//
//=======================================================================
// Copyright (c) 2004 Kristopher Beevers
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//=======================================================================
//

#ifndef BOOST_GRAPH_ASTAR_SEARCH_HPP
#define BOOST_GRAPH_ASTAR_SEARCH_HPP


#include <functional>
#include <vector>
#include <boost/limits.hpp>
#include <boost/throw_exception.hpp>
#include <boost/graph/named_function_params.hpp>
#include <boost/graph/relax.hpp>
#include <boost/graph/exception.hpp>
#include <boost/graph/breadth_first_search.hpp>
#include <boost/graph/detail/d_ary_heap.hpp>
#include <boost/property_map/property_map.hpp>
#include <boost/property_map/vector_property_map.hpp>


namespace boost {


  template <class Heuristic, class Graph>
  struct AStarHeuristicConcept {
    void constraints()
    {
      function_requires< CopyConstructibleConcept<Heuristic> >();
      h(u);
    }
    Heuristic h;
    typename graph_traits<Graph>::vertex_descriptor u;
  };


  template <class Graph, class CostType>
  class astar_heuristic : public std::unary_function<
    typename graph_traits<Graph>::vertex_descriptor, CostType>
  {
  public:
    typedef typename graph_traits<Graph>::vertex_descriptor Vertex;
    astar_heuristic() {}
    CostType operator()(Vertex u) { return static_cast<CostType>(0); }
  };



  template <class Visitor, class Graph>
  struct AStarVisitorConcept {
    void constraints()
    {
      function_requires< CopyConstructibleConcept<Visitor> >();
      vis.initialize_vertex(u, g);
      vis.discover_vertex(u, g);
      vis.examine_vertex(u, g);
      vis.examine_edge(e, g);
      vis.edge_relaxed(e, g);
      vis.edge_not_relaxed(e, g);
      vis.black_target(e, g);
      vis.finish_vertex(u, g);
    }
    Visitor vis;
    Graph g;
    typename graph_traits<Graph>::vertex_descriptor u;
    typename graph_traits<Graph>::edge_descriptor e;
  };


  template <class Visitors = null_visitor>
  class astar_visitor : public bfs_visitor<Visitors> {
  public:
    astar_visitor() {}
    astar_visitor(Visitors vis)
      : bfs_visitor<Visitors>(vis) {}

    template <class Edge, class Graph>
    void edge_relaxed(Edge e, const Graph& g) {
      invoke_visitors(this->m_vis, e, g, on_edge_relaxed());
    }
    template <class Edge, class Graph>
    void edge_not_relaxed(Edge e, const Graph& g) {
      invoke_visitors(this->m_vis, e, g, on_edge_not_relaxed());
    }
  private:
    template <class Edge, class Graph>
    void tree_edge(Edge e, const Graph& g) {}
    template <class Edge, class Graph>
    void non_tree_edge(Edge e, const Graph& g) {}
  };
  template <class Visitors>
  astar_visitor<Visitors>
  make_astar_visitor(Visitors vis) {
    return astar_visitor<Visitors>(vis);
  }
  typedef astar_visitor<> default_astar_visitor;


  namespace detail {

    template <class AStarHeuristic, class UniformCostVisitor,
              class UpdatableQueue, class PredecessorMap,
              class CostMap, class DistanceMap, class WeightMap,
              class ColorMap, class BinaryFunction,
              class BinaryPredicate>
    struct astar_bfs_visitor
    {

      typedef typename property_traits<CostMap>::value_type C;
      typedef typename property_traits<ColorMap>::value_type ColorValue;
      typedef color_traits<ColorValue> Color;
      typedef typename property_traits<DistanceMap>::value_type distance_type;

      astar_bfs_visitor(AStarHeuristic h, UniformCostVisitor vis,
                        UpdatableQueue& Q, PredecessorMap p,
                        CostMap c, DistanceMap d, WeightMap w,
                        ColorMap col, BinaryFunction combine,
                        BinaryPredicate compare, C zero)
        : m_h(h), m_vis(vis), m_Q(Q), m_predecessor(p), m_cost(c),
          m_distance(d), m_weight(w), m_color(col),
          m_combine(combine), m_compare(compare), m_zero(zero) {}


      template <class Vertex, class Graph>
      void initialize_vertex(Vertex u, const Graph& g) {
        m_vis.initialize_vertex(u, g);
      }
      template <class Vertex, class Graph>
      void discover_vertex(Vertex u, const Graph& g) {
        m_vis.discover_vertex(u, g);
      }
      template <class Vertex, class Graph>
      void examine_vertex(Vertex u, const Graph& g) {
        m_vis.examine_vertex(u, g);
      }
      template <class Vertex, class Graph>
      void finish_vertex(Vertex u, const Graph& g) {
        m_vis.finish_vertex(u, g);
      }
      template <class Edge, class Graph>
      void examine_edge(Edge e, const Graph& g) {
        if (m_compare(get(m_weight, e), m_zero))
          BOOST_THROW_EXCEPTION(negative_edge());
        m_vis.examine_edge(e, g);
      }
      template <class Edge, class Graph>
      void non_tree_edge(Edge, const Graph&) {}



