# Copyright (c) 2014, 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.
#
# Without limiting anything contained in the foregoing, this file,
# which is part of MySQL Connector/Python, is also subject to the
# Universal FOSS Exception, version 1.0, a copy of which can be found at
# http://oss.oracle.com/licenses/universal-foss-exception.
#
# 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

"""Connection class using the C Extension
"""

# Detection of abstract methods in pylint is not working correctly
#pylint: disable=W0223

import os
import socket
import sysconfig

from . import errors, version
from .constants import (
    CharacterSet, FieldFlag, ServerFlag, ShutdownType, ClientFlag
)
from .abstracts import MySQLConnectionAbstract, MySQLCursorAbstract
from .protocol import MySQLProtocol

HAVE_CMYSQL = False
# pylint: disable=F0401,C0413
try:
    import _mysql_connector
    from .cursor_cext import (
        CMySQLCursor, CMySQLCursorRaw,
        CMySQLCursorBuffered, CMySQLCursorBufferedRaw, CMySQLCursorPrepared,
        CMySQLCursorDict, CMySQLCursorBufferedDict, CMySQLCursorNamedTuple,
        CMySQLCursorBufferedNamedTuple)
    from _mysql_connector import MySQLInterfaceError  # pylint: disable=F0401
except ImportError as exc:
    raise ImportError(
        "MySQL Connector/Python C Extension not available ({0})".format(
            str(exc)
        ))
else:
    HAVE_CMYSQL = True
# pylint: enable=F0401,C0413


class CMySQLConnection(MySQLConnectionAbstract):

    """Class initiating a MySQL Connection using Connector/C"""

    def __init__(self, **kwargs):
        """Initialization"""
        if not HAVE_CMYSQL:
            raise RuntimeError(
                "MySQL Connector/Python C Extension not available")
        self._cmysql = None
        self._columns = []
        self._plugin_dir = os.path.join(
            os.path.dirname(os.path.abspath(_mysql_connector.__file__)),
            "mysql", "vendor", "plugin"
        )
        self.converter = None
        super(CMySQLConnection, self).__init__(**kwargs)

        if kwargs:
            self.connect(**kwargs)

    def _add_default_conn_attrs(self):
        """Add default connection attributes"""
        license_chunks = version.LICENSE.split(" ")
        if license_chunks[0] == "GPLv2":
            client_license = "GPL-2.0"
        else:
            client_license = "Commercial"

        self._conn_attrs.update({
            "_connector_name": "mysql-connector-python",
            "_connector_license": client_license,
            "_connector_version": ".".join(
                [str(x) for x in version.VERSION[0:3]]),
            "_source_host": socket.gethostname()
            })

    def _do_handshake(self):
        """Gather information of the MySQL server before authentication"""
        self._handshake = {
            'protocol': self._cmysql.get_proto_info(),
            'server_version_original': self._cmysql.get_server_info(),
            'server_threadid': self._cmysql.thread_id(),
            'charset': None,
            'server_status': None,
            'auth_plugin': None,
            'auth_data': None,
            'capabilities': self._cmysql.st_server_capabilities(),
        }

        self._server_version = self._check_server_version(
            self._handshake['server_version_original']
        )

    @property
    def _server_status(self):
        """Returns the server status attribute of MYSQL structure"""
        return self._cmysql.st_server_status()

    def set_allow_local_infile_in_path(self, path):
        """set local_infile_in_path

        Set allow_local_infile_in_path.
        """

        if self._cmysql:
            self._cmysql.set_load_data_local_infile_option(path)

    def set_unicode(self, value=True):
        """Toggle unicode mode

        Set whether we return string fields as unicode or not.
        Default is True.
        """
        self._use_unicode = value
        if self._cmysql:
            self._cmysql.use_unicode(value)
        if self.converter:
            self.converter.set_unicode(value)

    @property
    def autocommit(self):
        """Get whether autocommit is on or off"""
        value = self.info_query("SELECT @@session.autocommit")[0]
        return True if value == 1 else False

    @autocommit.setter
    def autocommit(self, value):  # pylint: disable=W0221
        """Toggle autocommit"""
        try:
            self._cmysql.autocommit(value)
            self._autocommit = value
        except MySQLInterfaceError as exc:
            raise errors.get_mysql_exception(msg=exc.msg, errno=exc.errno,
                                             sqlstate=exc.sqlstate)

