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from __future__ import annotations

from sqlalchemy import select

from airflow.ti_deps.deps.base_ti_dep import BaseTIDep
from airflow.utils.session import provide_session


class DagUnpausedDep(BaseTIDep):
    """Determines whether a task's DAG is not paused."""

    NAME = "Dag Not Paused"
    IGNORABLE = True

    @staticmethod
    def _is_dag_paused(dag_id: str, session) -> bool:
        """Check if a dag is paused. Extracted to simplify testing."""
        from airflow.models.dag import DagModel

        return session.scalar(select(DagModel.is_paused).where(DagModel.dag_id == dag_id))

    @provide_session
    def _get_dep_statuses(self, ti, session, dep_context):
        if self._is_dag_paused(ti.dag_id, session):
            yield self._failing_status(reason=f"Task's DAG '{ti.dag_id}' is paused.")
