# Copyright 2018 TrilioData Inc.
# All Rights Reserved.

import oslo_messaging
from oslo_messaging import serializer as oslo_serializer

DEFAULT_URL = "__default__"
TRANSPORTS = {}
_SERIALIZER = oslo_serializer.JsonPayloadSerializer()


def setup():
    oslo_messaging.set_transport_defaults('dmapi')


def get_transport(conf, url=None, optional=False, cache=True):
    """Initialise the oslo_messaging layer."""
    global TRANSPORTS, DEFAULT_URL
    cache_key = url or DEFAULT_URL
    transport = TRANSPORTS.get(cache_key)
    if not transport or not cache:
        try:
            transport = oslo_messaging.get_notification_transport(conf, url)
        except (oslo_messaging.InvalidTransportURL,
                oslo_messaging.DriverLoadFailure):
            if not optional or url:
                # NOTE(sileht): oslo_messaging is configured but unloadable
                # so reraise the exception
                raise
            return None
        else:
            if cache:
                TRANSPORTS[cache_key] = transport
    return transport


def get_batch_notification_listener(transport, targets, endpoints,
                                    allow_requeue=False,
                                    batch_size=1, batch_timeout=None):
    """Return a configured oslo_messaging notification listener."""
    return oslo_messaging.get_batch_notification_listener(
        transport, targets, endpoints, executor='threading',
        allow_requeue=allow_requeue,
        batch_size=batch_size, batch_timeout=batch_timeout)


def get_notifier(transport, publisher_id):
    """Return a configured oslo_messaging notifier."""
    notifier = oslo_messaging.Notifier(transport, serializer=_SERIALIZER)
    return notifier.prepare(publisher_id=publisher_id)