/* Copyright (c) 2000, 2024, 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 designed to work with certain software (including
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   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
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   the program or referenced in the documentation.

   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 SQL_RANGE_OPTIMIZER_INDEX_SKIP_SCAN_H_
#define SQL_RANGE_OPTIMIZER_INDEX_SKIP_SCAN_H_

#include <sys/types.h>

#include "my_alloc.h"
#include "my_base.h"
#include "my_bitmap.h"
#include "my_inttypes.h"
#include "sql/field.h"  // Field
#include "sql/key.h"
#include "sql/malloc_allocator.h"  // IWYU pragma: keep
#include "sql/range_optimizer/index_skip_scan_plan.h"
#include "sql/range_optimizer/range_optimizer.h"

class Cost_estimate;
class JOIN;
class SEL_ARG;
class SEL_ROOT;
class String;
struct TABLE;

/*
  Index scan for range queries that can use skip scans.

  This class provides a specialized index access method for the queries
  of the forms:

       SELECT A_1,...,A_k, B_1,...,B_m, C
         FROM T
        WHERE
         EQ(A_1,...,A_k)
         AND RNG(C);

  where all selected fields are parts of the same index.
  The class of queries that can be processed by this quick select is fully
  specified in the description of get_best_skip_scan() in opt_range.cc.

  Since one of the requirements is that all select fields are part of the same
  index, this class produces only index keys, and not complete records.
*/

class IndexSkipScanIterator : public TableRowIterator {
 private:
  uint index;              /* Index this quick select uses */
  KEY *index_info;         /* Index for skip scan */
  MY_BITMAP column_bitmap; /* Map of key parts to be read */

  const uint eq_prefix_len; /* Total length of the equality prefix. */
  uint eq_prefix_key_parts; /* A number of keyparts in skip scan prefix */
  EQPrefix *eq_prefixes;
  uchar *eq_prefix; /* Storage for current equality prefix. */

  // Total length of first used_key_parts parts of the key.
  uint max_used_key_length;

  // Max. number of (first) key parts this quick select uses for retrieval.
  // eg. for "(key1p1=c1 AND key1p2=c2) OR key1p1=c2" used_key_parts == 2.
  uint used_key_parts;

  uchar *distinct_prefix; /* Storage for prefix A_1, ... B_m. */
  uint distinct_prefix_len;
  uint distinct_prefix_key_parts;

  MEM_ROOT *mem_root;
  const uint range_key_len;
  /*
    Denotes whether the first key for the current equality prefix was
    retrieved.
  */
  bool seen_first_key;

  /* Storage for full lookup key for use with handler::read_range_first/next */
  uchar *const min_range_key;
  uchar *const max_range_key;
  uchar *const min_search_key;
  uchar *const max_search_key;
  const uint range_cond_flag;

  key_range start_key;
  key_range end_key;

  bool has_aggregate_function;

  bool next_eq_prefix();

 public:
  IndexSkipScanIterator(THD *thd, TABLE *table, KEY *index_info, uint index,
                        uint eq_prefix_len, uint eq_prefix_key_parts,
                        EQPrefix *eq_prefixes, uint used_key_parts,
                        MEM_ROOT *temp_mem_root, bool has_aggregate_function,
                        uchar *min_range_key, uchar *max_range_key,
                        uchar *min_search_key, uchar *max_search_key,
                        uint range_cond_flag, uint range_key_len);
  ~IndexSkipScanIterator() override;
  bool Init() override;
  int Read() override;
};

#endif  // SQL_RANGE_OPTIMIZER_INDEX_SKIP_SCAN_H_