//
//=======================================================================
// Copyright 1997, 1998, 1999, 2000 University of Notre Dame.
// Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek
//
// This file is part of the Generic Graph Component Library
//
// You should have received a copy of the License Agreement for the
// Generic Graph Component Library along with the software;  see the
// file LICENSE.  If not, contact Office of Research, University of Notre
// Dame, Notre Dame, IN  46556.
//
// 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.
//=======================================================================
//
#ifndef BOOST_MUTABLE_QUEUE_HPP
#define BOOST_MUTABLE_QUEUE_HPP

#include <vector>
#include <algorithm>
#include <functional>
#include <boost/property_map.hpp>
#include <boost/pending/mutable_heap.hpp>
#include <boost/pending/is_heap.hpp>
#include <boost/graph/detail/array_binary_tree.hpp>

namespace boost {

  // The mutable queue whose elements are indexed
  // 
  // This adaptor provides a special kind of priority queue that has
  // and update operation. This allows the ordering of the items to
  // change. After the ordering criteria for item x changes, one must
  // call the Q.update(x)
  // 
  // In order to efficiently find x in the queue, a functor must be
  // provided to map value_type to a unique ID, which the
  // mutable_queue will then use to map to the location of the
  // item. The ID's generated must be between 0 and N, where N is the
  // value passed to the constructor of mutable_queue

  template <class IndexedType, 
            class RandomAccessContainer = std::vector<IndexedType>, 
            class Comp = std::less<typename RandomAccessContainer::value_type>,
            class ID = identity_property_map >
  class mutable_queue {
  public:
    typedef IndexedType value_type;
    typedef typename RandomAccessContainer::size_type size_type;
  protected:
    typedef typename RandomAccessContainer::iterator iterator;
#if !defined BOOST_NO_STD_ITERATOR_TRAITS
    typedef  adstl::array_binary_tree_node<iterator, ID> Node;
#else
    typedef  adstl::array_binary_tree_node<iterator, value_type, ID> Node;
#endif
    typedef  adstl::compare_array_node<RandomAccessContainer,Comp> Compare;
    typedef std::vector<size_type> IndexArray;
  public:
    typedef Compare value_compare;
    typedef ID id_generator;

    mutable_queue(size_type n, const Comp& x, const ID& _id) 
      : index_array(n), comp(x), id(_id) {
      c.reserve(n); 
    }
    template <class InputIterator>
    mutable_queue(InputIterator first, InputIterator last, 
                  const Comp& x, const ID& _id) 
      : index_array(last-first), c(first, last), comp(x), id(_id)
    {
      while( first != last ) {
        push(*first);
        ++first;
      }
    }

    bool empty() const { return c.empty(); }
    
    void pop() {
      value_type tmp = c.back();
      c.back() = c.front();
      c.front() = tmp;

      size_type id_f = get(id, c.back());
      size_type id_b = get(id, tmp);
      size_type i = index_array[ id_b ];
      index_array[ id_b ] = index_array[ id_f ];
      index_array[ id_f ] = i;

      c.pop_back();
      Node node(c.begin(), c.end(), c.begin(), id);
      down_heap(node, comp, index_array);       
    }
    void push(const IndexedType& x) {
      c.push_back(x);
      /*set index-array*/
      index_array[ get(id, x) ] = c.size()-1;
      Node node(c.begin(), c.end(), c.end() - 1, id);
      up_heap(node, comp, index_array);
    }

    void update(const IndexedType& x) {
      size_type current_pos = index_array[ get(id, x) ];
      c[current_pos] = x;

      Node node(c.begin(), c.end(), c.begin()+current_pos, id);
      update_heap(node, comp, index_array);
    }

    value_type& front() { return c.front(); }
    value_type& top() { return c.front(); }

    const value_type& front() const { return c.front(); }
    const value_type& top() const { return c.front(); }

    size_type size() const { return c.size(); }

    bool test() {
      return std::is_heap(c.begin(), c.end(), Comp());
    }

   protected:
    IndexArray index_array;
    Compare comp;
    RandomAccessContainer c;
    ID id;
  };


}

#endif // BOOST_MUTABLE_QUEUE_HPP
