#!/usr/bin/env python2.6
#Normally the above would be !/usr/bin/env python, 
#but I wished to run this under Python 2.6 which isn't 
#the system-wide standard on Debian right now
 
#Subprocess so we can execute make_license
import subprocess
# Time so we can stash the Unix time of purchase into database
from time import time
# urlencode in order to encode the data being sent back to Paypal
from urllib import urlencode
# SQLite connection and erorr handler for the local database
from sqlite3 import connect, Error as sqerr
# urlopen and request to send the data back to Paypal and receive it's response
from urllib2 import urlopen, Request
# Controller and Server from Circuits.web to make serving this app on the web easier
from circuits.web import Controller, Server
 
def ierr(msg):
	return "ERROR - " + msg
 
def verify_ipn(data):
	# Posts the data sent back to PayPal for verification
	data["cmd"] = "_notify-validate"
	params = urlencode(data)
 
	# Simply remove .sandbox for the live site
	req = Request("""https://www.sandbox.paypal.com/cgi-bin/webscr""", params)
	req.add_header("Content-type", "application/x-www-form-urlencoded")
	response = urlopen(req)
	status = response.read()
 
	if not status == "VERIFIED":
		return False
 
	# Additional Checks - Just because its verified does not mean all went well
 
	# Receiver ID - makes sure payment was sent specifically to you, not someone else
	# This ID can be found on your account's profile page
	if not data["receiver_id"] == "DDBSOMETHING4KE":
		return False
 
	# Currency - 100 Zimbewe dollars and 100 US Dollars is quite a difference, 
	# mc_gross and item prices do not distinguish the difference
	if not data["mc_currency"] == "USD":
		return False
 
	# If process made it to this point, purchase should be good to go.
	return True
 
class Root(Controller):
	# / root path
	def index(self, **data):
		if not "txn_id" in data:
			return "No Parameters"
 
		if not verify_entry(data):
			return "Unable to Verify"
 
		# Suggested Check : check the item IDs and Prices to make sure they match with records
 
		reference = data["txn_id"]
		amount = data["mc_gross"]
		email = data["payer_email"]
		name = data["first_name"] + " " + data["last_name"]
		status = data["payment_status"]
 
		conn = connect('ipn.db')
		curs = conn.cursor()
		try:
			curs.execute("""INSERT INTO ipn (id, purchased, txn, name, email, price, notes, status) 
			VALUES (NULL, ?, ?, ?, ?, ?, NULL, ?)""", (time(), reference, name, email, amount, status,))
			conn.commit()
		except sqerr, e:
			return "SQL Error: " + e.args[0]
		conn.close()
 
		return "Success"
	#The generate parameter (shows up like http://appdomain/generate/transaction/domain/) 
	#Will return the output of the make_license file, but only if the transaction exists
	#Note: some extra error control can be added here
	def generate(self, id, domain):
		if not id:
			return ierr("No Transaction Provided")
 
		if not domain:
			return ierr("No Domain Provided")
 
		# in the following we'll be allowing a wildcard subdomain on the requested domain
		conn = connect('ipn.db')
		curs = conn.cursor()
		try:
			curs.execute("""SELECT name FROM ipn WHERE txn = ? LIMIT 1""", (id,))
			row = curs.fetchone()
			proc = subprocess.Popen(['make_license', 
				'--passphrase', 'yourpassphrase', 
				'--header-line', '<?php exit(0); ?>',
				'--properties', "UserName='%s',txn='%s'" % (row[0], id), 
				'--allowed-server', '*.%s' % domain],
				shell=False,
				stdout=subprocess.PIPE)
			ret = proc.communicate()[0]			
		except sqerr, e:
			ret = ierr(e.args[0])
 
		return ret
 
# Standard TCP method, in Nginx this would be: proxy_pass http://127.0.0.1:9002;		
# (Server(("0.0.0.0", 9002)) + Root()).run()
 
# Unix Socket Method - make sure webserver can read and write to the socket file
# in the Nginx webserver this would be: proxy_pass	http://unix:/tmp/ipn.sock:/;
(Server(("/tmp/ipn.sock")) + Root()).run()