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from typing import Iterable, Mapping, Optional, Union

from airflow.exceptions import AirflowException
from airflow.models import BaseOperator
from airflow.providers.microsoft.mssql.hooks.mssql import MsSqlHook
from airflow.providers.odbc.hooks.odbc import OdbcHook
from airflow.utils.decorators import apply_defaults


class MsSqlOperator(BaseOperator):
    """
    Executes sql code in a specific Microsoft SQL database

    This operator may use one of two hooks, depending on the ``conn_type`` of the connection.

    If conn_type is ``'odbc'``, then :py:class:`~airflow.providers.odbc.hooks.odbc.OdbcHook`
    is used.  Otherwise, :py:class:`~airflow.providers.microsoft.mssql.hooks.mssql.MsSqlHook` is used.

    :param sql: the sql code to be executed
    :type sql: str or string pointing to a template file with .sql
        extension. (templated)
    :param mssql_conn_id: reference to a specific mssql database
    :type mssql_conn_id: str
    :param parameters: (optional) the parameters to render the SQL query with.
    :type parameters: dict or iterable
    :param autocommit: if True, each command is automatically committed.
        (default value: False)
    :type autocommit: bool
    :param database: name of database which overwrite defined one in connection
    :type database: str
    """

    template_fields = ("sql",)
    template_ext = (".sql",)
    ui_color = "#ededed"

    @apply_defaults
    def __init__(
        self,
        *,
        sql: str,
        mssql_conn_id: str = "mssql_default",
        parameters: Optional[Union[Mapping, Iterable]] = None,
        autocommit: bool = False,
        database: Optional[str] = None,
        **kwargs,
    ) -> None:
        super().__init__(**kwargs)
        self.mssql_conn_id = mssql_conn_id
        self.sql = sql
        self.parameters = parameters
        self.autocommit = autocommit
        self.database = database
        self._hook: Optional[Union[MsSqlHook, OdbcHook]] = None

    def get_hook(self) -> Optional[Union[MsSqlHook, OdbcHook]]:
        """
        Will retrieve hook as determined by Connection.

        If conn_type is ``'odbc'``, will use
        :py:class:`~airflow.providers.odbc.hooks.odbc.OdbcHook`.
        Otherwise, :py:class:`~airflow.providers.microsoft.mssql.hooks.mssql.MsSqlHook` will be used.
        """
        if not self._hook:
            conn = MsSqlHook.get_connection(conn_id=self.mssql_conn_id)
            try:
                self._hook = conn.get_hook()
                self._hook.schema = self.database  # type: ignore[union-attr]
            except AirflowException:
                self._hook = MsSqlHook(
                    mssql_conn_id=self.mssql_conn_id, schema=self.database
                )
        return self._hook

    def execute(self, context: dict) -> None:
        self.log.info("Executing: %s", self.sql)
        hook = self.get_hook()
        hook.run(  # type: ignore[union-attr]
            sql=self.sql, autocommit=self.autocommit, parameters=self.parameters
        )