    @property
    def database(self):
        """Get the current database"""
        return self.info_query("SELECT DATABASE()")[0]

    @database.setter
    def database(self, value):  # pylint: disable=W0221
        """Set the current database"""
        self._cmysql.select_db(value)

    @property
    def in_transaction(self):
        """MySQL session has started a transaction"""
        return self._server_status & ServerFlag.STATUS_IN_TRANS

    def _open_connection(self):
        charset_name = CharacterSet.get_info(self._charset_id)[0]
        self._cmysql = _mysql_connector.MySQL(  # pylint: disable=E1101,I1101
            buffered=self._buffered,
            raw=self._raw,
            charset_name=charset_name,
            connection_timeout=(self._connection_timeout or 0),
            use_unicode=self._use_unicode,
            auth_plugin=self._auth_plugin,
            plugin_dir=self._plugin_dir)
        if not self.isset_client_flag(ClientFlag.CONNECT_ARGS):
            self._conn_attrs = {}
        cnx_kwargs = {
            'host': self._host,
            'user': self._user,
            'password': self._password,
            'password1': self._password1,
            'password2': self._password2,
            'password3': self._password3,
            'database': self._database,
            'port': self._port,
            'client_flags': self._client_flags,
            'unix_socket': self._unix_socket,
            'compress': self.isset_client_flag(ClientFlag.COMPRESS),
            'ssl_disabled': True,
            "conn_attrs": self._conn_attrs,
            "local_infile": self._allow_local_infile,
            "load_data_local_dir": self._allow_local_infile_in_path,
            "oci_config_file": self._oci_config_file,
        }

        tls_versions = self._ssl.get('tls_versions')
        if tls_versions is not None:
            tls_versions.sort(reverse=True)
            tls_versions = ",".join(tls_versions)
        if self._ssl.get('tls_ciphersuites') is not None:
            ssl_ciphersuites = self._ssl.get('tls_ciphersuites')[0]
            tls_ciphersuites = self._ssl.get('tls_ciphersuites')[1]
        else:
            ssl_ciphersuites = None
            tls_ciphersuites = None
        if tls_versions is not None and "TLSv1.3" in tls_versions and \
           not tls_ciphersuites:
            tls_ciphersuites = "TLS_AES_256_GCM_SHA384"
        if not self._ssl_disabled:
            cnx_kwargs.update({
                'ssl_ca': self._ssl.get('ca'),
                'ssl_cert': self._ssl.get('cert'),
                'ssl_key': self._ssl.get('key'),
                'ssl_cipher_suites': ssl_ciphersuites,
                'tls_versions': tls_versions,
                'tls_cipher_suites': tls_ciphersuites,
                'ssl_verify_cert': self._ssl.get('verify_cert') or False,
                'ssl_verify_identity':
                    self._ssl.get('verify_identity') or False,
                'ssl_disabled': self._ssl_disabled
            })

        try:
            self._cmysql.connect(**cnx_kwargs)
            self._cmysql.converter_str_fallback = self._converter_str_fallback
            if self.converter:
                self.converter.str_fallback = self._converter_str_fallback
        except MySQLInterfaceError as exc:
            raise errors.get_mysql_exception(msg=exc.msg, errno=exc.errno,
                                             sqlstate=exc.sqlstate)

        self._do_handshake()

    def close(self):
        """Disconnect from the MySQL server"""
        if self._cmysql:
            try:
                self.free_result()
                self._cmysql.close()
            except MySQLInterfaceError as exc:
                raise errors.get_mysql_exception(msg=exc.msg, errno=exc.errno,
                                                 sqlstate=exc.sqlstate)
    disconnect = close

    def is_closed(self):
        """Return True if the connection to MySQL Server is closed."""
        return not self._cmysql.connected()

    def is_connected(self):
        """Reports whether the connection to MySQL Server is available"""
        if self._cmysql:
            return self._cmysql.ping()

        return False

    def ping(self, reconnect=False, attempts=1, delay=0):
        """Check availability of the MySQL server

        When reconnect is set to True, one or more attempts are made to try
        to reconnect to the MySQL server using the reconnect()-method.

        delay is the number of seconds to wait between each retry.

