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import logging
from typing import Dict, Optional

import pendulum
from slugify import slugify

from airflow.models.taskinstance import TaskInstanceKey

log = logging.getLogger(__name__)


def _strip_unsafe_kubernetes_special_chars(string: str) -> str:
    """
    Kubernetes only supports lowercase alphanumeric characters, "-" and "." in
    the pod name.
    However, there are special rules about how "-" and "." can be used so let's
    only keep
    alphanumeric chars  see here for detail:
    https://kubernetes.io/docs/concepts/overview/working-with-objects/names/

    :param string: The requested Pod name
    :return: Pod name stripped of any unsafe characters
    """
    return slugify(string, separator='', lowercase=True)


def create_pod_id(dag_id: str, task_id: str) -> str:
    """
    Generates the kubernetes safe pod_id. Note that this is
    NOT the full ID that will be launched to k8s. We will add a uuid
    to ensure uniqueness.

    :param dag_id: DAG ID
    :param task_id: Task ID
    :return: The non-unique pod_id for this task/DAG pairing
    """
    safe_dag_id = _strip_unsafe_kubernetes_special_chars(dag_id)
    safe_task_id = _strip_unsafe_kubernetes_special_chars(task_id)
    return safe_dag_id + safe_task_id


def annotations_to_key(annotations: Dict[str, str]) -> Optional[TaskInstanceKey]:
    """Build a TaskInstanceKey based on pod annotations"""
    log.debug("Creating task key for annotations %s", annotations)
    dag_id = annotations['dag_id']
    task_id = annotations['task_id']
    try_number = int(annotations['try_number'])
    run_id = annotations.get('run_id')
    if not run_id and 'execution_date' in annotations:
        # Compat: Look up the run_id from the TI table!
        from airflow.models.dagrun import DagRun
        from airflow.models.taskinstance import TaskInstance
        from airflow.settings import Session

        execution_date = pendulum.parse(annotations['execution_date'])
        # Do _not_ use create-session, we don't want to expunge
        session = Session()

        run_id: str = (
            session.query(TaskInstance.run_id)
            .join(TaskInstance.dag_run)
            .filter(
                TaskInstance.dag_id == dag_id,
                TaskInstance.task_id == task_id,
                DagRun.execution_date == execution_date,
            )
            .scalar()
        )

    return TaskInstanceKey(dag_id, task_id, run_id, try_number)