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# to you under the Apache License, Version 2.0 (the
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#   http://www.apache.org/licenses/LICENSE-2.0
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"""Experimental APIs."""
from datetime import datetime
from typing import Optional

from airflow.exceptions import DagNotFound, DagRunNotFound, TaskNotFound
from airflow.models import DagBag, DagModel, DagRun


def check_and_get_dag(dag_id: str, task_id: Optional[str] = None) -> DagModel:
    """Checks that DAG exists and in case it is specified that Task exist"""
    dag_model = DagModel.get_current(dag_id)
    if dag_model is None:
        raise DagNotFound(f"Dag id {dag_id} not found in DagModel")

    dagbag = DagBag(dag_folder=dag_model.fileloc, read_dags_from_db=True)
    dag = dagbag.get_dag(dag_id)
    if not dag:
        error_message = f"Dag id {dag_id} not found"
        raise DagNotFound(error_message)
    if task_id and not dag.has_task(task_id):
        error_message = f'Task {task_id} not found in dag {dag_id}'
        raise TaskNotFound(error_message)
    return dag


def check_and_get_dagrun(dag: DagModel, execution_date: datetime) -> DagRun:
    """Get DagRun object and check that it exists"""
    dagrun = dag.get_dagrun(execution_date=execution_date)
    if not dagrun:
        error_message = f'Dag Run for date {execution_date} not found in dag {dag.dag_id}'
        raise DagRunNotFound(error_message)
    return dagrun