/* -*- 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 : public AlterationObserverRegistry<Node>::ObserverBase,

		     public 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