#!/usr/bin/env python3

import requests
import json
import icalendar
import datetime
import hashlib
import time
import re
import sys

OFFSET = -time.timezone
events_url = "https://bitlair.nl/Special:Ask/-5B-5BCategory:Event-5D-5D-20-5B-5BStart::%E2%89%A519-20January-202023-5D-5D/-3FStart/-3FEnd/-3FEvent-20location/mainlabel%3D/limit%3D50/order%3DASC/sort%3DStart/prettyprint%3Dtrue/format%3Djson"
# above URL asks for all events and returns their name, start, end and location
events_page = requests.get(events_url)
events = events_page.json()

cal = icalendar.Calendar()

# Some properties are required to be compliant
cal.add('prodid', '-//Bitlair event calendar//bitlair.nl//')
cal.add('version', '2.0')

for key, value in events['results'].items():
    # unix timestamps from semwiki are not in UTC but in $localtime
    start_time = int(value['printouts']['Start'][0]['timestamp']) - OFFSET
    end_time = int(value['printouts']['End'][0]['timestamp']) - OFFSET

    # remove preceding 'Events/YYYY-MM-DD ' if existant from pagename to result in the actual event name
    result = re.search(r"Events\/....-..-.. (.*)", key)
    if result:
        groups = result.groups()
        if len (groups) == 1:
            eventname = groups[0]
        else:
            eventname = key
    else:
        eventname = key

    event = icalendar.Event()
    event.add('summary', eventname)

    event.add('description', f'{key}\n {value["fullurl"]}')
    event.add('dtstamp', datetime.datetime.now())
    event.add('dtstart', datetime.datetime.fromtimestamp(start_time))
    event.add('dtend', datetime.datetime.fromtimestamp(end_time))
    event.add('url', value['fullurl'])
    event['location'] = icalendar.vText(value['printouts']['Event location'][0]['fulltext'])

    url_hash_substr = hashlib.md5(value["fullurl"].encode()).hexdigest()[0:10]
    # we need to use something that is relatively safe as a UID, so use the first 10 characters of the hexdigest of the wikiurl
    event['uid'] = f'{url_hash_substr}@bitlair.nl'

    # Add the event to the calendar
    cal.add_component(event)


f = open(sys.argv[1], 'wb')
f.write(cal.to_ical())
f.close()