/* -*- C++ -*-
 *
 * This file is a part of LEMON, a generic C++ optimization library
 *
 * Copyright (C) 2003-2008
 * 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_STATIC_GRAPH_H
#define LEMON_STATIC_GRAPH_H

///\ingroup graphs
///\file
///\brief StaticDigraph class.

#include <lemon/core.h>
#include <lemon/bits/graph_extender.h>

namespace lemon {

  class StaticDigraphBase {
  public:

    StaticDigraphBase() 
      : built(false), node_num(0), arc_num(0), 
        node_first_out(NULL), node_first_in(NULL),
        arc_source(NULL), arc_target(NULL), 
        arc_next_in(NULL), arc_next_out(NULL) {}
    
    ~StaticDigraphBase() {
      if (built) {
        delete[] node_first_out;
        delete[] node_first_in;
        delete[] arc_source;
        delete[] arc_target;
        delete[] arc_next_out;
        delete[] arc_next_in;
      }
    }

    class Node {
      friend class StaticDigraphBase;
    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 Arc {
      friend class StaticDigraphBase;      
    protected:
      int id;
      Arc(int _id) : id(_id) {}
    public:
      Arc() { }
      Arc (Invalid) : id(-1) {}
      bool operator==(const Arc& arc) const { return id == arc.id; }
      bool operator!=(const Arc& arc) const { return id != arc.id; }
      bool operator<(const Arc& arc) const { return id < arc.id; }
    };

    Node source(const Arc& e) const { return Node(arc_source[e.id]); }
    Node target(const Arc& e) const { return Node(arc_target[e.id]); }

    void first(Node& n) const { n.id = node_num - 1; }
    static void next(Node& n) { --n.id; }

    void first(Arc& e) const { e.id = arc_num - 1; }
    static void next(Arc& e) { --e.id; }

    void firstOut(Arc& e, const Node& n) const { 
      e.id = node_first_out[n.id] != node_first_out[n.id + 1] ? 
        node_first_out[n.id] : -1;
    }
    void nextOut(Arc& e) const { e.id = arc_next_out[e.id]; }

    void firstIn(Arc& e, const Node& n) const { e.id = node_first_in[n.id]; }
    void nextIn(Arc& e) const { e.id = arc_next_in[e.id]; }

    static int id(const Node& n) { return n.id; }
    static Node nodeFromId(int id) { return Node(id); }
    int maxNodeId() const { return node_num - 1; }

    static int id(const Arc& e) { return e.id; }
    static Arc arcFromId(int id) { return Arc(id); }
    int maxArcId() const { return arc_num - 1; }

    typedef True NodeNumTag;
    typedef True ArcNumTag;

    int nodeNum() const { return node_num; }
    int arcNum() const { return arc_num; }

  private:

    template <typename Digraph, typename NodeRefMap>
    class ArcLess {
    public:
      typedef typename Digraph::Arc Arc;

      ArcLess(const Digraph &_graph, const NodeRefMap& _nodeRef) 
        : digraph(_graph), nodeRef(_nodeRef) {}
      
      bool operator()(const Arc& left, const Arc& right) const {
	return nodeRef[digraph.target(left)] < nodeRef[digraph.target(right)];
      }
    private:
      const Digraph& digraph;
      const NodeRefMap& nodeRef;
    };
    
  public:

    typedef True BuildTag;
    
    void clear() {
      if (built) {
        delete[] node_first_out;
        delete[] node_first_in;
        delete[] arc_source;
        delete[] arc_target;
        delete[] arc_next_out;
        delete[] arc_next_in;
      }
      built = false;
      node_num = 0;
      arc_num = 0;
    }
    
    template <typename Digraph, typename NodeRefMap, typename ArcRefMap>
    void build(const Digraph& digraph, NodeRefMap& nodeRef, ArcRefMap& arcRef) {
      typedef typename Digraph::Node GNode;
      typedef typename Digraph::Arc GArc;

      built = true;

      node_num = countNodes(digraph);
      arc_num = countArcs(digraph);

      node_first_out = new int[node_num + 1];
      node_first_in = new int[node_num];

      arc_source = new int[arc_num];
      arc_target = new int[arc_num];
      arc_next_out = new int[arc_num];
      arc_next_in = new int[arc_num];

      int node_index = 0;
      for (typename Digraph::NodeIt n(digraph); n != INVALID; ++n) {
        nodeRef[n] = Node(node_index);
        node_first_in[node_index] = -1;
        ++node_index;
      }

