/* Copyright (c) 2016, 2025, 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
  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 either included with
  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
  */

/**
  @file storage/perfschema/table_esmh_global.cc
  Table EVENTS_STATEMENTS_HISTOGRAM_GLOBAL (implementation).
*/

#include "storage/perfschema/table_esmh_global.h"

#include "my_thread.h"
#include "sql/field.h"
#include "sql/plugin_table.h"
#include "sql/table.h"
#include "storage/perfschema/pfs_column_types.h"
#include "storage/perfschema/pfs_column_values.h"
#include "storage/perfschema/pfs_digest.h"
#include "storage/perfschema/pfs_global.h"
#include "storage/perfschema/pfs_instr.h"
#include "storage/perfschema/pfs_instr_class.h"
#include "storage/perfschema/pfs_timer.h"
#include "storage/perfschema/pfs_visitor.h"

THR_LOCK table_esmh_global::m_table_lock;

Plugin_table table_esmh_global::m_table_def(
    /* Schema name */
    "performance_schema",
    /* Name */
    "events_statements_histogram_global",
    /* Definition */
    "  BUCKET_NUMBER INTEGER unsigned not null,\n"
    "  BUCKET_TIMER_LOW BIGINT unsigned not null,\n"
    "  BUCKET_TIMER_HIGH BIGINT unsigned not null,\n"
    "  COUNT_BUCKET BIGINT unsigned not null,\n"
    "  COUNT_BUCKET_AND_LOWER BIGINT unsigned not null,\n"
    "  BUCKET_QUANTILE DOUBLE(7,6) not null,\n"
    "  PRIMARY KEY (BUCKET_NUMBER) USING HASH\n",
    /* Options */
    " ENGINE=PERFORMANCE_SCHEMA",
    /* Tablespace */
    nullptr);

PFS_engine_table_share table_esmh_global::m_share = {
    &pfs_truncatable_acl,
    table_esmh_global::create,
    nullptr,
    table_esmh_global::delete_all_rows,
    table_esmh_global::get_row_count,
    sizeof(pos_t),
    &m_table_lock,
    &m_table_def,
    false,
    PFS_engine_table_proxy(),
    {0},
    false /* m_in_purgatory */
};

bool PFS_index_esmh_global::match_bucket(ulong bucket_index) {
  if (m_fields >= 1) {
    return m_key_1.match(bucket_index);
  }

  return true;
}

PFS_engine_table *table_esmh_global::create(PFS_engine_table_share *) {
  auto *table = new table_esmh_global();
  table->materialize();
  return table;
}

int table_esmh_global::delete_all_rows() {
  reset_histogram_global();
  return 0;
}

ha_rows table_esmh_global::get_row_count() { return NUMBER_OF_BUCKETS; }

table_esmh_global::table_esmh_global()
    : PFS_engine_table(&m_share, &m_pos),
      m_pos(0),
      m_next_pos(0),
      m_materialized(false) {}

void table_esmh_global::reset_position() {
  m_pos.m_index = 0;
  m_next_pos.m_index = 0;
}

int table_esmh_global::rnd_next() {
  for (m_pos.set_at(&m_next_pos); m_pos.m_index < NUMBER_OF_BUCKETS;
       m_pos.next()) {
    make_row(m_pos.m_index);
    m_next_pos.set_after(&m_pos);
    return 0;
  }

  return HA_ERR_END_OF_FILE;
}

int table_esmh_global::rnd_pos(const void *pos) {
  set_position(pos);

  if (m_pos.m_index < NUMBER_OF_BUCKETS) {
    return make_row(m_pos.m_index);
  }

  return HA_ERR_RECORD_DELETED;
}

int table_esmh_global::index_init(uint idx [[maybe_unused]], bool) {
  PFS_index_esmh_global *result = nullptr;
  assert(idx == 0);
  result = PFS_NEW(PFS_index_esmh_global);
  m_opened_index = result;
  m_index = result;
  return 0;
}

int table_esmh_global::index_next() {
  for (m_pos.set_at(&m_next_pos); m_pos.m_index < NUMBER_OF_BUCKETS;
       m_pos.next()) {
    if (m_opened_index->match_bucket(m_pos.m_index)) {
      make_row(m_pos.m_index);
      m_next_pos.set_after(&m_pos);
      return 0;
    }
  }

  return HA_ERR_END_OF_FILE;
}

void table_esmh_global::materialize() {
  if (!m_materialized) {
    PFS_histogram *histogram = &global_statements_histogram;

    ulong index;
    ulonglong count = 0;
    ulonglong count_and_lower = 0;

    for (index = 0; index < NUMBER_OF_BUCKETS; index++) {
      count = histogram->read_bucket(index);
      count_and_lower += count;

      PFS_esmh_global_bucket &b = m_materialized_histogram.m_buckets[index];

      b.m_count_bucket = count;
      b.m_count_bucket_and_lower = count_and_lower;
    }

    m_materialized = true;
  }
}

int table_esmh_global::make_row(ulong bucket_index) {
  assert(m_materialized);
  assert(bucket_index < NUMBER_OF_BUCKETS);

  m_row.m_bucket_number = bucket_index;
  m_row.m_bucket_timer_low =
      g_histogram_pico_timers.m_bucket_timer[bucket_index];
  m_row.m_bucket_timer_high =
      g_histogram_pico_timers.m_bucket_timer[bucket_index + 1];

  m_row.m_count_bucket =
      m_materialized_histogram.m_buckets[bucket_index].m_count_bucket;
  m_row.m_count_bucket_and_lower =
      m_materialized_histogram.m_buckets[bucket_index].m_count_bucket_and_lower;

  const ulonglong count_star =
      m_materialized_histogram.m_buckets[NUMBER_OF_BUCKETS - 1]
          .m_count_bucket_and_lower;

  if (count_star > 0) {
    const double dividend = m_row.m_count_bucket_and_lower;
    const double divisor = count_star;
    m_row.m_percentile = dividend / divisor; /* computed with double, not int */
  } else {
    m_row.m_percentile = 0.0;
  }

  return 0;
}

int table_esmh_global::read_row_values(TABLE *table, unsigned char *buf,
                                       Field **fields, bool read_all) {
  Field *f;

  /*
    Set the null bits. It indicates how many fields could be null
    in the table.
  */
  assert(table->s->null_bytes == 1);  // TODO: WHY ?
  buf[0] = 0;

  for (; (f = *fields); fields++) {
    if (read_all || bitmap_is_set(table->read_set, f->field_index())) {
      switch (f->field_index()) {
        case 0: /* BUCKET_NUMBER */
          set_field_ulong(f, m_row.m_bucket_number);
          break;
        case 1: /* BUCKET_TIMER_LOW */
          set_field_ulonglong(f, m_row.m_bucket_timer_low);
          break;
        case 2: /* BUCKET_TIMER_HIGH */
          set_field_ulonglong(f, m_row.m_bucket_timer_high);
          break;
        case 3: /* COUNT_BUCKET */
          set_field_ulonglong(f, m_row.m_count_bucket);
          break;
        case 4: /* COUNT_BUCKET_AND_LOWER */
          set_field_ulonglong(f, m_row.m_count_bucket_and_lower);
          break;
        case 5: /* BUCKET_QUANTILE */
          set_field_double(f, m_row.m_percentile);
          break;
        default:
          assert(false);
          break;
      }
    }
  }

  return 0;
}