/* -*- mode: C++; indent-tabs-mode: nil; -*-

 *

 * 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 HYPERCUBE_GRAPH_H

#define HYPERCUBE_GRAPH_H

#include <iostream>

#include <vector>

#include <lemon/core.h>

#include <lemon/error.h>

#include <lemon/bits/base_extender.h>

#include <lemon/bits/graph_extender.h>

///\ingroup graphs

///\file

///\brief HypercubeDigraph class.

namespace lemon {

  class HypercubeDigraphBase {

  public:

    typedef HypercubeDigraphBase Digraph;

    class Node;

    class Arc;

  public:

    HypercubeDigraphBase() {}

  protected:

    void construct(int dim) {

      _dim = dim;

      _nodeNum = 1 << dim;

    }

  public:

    typedef True NodeNumTag;

    typedef True ArcNumTag;

    int nodeNum() const { return _nodeNum; }

    int arcNum() const { return _nodeNum * _dim; }

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

    int maxArcId() const { return arcNum() - 1; }

    Node source(Arc e) const {

      return e.id / _dim;

    }

    Node target(Arc e) const {

      return (e.id / _dim) ^ (1 << (e.id % _dim));

    }

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

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

    static Node nodeFromId(int id) { return Node(id); }

    static Arc arcFromId(int id) { return Arc(id); }

    class Node {

      friend class HypercubeDigraphBase;

    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 HypercubeDigraphBase;

    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; }

    };

    void first(Node& node) const {

      node.id = nodeNum() - 1;

    }

    static void next(Node& node) {

      --node.id;

    }

    void first(Arc& arc) const {

      arc.id = arcNum() - 1;

    }

    static void next(Arc& arc) {

      --arc.id;

    }

    void firstOut(Arc& arc, const Node& node) const {

      arc.id = node.id * _dim;

    }

    void nextOut(Arc& arc) const {

      ++arc.id;

      if (arc.id % _dim == 0) arc.id = -1;

    }

    void firstIn(Arc& arc, const Node& node) const {

      arc.id = (node.id ^ 1) * _dim;

    }

    void nextIn(Arc& arc) const {

      int cnt = arc.id % _dim;

      if ((cnt + 1) % _dim == 0) {

        arc.id = -1;

      } else {

        arc.id = ((arc.id / _dim) ^ ((1 << cnt) * 3)) * _dim + cnt + 1;

      }

    }

    int dimension() const {

      return _dim;

    }

    bool projection(Node node, int n) const {

      return static_cast<bool>(node.id & (1 << n));

    }

    int dimension(Arc arc) const {

      return arc.id % _dim;

    }

    int index(Node node) const {

      return node.id;

    }

    Node operator()(int ix) const {

      return Node(ix);

    }

  private:

    int _dim, _nodeNum;

  };

  typedef DigraphExtender<HypercubeDigraphBase> ExtendedHypercubeDigraphBase;

  /// \ingroup digraphs

  ///

  /// \brief Hypercube digraph class

  ///

  /// This class implements a special digraph type. The nodes of the

  /// digraph are indiced with integers with at most \c dim binary digits.

  /// Two nodes are connected in the digraph if the indices differ only

  /// on one position in the binary form.

  ///

  /// \note The type of the \c ids is chosen to \c int because efficiency

  /// reasons. Thus the maximum dimension of this implementation is 26.

  ///

  /// The digraph type is fully conform to the \ref concepts::Digraph

  /// concept but it does not conform to \ref concepts::Graph.

  class HypercubeDigraph : public ExtendedHypercubeDigraphBase {

  public:

    typedef ExtendedHypercubeDigraphBase Parent;

    /// \brief Construct a hypercube digraph with \c dim dimension.

    ///

    /// Construct a hypercube digraph with \c dim dimension.

    HypercubeDigraph(int dim) { construct(dim); }

    /// \brief Gives back the number of the dimensions.

    ///

    /// Gives back the number of the dimensions.

    int dimension() const {

      return Parent::dimension();

    }

    /// \brief Returns true if the n'th bit of the node is one.

    ///

    /// Returns true if the n'th bit of the node is one.

    bool projection(Node node, int n) const {

      return Parent::projection(node, n);

    }

    /// \brief The dimension id of the arc.

    ///

    /// It returns the dimension id of the arc. It can

    /// be in the \f$ \{0, 1, \dots, dim-1\} \f$ interval.

    int dimension(Arc arc) const {

      return Parent::dimension(arc);

    }

    /// \brief Gives back the index of the node.

    ///

    /// Gives back the index of the node. The lower bits of the

    /// integer describes the node.

    int index(Node node) const {

      return Parent::index(node);

    }

    /// \brief Gives back the node by its index.

    ///

    /// Gives back the node by its index.

    Node operator()(int ix) const {

      return Parent::operator()(ix);

    }

    /// \brief Number of nodes.

    int nodeNum() const { return Parent::nodeNum(); }

    /// \brief Number of arcs.

    int arcNum() const { return Parent::arcNum(); }

    /// \brief Linear combination map.

    ///

    /// It makes possible to give back a linear combination

    /// for each node. This function works like the \c std::accumulate

    /// so it accumulates the \c bf binary function with the \c fv

    /// first value. The map accumulates only on that dimensions where

    /// the node's index is one. The accumulated values should be

    /// given by the \c begin and \c end iterators and the length of this

    /// range should be equal to the dimension number of the digraph.

    ///

    ///\code

    /// const int DIM = 3;

    /// HypercubeDigraph digraph(DIM);

    /// dim2::Point<double> base[DIM];

    /// for (int k = 0; k < DIM; ++k) {

    ///   base[k].x = rnd();

    ///   base[k].y = rnd();

    /// }

    /// HypercubeDigraph::HyperMap<dim2::Point<double> >

    ///   pos(digraph, base, base + DIM, dim2::Point<double>(0.0, 0.0));

    ///\endcode

    ///

    /// \see HypercubeDigraph

    template <typename T, typename BF = std::plus<T> >

    class HyperMap {

    public:

      typedef Node Key;

      typedef T Value;

      /// \brief Constructor for HyperMap.

      ///

      /// Construct a HyperMap for the given digraph. The accumulated values

      /// should be given by the \c begin and \c end iterators and the length

      /// of this range should be equal to the dimension number of the digraph.

      ///

      /// This function accumulates the \c bf binary function with

      /// the \c fv first value. The map accumulates only on that dimensions

      /// where the node's index is one.

      template <typename It>

      HyperMap(const Digraph& digraph, It begin, It end,

               T fv = 0.0, const BF& bf = BF())

        : _graph(digraph), _values(begin, end), _first_value(fv), _bin_func(bf)

      {

        LEMON_ASSERT(_values.size() == digraph.dimension(),

                     "Wrong size of dimension");

      }

      /// \brief Gives back the partial accumulated value.

      ///

      /// Gives back the partial accumulated value.

      Value operator[](Key k) const {

        Value val = _first_value;

        int id = _graph.index(k);

        int n = 0;

        while (id != 0) {

          if (id & 1) {

            val = _bin_func(val, _values[n]);

          }

          id >>= 1;

          ++n;

        }

        return val;

      }

    private:

      const Digraph& _graph;

      std::vector<T> _values;

      T _first_value;

      BF _bin_func;

    };

  };

}

#endif