      ArcLess<Digraph, NodeRefMap> arcLess(digraph, nodeRef);

      int arc_index = 0;
      for (typename Digraph::NodeIt n(digraph); n != INVALID; ++n) {
        int source = nodeRef[n].id;
        std::vector<GArc> arcs;
        for (typename Digraph::OutArcIt e(digraph, n); e != INVALID; ++e) {
          arcs.push_back(e);
        }
        if (!arcs.empty()) {
          node_first_out[source] = arc_index;
          std::sort(arcs.begin(), arcs.end(), arcLess);
          for (typename std::vector<GArc>::iterator it = arcs.begin();
               it != arcs.end(); ++it) {
            int target = nodeRef[digraph.target(*it)].id;
            arcRef[*it] = Arc(arc_index);
            arc_source[arc_index] = source; 
            arc_target[arc_index] = target;
            arc_next_in[arc_index] = node_first_in[target];
            node_first_in[target] = arc_index;
            arc_next_out[arc_index] = arc_index + 1;
            ++arc_index;
          }
          arc_next_out[arc_index - 1] = -1;
        } else {
          node_first_out[source] = arc_index;
        }
      }
      node_first_out[node_num] = arc_num;
    }
    
    template <typename ArcListIterator>
    void build(int n, ArcListIterator first, ArcListIterator last) {
      built = true;

      node_num = n;
      arc_num = std::distance(first, last);

      node_first_out = new int[node_num + 1];
      node_first_in = new int[node_num];

      arc_source = new int[arc_num];
      arc_target = new int[arc_num];
      arc_next_out = new int[arc_num];
      arc_next_in = new int[arc_num];
      
      for (int i = 0; i != node_num; ++i) {
        node_first_in[i] = -1;
      }      
      
      int arc_index = 0;
      for (int i = 0; i != node_num; ++i) {
        node_first_out[i] = arc_index;
        for ( ; first != last && (*first).first == i; ++first) {
          int j = (*first).second;
          LEMON_ASSERT(j >= 0 && j < node_num,
            "Wrong arc list for StaticDigraph::build()");
          arc_source[arc_index] = i;
          arc_target[arc_index] = j;
          arc_next_in[arc_index] = node_first_in[j];
          node_first_in[j] = arc_index;
          arc_next_out[arc_index] = arc_index + 1;
          ++arc_index;
        }
        if (arc_index > node_first_out[i])
          arc_next_out[arc_index - 1] = -1;
      }
      LEMON_ASSERT(first == last,
        "Wrong arc list for StaticDigraph::build()");
      node_first_out[node_num] = arc_num;
    }

  protected:

    void fastFirstOut(Arc& e, const Node& n) const {
      e.id = node_first_out[n.id];
    }

    static void fastNextOut(Arc& e) {
      ++e.id;
    }
    void fastLastOut(Arc& e, const Node& n) const {
      e.id = node_first_out[n.id + 1];
    }

  protected:
    bool built;
    int node_num;
    int arc_num;
    int *node_first_out;
    int *node_first_in;
    int *arc_source;
    int *arc_target;
    int *arc_next_in;
    int *arc_next_out;
  };

  typedef DigraphExtender<StaticDigraphBase> ExtendedStaticDigraphBase;


  /// \ingroup graphs
  ///
  /// \brief A static directed graph class.
  ///
  /// \ref StaticDigraph is a highly efficient digraph implementation,
  /// but it is fully static.
  /// It stores only two \c int values for each node and only four \c int
  /// values for each arc. Moreover it provides faster item iteration than
  /// \ref ListDigraph and \ref SmartDigraph, especially using \c OutArcIt
  /// iterators, since its arcs are stored in an appropriate order.
  /// However it only provides build() and clear() functions and does not
  /// support any other modification of the digraph.
  ///
  /// Since this digraph structure is completely static, its nodes and arcs
  /// can be indexed with integers from the ranges <tt>[0..nodeNum()-1]</tt>
  /// and <tt>[0..arcNum()-1]</tt>, respectively. 
  /// The index of an item is the same as its ID, it can be obtained
  /// using the corresponding \ref index() or \ref concepts::Digraph::id()
  /// "id()" function. A node or arc with a certain index can be obtained
  /// using node() or arc().
  ///
  /// This type fully conforms to the \ref concepts::Digraph "Digraph concept".
  /// Most of its member functions and nested classes are documented
  /// only in the concept class.
  ///
  /// This class provides constant time counting for nodes and arcs.
  ///
  /// \sa concepts::Digraph
  class StaticDigraph : public ExtendedStaticDigraphBase {
  public:

    typedef ExtendedStaticDigraphBase Parent;
  
  public:
  
    /// \brief Constructor
    ///
    /// Default constructor.
    StaticDigraph() : Parent() {}

    /// \brief The node with the given index.
    ///
    /// This function returns the node with the given index.
    /// \sa index()
    static Node node(int ix) { return Parent::nodeFromId(ix); }

    /// \brief The arc with the given index.
    ///
    /// This function returns the arc with the given index.
    /// \sa index()
    static Arc arc(int ix) { return Parent::arcFromId(ix); }

    /// \brief The index of the given node.
    ///
    /// This function returns the index of the the given node.
    /// \sa node()
    static int index(Node node) { return Parent::id(node); }

    /// \brief The index of the given arc.
    ///
    /// This function returns the index of the the given arc.
    /// \sa arc()
    static int index(Arc arc) { return Parent::id(arc); }

