#!/usr/bin/python

from time import time
from zope.interface import implements
from application.notification import IObserver, NotificationData, NotificationCenter, ObserverWeakrefProxy


class Sender(object):
    def publish(self):
        center = NotificationCenter()
        print("Sending notification with name 'simple':")
        print("Expecting CatchAllObserver, SimpleObserver, ObjectObserver and VolatileAllObserver to receive notifications")
        center.post_notification(name='simple', sender=self)
        print("\nSending notification with name 'complex':")
        print("Expecting CatchAllObserver, ObjectObserver and VolatileAllObserver to receive notifications")
        center.post_notification(name='complex', sender=self, data=NotificationData(
            timestamp=time(), complex_attribute='complex_value'))

    def __repr__(self):
        return '%s()' % self.__class__.__name__


class AnonymousSender(Sender):
    def publish(self):
        center = NotificationCenter()
        print("Sending notification with name 'simple':")
        print("Expecting SimpleObserver to receive notifications (CatchAllObserver and VolatileAllObserver have been unregistered)")
        center.post_notification(name='simple')
        print("\nSending notification with name 'empty':")
        print("Expecting no observer to receive notifications (CatchAllObserver and VolatileAllObserver have been unregistered)")
        center.post_notification(name='empty', data=None)


class CatchAllObserver(object):
    """An observer that registers itself to receive all notifications."""
    implements(IObserver)

    def register(self):
        print("Registering CatchAllObserver to receive all notifications")
        NotificationCenter().add_observer(self)

    def unregister(self):
        print("Unregistering CatchAllObserver from receiving all notifications")
        NotificationCenter().remove_observer(self)

    def handle_notification(self, notification):
        print("In CatchAllObserver got %r" % (notification,))


class SimpleObserver(object):
    """An observer that registers itself for notifications with name 'simple'."""
    implements(IObserver)

    def register(self):
        print("Registering SimpleObserver to receive notifications with name 'simple' from any sender")
        NotificationCenter().add_observer(self, name='simple')

    def unregister(self):
        print("Unregistering SimpleObserver from receiving notifications with name 'simple' from any sender")
        NotificationCenter().remove_observer(self, name='simple')

    def handle_notification(self, notification):
        print("In SimpleObserver got %r" % (notification,))


class ObjectObserver(object):
    """An observer that registers itself for notifications coming from a specific object."""
    implements(IObserver)

    def __init__(self, sender):
        self.sender = sender

    def register(self):
        print("Registering ObjectObserver to receive notifications with any name from sender %r" % (
            self.sender,))
        NotificationCenter().add_observer(self, sender=self.sender)

    def unregister(self):
        print("Unregistering ObjectObserver from receiving notifications with any name from sender %r" % (
            self.sender,))
        NotificationCenter().remove_observer(self, sender=self.sender)

    def handle_notification(self, notification):
        print("In ObjectObserver got %r" % (notification,))


class VolatileAllObserver(object):
    """An observer that registers itself to receive all notifications and it is weakly referenced"""
    implements(IObserver)

    def __init__(self):
        print("Registering VolatileAllObserver to receive all notifications")
        NotificationCenter().add_observer(ObserverWeakrefProxy(self))

    def handle_notification(self, notification):
        print("In VolatileAllObserver got %r" % (notification,))


# instantiate senders
sender = Sender()
anonymous = AnonymousSender()

# instantiate the observers and register them
print("Creating and registering observers:")
catchall_observer = CatchAllObserver()
catchall_observer.register()
simple_observer = SimpleObserver()
simple_observer.register()
object_observer = ObjectObserver(sender)
object_observer.register()
volatile_observer = VolatileAllObserver()

# send notifications
print("\nSending notifications from Sender:")
print("----------------------------------")
sender.publish()

print("\nUnregistering some observers:")
catchall_observer.unregister()
print("Deleting VolatileAllObserver which will automatically unregister it from receiving all notifications")
del volatile_observer

print("\nSending notifications from AnonymousSender:")
print("-------------------------------------------")
anonymous.publish()
