/* -*- C++ -*-
 * src/lemon/graph_utils.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_GRAPH_UTILS_H
#define LEMON_GRAPH_UTILS_H

#include <iterator>

#include <lemon/invalid.h>

///\ingroup gutils
///\file
///\brief Graph utilities.
///


namespace lemon {

/// \addtogroup gutils
/// @{

  // counters in the graph
  /// \brief Function to count the items in the graph.
  ///
  /// This function counts the items in the graph.
  /// The complexity of the function is O(n) because
  /// it iterates on all of the items.

  template <typename Graph, typename ItemIt>
  inline int countItems(const Graph& _g) {
    int num = 0;
    for (ItemIt it(_g); it != INVALID; ++it) {
      ++num;
    }
    return num;
  }

  /// \brief Function to count the nodes in the graph.
  ///
  /// This function counts the nodes in the graph.
  /// The complexity of the function is O(n) but for some
  /// graph structure it is specialized to O(1).

  template <typename Graph>
  inline int countNodes(const Graph& _g) {
    return countItems<Graph, typename Graph::NodeIt>(_g);
  }

  /// \brief Function to count the edges in the graph.
  ///
  /// This function counts the edges in the graph.
  /// The complexity of the function is O(e) but for some
  /// graph structure it is specialized to O(1).
  template <typename Graph>
  inline int countEdges(const Graph& _g) {
    return countItems<Graph, typename Graph::EdgeIt>(_g);
  }

  /// \brief Function to count the symmetric edges in the graph.
  ///
  /// This function counts the symmetric edges in the graph.
  /// The complexity of the function is O(e) but for some
  /// graph structure it is specialized to O(1).
  template <typename Graph>
  inline int countSymEdges(const Graph& _g) {
    return countItems<Graph, typename Graph::SymEdgeIt>(_g);
  }

  template <typename Graph, typename DegIt>
  inline int countNodeDegree(const Graph& _g, const typename Graph::Node& _n) {
    int num = 0;
    for (DegIt it(_g, _n); it != INVALID; ++it) {
      ++num;
    }
    return num;
  }

  template <typename Graph>
  inline int countOutEdges(const Graph& _g,  const typename Graph::Node& _n) {
    return countNodeDegree<Graph, typename Graph::OutEdgeIt>(_g, _n);
  }

  template <typename Graph>
  inline int countInEdges(const Graph& _g,  const typename Graph::Node& _n) {
    return countNodeDegree<Graph, typename Graph::InEdgeIt>(_g, _n);
  }

  // graph copy

  template <
    typename DestinationGraph, 
    typename SourceGraph, 
    typename NodeBijection>
  void copyNodes(DestinationGraph& _d, const SourceGraph& _s, 
		 NodeBijection& _nb) {    
    for (typename SourceGraph::NodeIt it(_s); it != INVALID; ++it) {
      _nb[it] = _d.addNode();
    }
  }

  template <
    typename DestinationGraph, 
    typename SourceGraph, 
    typename NodeBijection,
    typename EdgeBijection>
  void copyEdges(DestinationGraph& _d, const SourceGraph& _s,
		 const NodeBijection& _nb, EdgeBijection& _eb) {    
    for (typename SourceGraph::EdgeIt it(_s); it != INVALID; ++it) {
      _eb[it] = _d.addEdge(_nb[_s.tail(it)], _nb[_s.head(it)]);
    }
  }

  template <
    typename DestinationGraph, 
    typename SourceGraph, 
    typename NodeBijection,
    typename EdgeBijection>
  void copyGraph(DestinationGraph& _d, const SourceGraph& _s, 
		 NodeBijection& _nb, EdgeBijection& _eb) {
    nodeCopy(_d, _s, _nb);
    edgeCopy(_d, _s, _nb, _eb);
  }
 
   template <
    typename _DestinationGraph, 
    typename _SourceGraph, 
    typename _NodeBijection 
    =typename _SourceGraph::template NodeMap<typename _DestinationGraph::Node>,
    typename _EdgeBijection 
    =typename _SourceGraph::template EdgeMap<typename _DestinationGraph::Edge>
   >
   class GraphCopy {
   public:

     typedef _DestinationGraph DestinationGraph;
     typedef _SourceGraph SourceGraph;

     typedef _NodeBijection NodeBijection;
     typedef _EdgeBijection EdgeBijection;

   protected:          

     NodeBijection node_bijection;
     EdgeBijection edge_bijection;     

   public:
     
     GraphCopy(DestinationGraph& _d, const SourceGraph& _s) {
       copyGraph(_d, _s, node_bijection, edge_bijection);
     }

     const NodeBijection& getNodeBijection() const {
       return node_bijection;
     }

     const EdgeBijection& getEdgeBijection() const {
       return edge_bijection;
     }
     
   };

/// @}
  
} //END OF NAMESPACE LEMON

#endif