#!/usr/bin/env python

# Written by Adrianna Pinska
# Licence: GPLv3

import sys
import re
import urllib2
import xml.dom.minidom
import os.path
import pickle
import time

crosspost_limit = 3
subject_filename = ".usenet_filter_subject_cache"
useragent = 'Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.1.16) Gecko/20080702 (Debian-1.8.1.16+nobinonly-0ubuntu1) Galeon/2.0.4 (Ubuntu 2.0.4-1ubuntu1)'

# Add crap you don't want to see to these lists:
badgroups = ["celebrities", "gossip", "acting", "rec\.arts\.tv", "religion", "talk\.origins", "sci\.meow", "politics", "autism", "depression", "economics", "alt\.community", "kooks", "psychology", "revisionism", "comedy", "jewish"]
badauthors = ["Day Brown", "Colonel Jake"]
badkeywords = ["libertarian", "WTC", "truther", "9/11"]

patterns = {
    "badgroups": ("(%s)" % "|".join(badgroups), re.IGNORECASE),
    "badauthors": ("(%s)" % "|".join(badauthors), re.IGNORECASE),
    "badkeywords": ("(%s)" % "|".join(badkeywords), re.IGNORECASE),
    "postid": (".*show_docid=([a-f0-9]*$)", 0),
    "group": ("(.*) Google Group", 0),
    "newsgroups": ("Newsgroups: (.*)", 0),
    "author": ("From: (.*)", 0),
    "charset": ('Content-Type: .*charset="?([^ ;"\n]*)"?', 0),
    "body": ("\n\n(.*)", re.DOTALL),
}

compiled = {}
for name, (pattern, flags) in patterns.items():
    compiled[name] = re.compile(pattern, flags)

blacklisted_subjects = {}
if os.path.exists(subject_filename):
    subject_file = open(subject_filename, "r")
    blacklisted_subjects = pickle.loads(subject_file.read())
    subject_file.close()

now = time.time()

xml = xml.dom.minidom.parseString(sys.stdin.read())
channel = xml.getElementsByTagName("rss")[0].getElementsByTagName("channel")[0]
channeltitle = channel.getElementsByTagName("title")[0].firstChild.data
group = compiled["group"].match(channeltitle).group(1)

for item in channel.getElementsByTagName("item"):
    # Check if subject matches blacklist or bad keyword
    title = item.getElementsByTagName("title")[0].firstChild.data
    if title in blacklisted_subjects or compiled["badkeywords"].search(title):
        blacklisted_subjects[title] = now
        channel.removeChild(item)
        item.unlink()
        continue

    # Otherwise fetch the whole post
    link = item.getElementsByTagName("link")[0].firstChild.data
    postid = compiled["postid"].match(link).group(1)
    request = urllib2.Request("http://groups.google.co.za/group/%s/msg/%s?dmode=source&output=gplain" % (group, postid), None, {"User-Agent": useragent})
    response = urllib2.urlopen(request)
    text = response.read()

    # Do more filtering
    newsgroups = compiled["newsgroups"].search(text).group(1)
    crosspost_count = len(newsgroups.split(","))
    author = compiled["author"].search(text).group(1)
    body = compiled["body"].search(text).group(1)

    if crosspost_count > crosspost_limit or compiled["badgroups"].search(newsgroups) or compiled["badauthors"].search(author) or compiled["badkeywords"].search(body):
        blacklisted_subjects[title] = now
        channel.removeChild(item)
        item.unlink()
        continue

    # Put full body in feed
    charset = compiled["charset"].search(text)
    if charset:
        body = body.decode(charset.group(1)).encode('utf-8')
    item.getElementsByTagName("description")[0].firstChild.data = body

# remove old subjects from blacklist
for subject, lastseen in list(blacklisted_subjects.items()):
    if now - lastseen > 2*30*24*60*60:
        del(blacklisted_subjects[subject])
# save blacklist
subject_file = open(subject_filename, "w")
subject_file.write(pickle.dumps(blacklisted_subjects))
subject_file.close()

print xml.toxml(encoding="UTF-8")