      template <class Edge, class Graph>
      void tree_edge(Edge e, const Graph& g) {
        m_decreased = relax(e, g, m_weight, m_predecessor, m_distance,
                            m_combine, m_compare);

        if(m_decreased) {
          m_vis.edge_relaxed(e, g);
          put(m_cost, target(e, g),
              m_combine(get(m_distance, target(e, g)),
                        m_h(target(e, g))));
        } else
          m_vis.edge_not_relaxed(e, g);
      }


      template <class Edge, class Graph>
      void gray_target(Edge e, const Graph& g) {
        m_decreased = relax(e, g, m_weight, m_predecessor, m_distance,
                            m_combine, m_compare);

        if(m_decreased) {
          put(m_cost, target(e, g),
              m_combine(get(m_distance, target(e, g)),
                        m_h(target(e, g))));
          m_Q.update(target(e, g));
          m_vis.edge_relaxed(e, g);
        } else
          m_vis.edge_not_relaxed(e, g);
      }


      template <class Edge, class Graph>
      void black_target(Edge e, const Graph& g) {
        m_decreased = relax(e, g, m_weight, m_predecessor, m_distance,
                            m_combine, m_compare);

        if(m_decreased) {
          m_vis.edge_relaxed(e, g);
          put(m_cost, target(e, g),
              m_combine(get(m_distance, target(e, g)),
                        m_h(target(e, g))));
          m_Q.push(target(e, g));
          put(m_color, target(e, g), Color::gray());
          m_vis.black_target(e, g);
        } else
          m_vis.edge_not_relaxed(e, g);
      }



      AStarHeuristic m_h;
      UniformCostVisitor m_vis;
      UpdatableQueue& m_Q;
      PredecessorMap m_predecessor;
      CostMap m_cost;
      DistanceMap m_distance;
      WeightMap m_weight;
      ColorMap m_color;
      BinaryFunction m_combine;
      BinaryPredicate m_compare;
      bool m_decreased;
      C m_zero;

    };

  } // namespace detail



  template <typename VertexListGraph, typename AStarHeuristic,
            typename AStarVisitor, typename PredecessorMap,
            typename CostMap, typename DistanceMap,
            typename WeightMap, typename ColorMap,
            typename VertexIndexMap,
            typename CompareFunction, typename CombineFunction,
            typename CostInf, typename CostZero>
  inline void
  astar_search_no_init
    (const VertexListGraph &g,
     typename graph_traits<VertexListGraph>::vertex_descriptor s,
     AStarHeuristic h, AStarVisitor vis,
     PredecessorMap predecessor, CostMap cost,
     DistanceMap distance, WeightMap weight,
     ColorMap color, VertexIndexMap index_map,
     CompareFunction compare, CombineFunction combine,
     CostInf /*inf*/, CostZero zero)
  {
    typedef typename graph_traits<VertexListGraph>::vertex_descriptor
      Vertex;
    typedef boost::vector_property_map<std::size_t, VertexIndexMap> IndexInHeapMap;
    IndexInHeapMap index_in_heap(index_map);
    typedef d_ary_heap_indirect<Vertex, 4, IndexInHeapMap, CostMap, CompareFunction>
      MutableQueue;
    MutableQueue Q(cost, index_in_heap, compare);

    detail::astar_bfs_visitor<AStarHeuristic, AStarVisitor,
        MutableQueue, PredecessorMap, CostMap, DistanceMap,
        WeightMap, ColorMap, CombineFunction, CompareFunction>
      bfs_vis(h, vis, Q, predecessor, cost, distance, weight,
              color, combine, compare, zero);

    breadth_first_visit(g, s, Q, bfs_vis, color);
  }


  // Non-named parameter interface
  template <typename VertexListGraph, typename AStarHeuristic,
            typename AStarVisitor, typename PredecessorMap,
            typename CostMap, typename DistanceMap,
            typename WeightMap, typename VertexIndexMap,
            typename ColorMap,
            typename CompareFunction, typename CombineFunction,
            typename CostInf, typename CostZero>
  inline void
  astar_search
    (const VertexListGraph &g,
     typename graph_traits<VertexListGraph>::vertex_descriptor s,
     AStarHeuristic h, AStarVisitor vis,
     PredecessorMap predecessor, CostMap cost,
     DistanceMap distance, WeightMap weight,
     VertexIndexMap index_map, ColorMap color,
     CompareFunction compare, CombineFunction combine,
     CostInf inf, CostZero zero)
  {

