# -*- Mode: Python -*-
# vi:si:et:sw=4:sts=4:ts=4

# show how classes can have deferreds for their subclassable methods
# and still execute in the right order
# and have the child decide on what aggregate result to return

from twisted.internet import reactor, defer

import os
import sys
import signal

class Parent:
    def stop(self):
        print "Parent.stop() begin"
        d = defer.Deferred()
        self.__doStopStuff(d)
        print "Parent.stop() end, returning %r" % d
        return d

    def __doStopStuff(self, d):
        print "Parent: doing stoppy stuff"
        reactor.callLater(1, self.__doneStopStuff, d)
    
    def __doneStopStuff(self, d):
        print "Parent: done stoppy stuff, callbacking %r" % d
        d.callback("parent")

class Child(Parent):
    def stop(self):
        print "Child.stop() begin"
        d = defer.Deferred()
        self.__doStopStuff(d)
        #d.addCallback(lambda r: Parent.stop(self))
        print "Child.stop() end, returning %r" % d
        return d

    def __doStopStuff(self, d):
        print "Child: doing stoppy stuff"
        reactor.callLater(1, self.__doneStopStuff, d)
    
    def __doneStopStuff(self, d):
        print "Child: done stoppy stuff"
        pd = Parent.stop(self)
        pd.addCallback(self.__processParentStop, d)
        
    def __processParentStop(self, result, d):
        print "Child: parent's stop returned %r" % result
        print "Child: callbacking %r" % d
        d.callback("child")


def beforeShutdown():
    print "before shutdown"

def afterShutdown():
    print "after shutdown"

def doParentStuff():
    p = Parent()
    d = p.stop()
    print "doParentStuff(): adding doneParentStuff callback to %r" % d
    d.addCallback(doneParentStuff)

def doneParentStuff(result):
    print "doneParentStuff(): result %r" % result
    reactor.callLater(0, doChildStuff)

def doChildStuff():
    c = Child()
    d = c.stop()
    print "doChildStuff(): adding doneChildStuff callback to %r" % d
    d.addCallback(doneChildStuff)
    
def doneChildStuff(result):
    print "doneChildStuff(): result %r" % result
    reactor.callLater(0, reactor.stop)

reactor.addSystemEventTrigger('before', 'shutdown', beforeShutdown)
reactor.addSystemEventTrigger('after', 'shutdown', afterShutdown)

reactor.callLater(0, doParentStuff)
reactor.run()

print "done"