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from typing import Optional

from airflow.providers.amazon.aws.hooks.ec2 import EC2Hook
from airflow.sensors.base import BaseSensorOperator
from airflow.utils.decorators import apply_defaults


class EC2InstanceStateSensor(BaseSensorOperator):
    """
    Check the state of the AWS EC2 instance until
    state of the instance become equal to the target state.

    :param target_state: target state of instance
    :type target_state: str
    :param instance_id: id of the AWS EC2 instance
    :type instance_id: str
    :param region_name: (optional) aws region name associated with the client
    :type region_name: Optional[str]
    """

    template_fields = ("target_state", "instance_id", "region_name")
    ui_color = "#cc8811"
    ui_fgcolor = "#ffffff"
    valid_states = ["running", "stopped", "terminated"]

    @apply_defaults
    def __init__(
        self,
        *,
        target_state: str,
        instance_id: str,
        aws_conn_id: str = "aws_default",
        region_name: Optional[str] = None,
        **kwargs,
    ):
        if target_state not in self.valid_states:
            raise ValueError(f"Invalid target_state: {target_state}")
        super().__init__(**kwargs)
        self.target_state = target_state
        self.instance_id = instance_id
        self.aws_conn_id = aws_conn_id
        self.region_name = region_name

    def poke(self, context):
        ec2_hook = EC2Hook(aws_conn_id=self.aws_conn_id, region_name=self.region_name)
        instance_state = ec2_hook.get_instance_state(instance_id=self.instance_id)
        self.log.info("instance state: %s", instance_state)
        return instance_state == self.target_state