yf_db_utils_mysql class

    public function add_user($name, array $data, $extra = [], &$error = false)
    {
        list($host, $user) = explode('@', $name);
        // TODO: allow add only password in addition to host and user
        if ( ! strlen($host) || ! strlen($name) || ! strlen($data['pswd'])) {
            $error = 'Missing required params';
            return false;
        }
        $sql = '';
        return ($extra['sql'] ?? null) ? $sql : $this->db->query($sql);
    }

    public function check_table($table, $extra = [], &$error = false)
    {
        if ( ! $table) {
            $error = 'table_name is empty';
            return false;
        }
        $sql = 'CHECK TABLE ' . $this->_escape_table_name($table);
        return ($extra['sql'] ?? null) ? $sql : $this->db->query($sql);
    }

    public function create_event($name, $event_shedule, $event_body, $extra = [], &$error = false)
    {
        $db_name = null;
        if (strpos($name, '.') !== false) {
            list($db_name, $name) = explode('.', trim($name));
        }
        if ( ! strlen($name)) {
            $error = 'event name is empty';
            return false;
        }
        if ( ! $db_name) {
            $db_name = $this->db->DB_NAME;
        }
        if ( ! $db_name) {
            $error = 'db_name is empty';
            return false;
        }
        if ( ! strlen($event_shedule)) {
            $error = 'event shedule is empty';
            return false;
        }
        if ( ! strlen($event_body)) {
            $error = 'event body is empty';
            return false;
        }
        $supported_event_intervals = [
            'YEAR', 'QUARTER', 'MONTH', 'DAY', 'HOUR', 'MINUTE',
            'WEEK', 'SECOND', 'YEAR_MONTH', 'DAY_HOUR', 'DAY_MINUTE', 'DAY_SECOND',
            'HOUR_MINUTE', 'HOUR_SECOND', 'MINUTE_SECOND',
        ];
        // TODO: implement strict shedule contents checks
        $sql = 'CREATE EVENT IF NOT EXISTS ' . $this->_escape_table_name($db_name . '.' . $name) . ' ' . PHP_EOL
            . 'ON SCHEDULE ' . $event_shedule . PHP_EOL
            . 'DO ' . $event_body;
        return ($extra['sql'] ?? null) ? $sql : $this->db->query($sql);
    }

    public function create_function($name, $sql_body, $sql_returns_type, $sql_params = '', $extra = [], &$error = false)
    {
        $db_name = null;
        if (strpos($name, '.') !== false) {
            list($db_name, $name) = explode('.', trim($name));
        }
        if ( ! strlen($name)) {
            $error = 'name is empty';
            return false;
        }
        if ( ! $db_name) {
            $db_name = $this->db->DB_NAME;
        }
        if ( ! $db_name) {
            $error = 'db_name is empty';
            return false;
        }
        $sql = ' CREATE FUNCTION ' . $this->_escape_table_name($db_name . '.' . $name) . ' (' . $sql_params . ')' . PHP_EOL
            . 'RETURNS ' . $sql_returns_type . ' DETERMINISTIC' . PHP_EOL
            . 'RETURN ' . $sql_body;
        return ($extra['sql'] ?? null) ? $sql : $this->db->query($sql);
    }

    public function create_procedure($name, $sql_body, $sql_params = '', $extra = [], &$error = false)
    {
        if ( ! strlen($name)) {
            $error = 'name is empty';
            return false;
        }
        $sql = 'CREATE PROCEDURE ' . $this->_escape_key($name) . ' (' . $sql_params . ')' . PHP_EOL
            . 'BEGIN' . PHP_EOL . $sql_body . PHP_EOL . 'END';
        return ($extra['sql'] ?? null) ? $sql : $this->db->query($sql);
    }

    public function delete_user($name, $extra = [], &$error = false)
    {
        list($host, $user) = explode('@', $name);
        $sql = 'DELETE FROM mysql.user WHERE host=' . $this->_escape_val($host) . ' AND user=' . $this->_escape_val($user);
        return ($extra['sql'] ?? null) ? $sql : $this->db->query($sql);
    }

    public function drop_event($name, $extra = [], &$error = false)
    {
        if ( ! strlen($name)) {
            $error = 'event name is empty';
            return false;
        }
        $sql = 'DROP EVENT IF EXISTS ' . $this->_escape_table_name($name);
        return ($extra['sql'] ?? null) ? $sql : $this->db->query($sql);
    }

    public function drop_function($name, $extra = [], &$error = false)
    {
        $db_name = null;
        if (strpos($name, '.') !== false) {
            list($db_name, $name) = explode('.', trim($name));
        }
        if ( ! strlen($name)) {
            $error = 'name is empty';
            return false;
        }
        if ( ! $db_name) {
            $db_name = $this->db->DB_NAME;
        }
        if ( ! $db_name) {
            $error = 'db_name is empty';
            return false;
        }
        $sql = 'DROP FUNCTION IF EXISTS ' . $this->_escape_table_name($db_name . '.' . $name);
        return ($extra['sql'] ?? null) ? $sql : $this->db->query($sql);
    }