        When the connection is not available, an InterfaceError is raised. Use
        the is_connected()-method if you just want to check the connection
        without raising an error.

        Raises InterfaceError on errors.
        """
        errmsg = "Connection to MySQL is not available"

        try:
            connected = self._cmysql.ping()
        except AttributeError:
            pass  # Raise or reconnect later
        else:
            if connected:
                return

        if reconnect:
            self.reconnect(attempts=attempts, delay=delay)
        else:
            raise errors.InterfaceError(errmsg)

    def set_character_set_name(self, charset):
        """Sets the default character set name for current connection.
        """
        self._cmysql.set_character_set(charset)

    def info_query(self, query):
        """Send a query which only returns 1 row"""
        self._cmysql.query(query)
        first_row = ()
        if self._cmysql.have_result_set:
            first_row = self._cmysql.fetch_row()
            if self._cmysql.fetch_row():
                self._cmysql.free_result()
                raise errors.InterfaceError(
                    "Query should not return more than 1 row")
        self._cmysql.free_result()

        return first_row

    @property
    def connection_id(self):
        """MySQL connection ID"""
        try:
            return self._cmysql.thread_id()
        except MySQLInterfaceError:
            pass  # Just return None

        return None

    def get_rows(self, count=None, binary=False, columns=None, raw=None,
                 prep_stmt=None):
        """Get all or a subset of rows returned by the MySQL server"""
        unread_result = prep_stmt.have_result_set if prep_stmt \
            else self.unread_result
        if not (self._cmysql and unread_result):
            raise errors.InternalError("No result set available")

        if raw is None:
            raw = self._raw

        rows = []
        if count is not None and count <= 0:
            raise AttributeError("count should be 1 or higher, or None")

        counter = 0
        try:
            fetch_row = (
                prep_stmt.fetch_row if prep_stmt
                else self._cmysql.fetch_row
            )
            if self.converter:
                # When using a converter class, the C extension should not
                # convert the values. This can be accomplished by setting
                # the raw option to True.
                self._cmysql.raw(True)
            row = fetch_row()
            while row:
                if not self._raw and self.converter:
                    row = list(row)
                    for i, _ in enumerate(row):
                        if not raw:
                            row[i] = self.converter.to_python(self._columns[i],
                                                              row[i])
                    row = tuple(row)
                rows.append(row)
                counter += 1
                if count and counter == count:
                    break
                row = fetch_row()
            if not row:
                _eof = self.fetch_eof_columns(prep_stmt)['eof']
                if prep_stmt:
                    prep_stmt.free_result()
                    self._unread_result = False
                else:
                    self.free_result()
            else:
                _eof = None
        except MySQLInterfaceError as exc:
            if prep_stmt:
                prep_stmt.free_result()
                raise errors.InterfaceError(str(exc))
            else:
                self.free_result()
                raise errors.get_mysql_exception(msg=exc.msg, errno=exc.errno,
                                                 sqlstate=exc.sqlstate)

        return rows, _eof

    def get_row(self, binary=False, columns=None, raw=None, prep_stmt=None):
        """Get the next rows returned by the MySQL server"""
        try:
            rows, eof = self.get_rows(count=1, binary=binary, columns=columns,
                                      raw=raw, prep_stmt=prep_stmt)
            if rows:
                return (rows[0], eof)
            return (None, eof)
        except IndexError:
            # No row available
            return (None, None)

    def next_result(self):
        """Reads the next result"""
        if self._cmysql:
            self._cmysql.consume_result()
            return self._cmysql.next_result()
        return None

    def free_result(self):
        """Frees the result"""
        if self._cmysql:
            self._cmysql.free_result()

    def commit(self):
        """Commit current transaction"""
        if self._cmysql:
            self._cmysql.commit()

    def rollback(self):
        """Rollback current transaction"""
        if self._cmysql:
            self._cmysql.consume_result()
            self._cmysql.rollback()

    def cmd_init_db(self, database):
        """Change the current database"""
        try:
            self._cmysql.select_db(database)
        except MySQLInterfaceError as exc:
            raise errors.get_mysql_exception(msg=exc.msg, errno=exc.errno,
                                             sqlstate=exc.sqlstate)

