from django.db.models.signals import pre_save, post_delete, post_save
from django.dispatch import receiver

from . import settings
from .models import Mailbox, Address


# Admin bulk deletion doesn't call model.delete()
# So, signals are used instead of model method overriding

@receiver(post_delete, sender=Mailbox, dispatch_uid='mailboxes.delete_forwards')
def delete_forwards(sender, *args, **kwargs):
    # Cleanup related addresses
    instance = kwargs['instance']
    for address in instance.get_forwards():
        forward = address.forward.split()
        forward.remove(instance.name)
        address.forward = ' '.join(forward)
        if not address.destination:
            address.delete()
        else:
            address.save()


@receiver(pre_save, sender=Mailbox, dispatch_uid='mailboxes.create_local_address')
def create_local_address(sender, *args, **kwargs):
    mbox = kwargs['instance']
    local_domain = settings.MAILBOXES_LOCAL_DOMAIN
    if not mbox.pk and local_domain:
        Domain = Address._meta.get_field('domain').remote_field.model
        try:
            domain = Domain.objects.get(name=local_domain)
        except Domain.DoesNotExist:
            pass
        else:
            addr, created = Address.objects.get_or_create(
                name=mbox.name, domain=domain, account_id=domain.account_id)
            if created:
                if domain.account_id == mbox.account_id:
                    mbox._post_save_add_address = addr
                else:
                    addr.forward = mbox.name
                    addr.save(update_fields=('forward',))


@receiver(post_save, sender=Mailbox, dispatch_uid='mailboxes.add_local_address')
def add_local_address(sender, *args, **kwargs):
    mbox = kwargs['instance']
    addr = getattr(mbox, '_post_save_add_address', None)
    if addr:
        addr.mailboxes.add(mbox)