    public function drop_procedure($name, $extra = [], &$error = false)
    {
        if ( ! strlen($name)) {
            $error = 'name is empty';
            return false;
        }
        $sql = 'DROP PROCEDURE IF EXISTS ' . $this->_escape_key($name);
        return ($extra['sql'] ?? null) ? $sql : $this->db->query($sql);
    }

    public function event_exists($name, $extra = [], &$error = false)
    {
        $db_name = null;
        if (strpos($name, '.') !== false) {
            list($db_name, $name) = explode('.', trim($name));
        }
        if ( ! $name) {
            $error = 'event name is empty';
            return false;
        }
        if ( ! $db_name) {
            $db_name = $this->db->DB_NAME;
        }
        if ( ! $db_name) {
            $error = 'db_name is empty';
            return false;
        }
        $events = $this->list_events($db_name, $extra, $error);
        return (bool) isset($events[$name]);
    }

    public function event_info($name, $extra = [], &$error = false)
    {
        $db_name = null;
        if (strpos($name, '.') !== false) {
            list($db_name, $name) = explode('.', trim($name));
        }
        if ( ! $name) {
            $error = 'event name is empty';
            return false;
        }
        if ( ! $db_name) {
            $db_name = $this->db->DB_NAME;
        }
        if ( ! $db_name) {
            $error = 'db_name is empty';
            return false;
        }
        $events = $this->list_events($db_name, $extra, $error);
        return isset($events[$name]) ? $events[$name] : false;
    }

    public function function_exists($name, $extra = [], &$error = false)
    {
        if (strpos($name, '.') !== false) {
            list($db_name, $name) = explode('.', trim($name));
        }
        if ( ! $name) {
            $error = 'function name is empty';
            return false;
        }
        $funcs = $this->list_functions();
        return (bool) isset($funcs[$name]);
    }

    public function function_info($name, $extra = [], &$error = false)
    {
        if (strpos($name, '.') !== false) {
            list($db_name, $name) = explode('.', trim($name));
        }
        if ( ! $name) {
            $error = 'function name is empty';
            return false;
        }
        $funcs = $this->list_functions();
        return isset($funcs[$name]) ? $funcs[$name] : false;
    }

    public function list_charsets($extra = [])
    {
        return $this->db->get_all('SHOW CHARACTER SET');
    }

    public function list_collations($extra = [])
    {
        return $this->db->get_all('SHOW COLLATION');
    }

    public function list_events($db_name = '', $extra = [], &$error = false)
    {
        if ( ! $db_name) {
            $db_name = $this->db->DB_NAME;
        }
        if ( ! $db_name) {
            $error = 'db_name is empty';
            return false;
        }
        $events = [];
        foreach ((array) $this->db->get_all('SHOW EVENTS FROM ' . $this->_escape_database_name($db_name)) as $a) {
            $name = $a['Name'];
            $events[$name] = [
                'name' => $name,
                'db' => $a['Db'],
                'definer' => $a['definer'],
                'timezone' => $a['Time_zone'],
                'type' => $a['Type'],
                'execute_at' => $a['Execute_at'],
                'interval_value' => $a['Interval_value'],
                'interval_field' => $a['Interval_field'],
                'starts' => $a['Starts'],
                'ends' => $a['Ends'],
                'status' => $a['Status'],
                'originator' => $a['Originator'],
            ];
        }
        return $events;
    }

    public function list_functions($extra = [], &$error = false)
    {
        $data = [];
        foreach ((array) $this->db->get_all('SHOW FUNCTION STATUS') as $a) {
            $_a = [];
            foreach ((array) $a as $k => $v) {
                $_a[strtolower($k)] = $v;
            }
            $a = $_a;
            $name = $a['name'];
            $data[$name] = $a;
        }
        return $data;
    }

    public function list_procedures($db_name = '', $extra = [], &$error = false)
    {
        if ( ! $db_name) {
            $db_name = $this->db->DB_NAME;
        }
        if ( ! $db_name) {
            $error = 'db_name is empty';
            return false;
        }
        $data = [];
        foreach ((array) $this->db->get_all('SHOW PROCEDURE STATUS') as $a) {
            $_a = [];
            foreach ((array) $a as $k => $v) {
                $_a[strtolower($k)] = $v;
            }
            $a = $_a;
            $name = $a['name'];
            $data[$name] = $a;
        }
        return $data;
    }

    public function list_users($extra = [], &$error = false)
    {
        $users = [];
        foreach ((array) $this->db->get_all('SELECT * FROM mysql.user') as $a) {
            $user = [];
            foreach ((array) $a as $k => $v) {
                $user[strtolower($k)] = $v;
            }
            $name = $user['user'] . '@' . $user['host'];
            $users[$name] = $user;
        }
        return $users;
    }