    def fetch_eof_columns(self, prep_stmt=None):
        """Fetch EOF and column information"""
        have_result_set = prep_stmt.have_result_set if prep_stmt \
            else self._cmysql.have_result_set
        if not have_result_set:
            raise errors.InterfaceError("No result set")

        fields = prep_stmt.fetch_fields() if prep_stmt \
            else self._cmysql.fetch_fields()
        self._columns = []
        for col in fields:
            self._columns.append((
                col[4],
                int(col[8]),
                None,
                None,
                None,
                None,
                ~int(col[9]) & FieldFlag.NOT_NULL,
                int(col[9]),
                int(col[6]),
            ))

        return {
            'eof': {
                'status_flag': self._server_status,
                'warning_count': self._cmysql.st_warning_count(),
            },
            'columns': self._columns,
        }

    def fetch_eof_status(self):
        """Fetch EOF and status information"""
        if self._cmysql:
            return {
                'warning_count': self._cmysql.st_warning_count(),
                'field_count': self._cmysql.st_field_count(),
                'insert_id': self._cmysql.insert_id(),
                'affected_rows': self._cmysql.affected_rows(),
                'server_status': self._server_status,
            }

        return None

    def cmd_stmt_prepare(self, statement):
        """Prepares the SQL statement"""
        if not self._cmysql:
            raise errors.OperationalError("MySQL Connection not available")

        try:
            stmt = self._cmysql.stmt_prepare(statement)
            stmt.converter_str_fallback = self._converter_str_fallback
            return stmt
        except MySQLInterfaceError as err:
            raise errors.InterfaceError(str(err))

    # pylint: disable=W0221
    def cmd_stmt_execute(self, prep_stmt, *args):
        """Executes the prepared statement"""
        try:
            prep_stmt.stmt_execute(*args)
        except MySQLInterfaceError as err:
            raise errors.InterfaceError(str(err))

        self._columns = []
        if not prep_stmt.have_result_set:
            # No result
            self._unread_result = False
            return self.fetch_eof_status()

        self._unread_result = True
        return self.fetch_eof_columns(prep_stmt)

    def cmd_stmt_close(self, prep_stmt):
        """Closes the prepared statement"""
        if self._unread_result:
            raise errors.InternalError("Unread result found")
        prep_stmt.stmt_close()

    def cmd_stmt_reset(self, prep_stmt):
        """Resets the prepared statement"""
        if self._unread_result:
            raise errors.InternalError("Unread result found")
        prep_stmt.stmt_reset()
    # pylint: enable=W0221

    def cmd_query(self, query, raw=None, buffered=False, raw_as_string=False):
        """Send a query to the MySQL server"""
        self.handle_unread_result()
        if raw is None:
            raw = self._raw
        try:
            if not isinstance(query, bytes):
                query = query.encode('utf-8')
            self._cmysql.query(query,
                               raw=raw, buffered=buffered,
                               raw_as_string=raw_as_string,
                               query_attrs=self._query_attrs)
        except MySQLInterfaceError as exc:
            raise errors.get_mysql_exception(exc.errno, msg=exc.msg,
                                             sqlstate=exc.sqlstate)
        except AttributeError:
            if self._unix_socket:
                addr = self._unix_socket
            else:
                addr = self._host + ':' + str(self._port)
            raise errors.OperationalError(
                errno=2055, values=(addr, 'Connection not available.'))

        self._columns = []
        if not self._cmysql.have_result_set:
            # No result
            return self.fetch_eof_status()

        return self.fetch_eof_columns()
    _execute_query = cmd_query

    def cursor(self, buffered=None, raw=None, prepared=None, cursor_class=None,
               dictionary=None, named_tuple=None):
        """Instantiates and returns a cursor using C Extension

        By default, CMySQLCursor is returned. Depending on the options
        while connecting, a buffered and/or raw cursor is instantiated
        instead. Also depending upon the cursor options, rows can be
        returned as dictionary or named tuple.

        Dictionary and namedtuple based cursors are available with buffered
        output but not raw.

        It is possible to also give a custom cursor through the
        cursor_class parameter, but it needs to be a subclass of
        mysql.connector.cursor_cext.CMySQLCursor.

        Raises ProgrammingError when cursor_class is not a subclass of
        CursorBase. Raises ValueError when cursor is not available.

