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View File Name : cursor.py

# Copyright (c) 2023, 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
# but not limited to OpenSSL) that is licensed under separate terms,
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#
# 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.
#
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# WITHOUT ANY WARRANTY; without even the implied warranty of
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# See the GNU General Public License, version 2.0, for more details.
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# 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA

# mypy: disable-error-code="assignment,arg-type,attr-defined,index,override,call-overload"

"""Implementation of cursor classes in pure Python."""

__all__ = ["MySQLCursor"]

import re
import warnings

from collections import namedtuple
from decimal import Decimal
from typing import (
    Any,
    AsyncGenerator,
    Dict,
    Iterator,
    List,
    NoReturn,
    Optional,
    Sequence,
    Tuple,
    Union,
)

from ..constants import ServerFlag
from ..cursor import (
    MAX_RESULTS,
    RE_PY_MAPPING_PARAM,
    RE_PY_PARAM,
    RE_SQL_COMMENT,
    RE_SQL_FIND_PARAM,
    RE_SQL_INSERT_STMT,
    RE_SQL_INSERT_VALUES,
    RE_SQL_ON_DUPLICATE,
    RE_SQL_PYTHON_CAPTURE_PARAM_NAME,
    RE_SQL_PYTHON_REPLACE_PARAM,
    is_eol_comment,
    parse_multi_statement_query,
)
from ..errors import (
    Error,
    InterfaceError,
    NotSupportedError,
    ProgrammingError,
    get_mysql_exception,
)
from ..types import (
    DescriptionType,
    EofPacketType,
    ParamsDictType,
    ParamsSequenceOrDictType,
    ParamsSequenceType,
    ResultType,
    RowItemType,
    RowType,
    StrOrBytes,
    WarningType,
)
from .abstracts import NAMED_TUPLE_CACHE, MySQLConnectionAbstract, MySQLCursorAbstract

ERR_NO_RESULT_TO_FETCH = "No result set to fetch from"


class _ParamSubstitutor:
    """Substitute parameters into a SQL statement."""

    def __init__(self, params: Sequence[bytes]) -> None:
        self.params: Sequence[bytes] = params
        self.index: int = 0

    def __call__(self, matchobj: re.Match) -> bytes:
        index = self.index
        self.index += 1
        try:
            return bytes(self.params[index])
        except IndexError:
            raise ProgrammingError(
                "Not enough parameters for the SQL statement"
            ) from None

    @property
    def remaining(self) -> int:
        """Return the number of parameters remaining to be substituted."""
        return len(self.params) - self.index


def _bytestr_format_dict(bytestr: bytes, value_dict: Dict[bytes, bytes]) -> bytes:
    """
    >>> _bytestr_format_dict(b'%(a)s', {b'a': b'foobar'})
    b'foobar
    >>> _bytestr_format_dict(b'%%(a)s', {b'a': b'foobar'})
    b'%%(a)s'
    >>> _bytestr_format_dict(b'%%%(a)s', {b'a': b'foobar'})
    b'%%foobar'
    >>> _bytestr_format_dict(b'%(x)s %(y)s',
    ...                      {b'x': b'x=%(y)s', b'y': b'y=%(x)s'})
    b'x=%(y)s y=%(x)s'
    """

    def replace(matchobj: re.Match) -> bytes:
        """Replace pattern."""
        value: Optional[bytes] = None
        groups = matchobj.groupdict()
        if groups["conversion_type"] == b"%":
            value = b"%"
        if groups["conversion_type"] == b"s":
            key = groups["mapping_key"]
            value = value_dict[key]
        if value is None:
            raise ValueError(
                f"Unsupported conversion_type: {groups['conversion_type']}"
            )
        return value

    stmt = RE_PY_MAPPING_PARAM.sub(replace, bytestr)
    return stmt


class MySQLCursor(MySQLCursorAbstract):
    """Default cursor for interacting with MySQL.

    This cursor will execute statements and handle the result. It will not automatically
    fetch all rows.

    MySQLCursor should be inherited whenever other functionallity is required.
    An example would to change the fetch* member functions to return dictionaries instead
    of lists of values.

    Implements the Python Database API Specification v2.0 (PEP-249).
    """

    async def __anext__(self) -> RowType:
        res = await self.fetchone()
        if res is not None:
            return res
        raise StopAsyncIteration

    async def close(self) -> bool:
        if not self._connection:
            return False
        self._connection.remove_cursor(self)
        await self._connection.handle_unread_result()
        await self._reset_result()
        self._connection = None
        return True

    def _process_params_dict(
        self, params: ParamsDictType
    ) -> Dict[bytes, Union[bytes, Decimal]]:
        """Process query parameters given as dictionary."""
        res: Dict[bytes, Any] = {}
        try:
            to_mysql = self._connection.converter.to_mysql
            escape = self._connection.converter.escape
            quote = self._connection.converter.quote
            for key, value in params.items():
                conv = value
                conv = to_mysql(conv)
                conv = escape(conv)
                if not isinstance(value, Decimal):
                    conv = quote(conv)
                res[key.encode()] = conv
        except Exception as err:
            raise ProgrammingError(
                f"Failed processing pyformat-parameters; {err}"
            ) from err
        return res

    def _process_params(
        self, params: ParamsSequenceType
    ) -> Tuple[Union[bytes, Decimal], ...]:
        """Process query parameters."""
        result = params[:]
        try:
            to_mysql = self._connection.converter.to_mysql
            escape = self._connection.converter.escape
            quote = self._connection.converter.quote
            result = [to_mysql(value) for value in result]
            result = [escape(value) for value in result]
            result = [
                quote(value) if not isinstance(params[i], Decimal) else value
                for i, value in enumerate(result)
            ]
        except Exception as err:
            raise ProgrammingError(
                f"Failed processing format-parameters; {err}"
            ) from err
        return tuple(result)

    async def _execute_iter(
        self, query_iter: AsyncGenerator[ResultType, None]
    ) -> AsyncGenerator[MySQLCursorAbstract, None]:
        """Generator returns MySQLCursor objects for multiple statements

        This method is only used when multiple statements are executed
        by the `cursor.execute(multi_stmt_query, multi=True)` method.

