/* -*- 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_FULL_UGRAPH_H

#define LEMON_FULL_UGRAPH_H

#include <cmath>

#include <lemon/bits/base_extender.h>

#include <lemon/bits/ugraph_extender.h>

#include <lemon/bits/invalid.h>

#include <lemon/bits/utility.h>

///\ingroup graphs

///\file

///\brief FullUGraph classes.

namespace lemon {

  /// \brief Base of the FullUGrpah.

  ///

  /// Base of the FullUGrpah.

  class FullUGraphBase {

    int _nodeNum;

    int _edgeNum;

  public:

    typedef FullUGraphBase Graph;

    class Node;

    class Edge;

  public:

    FullUGraphBase() {}

    ///Creates a full graph with \c n nodes.

    void construct(int n) { _nodeNum = n; _edgeNum = n * (n - 1) / 2; }

    /// \brief Returns the node with the given index.

    ///

    /// Returns the node with the given index. Because it is a

    /// static size graph the node's of the graph can be indiced

    /// by the range from 0 to \e nodeNum()-1 and the index of

    /// the node can accessed by the \e index() member.

    Node operator()(int index) const { return Node(index); }

    /// \brief Returns the index of the node.

    ///

    /// Returns the index of the node. Because it is a

    /// static size graph the node's of the graph can be indiced

    /// by the range from 0 to \e nodeNum()-1 and the index of

    /// the node can accessed by the \e index() member.

    int index(const Node& node) const { return node.id; }

    typedef True NodeNumTag;

    typedef True EdgeNumTag;

    ///Number of nodes.

    int nodeNum() const { return _nodeNum; }

    ///Number of edges.

    int edgeNum() const { return _edgeNum; }

    /// Maximum node ID.

    /// Maximum node ID.

    ///\sa id(Node)

    int maxNodeId() const { return _nodeNum-1; }

    /// Maximum edge ID.

    /// Maximum edge ID.

    ///\sa id(Edge)

    int maxEdgeId() const { return _edgeNum-1; }

    /// \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 source(Edge e) const { 

      /// \todo we may do it faster

      return Node(((int)sqrt((double)(1 + 8 * e.id)) + 1) / 2);

    }

    Node target(Edge e) const { 

      int source = ((int)sqrt((double)(1 + 8 * e.id)) + 1) / 2;;

      return Node(e.id - (source) * (source - 1) / 2);

    }

    /// \brief 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.id; }

    /// \brief 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.id; }

    /// \brief 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) const {

      if (prev.id != -1 || u.id <= v.id) return Edge(-1);

      return Edge(u.id * (u.id - 1) / 2 + v.id);

    }

    typedef True FindEdgeTag;

    class Node {

      friend class FullUGraphBase;

    protected:

      int id;

      Node(int _id) { id = _id;}

    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 FullUGraphBase;

    protected:

      int id;  // _nodeNum * target + source;

      Edge(int _id) : id(_id) {}

    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;}

    };

    void first(Node& node) const {

      node.id = _nodeNum - 1;

    }

    static void next(Node& node) {

      --node.id;

    }

    void first(Edge& edge) const {

      edge.id = _edgeNum - 1;

    }

    static void next(Edge& edge) {

      --edge.id;

    }

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

      int src = node.id;

      int trg = 0;

      edge.id = (trg < src ? src * (src - 1) / 2 + trg : -1);

    }

    /// \todo with specialized iterators we can make faster iterating

    void nextOut(Edge& edge) const {

      int src = source(edge).id;

      int trg = target(edge).id;

      ++trg;

      edge.id = (trg < src ? src * (src - 1) / 2 + trg : -1);

    }

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

      int src = node.id + 1;

      int trg = node.id;

      edge.id = (src < _nodeNum ? src * (src - 1) / 2 + trg : -1);

    }

    void nextIn(Edge& edge) const {

      int src = source(edge).id;

      int trg = target(edge).id;

      ++src;

      edge.id = (src < _nodeNum ? src * (src - 1) / 2 + trg : -1);

    }

  };

  typedef UGraphExtender<UndirGraphExtender<FullUGraphBase> > 

  ExtendedFullUGraphBase;

  /// \ingroup graphs

  ///

  /// \brief An undirected full graph class.

  ///

  /// This is a simple and fast undirected full graph implementation.

  /// It is completely static, so you can neither add nor delete either

  /// edges or nodes.

  ///

  /// The main difference beetween the \e FullGraph and \e FullUGraph class

  /// is that this class conforms to the undirected graph concept and

  /// it does not contain the loop edges.

  ///

  /// \sa FullUGraphBase

  /// \sa FullGraph

  ///

  /// \author Balazs Dezso

  class FullUGraph : public ExtendedFullUGraphBase {

  public:

    typedef ExtendedFullUGraphBase Parent;

    /// \brief Constructor

    FullUGraph() { construct(0); }

    /// \brief Constructor

    FullUGraph(int n) { construct(n); }

    /// \brief Resize the graph

    ///

    /// Resize the graph. The function will fully destroy and build the graph.

    /// This cause that the maps of the graph will reallocated

    /// automatically and the previous values will be lost.

    void resize(int n) {

      Parent::getNotifier(Edge()).clear();

      Parent::getNotifier(UEdge()).clear();

      Parent::getNotifier(Node()).clear();

      construct(n);

      Parent::getNotifier(Node()).build();

      Parent::getNotifier(UEdge()).build();

      Parent::getNotifier(Edge()).build();

    }

  };

} //namespace lemon

#endif //LEMON_FULL_GRAPH_H