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from airflow.sensors.base_sensor_operator import BaseSensorOperator
from airflow.utils.decorators import apply_defaults


class AwsGlueCatalogPartitionSensor(BaseSensorOperator):
    """
    Waits for a partition to show up in AWS Glue Catalog.

    :param table_name: The name of the table to wait for, supports the dot
        notation (my_database.my_table)
    :type table_name: str
    :param expression: The partition clause to wait for. This is passed as
        is to the AWS Glue Catalog API's get_partitions function,
        and supports SQL like notation as in ``ds='2015-01-01'
        AND type='value'`` and comparison operators as in ``"ds>=2015-01-01"``.
        See https://docs.aws.amazon.com/glue/latest/dg/aws-glue-api-catalog-partitions.html
        #aws-glue-api-catalog-partitions-GetPartitions
    :type expression: str
    :param aws_conn_id: ID of the Airflow connection where
        credentials and extra configuration are stored
    :type aws_conn_id: str
    :param region_name: Optional aws region name (example: us-east-1). Uses region from connection
        if not specified.
    :type region_name: str
    :param database_name: The name of the catalog database where the partitions reside.
    :type database_name: str
    :param poke_interval: Time in seconds that the job should wait in
        between each tries
    :type poke_interval: int
    """
    template_fields = ('database_name', 'table_name', 'expression',)
    ui_color = '#C5CAE9'

    @apply_defaults
    def __init__(self,
                 table_name, expression="ds='{{ ds }}'",
                 aws_conn_id='aws_default',
                 region_name=None,
                 database_name='default',
                 poke_interval=60 * 3,
                 *args,
                 **kwargs):
        super(AwsGlueCatalogPartitionSensor, self).__init__(
            poke_interval=poke_interval, *args, **kwargs)
        self.aws_conn_id = aws_conn_id
        self.region_name = region_name
        self.table_name = table_name
        self.expression = expression
        self.database_name = database_name

    def poke(self, context):
        """
        Checks for existence of the partition in the AWS Glue Catalog table
        """
        if '.' in self.table_name:
            self.database_name, self.table_name = self.table_name.split('.')
        self.log.info(
            'Poking for table %s. %s, expression %s', self.database_name, self.table_name, self.expression
        )

        return self.get_hook().check_for_partition(
            self.database_name, self.table_name, self.expression)

    def get_hook(self):
        """
        Gets the AwsGlueCatalogHook
        """
        if not hasattr(self, 'hook'):
            from airflow.contrib.hooks.aws_glue_catalog_hook import AwsGlueCatalogHook
            self.hook = AwsGlueCatalogHook(
                aws_conn_id=self.aws_conn_id,
                region_name=self.region_name)

        return self.hook
