#!/usr/bin/env python

"""
@file ooidx/distributor.py
@author Paul Hubbard
@date 12-15-0
@package ooidx.distributor User-level fanout exchange service for data exchange.
@brief Pull address lists from attribute store, send message to everyone on the list.
"""

import logging
import simplejson as json

from twisted.internet import reactor
from twisted.internet.defer import inlineCallbacks
from twisted.internet import protocol

from magnet.preactor import Preactor

from ooidx.common import routing_keys, simpleSend

from ooici.protocol import ApplicationProtocol

class DistributorProtocol(ApplicationProtocol):
    """
    Implements the distributor.

    Protocol:
     Header 'command' must contain 'send_to_list'
     Header 'dest_list' should be a json-encoded list of destination addresses,
      which cannot be empty.

    @note Stateless and simple, just a placeholder for the real AMQP-based mcast.
    """
    def messageReceived(self, msg):
        logging.debug(msg.getHeaderKeys())

        try:
            cmd = msg.getHeader('command')
        except KeyError:
            logging.error('Missing command field in message')
            return

        if cmd == 'send_to_list':
            logging.info('Got broadcast request')
            self.send_to_list(msg)
            return

        # Unknown commands caught here
        logging.warn('Unknown command ' + cmd)

    def send_to_list(self, msg):

        #Send-to list is json-encoded, unpack.
        try:
            dest_list = json.loads(msg.getHeader('dest_list'))
            logging.debug('list is ' + str(dest_list))
        except:
            logging.exception('Error parsing destination list!')
            return

        for send_to in dest_list:
            logging.debug('Sending to %s...' % send_to)
            """
            Just send the same message - receivers should not even notice the
            extra dest_list header.
            """
            simpleSend(self.factory.preactor, msg, send_to)
            logging.debug('Send completed')

        logging.info('Broadcast complete')

class DistributorProtocolFactory(protocol.ClientFactory):
    """
    Protocol factor for the distributor; as is the common ooidx pattern all
    it does is set the protocol pointer and save a reference to the pocket
    reactor.
    """
    def set_preactor(self, preactor):
        self.preactor = preactor

    protocol = DistributorProtocol

@inlineCallbacks
def main():
    logging.basicConfig(level=logging.DEBUG, \
                format='%(asctime)s %(levelname)s [%(funcName)s] %(message)s')
    preactor = yield Preactor()
    f = DistributorProtocolFactory()
    f.set_preactor(preactor)
    preactor.connectSimpleConsumer(routing_keys['distributor'], f)
    logging.info('Distributor running OK')

if __name__ == '__main__':
    main()
    reactor.run()