from django.contrib.contenttypes.models import ContentType

from openslides.utils.autoupdate import inform_changed_data

from .models import Item


def listen_to_related_object_post_save(sender, instance, created, **kwargs):
    """
    Receiver function to create agenda items. It is connected to the signal
    django.db.models.signals.post_save during app loading.
    """
    if created and hasattr(instance, 'get_agenda_title'):
        Item.objects.create(content_object=instance)
        inform_changed_data(instance)


def listen_to_related_object_post_delete(sender, instance, **kwargs):
    """
    Receiver function to delete agenda items. It is connected to the signal
    django.db.models.signals.post_delete during app loading.
    """
    if hasattr(instance, 'get_agenda_title'):
        content_type = ContentType.objects.get_for_model(instance)
        try:
            Item.objects.get(object_id=instance.pk, content_type=content_type).delete()
        except Item.DoesNotExist:
            # Item does not exist so we do not have to delete it.
            pass