/* Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

#include "bounded_queue_boost.h"
#include <boost/heap/skew_heap.hpp>

namespace bh = boost::heap;

template<typename Key_type, typename Key_compare>
struct heap_data
{
  typedef typename bh::skew_heap<heap_data,
                                 bh::mutable_<true> >::handle_type handle_type;

  handle_type m_handle;
  Key_type    m_key;
  Key_compare m_cmp;

  heap_data(Key_type key, const Key_compare &cmp) : m_key(key), m_cmp(cmp)
  {
  }

  heap_data(const heap_data &that)
    : m_handle(that.m_handle),
      m_key(that.m_key), m_cmp(that.m_cmp)
  {
  }

  heap_data &operator=(const heap_data &that)
  {
    m_handle= that.m_handle;
    m_key= that.m_key;
    m_cmp= that.m_cmp;
    return *this;
  }

  bool operator<(const heap_data &rhs) const
  {
    return m_cmp(this->m_key, rhs.m_key);
  }
};

template<typename Element_type,
         typename Key_type,
         typename Key_generator,
         typename Key_compare>
  class Bounded_queue_impl
{
public:
  typename bh::skew_heap<heap_data<Key_type, Key_compare>, bh::mutable_<true> >
  m_queue;
};


template<typename Element_type,
         typename Key_type,
         typename Key_generator,
         typename Key_compare>
Bounded_queue_boost<Element_type,
                   Key_type,
                   Key_generator,
                   Key_compare>
::Bounded_queue_boost()
  : m_cmp(Key_compare()),
    m_sort_keys(NULL),
    m_compare_length(0),
    m_sort_param(NULL),
    m_max_elements(0),
    m_num_elements(0),
    pimpl(NULL)
{
}

template<typename Element_type,
         typename Key_type,
         typename Key_generator,
         typename Key_compare>
Bounded_queue_boost<Element_type,
                   Key_type, Key_generator, Key_compare>::~Bounded_queue_boost()
{
  delete pimpl;
}

template<typename Element_type,
         typename Key_type,
         typename Key_generator,
         typename Key_compare>
int Bounded_queue_boost<Element_type, Key_type, Key_generator, Key_compare>
  ::init(ha_rows max_elements,
         Key_generator *sort_param,
         Key_type *sort_keys)
{
  m_sort_keys=      sort_keys;
  m_compare_length= sort_param->compare_length();
  m_sort_param=     sort_param;

  m_max_elements= max_elements + 1;
  pimpl= new Bounded_queue_impl<Element_type,
                                Key_type, Key_generator, Key_compare>();
  return 0;
}

template<typename Element_type,
         typename Key_type,
         typename Key_generator,
         typename Key_compare>
void Bounded_queue_boost<Element_type, Key_type, Key_generator, Key_compare>
  ::push(Element_type element)
{
  DBUG_ASSERT(pimpl != NULL);
  if (m_num_elements == m_max_elements)
  {
    const heap_data<Key_type, Key_compare> &pq_top= pimpl->m_queue.top();
    m_sort_param->make_sortkey(pq_top.m_key, element);
    pimpl->m_queue.update(pq_top.m_handle);
  } else {
    m_sort_param->make_sortkey(m_sort_keys[m_num_elements], element);
    typename heap_data<Key_type, Key_compare>::handle_type handle=
      pimpl->m_queue.push(heap_data<Key_type,
                          Key_compare>(m_sort_keys[m_num_elements], m_cmp));
    ++m_num_elements;
    (*handle).m_handle= handle;
  }
}