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from airflow.sensors.base import BaseSensorOperator
from airflow.triggers.temporal import DateTimeTrigger
from airflow.utils import timezone


class TimeDeltaSensor(BaseSensorOperator):
    """
    Waits for a timedelta after the run's data interval.

    :param delta: time length to wait after the data interval before succeeding.
    :type delta: datetime.timedelta
    """

    def __init__(self, *, delta, **kwargs):
        super().__init__(**kwargs)
        self.delta = delta

    def poke(self, context):
        target_dttm = context['data_interval_end']
        target_dttm += self.delta
        self.log.info('Checking if the time (%s) has come', target_dttm)
        return timezone.utcnow() > target_dttm


class TimeDeltaSensorAsync(TimeDeltaSensor):
    """
    A drop-in replacement for TimeDeltaSensor that defers itself to avoid
    taking up a worker slot while it is waiting.

    :param delta: time length to wait after the data interval before succeeding.
    :type delta: datetime.timedelta
    """

    def execute(self, context):
        target_dttm = context['data_interval_end']
        target_dttm += self.delta
        self.defer(trigger=DateTimeTrigger(moment=target_dttm), method_name="execute_complete")

    def execute_complete(self, context, event=None):  # pylint: disable=unused-argument
        """Callback for when the trigger fires - returns immediately."""
        return None