//=======================================================================
// Copyright 2002 Indiana University.
// Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek
//
// This file is part of the Boost Graph Library
//
// You should have received a copy of the License Agreement for the
// Boost Graph Library along with the software; see the file LICENSE.
//
// Permission to modify the code and to distribute modified code is
// granted, provided the text of this NOTICE is retained, a notice that
// the code was modified is included with the above COPYRIGHT NOTICE and
// with the COPYRIGHT NOTICE in the LICENSE file, and that the LICENSE
// file is distributed with the modified code.
//
// LICENSOR MAKES NO REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED.
// By way of example, but not limitation, Licensor MAKES NO
// REPRESENTATIONS OR WARRANTIES OF MERCHANTABILITY OR FITNESS FOR ANY
// PARTICULAR PURPOSE OR THAT THE USE OF THE LICENSED SOFTWARE COMPONENTS
// OR DOCUMENTATION WILL NOT INFRINGE ANY PATENTS, COPYRIGHTS, TRADEMARKS
// OR OTHER RIGHTS.
//=======================================================================

/*
  Adapted from the GIRTH program of the Stanford GraphBase.

  Sample output:

  This program explores the girth and diameter of Ramanujan graphs.
  The bipartite graphs have q^3-q vertices, and the non-bipartite
  graphs have half that number. Each vertex has degree p+1.
  Both p and q should be odd prime numbers;
    or you can try p = 2 with q = 17 or 43.

  Choose a branching factor, p: 2
  Ok, now choose the cube root of graph size, q: 17
  Starting at any given vertex, there are
  3 vertices at distance 1,
  6 vertices at distance 2,
  12 vertices at distance 3,
  24 vertices at distance 4,
  46 vertices at distance 5,
  90 vertices at distance 6,
  169 vertices at distance 7,
  290 vertices at distance 8,
  497 vertices at distance 9,
  634 vertices at distance 10,
  521 vertices at distance 11,
  138 vertices at distance 12,
  13 vertices at distance 13,
  3 vertices at distance 14,
  1 vertices at distance 15.
  So the diameter is 15, and the girth is 9.
  
 */

#include <boost/config.hpp>
#include <vector>
#include <list>
#include <iostream>
#include <boost/limits.hpp>
#include <boost/graph/stanford_graph.hpp>
#include <boost/graph/breadth_first_search.hpp>
#include <boost/graph/graph_utility.hpp>

typedef boost::graph_traits<Graph*> Traits;
typedef Traits::vertex_descriptor vertex_descriptor;
typedef Traits::edge_descriptor edge_descriptor;
typedef Traits::vertex_iterator vertex_iterator;

std::vector<std::size_t> distance_list;

typedef boost::v_property<long> dist_t;
boost::property_map<Graph*, dist_t>::type d_map;

typedef boost::u_property<vertex_descriptor> pred_t;
boost::property_map<Graph*, pred_t>::type p_map;

typedef boost::w_property<long> color_t;
boost::property_map<Graph*, color_t>::type c_map;

class diameter_and_girth_visitor : public boost::bfs_visitor<>
{
public:
  diameter_and_girth_visitor(std::size_t& k_, std::size_t& girth_)
    : k(k_), girth(girth_) { }

  void tree_edge(edge_descriptor e, Graph* g) {
    vertex_descriptor u = source(e, g), v = target(e, g);
    k = d_map[u] + 1;
    d_map[v] = k;
    ++distance_list[k];
    p_map[v] = u;
  }
  void non_tree_edge(edge_descriptor e, Graph* g) {
    vertex_descriptor u = source(e, g), v = target(e, g);
    k = d_map[u] + 1;
    if (d_map[v] + k < girth && v != p_map[u])
      girth = d_map[v]+ k;
  }
private:
  std::size_t& k;
  std::size_t& girth;
};


int
main()
{
  std::cout <<
    "This program explores the girth and diameter of Ramanujan graphs." 
            << std::endl;
  std::cout <<
    "The bipartite graphs have q^3-q vertices, and the non-bipartite" 
            << std::endl;
  std::cout << 
    "graphs have half that number. Each vertex has degree p+1." 
            << std::endl;
  std::cout << "Both p and q should be odd prime numbers;" << std::endl;
  std::cout << "  or you can try p = 2 with q = 17 or 43." << std::endl;

  while (1) {

    std::cout << std::endl
              << "Choose a branching factor, p: ";
    long p = 0, q = 0;
    std::cin >> p;
    if (p == 0)
      break;
    std::cout << "Ok, now choose the cube root of graph size, q: ";
    std::cin >> q;
    if (q == 0)
      break;

    Graph* g;
    g = raman(p, q, 0L, 0L);
    if (g == 0) {
      std::cerr << " Sorry, I couldn't make that graph (error code "
        << panic_code << ")" << std::endl;
      continue;
    }
    distance_list.clear();
    distance_list.resize(boost::num_vertices(g), 0);

    // obtain property maps
    d_map = get(dist_t(), g);
    p_map = get(pred_t(), g);
    c_map = get(color_t(), g);

    vertex_iterator i, end;
    for (boost::tie(i, end) = boost::vertices(g); i != end; ++i)
      d_map[*i] = 0;

    std::size_t k = 0;
    std::size_t girth = std::numeric_limits<std::size_t>::max();
    diameter_and_girth_visitor vis(k, girth);

    vertex_descriptor s = *boost::vertices(g).first;

    boost::breadth_first_search(g, s, visitor(vis).color_map(c_map));

    std::cout << "Starting at any given vertex, there are" << std::endl;

    for (long d = 1; distance_list[d] != 0; ++d)
      std::cout << distance_list[d] << " vertices at distance " << d
                << (distance_list[d+1] != 0 ? "," : ".") << std::endl;

    std::cout << "So the diameter is " << k - 1
              << ", and the girth is " << girth
              << "." << std::endl;
  } // end while

  return 0;
}
