/* Copyright (c) 2006, 2021, Oracle and/or its affiliates.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

   This program is also distributed with certain software (including
   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have included with MySQL.

   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, version 2.0, 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 */

#ifndef FILESORT_INCLUDED
#define FILESORT_INCLUDED

#include "my_global.h"                          /* uint, uchar */
#include "my_base.h"                            /* ha_rows */
#include "sql_list.h"                           /* Sql_alloc */
class THD;
struct TABLE;
struct st_sort_field;
struct st_order;
class Addon_fields;
class Field;


class QEP_TAB;

/**
  Sorting related info.
*/
class Filesort: public Sql_alloc
{
public:
  /// The QEP entry for the table to be sorted
  QEP_TAB *const tab;
  /// List of expressions to order the table by
  st_order *order;
  /// Maximum number of rows to return
  ha_rows limit;
  /// ORDER BY list with some precalculated info for filesort
  st_sort_field *sortorder;
  /// true means we are using Priority Queue for order by with limit.
  bool using_pq;
  /// Addon fields descriptor
  Addon_fields *addon_fields;

  Filesort(QEP_TAB *tab_arg, st_order *order_arg, ha_rows limit_arg):
    tab(tab_arg),
    order(order_arg),
    limit(limit_arg),
    sortorder(NULL),
    using_pq(false),
    addon_fields(NULL)
  {
    assert(order);
  };

  /* Prepare ORDER BY list for sorting. */
  uint make_sortorder();

  Addon_fields *get_addon_fields(ulong max_length_for_sort_data,
                                 Field **ptabfield,
                                 uint sortlength, uint *plength,
                                 uint *ppackable_length);
private:
  void cleanup();
};

bool filesort(THD *thd, Filesort *fsort, bool sort_positions,
              ha_rows *examined_rows, ha_rows *found_rows,
              ha_rows *returned_rows);
void filesort_free_buffers(TABLE *table, bool full);
void change_double_for_sort(double nr,uchar *to);

/// Declared here so we can unit test it.
uint sortlength(THD *thd, st_sort_field *sortorder, uint s_length,
                bool *multi_byte_charset, bool *use_hash);

#endif /* FILESORT_INCLUDED */
