# -*- coding: utf-8 -*-

# copyright 2012-2014 LOGILAB S.A. (Paris, FRANCE), all rights reserved.

# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr

#

# This file is part of CubicWeb.

#

# CubicWeb is free software: you can redistribute it and/or modify it under the

# terms of the GNU Lesser General Public License as published by the Free

# Software Foundation, either version 2.1 of the License, or (at your option)

# any later version.

#

# CubicWeb is distributed in the hope that it will be useful, but WITHOUT

# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

# FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more

# details.

#

# You should have received a copy of the GNU Lesser General Public License along

# with CubicWeb.  If not, see <http://www.gnu.org/licenses/>.

from threading import Thread

from logging import getLogger

import zmq

from zmq.eventloop import ioloop

import zmq.eventloop.zmqstream

from cubicweb import set_log_methods

ctx = zmq.Context()

class ZMQComm(object):

    """

    A simple ZMQ-based notification bus.

    There should at most one instance of this class attached to a

    Repository. A typical usage may be something like::

        def callback(msg):

            self.info('received message: %s', ' '.join(msg))

        repo.app_instances_bus.subscribe('hello', callback)

    to subsribe to the 'hello' kind of message. On the other side, to

    emit a notification, call::

       repo.app_instances_bus.publish(['hello', 'world'])

    See http://docs.cubicweb.org for more details.

    """

    def __init__(self):

        self.ioloop = ioloop.IOLoop()

        self._topics = {}

        self._subscribers = []

        self.publisher = None

    def add_publisher(self, address):

        assert self.publisher is None, "more than one publisher is not supported"

        self.publisher = Publisher(self.ioloop, address)

    def add_subscription(self, topic, callback):

        for subscriber in self._subscribers:

            subscriber.subscribe(topic, callback)

        self._topics[topic] = callback

    def add_subscriber(self, address):

        subscriber = Subscriber(self.ioloop, address)

        for topic, callback in self._topics.items():

            subscriber.subscribe(topic, callback)

        self._subscribers.append(subscriber)

    def publish(self, msg):

        if self.publisher is None:

            return

        self.publisher.send(msg)

    def start(self):

        Thread(target=self.ioloop.start).start()

    def stop(self):

        self.ioloop.add_callback(self.ioloop.stop)

    def __del__(self):

        self.ioloop.close()

class Publisher(object):

    def __init__(self, ioloop, address):

        self.address = address

        self._topics = {}

        self._subscribers = []

        self.ioloop = ioloop

        def callback():

            s = ctx.socket(zmq.PUB)

            self.stream = zmq.eventloop.zmqstream.ZMQStream(s, io_loop=ioloop)

            self.stream.bind(self.address)

            self.debug('start publisher on %s', self.address)

        ioloop.add_callback(callback)

    def send(self, msg):

        self.ioloop.add_callback(lambda:self.stream.send_multipart(msg))

class Subscriber(object):

    def __init__(self, ioloop, address):

        self.address = address

        self.dispatch_table = {}

        self.ioloop = ioloop

        def callback():

            s = ctx.socket(zmq.SUB)

            self.stream = zmq.eventloop.zmqstream.ZMQStream(s, io_loop=ioloop)

            self.stream.on_recv(self.dispatch)

            self.stream.connect(self.address)

            self.debug('start subscriber on %s', self.address)

        ioloop.add_callback(callback)

    def dispatch(self, msg):

        try:

            f = self.dispatch_table[msg[0]]

        except KeyError:

            return

        f(msg)

    def subscribe(self, topic, callback):

        self.dispatch_table[topic] = callback

        self.ioloop.add_callback(lambda: self.stream.setsockopt(zmq.SUBSCRIBE, topic))

set_log_methods(Publisher, getLogger('cubicweb.zmq.pub'))

set_log_methods(Subscriber, getLogger('cubicweb.zmq.sub'))