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#
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import json
from typing import Optional

from airflow.exceptions import AirflowException
from airflow.providers.amazon.aws.hooks.step_function import StepFunctionHook
from airflow.sensors.base import BaseSensorOperator
from airflow.utils.decorators import apply_defaults


class StepFunctionExecutionSensor(BaseSensorOperator):
    """
    Asks for the state of the Step Function State Machine Execution until it
    reaches a failure state or success state.
    If it fails, failing the task.

    On successful completion of the Execution the Sensor will do an XCom Push
    of the State Machine's output to `output`

    :param execution_arn: execution_arn to check the state of
    :type execution_arn: str
    :param aws_conn_id: aws connection to use, defaults to 'aws_default'
    :type aws_conn_id: str
    """

    INTERMEDIATE_STATES = ("RUNNING",)
    FAILURE_STATES = (
        "FAILED",
        "TIMED_OUT",
        "ABORTED",
    )
    SUCCESS_STATES = ("SUCCEEDED",)

    template_fields = ["execution_arn"]
    template_ext = ()
    ui_color = "#66c3ff"

    @apply_defaults
    def __init__(
        self,
        *,
        execution_arn: str,
        aws_conn_id: str = "aws_default",
        region_name: Optional[str] = None,
        **kwargs,
    ):
        super().__init__(**kwargs)
        self.execution_arn = execution_arn
        self.aws_conn_id = aws_conn_id
        self.region_name = region_name
        self.hook: Optional[StepFunctionHook] = None

    def poke(self, context):
        execution_status = self.get_hook().describe_execution(self.execution_arn)
        state = execution_status["status"]
        output = (
            json.loads(execution_status["output"])
            if "output" in execution_status
            else None
        )

        if state in self.FAILURE_STATES:
            raise AirflowException(
                f"Step Function sensor failed. State Machine Output: {output}"
            )

        if state in self.INTERMEDIATE_STATES:
            return False

        self.log.info("Doing xcom_push of output")
        self.xcom_push(context, "output", output)
        return True

    def get_hook(self) -> StepFunctionHook:
        """Create and return a StepFunctionHook"""
        if self.hook:
            return self.hook

        self.hook = StepFunctionHook(
            aws_conn_id=self.aws_conn_id, region_name=self.region_name
        )
        return self.hook