def is_admin(user):
    return (
        user.is_authenticated
        and (
            user.is_staff
            or user.is_superuser
        )
    )


def can_edit_note(user, note):
    if not user.is_authenticated:
        return False

    return (
        is_admin(user)
        or note.author_id == user.id
    )


def can_complete_note(user, note):
    if not user.is_authenticated:
        return False

    if note.kind != 'task':
        return False

    return (
        (note.is_public and not note.recipients.exists())
        or is_admin(user)
        or note.author_id == user.id
        or note.recipients.filter(
            pk=user.pk,
        ).exists()
    )