"""Base Implementation of a Delivery Backend."""
import abc
from json import dumps
import six
import pika
from django.contrib.auth import get_user_model
from .models import Notification
from . import default_settings as settings
@six.add_metaclass(abc.ABCMeta)
class BaseNotificationChannel():
"""Base channel for sending notifications."""
def __init__(self, **kwargs):
self.notification_kwargs = kwargs
@abc.abstractmethod
def construct_message(self):
"""Constructs a message from notification details."""
pass
@abc.abstractmethod
def notify(self, message):
"""Sends the notification."""
pass
class ConsoleChannel(BaseNotificationChannel):
"""Dummy channel that prints to the console."""
def construct_message(self):
"""Stringify the notification kwargs."""
return str(self.notification_kwargs)
def notify(self, message):
print(message)
class BasicWebSocketChannel(BaseNotificationChannel):
"""It creates a RabbitMQ user for each user (based on their username)."""
def _connect(self):
"""Connect to the RabbitMQ Server."""
rabbit_mq_url = settings.NOTIFICATIONS_RABBIT_MQ_URL
connection = pika.BlockingConnection(
pika.connection.URLParameters(rabbit_mq_url)
)
return connection
def construct_message(self):
"""Construct message from notification details."""
return self.notification_kwargs
def notify(self, message):
"""
Puts a new message on the queue.
The queue is named based on the username (for Uniqueness)
"""
connection = self._connect()
channel = connection.channel()
# Get user instance
User = get_user_model()
source = User.objects.get(id=message['source'])
recipient = User.objects.get(id=message['recipient'])
channel.queue_declare(queue=source.username)
jsonified_messasge = dumps(message)
channel.basic_publish(
exchange='', routing_key=recipient.username,
body=jsonified_messasge
)
connection.close()
