// Copyright (c) 2006-2011  GeometryFactory (France). All rights reserved.
//
// This file is part of CGAL (www.cgal.org); you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation; either version 3 of the License,
// or (at your option) any later version.
//
// Licensees holding a valid commercial license may use this file in
// accordance with the commercial license agreement provided with the software.
//
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
//
// $URL$
// $Id$
//
// Author(s)     : Fernando Cacciola <fernando.cacciola@geometryfactory.com>
//
#ifndef CONTRACTION_CGAL_QUEUE_MODIFIABLE_PRIORITY_QUEUE_H_
#define CONTRACTION_CGAL_QUEUE_MODIFIABLE_PRIORITY_QUEUE_H_

#define CGAL_SURFACE_MESH_SIMPLIFICATION_USE_RELAXED_HEAP

#include <boost/optional.hpp>
#include <boost/pending/relaxed_heap.hpp>

#include <climits>  // Neeeded by the following Boost header for CHAR_BIT.
#include <functional>  // for less

namespace CGAL {

template <class IndexedType_, class Compare_ = std::less<IndexedType_>, class ID_ = boost::identity_property_map>
class Modifiable_priority_queue {
 public:
  typedef Modifiable_priority_queue Self;

  typedef IndexedType_ IndexedType;
  typedef Compare_ Compare;
  typedef ID_ ID;

  typedef boost::relaxed_heap<IndexedType, Compare, ID> Heap;
  typedef typename Heap::value_type value_type;
  typedef typename Heap::size_type size_type;

  typedef bool handle;

 public:
  Modifiable_priority_queue(size_type largest_ID, Compare const& c, ID const& id) : mHeap(largest_ID, c, id) { }

  handle push(value_type const& v) {
    mHeap.push(v);
    return handle(true);
  }

  handle update(value_type const& v, handle h) {
    mHeap.update(v);
    return h;
  }

  handle erase(value_type const& v, handle) {
    mHeap.remove(v);
    return null_handle();
  }

  value_type top() const {
    return mHeap.top();
  }

  void pop() {
    mHeap.pop();
  }

  bool empty() const {
    return mHeap.empty();
  }

  bool contains(value_type const& v) {
    return mHeap.contains(v);
  }

  boost::optional<value_type> extract_top() {
    boost::optional<value_type> r;
    if (!empty()) {
      value_type v = top();
      pop();
      r = boost::optional<value_type>(v);
    }
    return r;
  }

  static handle null_handle() {
    return handle(false);
  }

 private:
  Heap mHeap;
};

}  // namespace CGAL

#endif  // CONTRACTION_CGAL_QUEUE_MODIFIABLE_PRIORITY_QUEUE_H_