        It matches the given `query_iter` (result of `MySQLConnection.cmd_query_iter()`)
        and the list of statements that were executed.

        How does this method work? To properly map each statement (stmt) to a result,
        the following facts must be considered:

        1. Read operations such as `SELECT` produce a non-empty result
            (calling `next(query_iter)` gets a result that includes at least one column).
        2. Write operatios such as `INSERT` produce an empty result
            (calling `next(query_iter)` gets a result with no columns - aka empty).
        3. End-of-line (EOL) comments do not produce a result, unless is the last stmt
            in which case produces an empty result.
        4. Calling procedures such as `CALL my_proc` produce a sequence `(1)*0` which
            means it may produce zero or more non-empty results followed by just one
            empty result. In other words, a callproc stmt always terminates with an
            empty result. E.g., `my_proc` includes an update + select + select + update,
            then the result sequence will be `110` - note how the write ops results get
            annulated, just the read ops results are produced. Other examples:
                * insert + insert -> 0
                * select + select + insert + select -> 1110
                * select -> 10
            Observe how 0 indicates the end of the result sequence. This property is
            vital to know what result corresponds to what callproc stmt.

        In this regard, the implementation is composed of:
        1. Parsing: the multi-statement is broken down into single statements, and then
            for each of these, leading white spaces are removed (including
            jumping line, vertical line, tab, etc.). Also, EOL comments are removed from
            the stream, except when the comment is the last statement of the
            multi-statement string.
        2. Mapping: the facts described above as used as "game rules" to properly match
        statements and results. In case, if we run out of statements before running out
        of results we use a sentinel named "stmt_overflow!" to indicate that the mapping
        went wrong.

        Acronyms
            1: a non-empty result
            2: an empty result
        """
        executed_list = parse_multi_statement_query(multi_stmt=self._executed)
        self._executed = None
        stmt = executed_list.popleft() if executed_list else b"stmt_overflow!"
        async for result in query_iter:
            await self._reset_result()
            await self._handle_result(result)

            if is_eol_comment(stmt):
                continue

            self._executed = stmt.rstrip()
            yield self

            if not stmt.upper().startswith(b"CALL") or "columns" not in result:
                stmt = executed_list.popleft() if executed_list else b"stmt_overflow!"

    async def _fetch_row(self, raw: bool = False) -> Optional[RowType]:
        """Return the next row in the result set."""
        if not self._connection.unread_result:
            return None
        row = None

        if self._nextrow == (None, None):
            (row, eof) = await self._connection.get_row(
                binary=self._binary, columns=self.description, raw=raw
            )
        else:
            (row, eof) = self._nextrow

        if row:
            self._nextrow = await self._connection.get_row(
                binary=self._binary, columns=self.description, raw=raw
            )
            eof = self._nextrow[1]
            if eof is not None:
                await self._handle_eof(eof)
            if self._rowcount == -1:
                self._rowcount = 1
            else:
                self._rowcount += 1
        if eof:
            await self._handle_eof(eof)

        return row

    async def _handle_result(self, result: ResultType) -> None:
        """Handle the result after a command was send.

        The result can be either an OK-packet or a dictionary containing column/eof
        information.

        Raises:
            InterfaceError: When result is not a dict() or result is invalid.
        """
        if not isinstance(result, dict):
            raise InterfaceError("Result was not a dict()")

        if "columns" in result:
            # Weak test, must be column/eof information
            self._description = result["columns"]
            self._connection.unread_result = True
            await self._handle_resultset()
        elif "affected_rows" in result:
            # Weak test, must be an OK-packet
            self._connection.unread_result = False
            await self._handle_noresultset(result)
        else:
            raise InterfaceError("Invalid result")

    async def _handle_resultset(self) -> None:
        """Handle the result set.

        This method handles the result set and is called after reading and storing
        column information in _handle_result(). For non-buffering cursors, this method
        is usually doing nothing.
        """

    async def _handle_noresultset(self, res: ResultType) -> None:
        """Handle result of execute() when there is no result set.

        Raises:
            ProgrammingError: When failing handling a non-resultset.
        """
        try:
            self._rowcount = res["affected_rows"]
            self._last_insert_id = res["insert_id"]
            self._warning_count = res["warning_count"]
        except (KeyError, TypeError) as err:
            raise ProgrammingError(f"Failed handling non-resultset; {err}") from None

        await self._handle_warnings()

    async def _handle_warnings(self) -> None:
        """Handle possible warnings after all results are consumed.

