referencing the moved edge remain

     ///valid. However <tt>OutEdge</tt>'s are invalidated.

     void moveSource(Edge e, Node n) { _moveSource(e,n); }

     /// Invert the direction of an edge.

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

     ///referencing the moved edge remain

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

     void reverseEdge(Edge e) {

       Node t=target(e);

       _moveTarget(e,source(e));

       _moveSource(e,t);

     }

     ///Using this it possible to avoid the superfluous memory allocation.

     ///Using this it possible to avoid the superfluous memory allocation.

     ///\todo more docs...

     void reserveEdge(int n) { edges.reserve(n); };

     ///Contract two nodes.

     ///This function contracts two nodes.

     ///

     ///Node \p b will be removed but instead of deleting

     ///its neighboring edges, they will be joined to \p a.

     ///The last parameter \p r controls whether to remove loops. \c true

     ///means that loops will be removed.

     ///

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

     ///referencing the moved edge remain

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

     ///may be invalidated.

     void contract(Node a,Node b,bool r=true) 

     {

       for(OutEdgeIt e(*this,b);e!=INVALID;) {

 	OutEdgeIt f=e;

 	++f;

 	if(r && target(e)==a) erase(e);

 	else moveSource(e,b);

 	e=f;

       }

       for(InEdgeIt e(*this,b);e!=INVALID;) {

 	InEdgeIt f=e;

 	++f;

 	if(r && source(e)==a) erase(e);

 	else moveTarget(e,b);

 	e=f;

       }

       erase(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.

     ///

     ///\warning Edge and node deletions cannot be restored.

     ///\warning SnapShots cannot be nested.

     ///\ingroup graphs

     class SnapShot : protected AlterationObserverRegistry<Node>::ObserverBase,

 		     protected AlterationObserverRegistry<Edge>::ObserverBase

     {

       protected:

       ListGraph *g;

       std::list<Node> added_nodes;

       std::list<Edge> added_edges;

       bool active;

       virtual void add(const Node& n) {

 	added_nodes.push_back(n);

       };

       ///\bug Exception...

       ///

       virtual void erase(const Node&) 

       {

 	exit(1);

       }

       virtual void add(const Edge& n) {

 	added_edges.push_back(n);

       };

       ///\bug Exception...

       ///

       virtual void erase(const Edge&) 

       {

 	exit(1);

       }

       void regist(ListGraph &_g) {

 	g=&_g;

 	AlterationObserverRegistry<Node>::ObserverBase::

 	  attach(g->node_observers);

 	AlterationObserverRegistry<Edge>::ObserverBase::

 	  attach(g->edge_observers);

       }

       void deregist() {

 	AlterationObserverRegistry<Node>::ObserverBase::

 	  detach();

 	AlterationObserverRegistry<Edge>::ObserverBase::

 	  detach();

 	g=0;

       }

     public:

       ///Default constructur.

       ///Default constructur.

       ///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(ListGraph &_g) {

 	regist(_g);

       }

       ///\bug Is it necessary?

       ///

       ~SnapShot() 

       {

 	if(g) deregist();

       }

       ///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(ListGraph &_g) 

       {

 	if(g!=&_g) {

 	  if(g) deregist();

 	  regist(_g);

 	}

 	added_nodes.clear();

 	added_edges.clear();

       }

     ///Undo the changes until the last snapshot.

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

     ///

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

       void restore() {

 	deregist();

 	while(!added_edges.empty()) {

 	  g->erase(added_edges.front());

 	  added_edges.pop_front();

 	}

  	while(!added_nodes.empty()) {

 	  g->erase(added_nodes.front());

 	  added_nodes.pop_front();

 	}

       }

     };

   };

   /// @}  

 } //namespace lemon

 #endif