#!/usr/bin/env python

'''
Reference: http://www.slideshare.net/ishraqabd/publish-subscribe-model-overview-13368808
Author: https://github.com/HanWenfang
'''


class Provider:
    def __init__(self):
        self.msgQueue = []
        self.subscribers = {}

    def notify(self, msg):
        self.msgQueue.append(msg)

    def subscribe(self, msg, subscriber):
        if not msg in self.subscribers:
            self.subscribers[msg] = []
            self.subscribers[msg].append(subscriber) #unfair
        else:
            self.subscribers[msg].append(subscriber)

    def unSubscribe(self, msg, subscriber):
        self.subscribers[msg].remove(subscriber)

    def update(self):
        for msg in self.msgQueue:
            if msg in self.subscribers:
                for sub in self.subscribers[msg]:
                    sub.run(msg)
        self.msgQueue = []


class Publisher:
    def __init__(self, msgCenter):
        self.provider = msgCenter

    def publish(self, msg):
        self.provider.notify(msg)


class Subscriber:
    def __init__(self, name, msgCenter):
        self.name = name
        self.provider = msgCenter

    def subscribe(self, msg):
        self.provider.subscribe(msg, self)

    def run(self, msg):
        print "%s got %s" % (self.name, msg)


def main():
    messageCenter = Provider()

    fftv = Publisher(messageCenter)

    jim = Subscriber("jim", messageCenter)
    jim.subscribe("cartoon")
    jack = Subscriber("jack", messageCenter)
    jack.subscribe("music")
    gee = Subscriber("gee", messageCenter)
    gee.subscribe("movie")

    fftv.publish("cartoon")
    fftv.publish("music")
    fftv.publish("ads")
    fftv.publish("movie")
    fftv.publish("cartoon")
    fftv.publish("cartoon")
    fftv.publish("movie")
    fftv.publish("blank")

    messageCenter.update()


if __name__ == "__main__":
    main()