        Raises:
            Error: Also raises exceptions if raise_on_warnings is set.
        """
        if self._connection.get_warnings and self._warning_count:
            self._warnings = await self._fetch_warnings()

        if not self._warnings:
            return

        err = get_mysql_exception(
            self._warnings[0][1],
            self._warnings[0][2],
            warning=not self._connection.raise_on_warnings,
        )

        if self._connection.raise_on_warnings:
            raise err

        warnings.warn(err, stacklevel=4)

    async def _handle_eof(self, eof: EofPacketType) -> None:
        """Handle EOF packet."""
        self._connection.unread_result = False
        self._nextrow = (None, None)
        self._warning_count = eof["warning_count"]
        await self._handle_warnings()

    async def _reset_result(self) -> None:
        """Reset the cursor to default."""
        self._description = None
        self._warnings = None
        self._warning_count = 0
        self._executed = None
        self._executed_list = []
        self._stored_results = []
        self._rowcount = -1
        self._nextrow = (None, None)
        await self.reset()

    def _have_unread_result(self) -> bool:
        """Check whether there is an unread result."""
        try:
            return self._connection.unread_result
        except AttributeError:
            return False

    def _check_executed(self) -> None:
        """Check if the statement has been executed.

        Raises:
            InterfaceError: If the statement has not been executed.
        """
        if self._executed is None:
            raise InterfaceError(ERR_NO_RESULT_TO_FETCH)

    def _prepare_statement(
        self,
        operation: StrOrBytes,
        params: Union[Sequence[Any], Dict[str, Any]] = (),
    ) -> bytes:
        """Prepare SQL statement for execution.

        Converts the SQL statement to bytes and replaces the parameters in the
        placeholders.

        Raises:
            ProgrammingError: On converting to bytes, missing parameters or invalid
                              parameters type.
        """
        try:
            stmt = (
                operation
                if isinstance(operation, (bytes, bytearray))
                else operation.encode(self._connection.python_charset)
            )
        except (UnicodeDecodeError, UnicodeEncodeError) as err:
            raise ProgrammingError(str(err)) from err

        if params:
            if isinstance(params, dict):
                stmt = _bytestr_format_dict(stmt, self._process_params_dict(params))
            elif isinstance(params, (list, tuple)):
                psub = _ParamSubstitutor(self._process_params(params))
                stmt = RE_PY_PARAM.sub(psub, stmt)
                if psub.remaining != 0:
                    raise ProgrammingError(
                        "Not all parameters were used in the SQL statement"
                    )
            else:
                raise ProgrammingError(
                    f"Could not process parameters: {type(params).__name__}({params}),"
                    " it must be of type list, tuple or dict"
                )

        return stmt

    async def _fetch_warnings(self) -> Optional[List[WarningType]]:
        """Fetch warnings doing a SHOW WARNINGS."""
        result = []
        async with await self._connection.cursor(raw=False) as cur:
            await cur.execute("SHOW WARNINGS")
            result = await cur.fetchall()
        return result if result else None  # type: ignore[return-value]

    def _batch_insert(
        self, operation: str, seq_params: Sequence[ParamsSequenceOrDictType]
    ) -> Optional[bytes]:
        """Implements multi row insert"""

        def remove_comments(match: re.Match) -> str:
            """Remove comments from INSERT statements.

            This function is used while removing comments from INSERT
            statements. If the matched string is a comment not enclosed
            by quotes, it returns an empty string, else the string itself.
            """
            if match.group(1):
                return ""
            return match.group(2)

        tmp = re.sub(
            RE_SQL_ON_DUPLICATE,
            "",
            re.sub(RE_SQL_COMMENT, remove_comments, operation),
        )

        matches = re.search(RE_SQL_INSERT_VALUES, tmp)
        if not matches:
            raise InterfaceError(
                "Failed rewriting statement for multi-row INSERT. Check SQL syntax"
            )
        fmt = matches.group(1).encode(self._connection.python_charset)
        values = []

        try:
            stmt = operation.encode(self._connection.python_charset)
            for params in seq_params:
                tmp = fmt
                if isinstance(params, dict):
                    tmp = _bytestr_format_dict(tmp, self._process_params_dict(params))
                else:
                    psub = _ParamSubstitutor(self._process_params(params))
                    tmp = RE_PY_PARAM.sub(psub, tmp)
                    if psub.remaining != 0:
                        raise ProgrammingError(
                            "Not all parameters were used in the SQL statement"
                        )
                values.append(tmp)
            if fmt in stmt:
                stmt = stmt.replace(fmt, b",".join(values), 1)
                self._executed = stmt
                return stmt
            return None
        except (UnicodeDecodeError, UnicodeEncodeError) as err:
            raise ProgrammingError(str(err)) from err
        except Error:
            raise
        except Exception as err:
            raise InterfaceError(f"Failed executing the operation; {err}") from None

    def stored_results(self) -> Iterator[MySQLCursorAbstract]:
        """Returns an iterator for stored results.

        This method returns an iterator over results which are stored when callproc()
        is called. The iterator will provide MySQLCursorBuffered instances.
        """
        return iter(self._stored_results)

    async def callproc(
        self,
        procname: str,
        args: Sequence[Any] = (),
    ) -> Optional[Union[Dict[str, RowItemType], RowType]]:
        """Calls a stored procedure with the given arguments

        The arguments will be set during this session, meaning
        they will be called like  _<procname>__arg<nr> where
        <nr> is an enumeration (+1) of the arguments.

        Coding Example:
          1) Defining the Stored Routine in MySQL:
          CREATE PROCEDURE multiply(IN pFac1 INT, IN pFac2 INT, OUT pProd INT)
          BEGIN
            SET pProd := pFac1 * pFac2;
          END

          2) Executing in Python:
          args = (5, 5, 0)  # 0 is to hold pprod
          await cursor.callproc('multiply', args)
          print(await cursor.fetchone())

        For OUT and INOUT parameters the user should provide the
        type of the parameter as well. The argument should be a
        tuple with first item as the value of the parameter to pass
        and second argument the type of the argument.