        Returns instance of CMySQLCursor or subclass.

        :param buffered: Return a buffering cursor
        :param raw: Return a raw cursor
        :param prepared: Return a cursor which uses prepared statements
        :param cursor_class: Use a custom cursor class
        :param dictionary: Rows are returned as dictionary
        :param named_tuple: Rows are returned as named tuple
        :return: Subclass of CMySQLCursor
        :rtype: CMySQLCursor or subclass
        """
        self.handle_unread_result(prepared)
        if not self.is_connected():
            raise errors.OperationalError("MySQL Connection not available.")
        if cursor_class is not None:
            if not issubclass(cursor_class, MySQLCursorAbstract):
                raise errors.ProgrammingError(
                    "Cursor class needs be to subclass"
                    " of cursor_cext.CMySQLCursor")
            return (cursor_class)(self)

        buffered = buffered or self._buffered
        raw = raw or self._raw

        cursor_type = 0
        if buffered is True:
            cursor_type |= 1
        if raw is True:
            cursor_type |= 2
        if dictionary is True:
            cursor_type |= 4
        if named_tuple is True:
            cursor_type |= 8
        if prepared is True:
            cursor_type |= 16

        types = {
            0: CMySQLCursor,  # 0
            1: CMySQLCursorBuffered,
            2: CMySQLCursorRaw,
            3: CMySQLCursorBufferedRaw,
            4: CMySQLCursorDict,
            5: CMySQLCursorBufferedDict,
            8: CMySQLCursorNamedTuple,
            9: CMySQLCursorBufferedNamedTuple,
            16: CMySQLCursorPrepared
        }
        try:
            return (types[cursor_type])(self)
        except KeyError:
            args = ('buffered', 'raw', 'dictionary', 'named_tuple', 'prepared')
            raise ValueError('Cursor not available with given criteria: ' +
                             ', '.join([args[i] for i in range(5)
                                        if cursor_type & (1 << i) != 0]))

    @property
    def num_rows(self):
        """Returns number of rows of current result set"""
        if not self._cmysql.have_result_set:
            raise errors.InterfaceError("No result set")

        return self._cmysql.num_rows()

    @property
    def warning_count(self):
        """Returns number of warnings"""
        if not self._cmysql:
            return 0

        return self._cmysql.warning_count()

    @property
    def result_set_available(self):
        """Check if a result set is available"""
        if not self._cmysql:
            return False

        return self._cmysql.have_result_set

    @property
    def unread_result(self):
        """Check if there are unread results or rows"""
        return self.result_set_available

    @property
    def more_results(self):
        """Check if there are more results"""
        return self._cmysql.more_results()

    def prepare_for_mysql(self, params):
        """Prepare parameters for statements

        This method is use by cursors to prepared parameters found in the
        list (or tuple) params.

        Returns dict.
        """
        if isinstance(params, (list, tuple)):
            if self.converter:
                result = [
                    self.converter.quote(
                        self.converter.escape(
                            self.converter.to_mysql(value)
                        )
                    ) for value in params
                ]
            else:
                result = self._cmysql.convert_to_mysql(*params)
        elif isinstance(params, dict):
            result = {}
            if self.converter:
                for key, value in params.items():
                    result[key] = self.converter.quote(
                        self.converter.escape(
                            self.converter.to_mysql(value)
                        )
                    )
            else:
                for key, value in params.items():
                    result[key] = self._cmysql.convert_to_mysql(value)[0]
        else:
            raise errors.ProgrammingError(
                f"Could not process parameters: {type(params).__name__}({params}),"
                " it must be of type list, tuple or dict")

        return result

    def consume_results(self):
        """Consume the current result

        This method consume the result by reading (consuming) all rows.
        """
        self._cmysql.consume_result()

    def cmd_change_user(self, username='', password='', database='',
                        charset=45, password1='', password2='', password3='',
                        oci_config_file=None):
        """Change the current logged in user"""
        try:
            self._cmysql.change_user(
                username,
                password,
                database,
                password1,
                password2,
                password3,
                oci_config_file)

        except MySQLInterfaceError as exc:
            raise errors.get_mysql_exception(msg=exc.msg, errno=exc.errno,
                                             sqlstate=exc.sqlstate)

        self._charset_id = charset
        self._post_connection()

    def cmd_reset_connection(self):
        """Resets the session state without re-authenticating

