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"""Objects relating to sourcing connections from metastore database."""

from __future__ import annotations

from typing import TYPE_CHECKING

from sqlalchemy import or_, select

from airflow.secrets import BaseSecretsBackend
from airflow.utils.session import NEW_SESSION, provide_session

if TYPE_CHECKING:
    from sqlalchemy.orm import Session

    from airflow.models import Connection


class MetastoreBackend(BaseSecretsBackend):
    """Retrieves Connection object and Variable from airflow metastore database."""

    @provide_session
    def get_connection(
        self, conn_id: str, team_name: str | None = None, *, session: Session = NEW_SESSION
    ) -> Connection | None:
        """
        Get Airflow Connection from Metadata DB.

        :param conn_id: Connection ID
        :param team_name: Team name associated to the task trying to access the connection (if any)
        :param session: SQLAlchemy Session
        :return: Connection Object
        """
        from airflow.models import Connection

        conn = session.scalar(
            select(Connection)
            .where(
                Connection.conn_id == conn_id,
                or_(Connection.team_name == team_name, Connection.team_name.is_(None)),
            )
            .limit(1)
        )
        if conn:
            session.expunge(conn)
        return conn

    @provide_session
    def get_variable(
        self, key: str, team_name: str | None = None, *, session: Session = NEW_SESSION
    ) -> str | None:
        """
        Get Airflow Variable from Metadata DB.

        :param key: Variable Key
        :param team_name: Team name associated to the task trying to access the variable (if any)
        :param session: SQLAlchemy Session
        :return: Variable Value
        """
        from airflow.models import Variable

        var_value = session.scalar(
            select(Variable)
            .where(Variable.key == key, or_(Variable.team_name == team_name, Variable.team_name.is_(None)))
            .limit(1)
        )
        if var_value:
            session.expunge(var_value)
            return var_value.val
        return None