        In the above example, one can call callproc method like:
          args = (5, 5, (0, 'INT'))
          await cursor.callproc('multiply', args)

        The type of the argument given in the tuple will be used by
        the MySQL CAST function to convert the values in the corresponding
        MySQL type (See CAST in MySQL Reference for more information)

        Does not return a value, but a result set will be
        available when the CALL-statement execute successfully.
        Raises exceptions when something is wrong.
        """
        if not procname or not isinstance(procname, str):
            raise ValueError("procname must be a string")

        if not isinstance(args, (tuple, list)):
            raise ValueError("args must be a sequence")

        self._stored_results = []

        results = []
        try:
            argnames = []
            argtypes = []

            # MySQL itself does support calling procedures with their full
            # name <database>.<procedure_name>. It's necessary to split
            # by '.' and grab the procedure name from procname.
            procname_abs = procname.split(".")[-1]
            if args:
                argvalues = []
                for idx, arg in enumerate(args):
                    argname = f"@_{procname_abs}_arg{idx + 1}"
                    argnames.append(argname)
                    if isinstance(arg, tuple):
                        argtypes.append(f" CAST({argname} AS {arg[1]})")
                        argvalues.append(arg[0])
                    else:
                        argtypes.append(argname)
                        argvalues.append(arg)

                placeholders = ",".join(f"{arg}=%s" for arg in argnames)
                await self.execute(f"SET {placeholders}", argvalues)

            call = f"CALL {procname}({','.join(argnames)})"

            # We disable consuming results temporary to make sure we
            # getting all results
            can_consume_results = self._connection.can_consume_results
            async for result in self._connection.cmd_query_iter(call):
                self._connection.can_consume_results = False
                if isinstance(self, (MySQLCursorDict, MySQLCursorBufferedDict)):
                    cursor_class = MySQLCursorBufferedDict
                elif isinstance(
                    self,
                    (MySQLCursorNamedTuple, MySQLCursorBufferedNamedTuple),
                ):
                    cursor_class = MySQLCursorBufferedNamedTuple
                elif self._raw:
                    cursor_class = MySQLCursorBufferedRaw
                else:
                    cursor_class = MySQLCursorBuffered
                # pylint: disable=protected-access

                # cursor_class = MySQLCursorBuffered
                cur = cursor_class(self._connection.get_self())
                cur._executed = f"(a result of {call})"
                await cur._handle_result(result)
                # pylint: enable=protected-access
                if cur.warnings is not None:
                    self._warnings = cur.warnings
                if "columns" in result:
                    results.append(cur)

            self._connection.can_consume_results = can_consume_results
            if argnames:
                # Create names aliases to be compatible with namedtuples
                args = [
                    f"{name} AS {alias}"
                    for name, alias in zip(
                        argtypes, [arg.lstrip("@_") for arg in argnames]
                    )
                ]
                select = f"SELECT {','.join(args)}"
                await self.execute(select)
                self._stored_results = results
                return await self.fetchone()

            self._stored_results = results
            return tuple()
        except Error:
            raise
        except Exception as err:
            raise InterfaceError(f"Failed calling stored routine; {err}") from None

    async def execute(
        self,
        operation: StrOrBytes,
        params: Union[Sequence[Any], Dict[str, Any]] = (),
        multi: bool = False,
    ) -> None:
        """Executes the given operation.

        Executes the given operation substituting any markers with the given parameters.

        For example, getting all rows where id is 5:
          await cursor.execute("SELECT * FROM t1 WHERE id = %s", (5,))

        If the `multi`` parameter is used a `ProgrammingError` is raised. The method for
        executing multiple statements is `executemulti()`.

        If warnings where generated, and connection.get_warnings is True, then
        self._warnings will be a list containing these warnings.

        Raises:
            ProgramingError: If multi parameter is used.
        """
        if not self._connection:
            raise ProgrammingError("Cursor is not connected")

        if not operation:
            return None

        if multi:
            raise ProgrammingError(
                "The `multi` parameter cannot be used in the Connector/Python Asyncio "
                "implementation. Please use `executemulti()` for executing multiple "
                "statements"
            )

        await self._connection.handle_unread_result()
        await self._reset_result()

        stmt = self._prepare_statement(operation, params)
        self._executed = stmt

        try:
            await self._handle_result(await self._connection.cmd_query(stmt))
        except InterfaceError as err:
            if self._connection.have_next_result:
                raise InterfaceError(
                    "Use `executemulti()` when executing multiple statements"
                ) from err
            raise
        return None

    async def executemulti(
        self,
        operation: StrOrBytes,
        params: Union[Sequence[Any], Dict[str, Any]] = (),
    ) -> AsyncGenerator[MySQLCursorAbstract, None]:
        """Execute multiple statements.

        Executes the given operation substituting any markers with the given
        parameters.
        """

        if not self._connection:
            raise ProgrammingError("Cursor is not connected")

        if not operation:
            raise StopAsyncIteration

        await self._connection.handle_unread_result()
        await self._reset_result()

        stmt = self._prepare_statement(operation, params)
        self._executed = stmt
        self._executed_list = []

        async for result in self._execute_iter(self._connection.cmd_query_iter(stmt)):
            yield result

    async def executemany(
        self,
        operation: str,
        seq_params: Sequence[ParamsSequenceType],
    ) -> None:
        """Prepare and execute a MySQL Prepared Statement many times.