    public function optimize_table($table, $extra = [], &$error = false)
    {
        if ( ! $table) {
            $error = 'table_name is empty';
            return false;
        }
        $sql = 'OPTIMIZE TABLE ' . $this->_escape_table_name($table);
        return ($extra['sql'] ?? null) ? $sql : $this->db->query($sql);
    }

    public function procedure_exists($name, $extra = [], &$error = false)
    {
        if (strpos($name, '.') !== false) {
            list($db_name, $name) = explode('.', trim($name));
        }
        if ( ! $name) {
            $error = 'procedure name is empty';
            return false;
        }
        $procedures = $this->list_procedures($extra, $error);
        return (bool) isset($procedures[$name]);
    }

    public function procedure_info($name, $extra = [], &$error = false)
    {
        if (strpos($name, '.') !== false) {
            list($db_name, $name) = explode('.', trim($name));
        }
        if ( ! $name) {
            $error = 'procedure name is empty';
            return false;
        }
        $procedures = $this->list_procedures($extra, $error);
        return isset($procedures[$name]) ? $procedures[$name] : false;
    }

    public function repair_table($table, $extra = [], &$error = false)
    {
        if ( ! $table) {
            $error = 'table_name is empty';
            return false;
        }
        $sql = 'REPAIR TABLE ' . $this->_escape_table_name($table);
        return ($extra['sql'] ?? null) ? $sql : $this->db->query($sql);
    }

    public function truncate_database($db_name, $extra = [], &$error = false)
    {
        if ( ! strlen($db_name)) {
            $error = 'db_name is empty';
            return false;
        }
        if ( ! isset($extra['if_exists'])) {
            $extra['if_exists'] = true;
        }
        if ( ! ($extra['sql'] ?? null) && ! $this->database_exists($db_name)) {
            return true;
        }
        $sql = [];
        $fk_sql = 'SET foreign_key_checks = 0;';
        if ( ! ($extra['sql'] ?? null)) {
            $this->db->query($fk_sql);
        } else {
            $sql[] = $fk_sql;
        }
        foreach ((array) $this->list_tables($db_name) as $table) {
            $sql[] = $this->drop_table($db_name . '.' . $table, $extra);
        }
        foreach ((array) $this->list_views($db_name) as $name => $tmp) {
            $sql[] = $this->drop_view($db_name . '.' . $name, $extra);
        }
        foreach ((array) $this->list_triggers($db_name) as $name => $tmp) {
            $sql[] = $this->drop_trigger($db_name . '.' . $name, $extra);
        }
        foreach ((array) $this->list_procedures($db_name) as $name => $tmp) {
            $sql[] = $this->drop_procedure($db_name . '.' . $name, $extra);
        }
        foreach ((array) $this->list_functions($db_name) as $name => $tmp) {
            $sql[] = $this->drop_function($db_name . '.' . $name, $extra);
        }
        foreach ((array) $this->list_events($db_name) as $name => $tmp) {
            $sql[] = $this->drop_event($db_name . '.' . $name, $extra);
        }
        $fk_sql = 'SET foreign_key_checks = 1;';
        if ( ! ($extra['sql'] ?? null)) {
            $this->db->query($fk_sql);
        } else {
            $sql[] = $fk_sql;
        }
        return ($extra['sql'] ?? null) ? implode(PHP_EOL, $sql) : true;
    }

    public function update_user($name, array $data, $extra = [], &$error = false)
    {
        list($host, $user) = explode('@', $name);
        // TODO: allow update only password
        if ( ! strlen($host) || ! strlen($name) || ! strlen($data['pswd'])) {
            $error = 'Missing required params';
            return false;
        }
        $sql = '';
        return ($extra['sql'] ?? null) ? $sql : $this->db->query($sql);
    }

    public function user_exists($name, $extra = [], &$error = false)
    {
        $users = $this->list_users($extra, $error);
        return (bool) isset($users[$name]);
    }

    public function user_info($name, $extra = [], &$error = false)
    {
        $users = $this->list_users($extra, $error);
        return isset($users[$name]) ? $users[$name] : false;
    }

    public function _get_supported_field_types()
    {
        return [
            'bit', 'tinyint', 'smallint', 'mediumint', 'bigint', 'integer', 'int',
            'real', 'float', 'double', 'decimal', 'numeric',
            'varchar', 'char', 'tinytext', 'mediumtext', 'longtext', 'text',
            'tinyblob', 'mediumblob', 'longblob', 'blob', 'varbinary', 'binary',
            'timestamp', 'datetime', 'time', 'date', 'year',
            'enum', 'set',
        ];
    }

    public function _get_supported_table_options()
    {
        return [
            'engine' => 'ENGINE',
            'charset' => 'DEFAULT CHARSET',
        ];
    }

    public function _get_unsigned_field_types()
    {
        return [
            'bit', 'tinyint', 'smallint', 'mediumint', 'bigint', 'integer', 'int',
            'real', 'double', 'float', 'decimal', 'numeric',
        ];
    }