from django.dispatch import receiver
from django.db.models.signals import pre_save
from django.contrib.auth.models import Permission

from .models import ServiceType


@receiver(pre_save, sender=ServiceType)
def update_user_permissions(sender, instance, raw, **kwargs):
    perms = [
        'add_user',
        'change_user',
        'change_profile',
        'add_adherent',
        'change_adherent',
        'add_payment',
        'change_payment',
        'delete_payment',
        'change_service',
    ]
    try:
        old_group = ServiceType.objects.get(pk=instance.pk).group
    except ServiceType.DoesNotExist:
        old_group = None
    new_group = instance.group
    perms = Permission.objects.filter(codename__in=perms).all()
    if old_group is None and new_group is not None:
        # add permissions to new_group
        new_group.permissions.add(*perms)
    elif old_group is not None and new_group is None:
        # remove permissions from old_group *if not needed elsewhere*
        if not old_group.service_types.exclude(pk=instance.pk).exists():
            old_group.permissions.remove(*perms)