        This method will prepare the given operation and execute with each tuple found
        the list seq_params.

        If the cursor instance already had a prepared statement, it is first closed.
        """
        if not operation or not seq_params:
            return None
        await self._connection.handle_unread_result()

        try:
            _ = iter(seq_params)
        except TypeError as err:
            raise ProgrammingError("Parameters for query must be an Iterable") from err

        # Optimize INSERTs by batching them
        if re.match(RE_SQL_INSERT_STMT, operation):
            if not seq_params:
                self._rowcount = 0
                return None
            stmt = self._batch_insert(operation, seq_params)
            if stmt is not None:
                self._executed = stmt
                return await self.execute(stmt)

        rowcnt = 0
        try:
            for params in seq_params:
                await self.execute(operation, params)
                if self.with_rows and self._have_unread_result():
                    await self.fetchall()
                rowcnt += self._rowcount
        except (ValueError, TypeError) as err:
            raise ProgrammingError(f"Failed executing the operation; {err}") from None
        self._rowcount = rowcnt

    async def fetchone(self) -> Optional[RowType]:
        """Return next row of a query result set.

        Raises:
            InterfaceError: If there is no result to fetch.

        Returns:
            tuple or None: A row from query result set.
        """
        if self._executed is None:
            raise InterfaceError(ERR_NO_RESULT_TO_FETCH)
        return await self._fetch_row()

    async def fetchall(self) -> List[RowType]:
        """Return all rows of a query result set.

        Returns:
            list: A list of tuples with all rows of a query result set.
        """
        if self._executed is None:
            raise InterfaceError(ERR_NO_RESULT_TO_FETCH)

        if not self._connection.unread_result:
            return []

        rows, eof = await self._connection.get_rows()
        if self._nextrow[0]:
            rows.insert(0, self._nextrow[0])

        await self._handle_eof(eof)
        rowcount = len(rows)
        if rowcount >= 0 and self._rowcount == -1:
            self._rowcount = 0
        self._rowcount += rowcount
        return rows

    async def fetchmany(self, size: Optional[int] = None) -> List[RowType]:
        """Return the next set of rows of a query result set.

        When no more rows are available, it returns an empty list.
        The number of rows returned can be specified using the size argument, which
        defaults to one.

        Returns:
            list: The next set of rows of a query result set.
        """
        self._check_executed()
        res = []
        cnt = size or self.arraysize
        while cnt > 0:
            cnt -= 1
            row = await self.fetchone()
            if row:
                res.append(row)

        return res


class MySQLCursorBuffered(MySQLCursor):
    """Cursor which fetches rows within execute()."""

    def __init__(self, connection: MySQLConnectionAbstract) -> None:
        super().__init__(connection)
        self._rows: Optional[List[RowType]] = None
        self._next_row: int = 0

    async def _handle_resultset(self) -> None:
        """Handle the result set.

        This method handles the result set and is called after reading and storing
        column information in _handle_result(). For non-buffering cursors, this method
        is usually doing nothing.
        """
        self._rows, eof = await self._connection.get_rows()
        self._rowcount = len(self._rows)
        await self._handle_eof(eof)
        self._next_row = 0
        self._connection.unread_result = False

    async def _fetch_row(self, raw: bool = False) -> Optional[RowType]:
        """Return the next row in the result set."""
        row = None
        try:
            row = self._rows[self._next_row]
        except (IndexError, TypeError):
            return None
        self._next_row += 1
        return row

    async def reset(self, free: bool = True) -> None:
        """Reset the cursor to default."""
        self._rows = None

    async def fetchone(self) -> Optional[RowType]:
        """Return next row of a query result set.

        Returns:
            tuple or None: A row from query result set.
        """
        self._check_executed()
        return await self._fetch_row()

    async def fetchall(self) -> List[RowType]:
        """Return all rows of a query result set.

        Returns:
            list: A list of tuples with all rows of a query result set.
        """
        if self._executed is None or self._rows is None:
            raise InterfaceError(ERR_NO_RESULT_TO_FETCH)
        res = []
        res = self._rows[self._next_row :]
        self._next_row = len(self._rows)
        return res

    @property
    def with_rows(self) -> bool:
        return self._rows is not None


class MySQLCursorRaw(MySQLCursor):
    """Skip conversion from MySQL datatypes to Python types when fetching rows."""

    def __init__(self, connection: MySQLConnectionAbstract) -> None:
        super().__init__(connection)
        self._raw: bool = True

    async def fetchone(self) -> Optional[RowType]:
        """Return next row of a query result set.

        Returns:
            tuple or None: A row from query result set.
        """
        self._check_executed()
        return await self._fetch_row(raw=True)

    async def fetchall(self) -> List[RowType]:
        """Return all rows of a query result set.

        Returns:
            list: A list of tuples with all rows of a query result set.
        """
        self._check_executed()
        if not self._have_unread_result():
            return []
        rows, eof = await self._connection.get_rows(raw=True)
        if self._nextrow[0]:
            rows.insert(0, self._nextrow[0])
        await self._handle_eof(eof)
        rowcount = len(rows)
        if rowcount >= 0 and self._rowcount == -1:
            self._rowcount = 0
        self._rowcount += rowcount
        return rows


class MySQLCursorBufferedRaw(MySQLCursorBuffered):
    """
    Cursor which skips conversion from MySQL datatypes to Python types when
    fetching rows and fetches rows within execute().
    """

    _raw: bool = True

    @property
    def with_rows(self) -> bool:
        return self._rows is not None


class MySQLCursorDict(MySQLCursor):
    """
    Cursor fetching rows as dictionaries.

