# horrible little module that fetches ICS files for the local trash public service.
#
# It tries its best to not overwrite existing ICS files in case the upstream goes down
# or returns empty ICS files.
import sys
import httpx
import asyncio
import icalendar
from datetime import datetime
import syslog
import os.path
# Internal id for the street (extracted from the ics download url)
ortsteil_id = "e9c32ab3-df25-4660-b88e-abda91897d7a"
# They are using a numeric encoding to refer to different kinds of trash
fraktionen = {
"restmüll": "1",
"bio": "5",
"papier": "7",
"gelbe_tonne": "13",
"problemmüllsammlung": "20"
}
def ics_url(year):
frakt = ','.join(fraktionen.values())
return f'https://awido.cubefour.de/Customer/aic-fdb/KalenderICS.aspx?oid={ortsteil_id}&jahr={year}&fraktionen={frakt}&reminder=1.12:00'
def fetchers_for_years(start_year, no_of_years_in_future):
"""given a starting year, and a number of years in the future,
return the years for which to fetch ics files"""
current_year = datetime.now().year
max_year = current_year + no_of_years_in_future
return {
"passed_years": range(start_year, current_year),
"this_and_future_years": range(current_year, 1 + max_year)
}
async def fetch_ics(c, url):
"""fetch an ICS file from an URL"""
try:
resp = await c.get(url)
except Exception as e:
return { "ics_does_not_exist_exc": e }
if resp.is_error:
return { "ics_does_not_exist": resp }
else:
try:
ics = icalendar.Calendar.from_ical(resp.content)
return { "ics": { "ics_parsed": ics, "ics_bytes": resp.content } }
except ValueError as e:
return { "ics_cannot_be_parsed": e }
def ics_has_events(ics):
"""Determine if there is any event in the ICS, otherwise we can assume it’s an empty file"""
for item in ics.walk():
if isinstance(item, icalendar.Event):
return True
return False
async def write_nonempty_ics(directory, year, ics):
# only overwrite if the new ics has any events
if ics_has_events(ics['ics_parsed']):
path = os.path.join(directory, f"{year}.ics")
with open(path, "wb") as f:
f.write(ics['ics_bytes'])
info(f"wrote ics for year {year} to file {path}")
else:
info(f"ics for year {year} was empty, skipping")
def main():
ics_directory = os.getenv("ICS_DIRECTORY", None)
if not ics_directory:
critical("please set ICS_DIRECTORY")
start_year = int(os.getenv("ICS_START_YEAR", 2022))
future_years = int(os.getenv("ICS_FUTURE_YEARS", 2))
years = fetchers_for_years(start_year, no_of_years_in_future=future_years)
async def go():
async with httpx.AsyncClient(follow_redirects=True) as c:
info(f"fetching ics for passed years: {years['passed_years']}")
for year in years["passed_years"]:
match await fetch_ics(c, ics_url(year)):
case { "ics_does_not_exist_exc": error }:
warn(f"The ics for the year {year} is gone, error when requesting: {error} for url {ics_url(year)}")
case { "ics_does_not_exist": resp }:
warn(f"The ics for the year {year} is gone, server returned status {resp.status} for url {ics_url(year)}")
case { "ics_cannot_be_parsed": error }:
warn(f"The returned ICS could not be parsed: {error} for url {ics_url(year)}")
case { "ics": ics }:
info(f"fetched ics from {ics_url(year)}")
await write_nonempty_ics(ics_directory, year, ics)
case _:
critical("unknown case for ics result")
info(f"fetching ics for current and upcoming years: {years['this_and_future_years']}")
for year in years["this_and_future_years"]:
match await fetch_ics(c, ics_url(year)):
case { "ics_does_not_exist_exc": error }:
critical(f"The ics for the year {year} is not available, error when requesting: {error} for url {ics_url(year)}")
case { "ics_does_not_exist": resp }:
critical(f"The ics for the year {year} is not available, server returned status {resp.status} for url {ics_url(year)}")
case { "ics_cannot_be_parsed": error }:
critical(f"The returned ICS could not be parsed: {error} for url {ics_url(year)}")
case { "ics": ics }:
info(f"fetched ics from {ics_url(year)}")
await write_nonempty_ics(ics_directory, year, ics)
case _:
critical("unknown case for ics result")
asyncio.run(go())
def info(msg):
syslog.syslog(syslog.LOG_INFO, msg)
def critical(msg):
syslog.syslog(syslog.LOG_CRIT, msg)
sys.exit(1)
def warn(msg):
syslog.syslog(syslog.LOG_WARNING, msg)
def debug(msg):
syslog.syslog(syslog.LOG_DEBUG, msg)
if __name__ == "__main__":
main()