    typedef typename property_traits<ColorMap>::value_type ColorValue;
    typedef color_traits<ColorValue> Color;
    typename graph_traits<VertexListGraph>::vertex_iterator ui, ui_end;
    for (boost::tie(ui, ui_end) = vertices(g); ui != ui_end; ++ui) {
      put(color, *ui, Color::white());
      put(distance, *ui, inf);
      put(cost, *ui, inf);
      put(predecessor, *ui, *ui);
      vis.initialize_vertex(*ui, g);
    }
    put(distance, s, zero);
    put(cost, s, h(s));

    astar_search_no_init
      (g, s, h, vis, predecessor, cost, distance, weight,
       color, index_map, compare, combine, inf, zero);

  }

  // Named parameter interfaces
  template <typename VertexListGraph,
            typename AStarHeuristic,
            typename P, typename T, typename R>
  void
  astar_search
    (const VertexListGraph &g,
     typename graph_traits<VertexListGraph>::vertex_descriptor s,
     AStarHeuristic h, const bgl_named_params<P, T, R>& params)
  {
    using namespace boost::graph::keywords;
    typedef bgl_named_params<P, T, R> params_type;
    BOOST_GRAPH_DECLARE_CONVERTED_PARAMETERS(params_type, params)

    // Distance type is the value type of the distance map if there is one,
    // otherwise the value type of the weight map.
    typedef
      typename detail::override_const_property_result<
                 arg_pack_type, tag::weight_map, edge_weight_t, VertexListGraph>::type
      weight_map_type;
    typedef typename boost::property_traits<weight_map_type>::value_type W;
    typedef
      typename detail::map_maker<VertexListGraph, arg_pack_type, tag::distance_map, W>::map_type
      distance_map_type;
    typedef typename boost::property_traits<distance_map_type>::value_type D;
    const D inf = arg_pack[_distance_inf | (std::numeric_limits<D>::max)()];

    astar_search
      (g, s, h,
       arg_pack[_visitor | make_astar_visitor(null_visitor())],
       arg_pack[_predecessor_map | dummy_property_map()],
       detail::make_property_map_from_arg_pack_gen<tag::rank_map, D>(D())(g, arg_pack),
       detail::make_property_map_from_arg_pack_gen<tag::distance_map, W>(W())(g, arg_pack),
       detail::override_const_property(arg_pack, _weight_map, g, edge_weight),
       detail::override_const_property(arg_pack, _vertex_index_map, g, vertex_index),
       detail::make_color_map_from_arg_pack(g, arg_pack),
       arg_pack[_distance_compare | std::less<D>()],
       arg_pack[_distance_combine | closed_plus<D>(inf)],
       inf,
       arg_pack[_distance_zero | D()]);
  }

  template <typename VertexListGraph,
            typename AStarHeuristic,
            typename P, typename T, typename R>
  void
  astar_search_no_init
    (const VertexListGraph &g,
     typename graph_traits<VertexListGraph>::vertex_descriptor s,
     AStarHeuristic h, const bgl_named_params<P, T, R>& params)
  {
    using namespace boost::graph::keywords;
    typedef bgl_named_params<P, T, R> params_type;
    BOOST_GRAPH_DECLARE_CONVERTED_PARAMETERS(params_type, params)
    typedef
      typename detail::override_const_property_result<
                 arg_pack_type, tag::weight_map, edge_weight_t, VertexListGraph>::type
               weight_map_type;
    typedef typename boost::property_traits<weight_map_type>::value_type D;
    const D inf = arg_pack[_distance_inf | (std::numeric_limits<D>::max)()];
    astar_search_no_init
      (g, s, h,
       arg_pack[_visitor | make_astar_visitor(null_visitor())],
       arg_pack[_predecessor_map | dummy_property_map()],
       detail::make_property_map_from_arg_pack_gen<tag::rank_map, D>(D())(g, arg_pack),
       detail::make_property_map_from_arg_pack_gen<tag::distance_map, D>(D())(g, arg_pack),
       detail::override_const_property(arg_pack, _weight_map, g, edge_weight),
       detail::override_const_property(arg_pack, _vertex_index_map, g, vertex_index),
       detail::make_color_map_from_arg_pack(g, arg_pack),
       arg_pack[_distance_compare | std::less<D>()],
       arg_pack[_distance_combine | closed_plus<D>(inf)],
       inf,
       arg_pack[_distance_zero | D()]);
  }

} // namespace boost

#endif // BOOST_GRAPH_ASTAR_SEARCH_HPP