from django.db.models.signals import pre_save, post_save
from django.dispatch import receiver
from netbox_dns.models import Zone
from .service.endpoint import catalog_zone_manager as catzm

@receiver(pre_save, sender=Zone)
def zone_pre_save(sender, instance, **kwargs):
    """
    Cache the old name so post_save can see if it changed.
    """
    if instance.pk:
        try:
            instance._old_name = (
                sender.objects
                .only("name")
                .get(pk=instance.pk)
                .name
            )
        except sender.DoesNotExist:
            instance._old_name = None
    else:
        instance._old_name = None

@receiver(post_save, sender=Zone)
def sync_catalog_zone_identifier(sender, instance, created, **kwargs):
    """
    Ensure CatalogZoneMemberIdentifier exists for each Zone
    and keep its identifier in sync.
    """
    if created:
        # Create the related object on Zone creation
        catzm.update_member_identifier(instance)
    else:
        old_name = getattr(instance, "_old_name", None)

        # If the name did not change, do nothing
        if old_name == instance.name:
            return

        catzm.update_member_identifier(instance)