    The fetch methods of this class will return dictionaries instead of tuples.
    Each row is a dictionary that looks like:
        row = {
            "col1": value1,
            "col2": value2
        }
    """

    def _row_to_python(
        self,
        rowdata: RowType,
        desc: Optional[List[DescriptionType]] = None,  # pylint: disable=unused-argument
    ) -> Optional[Dict[str, RowItemType]]:
        """Convert a MySQL text result row to Python types

        Returns a dictionary.
        """
        return dict(zip(self.column_names, rowdata)) if rowdata else None

    async def fetchone(self) -> Optional[Dict[str, RowItemType]]:
        """Return next row of a query result set.

        Returns:
            dict or None: A dict from query result set.
        """
        return self._row_to_python(await super().fetchone(), self.description)

    async def fetchall(self) -> List[Optional[Dict[str, RowItemType]]]:
        """Return all rows of a query result set.

        Returns:
            list: A list of dictionaries with all rows of a query
                  result set where column names are used as keys.
        """
        return [
            self._row_to_python(row, self.description)
            for row in await super().fetchall()
            if row
        ]


class MySQLCursorNamedTuple(MySQLCursor):
    """
    Cursor fetching rows as named tuple.

    The fetch methods of this class will return namedtuples instead of tuples.
    Each row is returned as a namedtuple and the values can be accessed as:
    row.col1, row.col2
    """

    def _row_to_python(
        self,
        rowdata: RowType,
        desc: Optional[List[DescriptionType]] = None,  # pylint: disable=unused-argument
    ) -> Optional[RowType]:
        """Convert a MySQL text result row to Python types

        Returns a named tuple.
        """
        row = rowdata

        if row:
            columns = tuple(self.column_names)
            try:
                named_tuple = NAMED_TUPLE_CACHE[columns]
            except KeyError:
                named_tuple = namedtuple("Row", columns)  # type:ignore[no-redef, misc]
                NAMED_TUPLE_CACHE[columns] = named_tuple
            return named_tuple(*row)
        return None

    async def fetchone(self) -> Optional[RowType]:
        """Return next row of a query result set.

        Returns:
            tuple or None: A row from query result set.
        """
        row = await super().fetchone()
        if not row:
            return None
        return (
            self._row_to_python(row, self.description)
            if hasattr(self._connection, "converter")
            else row
        )

    async def fetchall(self) -> List[Optional[RowType]]:
        """Return all rows of a query result set.

        Returns:
            list: A list of tuples with all rows of a query result set.
        """
        return [
            self._row_to_python(row, self.description)
            for row in await super().fetchall()
            if row
        ]


class MySQLCursorBufferedDict(MySQLCursorDict, MySQLCursorBuffered):
    """
    Buffered Cursor fetching rows as dictionaries.
    """

    async def fetchone(self) -> Optional[Dict[str, RowItemType]]:
        """Return next row of a query result set.

        Returns:
            tuple or None: A row from query result set.
        """
        self._check_executed()
        row = await self._fetch_row()
        if row:
            return self._row_to_python(row, self.description)
        return None

    async def fetchall(self) -> List[Optional[Dict[str, RowItemType]]]:
        """Return all rows of a query result set.

        Returns:
            list: A list of tuples with all rows of a query result set.
        """
        if self._executed is None or self._rows is None:
            raise InterfaceError(ERR_NO_RESULT_TO_FETCH)
        res = []
        for row in self._rows[self._next_row :]:
            res.append(self._row_to_python(row, self.description))
        self._next_row = len(self._rows)
        return res


class MySQLCursorBufferedNamedTuple(MySQLCursorNamedTuple, MySQLCursorBuffered):
    """
    Buffered Cursor fetching rows as named tuple.
    """

    async def fetchone(self) -> Optional[RowType]:
        """Return next row of a query result set.

        Returns:
            tuple or None: A row from query result set.
        """
        self._check_executed()
        row = await self._fetch_row()
        if row:
            return self._row_to_python(row, self.description)
        return None

    async def fetchall(self) -> List[Optional[RowType]]:
        """Return all rows of a query result set.

        Returns:
            list: A list of tuples with all rows of a query result set.
        """
        if self._executed is None or self._rows is None:
            raise InterfaceError(ERR_NO_RESULT_TO_FETCH)
        res = []
        for row in self._rows[self._next_row :]:
            res.append(self._row_to_python(row, self.description))
        self._next_row = len(self._rows)
        return res


class MySQLCursorPrepared(MySQLCursor):
    """Cursor using MySQL Prepared Statements"""

    def __init__(self, connection: MySQLConnectionAbstract):
        super().__init__(connection)
        self._rows: Optional[List[RowType]] = None
        self._next_row: int = 0
        self._prepared: Optional[Dict[str, Union[int, List[DescriptionType]]]] = None
        self._binary: bool = True
        self._have_result: Optional[bool] = None
        self._last_row_sent: bool = False
        self._cursor_exists: bool = False

    async def reset(self, free: bool = True) -> None:
        if self._prepared:
            try:
                await self._connection.cmd_stmt_close(self._prepared["statement_id"])
            except Error:
                # We tried to deallocate, but it's OK when we fail.
                pass
            self._prepared = None
        self._last_row_sent = False
        self._cursor_exists = False

