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# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
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# KIND, either express or implied.  See the License for the
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from functools import wraps
from typing import Callable, Optional, Sequence, Tuple, TypeVar, cast

from flask import Response, current_app

from airflow.api_connexion.exceptions import PermissionDenied, Unauthenticated

T = TypeVar("T", bound=Callable)


def check_authentication() -> None:
    """Checks that the request has valid authorization information."""
    response = current_app.api_auth.requires_authentication(Response)()
    if response.status_code != 200:
        # since this handler only checks authentication, not authorization,
        # we should always return 401
        raise Unauthenticated(headers=response.headers)


def requires_access(permissions: Optional[Sequence[Tuple[str, str]]] = None) -> Callable[[T], T]:
    """Factory for decorator that checks current user's permissions against required permissions."""
    appbuilder = current_app.appbuilder
    appbuilder.sm.sync_resource_permissions(permissions)

    def requires_access_decorator(func: T):
        @wraps(func)
        def decorated(*args, **kwargs):
            check_authentication()
            if appbuilder.sm.check_authorization(permissions, kwargs.get('dag_id')):
                return func(*args, **kwargs)
            raise PermissionDenied()

        return cast(T, decorated)

    return requires_access_decorator