/* -*- 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/idmappable_graph_extender.h>

#include <lemon/iterable_graph_extender.h>

#include <lemon/alteration_observer_registry.h>

#include <lemon/default_map.h>


namespace lemon {

  class ListGraphBase {

    struct NodeT {
      int first_in,first_out;
      int prev, next;
    };
 
    struct EdgeT {
      int head, tail;
      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 Graph;
    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 Graph;
    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) {}

    
    ///Using this it possible to avoid the superfluous memory allocation.
    ///\todo more docs...
    ///\todo It should be defined in ListGraph.
    void reserveEdge(int n) { edges.reserve(n); };
    
    /// 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.id].tail; }
    Node head(Edge e) const { return edges[e.id].head; }


    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].head].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].tail = u.id; 
      edges[n].head = 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].head].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].tail].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;
    }

  };

  typedef AlterableGraphExtender<ListGraphBase> AlterableListGraphBase;
  typedef IterableGraphExtender<AlterableListGraphBase> IterableListGraphBase;
  typedef IdMappableGraphExtender<IterableListGraphBase> IdMappableListGraphBase;
  typedef DefaultMappableGraphExtender<IdMappableListGraphBase> 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 conforms to the
  ///\ref skeleton::ErasableGraph "ErasableGraph" concept.
  ///\sa skeleton::ErasableGraph.

  class ListGraph : public ErasableListGraphBase 
  {
  public:
    /// Moves the head of \c e to \c n

    /// Moves the head of \c e to \c n
    ///
    void moveHead(Edge e, Node n) 
    {
      if(edges[e.n].next_in != -1)
	edges[edges[e.n].next_in].prev_in = edges[e.n].prev_in;
      if(edges[e.n].prev_in != -1)
	edges[edges[e.n].prev_in].next_in = edges[e.n].next_in;
      else nodes[edges[e.n].head].first_in = edges[e.n].next_in;
      edges[e.n].head = n.n;
      edges[e.n].prev_in = -1;
      edges[e.n].next_in = nodes[n.n].first_in;
      nodes[n.n].first_in = e.n;
    }
    /// Moves the tail of \c e to \c n

    /// Moves the tail of \c e to \c n
    ///
    void moveTail(Edge e, Node n) 
    {
      if(edges[e.n].next_out != -1)
	edges[edges[e.n].next_out].prev_out = edges[e.n].prev_out;
      if(edges[e.n].prev_out != -1)
	edges[edges[e.n].prev_out].next_out = edges[e.n].next_out;
      else nodes[edges[e.n].tail].first_out = edges[e.n].next_out;
      edges[e.n].tail = n.n;
      edges[e.n].prev_out = -1;
      edges[e.n].next_out = nodes[n.n].first_out;
      nodes[n.n].first_out = e.n;
    }
  }
  /// @}  
} //namespace lemon
  

#endif