from celery_haystack.indexes import CelerySearchIndex
from celery_haystack.signals import CelerySignalProcessor
from celery_haystack.utils import enqueue_task
from haystack.exceptions import NotHandled


class CelerySignalProcessor(CelerySignalProcessor):
    def enqueue(self, action, instance, sender, **kwargs):
        using_backends = self.connection_router.for_write(instance=instance)

        for using in using_backends:
            try:
                connection = self.connections[using]
                index = connection.get_unified_index().get_index(sender)
            except NotHandled:
                continue  # Check next backend

            if isinstance(index, CelerySearchIndex):
                if action == 'update' and not index.should_update(instance):
                    continue
                elif action == 'update' \
                        and instance not in index.index_queryset():
                    action = 'delete'
                enqueue_task(action, instance)