from django.contrib.auth.models import Permission
from django.contrib.contenttypes.models import ContentType
from django.db.models import Q
from django.dispatch import Signal

# This signal is sent when the migrate command is done. That means it is sent
# after post_migrate sending and creating all Permission objects. Don't use it
# for other things than dealing with Permission objects.
post_permission_creation = Signal()


def delete_django_app_permissions(sender, **kwargs):
    """
    Deletes the permissions, Django creates by default. Only required
    for auth, contenttypes and sessions.
    """
    contenttypes = ContentType.objects.filter(
        Q(app_label='auth') |
        Q(app_label='contenttypes') |
        Q(app_label='sessions'))
    Permission.objects.filter(content_type__in=contenttypes).delete()