/* Copyright (c) 2015, 2023, 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,
   51 Franklin Street, Suite 500, Boston, MA 02110-1335 USA */

/**
  @file rules_table_service.cc
  Implementation of the service for accessing the rewrite rules table.
*/

#include <mysql/service_rules_table.h>

#include "thr_lock.h"
#include "table.h"
#include "handler.h"
#include "my_base.h"
#include "my_bitmap.h"
#include "field.h"
#include "sql_string.h"
#include "transaction.h"
#include "sql_base.h"

namespace rules_table_service
{

int MY_ATTRIBUTE((visibility("default"))) 
dummy_function_to_ensure_we_are_linked_into_the_server() { return 1; }

const char *db_name= "query_rewrite";
const char *table_name= "rewrite_rules";

int Cursor::read()
{
  TABLE *table= m_table_list->table;
  m_last_read_status= table->file->ha_rnd_next(table->record[0]);
  if (m_last_read_status != 0)
    m_is_finished= true;
  return m_last_read_status;
}


void free_string(const char *str) { delete [] str; }


static void add_column(MY_BITMAP *map, Cursor::column_id column)
{
  if (column != Cursor::ILLEGAL_COLUMN_ID)
    bitmap_set_bit(map, column);
}


Cursor::Cursor(MYSQL_THD mysql_thd) :
  m_thd(mysql_thd),
  m_table_list(NULL),
  m_is_finished(true),
  m_table_is_malformed(true)
{
  m_table_list= new TABLE_LIST;
  if (m_table_list == NULL)
    return; // Error

  // The below function will memset() the whole object with 0's.
  m_table_list->init_one_table(db_name, strlen(db_name),
                               table_name, strlen(table_name),
                               "alias", TL_WRITE_DEFAULT);

  m_table_list->updating= true;

  if (open_and_lock_tables(m_thd, m_table_list, MYSQL_LOCK_IGNORE_GLOBAL_READ_ONLY))
    return; // Error

  TABLE *table= m_table_list->table;
  if (table == NULL)
    return; // Error

  m_pattern_column= field_index("pattern");
  m_pattern_database_column= field_index("pattern_database");
  m_replacement_column= field_index("replacement");
  m_enabled_column= field_index("enabled");

  // The following columns are not required for the Cursor to work.
  m_message_column= field_index("message");
  m_pattern_digest_column= field_index("pattern_digest");
  m_normalized_pattern_column= field_index("normalized_pattern");

  if (m_pattern_column == ILLEGAL_COLUMN_ID ||
      m_pattern_database_column == ILLEGAL_COLUMN_ID ||
      m_replacement_column == ILLEGAL_COLUMN_ID ||
      m_enabled_column == ILLEGAL_COLUMN_ID)
  {
    trans_rollback_stmt(m_thd);
    close_thread_tables(m_thd);

    /*
      We are never going to use this table, we might as well get rid of the
      reference to it.
    */
    delete m_table_list;
    m_table_list= NULL;
    m_table_is_malformed= true;
    return; // Error
  }
  else
    m_table_is_malformed= false;

  add_column(table->read_set, pattern_column());
  add_column(table->read_set, pattern_database_column());
  add_column(table->read_set, replacement_column());
  add_column(table->read_set, enabled_column());
  add_column(table->read_set, message_column());

  add_column(table->write_set, enabled_column());
  add_column(table->write_set, message_column());
  add_column(table->write_set, pattern_digest_column());    
  add_column(table->write_set, normalized_pattern_column());    

  if (m_table_list->table->file->ha_rnd_init(true) != 0)
    return; // Error

  // No error occured, set this to false.
  m_is_finished= false;

  read();
}


const char *Cursor::fetch_string(int fieldno)
{
  Field **fields= m_table_list->table->field;
  Field *field= fields[fieldno];
  if (field->is_null())
    return NULL;
  String value_buf;
  String *value= field->val_str(&value_buf);
  size_t length= value->length();
  char *res= new char[length + 1];
  strncpy(res, value->ptr(), length);
  res[length]= '\0';
  return res;
}


int Cursor::field_index(const char *field_name)
{
  TABLE *table= m_table_list->table;
  for (uint i= 0; i < table->s->fields; ++i)
    if (strcmp(table->field[i]->field_name, field_name) == 0)
      return i;
  return -1;
}


void Cursor::make_writeable()
{
  TABLE *table= m_table_list->table;
  memcpy(table->record[1], table->record[0], table->s->rec_buff_length);
}


void Cursor::set(int colno, const char* str, size_t length)
{
  TABLE *table= m_table_list->table;
  Field *field= table->field[colno];

  const CHARSET_INFO *charset= &my_charset_utf8_unicode_ci;
  if (str == NULL)
    field->set_null(0);
  else
  {
    field->store(str, length, charset);
    field->set_notnull(0);
  }
}


int Cursor::write()
{
  TABLE *table= m_table_list->table;
  return table->file->ha_update_row(table->record[1], table->record[0]);
}

bool Cursor::had_serious_read_error() const
{
  return
    m_last_read_status != 0 &&
    m_last_read_status != HA_ERR_END_OF_FILE;
}

Cursor::~Cursor()
{
  if (m_table_list != NULL && m_table_list->table != NULL)
    m_table_list->table->file->ha_rnd_end();
  delete m_table_list;
}


Cursor end() { return Cursor(); }

}