        Works only for MySQL server 5.7.3 or later.
        """
        if self._server_version < (5, 7, 3):
            raise errors.NotSupportedError("MySQL version 5.7.2 and "
                                           "earlier does not support "
                                           "COM_RESET_CONNECTION.")
        try:
            self._cmysql.reset_connection()
        except MySQLInterfaceError as exc:
            raise errors.get_mysql_exception(msg=exc.msg, errno=exc.errno,
                                             sqlstate=exc.sqlstate)

        self._post_connection()

    def cmd_refresh(self, options):
        """Send the Refresh command to the MySQL server"""
        try:
            self._cmysql.refresh(options)
        except MySQLInterfaceError as exc:
            raise errors.get_mysql_exception(msg=exc.msg, errno=exc.errno,
                                             sqlstate=exc.sqlstate)

        return self.fetch_eof_status()

    def cmd_quit(self):
        """Close the current connection with the server"""
        self.close()

    def cmd_shutdown(self, shutdown_type=None):
        """Shut down the MySQL Server"""
        if not self._cmysql:
            raise errors.OperationalError("MySQL Connection not available")

        if shutdown_type:
            if not ShutdownType.get_info(shutdown_type):
                raise errors.InterfaceError("Invalid shutdown type")
            level = shutdown_type
        else:
            level = ShutdownType.SHUTDOWN_DEFAULT

        try:
            self._cmysql.shutdown(level)
        except MySQLInterfaceError as exc:
            raise errors.get_mysql_exception(msg=exc.msg, errno=exc.errno,
                                             sqlstate=exc.sqlstate)
        self.close()

    def cmd_statistics(self):
        """Return statistics from the MySQL server"""
        self.handle_unread_result()

        try:
            stat = self._cmysql.stat()
            return MySQLProtocol().parse_statistics(stat, with_header=False)
        except (MySQLInterfaceError, errors.InterfaceError) as exc:
            raise errors.get_mysql_exception(msg=exc.msg, errno=exc.errno,
                                             sqlstate=exc.sqlstate)

    def cmd_process_kill(self, mysql_pid):
        """Kill a MySQL process"""
        if not isinstance(mysql_pid, int):
            raise ValueError("MySQL PID must be int")
        self.info_query("KILL {0}".format(mysql_pid))

    def handle_unread_result(self, prepared=False):
        """Check whether there is an unread result"""
        unread_result = self._unread_result if prepared is True \
            else self.unread_result
        if self.can_consume_results:
            self.consume_results()
        elif unread_result:
            raise errors.InternalError("Unread result found")

    def reset_session(self, user_variables=None, session_variables=None):
        """Clears the current active session

        This method resets the session state, if the MySQL server is 5.7.3
        or later active session will be reset without re-authenticating.
        For other server versions session will be reset by re-authenticating.

        It is possible to provide a sequence of variables and their values to
        be set after clearing the session. This is possible for both user
        defined variables and session variables.
        This method takes two arguments user_variables and session_variables
        which are dictionaries.

        Raises OperationalError if not connected, InternalError if there are
        unread results and InterfaceError on errors.
        """
        if not self.is_connected():
            raise errors.OperationalError("MySQL Connection not available.")

        try:
            self.cmd_reset_connection()
        except (errors.NotSupportedError, NotImplementedError):
            if self._compress:
                raise errors.NotSupportedError(
                    "Reset session is not supported with compression for "
                    "MySQL server version 5.7.2 or earlier.")
            elif self._server_version < (5, 7, 3):
                raise errors.NotSupportedError(
                    "Reset session is not supported with MySQL server "
                    "version 5.7.2 or earlier.")
            else:
                self.cmd_change_user(self._user, self._password,
                                     self._database, self._charset_id,
                                     self._password1, self._password2,
                                     self._password3, self._oci_config_file)

        if user_variables or session_variables:
            cur = self.cursor()
            if user_variables:
                for key, value in user_variables.items():
                    cur.execute("SET @`{0}` = %s".format(key), (value,))
            if session_variables:
                for key, value in session_variables.items():
                    cur.execute("SET SESSION `{0}` = %s".format(key), (value,))
            cur.close()