    /// \brief Number of nodes.
    ///
    /// This function returns the number of nodes.
    int nodeNum() const { return node_num; }

    /// \brief Number of arcs.
    ///
    /// This function returns the number of arcs.
    int arcNum() const { return arc_num; }

    /// \brief Build the digraph copying another digraph.
    ///
    /// This function builds the digraph copying another digraph of any
    /// kind. It can be called more than once, but in such case, the whole
    /// structure and all maps will be cleared and rebuilt.
    ///
    /// This method also makes possible to copy a digraph to a StaticDigraph
    /// structure using \ref DigraphCopy.
    /// 
    /// \param digraph An existing digraph to be copied.
    /// \param nodeRef The node references will be copied into this map.
    /// Its key type must be \c Digraph::Node and its value type must be
    /// \c StaticDigraph::Node.
    /// It must conform to the \ref concepts::ReadWriteMap "ReadWriteMap"
    /// concept.
    /// \param arcRef The arc references will be copied into this map.
    /// Its key type must be \c Digraph::Arc and its value type must be
    /// \c StaticDigraph::Arc.
    /// It must conform to the \ref concepts::WriteMap "WriteMap" concept.
    ///
    /// \note If you do not need the arc references, then you could use
    /// \ref NullMap for the last parameter. However the node references
    /// are required by the function itself, thus they must be readable
    /// from the map.
    template <typename Digraph, typename NodeRefMap, typename ArcRefMap>
    void build(const Digraph& digraph, NodeRefMap& nodeRef, ArcRefMap& arcRef) {
      if (built) Parent::clear();
      Parent::build(digraph, nodeRef, arcRef);
    }
  
    /// \brief Build the digraph from an arc list.
    ///
    /// This function builds the digraph from the given arc list.
    /// It can be called more than once, but in such case, the whole
    /// structure and all maps will be cleared and rebuilt.
    ///
    /// The list of the arcs must be given in the range <tt>[begin, end)</tt>
    /// specified by STL compatible itartors whose \c value_type must be
    /// <tt>std::pair<int,int></tt>.
    /// Each arc must be specified by a pair of integer indices
    /// from the range <tt>[0..n-1]</tt>. <i>The pairs must be in a
    /// non-decreasing order with respect to their first values.</i>
    /// If the k-th pair in the list is <tt>(i,j)</tt>, then
    /// <tt>arc(k-1)</tt> will connect <tt>node(i)</tt> to <tt>node(j)</tt>.
    ///
    /// \param n The number of nodes.
    /// \param begin An iterator pointing to the beginning of the arc list.
    /// \param end An iterator pointing to the end of the arc list.
    ///
    /// For example, a simple digraph can be constructed like this.
    /// \code
    ///   std::vector<std::pair<int,int> > arcs;
    ///   arcs.push_back(std::make_pair(0,1));
    ///   arcs.push_back(std::make_pair(0,2));
    ///   arcs.push_back(std::make_pair(1,3));
    ///   arcs.push_back(std::make_pair(1,2));
    ///   arcs.push_back(std::make_pair(3,0));
    ///   StaticDigraph gr;
    ///   gr.build(4, arcs.begin(), arcs.end());
    /// \endcode
    template <typename ArcListIterator>
    void build(int n, ArcListIterator begin, ArcListIterator end) {
      if (built) Parent::clear();
      StaticDigraphBase::build(n, begin, end);
      notifier(Node()).build();
      notifier(Arc()).build();
    }

    /// \brief Clear the digraph.
    ///
    /// This function erases all nodes and arcs from the digraph.
    void clear() {
      Parent::clear();
    }

  protected:

    using Parent::fastFirstOut;
    using Parent::fastNextOut;
    using Parent::fastLastOut;
    
  public:

    class OutArcIt : public Arc {
    public:

      OutArcIt() { }

      OutArcIt(Invalid i) : Arc(i) { }

      OutArcIt(const StaticDigraph& digraph, const Node& node) {
	digraph.fastFirstOut(*this, node);
	digraph.fastLastOut(last, node);
        if (last == *this) *this = INVALID;
      }

      OutArcIt(const StaticDigraph& digraph, const Arc& arc) : Arc(arc) {
        if (arc != INVALID) {
          digraph.fastLastOut(last, digraph.source(arc));
        }
      }

      OutArcIt& operator++() { 
        StaticDigraph::fastNextOut(*this);
        if (last == *this) *this = INVALID;
        return *this; 
      }

    private:
      Arc last;
    };

    Node baseNode(const OutArcIt &arc) const {
      return Parent::source(static_cast<const Arc&>(arc));
    }

    Node runningNode(const OutArcIt &arc) const {
      return Parent::target(static_cast<const Arc&>(arc));
    }

    Node baseNode(const InArcIt &arc) const {
      return Parent::target(static_cast<const Arc&>(arc));
    }

    Node runningNode(const InArcIt &arc) const {
      return Parent::source(static_cast<const Arc&>(arc));
    }

  };

}

#endif