    async def _handle_noresultset(self, res: ResultType) -> None:
        self._handle_server_status(
            res.get("status_flag", res.get("server_status", 0)),
        )
        await super()._handle_noresultset(res)

    def _handle_server_status(self, flags: int) -> None:
        self._cursor_exists = flags & ServerFlag.STATUS_CURSOR_EXISTS != 0
        self._last_row_sent = flags & ServerFlag.STATUS_LAST_ROW_SENT != 0

    async def _handle_eof(self, eof: EofPacketType) -> None:
        self._handle_server_status(
            eof.get("status_flag", eof.get("server_status", 0)),
        )
        await super()._handle_eof(eof)

    async def callproc(self, procname: Any, args: Any = ()) -> NoReturn:
        """Calls a stored procedue

        Not supported with MySQLCursorPrepared.
        """
        raise NotSupportedError()

    async def executemulti(
        self,
        operation: StrOrBytes,
        params: Union[Sequence[Any], Dict[str, Any]] = (),
    ) -> AsyncGenerator[MySQLCursorAbstract, None]:
        """Execute multiple statements.

        Executes the given operation substituting any markers with the given
        parameters.
        """
        raise NotSupportedError()

    async def close(self) -> None:
        """Close the cursor

        This method will try to deallocate the prepared statement and close
        the cursor.
        """
        await self.reset()
        await super().close()

    def _row_to_python(self, rowdata: Any, desc: Any = None) -> Any:
        """Convert row data from MySQL to Python types

        The conversion is done while reading binary data in the protocol module.
        """

    async def _handle_result(self, result: ResultType) -> None:
        """Handle result after execution"""
        if isinstance(result, dict):
            self._connection.unread_result = False
            self._have_result = False
            await self._handle_noresultset(result)
        else:
            self._description = result[1]
            self._connection.unread_result = True
            self._have_result = True
            if "status_flag" in result[2]:  # type: ignore[operator]
                self._handle_server_status(result[2]["status_flag"])
            elif "server_status" in result[2]:  # type: ignore[operator]
                self._handle_server_status(result[2]["server_status"])

    async def execute(
        self,
        operation: StrOrBytes,
        params: Optional[ParamsSequenceOrDictType] = None,
        multi: bool = False,
    ) -> None:  # multi is unused
        """Prepare and execute a MySQL Prepared Statement

        This method will prepare the given operation and execute it using
        the optionally given parameters.

        If the cursor instance already had a prepared statement, it is
        first closed.

        Note: argument "multi" is unused.
        """
        if not self._connection:
            raise ProgrammingError("Cursor is not connected")

        if not operation:
            return None

        charset = self._connection.charset
        if charset == "utf8mb4":
            charset = "utf8"

        if not isinstance(operation, str):
            try:
                operation = operation.decode(charset)
            except UnicodeDecodeError as err:
                raise ProgrammingError(str(err)) from err

        if isinstance(params, dict):
            replacement_keys = re.findall(RE_SQL_PYTHON_CAPTURE_PARAM_NAME, operation)
            try:
                # Replace params dict with params tuple in correct order
                params = tuple(params[key] for key in replacement_keys)
            except KeyError as err:
                raise ProgrammingError(
                    "Not all placeholders were found in the parameters dict"
                ) from err
            # Convert %(name)s to ? before sending it to MySQL
            operation = re.sub(RE_SQL_PYTHON_REPLACE_PARAM, "?", operation)

        if operation is not self._executed:
            if self._prepared:
                await self._connection.cmd_stmt_close(self._prepared["statement_id"])
            self._executed = operation

            try:
                operation = operation.encode(charset)
            except UnicodeEncodeError as err:
                raise ProgrammingError(str(err)) from err

            if b"%s" in operation:
                # Convert %s to ? before sending it to MySQL
                operation = re.sub(RE_SQL_FIND_PARAM, b"?", operation)

            try:
                self._prepared = await self._connection.cmd_stmt_prepare(operation)
            except Error:
                self._executed = None
                raise

        await self._connection.cmd_stmt_reset(self._prepared["statement_id"])

        if self._prepared["parameters"] and not params:
            return
        if params:
            if not isinstance(params, (tuple, list)):
                raise ProgrammingError(
                    errno=1210,
                    msg="Incorrect type of argument: "
                    f"{type(params).__name__}({params})"
                    ", it must be of type tuple or list the argument given to "
                    "the prepared statement",
                )
            if len(self._prepared["parameters"]) != len(params):
                raise ProgrammingError(
                    errno=1210,
                    msg="Incorrect number of arguments executing prepared statement",
                )

        if params is None:
            params = ()
        res = await self._connection.cmd_stmt_execute(
            self._prepared["statement_id"],
            data=params,
            parameters=self._prepared["parameters"],
        )
        await self._handle_result(res)

    async def executemany(
        self,
        operation: str,
        seq_params: Sequence[ParamsSequenceType],
    ) -> None:
        """Prepare and execute a MySQL Prepared Statement many times

        This method will prepare the given operation and execute with each
        tuple found the list seq_params.

