#!/usr/bin/env python

# Based on the PyObjC SystemConfiguration callback demos:
# <https://svn.red-bean.com/pyobjc/trunk/pyobjc/pyobjc-framework-SystemConfiguration/Examples/CallbackDemo/>

from Cocoa import *
from SystemConfiguration import *
import signal
import os
from syslog import *
import sys

# SystemConfiguration state change events obtained from a 10.5 system
# Use scutil list to list all possible events:
#  subKey [44] = State:/Network/Global/DNS
#  subKey [45] = State:/Network/Global/IPv4
#  subKey [46] = State:/Network/Global/Proxies
#  subKey [47] = State:/Network/Global/SMB
#  subKey [48] = State:/Network/Interface
#  subKey [49] = State:/Network/Interface/en0/IPv4
#  subKey [50] = State:/Network/Interface/en0/IPv6
#  subKey [51] = State:/Network/Interface/en0/Link
#  subKey [52] = State:/Network/Interface/en1/AirPort
#  subKey [53] = State:/Network/Interface/en1/Link
#  subKey [54] = State:/Network/Interface/fw0/Link
#  subKey [55] = State:/Network/Interface/lo0/IPv4
#  subKey [56] = State:/Network/Interface/lo0/IPv6
#  subKey [57] = State:/Network/MulticastDNS
#  subKey [58] = State:/Network/PrivateDNS
#  subKey [63] = State:/Users/ConsoleUser

# This contains the list of states we want to monitor and the command to run when a given event occurs:
handlerDict = {
	'State:/Network/Interface/Global/IPv4': "/bin/echo Global IPv4 config changed",
	'State:/Network/Interface/en0/IPv4': 		"/bin/echo en0 IPv4 config changed",
	'State:/Network/Interface/*/IPv4': 			"/bin/echo Some interface\'s IPv4 config changed",
	'State:/Network/Global/DNS': 						"/bin/echo Global DNS configuration changed"
}

def handleConfigChange(store, changedKeys, info):
	for key in changedKeys:
		syslog(LOG_NOTICE, "%s changed: running %s" % (key, handlerDict[key]))
		os.system(handlerDict[key])

def clean_shutdown():
	CFRunLoopStop(CFRunLoopGetCurrent())
	sys.exit(0)

openlog("kicker-replacement")

# This uses the SystemConfiguration framework to get a SCDynamicStore session
# and register for certain events. See the Appl SystemConfiguration
# documentation for details:
#
# <http://developer.apple.com/documentation/Networking/Reference/SysConfig/SCDynamicStore/CompositePage.html>
#
# TN1145 may also be of interest:
#	<http://developer.apple.com/technotes/tn/tn1145.html>

store = SCDynamicStoreCreate(None, "kicker-replacement", handleConfigChange, None)
SCDynamicStoreSetNotificationKeys(store, None, handlerDict.keys())

# Get a CFRunLoopSource for our store session and add it to the application's runloop:
CFRunLoopAddSource(CFRunLoopGetCurrent(), SCDynamicStoreCreateRunLoopSource(None, store, 0), kCFRunLoopCommonModes)

# Add a signal handler so we can shutdown cleanly if we get a ^C:
# BUG: This does not work - it's necessary to ^Z or kill from another window
signal.signal(signal.SIGINT, clean_shutdown)

syslog(LOG_NOTICE, "Listening for SystemConfiguration changes to these keys: %s" % ', '.join(handlerDict.keys()))
CFRunLoopRun()