#!/usr/bin/python2.4

import urllib
import sys
import cgi
from xml.dom.minidom import parse, parseString

AsirraServiceUrl = "http://challenge.asirra.com/cgi/Asirra"

def ValidateAsirraChallenge(form):
	# We get a quoted string and keep it quoted in order to construct a query url
	ticket = form.getfirst("Asirra_Ticket")
	validationUrl = ("%s?action=ValidateTicket&ticket=%s" % (AsirraServiceUrl, ticket))
	
	validationStream = urllib.urlopen(validationUrl)
	dom = parse(validationStream)
	validationStream.close()

	value = dom.getElementsByTagName("Result")[0].childNodes[0].data

	# If Asirra tells us the challenge was passed, return without
	# throwing an exception
	if (value == "Pass"):
		return

	# For the purpose of this example, we print some debug
	# info.  You'll probably want to remove this from your
	# real implementation, to prevent leaking information
	# to attackers.
	DebugMessage = "unknown captcha failure"
	try:
		DebugMessage = dom.getElementsByTagName("Debug")[0].childNodes[0].data
	except:
		pass

	raise Exception("Asirra Error: %s" % (DebugMessage))

def main():
	sys.stdout.write("Content-Type: text/html\n\n")
	
	try:
		form = cgi.FieldStorage()

		UserName = form.getfirst("UserName")
		FavoriteColor = form.getfirst("FavoriteColor")

		try:
			ValidateAsirraChallenge(form)
		except:
			sys.stdout.write("You're trying to cheat the system, aren't you? "
					 "Bots and cheaters are not allowed at ExampleService!\n")
			raise

		sys.stdout.write("<p>Welcome, new user %s!  You are a human!  And your favorite color is %s." %
				 (UserName, FavoriteColor))

	except Exception, ex:
		sys.stdout.write("<p><p>Got an exception: <pre>%s</pre>" % ex)

	sys.stdout.write("<p>You can try this <a href='ExampleService.html'>again</a>.\n")
	sys.stdout.write("You can also see the <a href='ExampleService.py.txt'>Source Code</a> to ExampleService")


main()