        If the cursor instance already had a prepared statement, it is
        first closed.

        executemany() simply calls execute().
        """
        if not operation or not seq_params:
            return None
        await self._connection.handle_unread_result()

        try:
            _ = iter(seq_params)
        except TypeError as err:
            raise ProgrammingError("Parameters for query must be an Iterable") from err

        rowcnt = 0
        try:
            for params in seq_params:
                await self.execute(operation, params)
                if self.with_rows and self._have_unread_result():
                    await self.fetchall()
                rowcnt += self._rowcount
        except (ValueError, TypeError) as err:
            raise InterfaceError(f"Failed executing the operation; {err}") from None
        self._rowcount = rowcnt

    async def fetchone(self) -> Optional[RowType]:
        """Return next row of a query result set.

        Returns:
            tuple or None: A row from query result set.
        """
        self._check_executed()
        if self._cursor_exists:
            await self._connection.cmd_stmt_fetch(self._prepared["statement_id"])
        return await self._fetch_row() or None

    async def fetchmany(self, size: Optional[int] = None) -> List[RowType]:
        """Return the next set of rows of a query result set.

        When no more rows are available, it returns an empty list.
        The number of rows returned can be specified using the size argument,
        which defaults to one.

        Returns:
            list: The next set of rows of a query result set.
        """
        self._check_executed()
        res = []
        cnt = size or self.arraysize
        while cnt > 0 and self._have_unread_result():
            cnt -= 1
            row = await self._fetch_row()
            if row:
                res.append(row)
        return res

    async def fetchall(self) -> List[RowType]:
        """Return all rows of a query result set.

        Returns:
            list: A list of tuples with all rows of a query result set.
        """
        self._check_executed()
        rows = []
        if self._nextrow[0]:
            rows.append(self._nextrow[0])
        while self._have_unread_result():
            if self._cursor_exists:
                await self._connection.cmd_stmt_fetch(
                    self._prepared["statement_id"], MAX_RESULTS
                )
            tmp, eof = await self._connection.get_rows(
                binary=self._binary, columns=self.description
            )
            rows.extend(tmp)
            await self._handle_eof(eof)
        self._rowcount = len(rows)
        return rows


class MySQLCursorPreparedDict(MySQLCursorDict, MySQLCursorPrepared):  # type: ignore[misc]
    """
    This class is a blend of features from MySQLCursorDict and MySQLCursorPrepared

    Multiple inheritance in python is allowed but care must be taken
    when assuming methods resolution. In the case of multiple
    inheritance, a given attribute is first searched in the current
    class if it's not found then it's searched in the parent classes.
    The parent classes are searched in a left-right fashion and each
    class is searched once.
    Based on python's attribute resolution, in this case, attributes
    are searched as follows:
    1. MySQLCursorPreparedDict (current class)
    2. MySQLCursorDict (left parent class)
    3. MySQLCursorPrepared (right parent class)
    4. MySQLCursor (base class)
    """

    async def fetchmany(
        self, size: Optional[int] = None
    ) -> List[Dict[str, RowItemType]]:
        """Return the next set of rows of a query result set.

        When no more rows are available, it returns an empty list.
        The number of rows returned can be specified using the size argument,
        which defaults to one.

        Returns:
            list: The next set of rows of a query result set represented
                  as a list of dictionaries where column names are used as keys.
        """
        return [
            self._row_to_python(row, self.description)
            for row in await super().fetchmany(size=size)
            if row
        ]


class MySQLCursorPreparedNamedTuple(MySQLCursorNamedTuple, MySQLCursorPrepared):
    """
    This class is a blend of features from MySQLCursorNamedTuple and MySQLCursorPrepared
    """

    async def fetchmany(self, size: Optional[int] = None) -> List[RowType]:
        """Return the next set of rows of a query result set.

        When no more rows are available, it returns an empty list.
        The number of rows returned can be specified using the size argument,
        which defaults to one.

        Returns:
            list: The next set of rows of a query result set represented
                  as a list of named tuples where column names are used as names.
        """
        return [
            self._row_to_python(row, self.description)
            for row in await super().fetchmany(size=size)
            if row
        ]


class MySQLCursorPreparedRaw(MySQLCursorPrepared):
    """
    This class is a blend of features from MySQLCursorRaw and MySQLCursorPrepared
    """

    _raw: bool = True

    async def fetchone(self) -> Optional[RowType]:
        """Return next row of a query result set.

        Returns:
            tuple or None: A row from query result set.
        """
        self._check_executed()
        if self._cursor_exists:
            await self._connection.cmd_stmt_fetch(self._prepared["statement_id"])
        return await self._fetch_row(raw=self._raw) or None

    async def fetchmany(self, size: Optional[int] = None) -> List[RowType]:
        """Return the next set of rows of a query result set.

        When no more rows are available, it returns an empty list.
        The number of rows returned can be specified using the size argument,
        which defaults to one.

        Returns:
            list: The next set of rows of a query result set.
        """
        self._check_executed()
        res = []
        cnt = size or self.arraysize
        while cnt > 0 and self._have_unread_result():
            cnt -= 1
            row = await self._fetch_row(raw=self._raw)
            if row:
                res.append(row)
        return res

    async def fetchall(self) -> List[RowType]:
        """Return all rows of a query result set.

        Returns:
            list: A list of tuples with all rows of a query result set.
        """
        self._check_executed()
        rows = []
        if self._nextrow[0]:
            rows.append(self._nextrow[0])
        while self._have_unread_result():
            if self._cursor_exists:
                await self._connection.cmd_stmt_fetch(
                    self._prepared["statement_id"], MAX_RESULTS
                )
            tmp, eof = await self._connection.get_rows(
                raw=self._raw, binary=self._binary, columns=self.description
            )
            rows.extend(tmp)
            await self._handle_eof(eof)
        self._rowcount = len(rows)
        return rows