// (C) Copyright 2007-2009 Andrew Sutton
//
// Use, modification and distribution are subject to the
// Boost Software License, Version 1.0 (See accompanying file
// LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt)

#ifndef BOOST_GRAPH_DEGREE_CENTRALITY_HPP
#define BOOST_GRAPH_DEGREE_CENTRALITY_HPP

#include <boost/graph/graph_concepts.hpp>

namespace boost {

template <typename Graph>
struct degree_centrality_measure
{
    typedef typename graph_traits<Graph>::degree_size_type degree_type;
    typedef typename graph_traits<Graph>::vertex_descriptor vertex_type;
};

template <typename Graph>
struct influence_measure
    : public degree_centrality_measure<Graph>
{
    typedef degree_centrality_measure<Graph> base_type;
    typedef typename base_type::degree_type degree_type;
    typedef typename base_type::vertex_type vertex_type;

    inline degree_type operator ()(vertex_type v, const Graph& g)
    {
        function_requires< IncidenceGraphConcept<Graph> >();
        return out_degree(v, g);
    }
};

template <typename Graph>
inline influence_measure<Graph>
measure_influence(const Graph&)
{ return influence_measure<Graph>(); }


template <typename Graph>
struct prestige_measure
    : public degree_centrality_measure<Graph>
{
    typedef degree_centrality_measure<Graph> base_type;
    typedef typename base_type::degree_type degree_type;
    typedef typename base_type::vertex_type vertex_type;

    inline degree_type operator ()(vertex_type v, const Graph& g)
    {
        function_requires< BidirectionalGraphConcept<Graph> >();
        return in_degree(v, g);
    }
};

template <typename Graph>
inline prestige_measure<Graph>
measure_prestige(const Graph&)
{ return prestige_measure<Graph>(); }


template <typename Graph, typename Vertex, typename Measure>
inline typename Measure::degree_type
degree_centrality(const Graph& g, Vertex v, Measure measure)
{
    function_requires< DegreeMeasureConcept<Measure, Graph> >();
    return measure(v, g);
}

template <typename Graph, typename Vertex>
inline typename graph_traits<Graph>::degree_size_type
degree_centrality(const Graph& g, Vertex v)
{
    return degree_centrality(g, v, measure_influence(g));
}


// These are alias functions, intended to provide a more expressive interface.

template <typename Graph, typename Vertex>
inline typename graph_traits<Graph>::degree_size_type
influence(const Graph& g, Vertex v)
{ return degree_centrality(g, v, measure_influence(g)); }


template <typename Graph, typename Vertex>
inline typename graph_traits<Graph>::degree_size_type
prestige(const Graph& g, Vertex v)
{ return degree_centrality(g, v, measure_prestige(g)); }


template <typename Graph, typename CentralityMap, typename Measure>
inline void
all_degree_centralities(const Graph& g, CentralityMap cent, Measure measure)
{
    function_requires< VertexListGraphConcept<Graph> >();
    typedef typename graph_traits<Graph>::vertex_descriptor Vertex;
    typedef typename graph_traits<Graph>::vertex_iterator VertexIterator;
    function_requires< WritablePropertyMapConcept<CentralityMap,Vertex> >();
    typedef typename property_traits<CentralityMap>::value_type Centrality;

    VertexIterator i, end;
    for(tie(i, end) = vertices(g); i != end; ++i) {
        Centrality c = degree_centrality(g, *i, measure);
        put(cent, *i, c);
    }
}

template <typename Graph, typename CentralityMap>
inline void all_degree_centralities(const Graph& g, CentralityMap cent)
{ all_degree_centralities(g, cent, measure_influence(g)); }

// More helper functions for computing influence and prestige.
// I hate the names of these functions, but influence and prestige
// don't pluralize too well.

template <typename Graph, typename CentralityMap>
inline void all_influence_values(const Graph& g, CentralityMap cent)
{ all_degree_centralities(g, cent, measure_influence(g)); }

template <typename Graph, typename CentralityMap>
inline void all_prestige_values(const Graph& g, CentralityMap cent)
{ all_degree_centralities(g, cent, measure_prestige(g)); }

} /* namespace boost */

#endif