cally.py

#!/usr/bin/env python
#-*- coding:utf-8 -*-

import sys, re
from ics import Calendar
from urllib2 import urlopen
import requests

print >>sys.stderr, "[i] Starting..."

urls = [
    "http://www.hackerrank.com/calendar/cal.ics",
    "https://calendar.google.com/calendar/ical/hackerearth.com_73f0o8kl62rb5v1htv19p607e4%40group.calendar.google.com/public/basic.ics",
]

whitelist_words = """
Codechef
101 Hack
20/20 Hack
Codeforces
SRM
TCO
cipher
crypto
Ad Infinitum
HourRank
Game Theory
Easy '
Clash '
Marathon '
Battle Of Bots
Circuits
Week of Code
""".strip().split("\n")

whitelist_regexp = [
]


events = []
for url in urls:
    print >>sys.stderr, "[i] Query", url
    if url.startswith("file://"):
        text = open(url[7:]).read().decode("utf-8")
    else:
        text = requests.get(url).text
    events += Calendar(text).events

print >>sys.stderr, "[i] Finished queries"

cal = Calendar()
for ev in events:
    name = ev.name.lower()
    good = (
        False
        | any(w for w in whitelist_words if w.lower() in name)
        | any(w for w in whitelist_regexp if re.search(w, name, flags=re.I))
    )
    if good:
        try:
            cal.events.add(ev)
        except:
            cal.events.append(ev)
    else:
        print >>sys.stderr, "REMOVED:", ev.name
print >>sys.stderr, "------\n"

print """
HTTP/1.1 200 OK
Cache-Control: max-age=0, private, must-revalidate
Content-Type: text; charset=utf-8
Server: nginx
Status: 200 OK
Vary: Accept-Encoding
Connection: keep-alive
""".strip() + "\n"

# hack?..
print "BEGIN:VCALENDAR"
print "VERSION:2.0"
print "CALSCALE:GREGORIAN"
print "METHOD:PUBLISH"
print "PRODID:hellman"
for e in cal.events:
    print str(e)
print "END:VCALENDAR"

$ screen -AmS cally socat TCP-l:3030,fork,reuseaddr 'system:./cally.py'