A simple example on how to create an ics calendar file in python

ics-creator.py

#!//usr/bin/python3
from icalendar import Calendar, Event
from datetime import datetime, timedelta
from uuid import uuid4

"""
Please install dependencies with pip:
- icalendar 4.0.3
- uuid 1.30

Purpose of this script is to create a ics file based on the dates published
on www.entsorgungsdaten.de. The date will start at 16:00 on the day before
and end on 16:00 at the day itself. The description is hardcoded to trigger
an event in OpenHAB. An OpenHAB rule will evaluate this trigger and handle
it accordingly. The ics will be imported to Nextcloud Calendar, OpenHAB
reads from there with the CalDAV Command Binding.

Meaning of this is the need to activate a message and led on the day
before the trash can has to be put by the side of the street. On the morning
of the day itself it might be too late.

Execution of tests: 'python -m doctest -v ics-creator.py'
"""

# Copy and Paste from https://www.entsorgungsdaten.de/module.php5?mod=entsorgungsdaten&fid=15&gem=18
muelltermine = """Di. 08.01.Di. 22.01.Di. 05.02.Di. 19.02.Di. 05.03.Di. 19.03.Di. 02.04.Mo. 15.04.Di. 30.04.Di. 14.05.Di. 28.05.Mi. 12.06.Di. 25.06.Di. 09.07.Di. 23.07.Di. 06.08.Di. 20.08.Di. 03.09.Di. 17.09.Di. 01.10.Di. 15.10.Di. 29.10.Di. 12.11.Di. 26.11.Di. 10.12.Mo. 23.12."""
papiertermine = """Mo. 07.01.Do. 07.02.Do. 07.03.Do. 04.04.Mi. 08.05.Fr. 07.06.Fr. 05.07.Do. 08.08.Do. 05.09.Fr. 11.10.Fr. 08.11.Fr. 06.12."""


def splitAndCutDates(s, l, c):
    """Takes the copied date string from entsorgungsdaten.de and return an
    array of dates. s is the input string, l is the length of the repeating
    date string, c is the length of the string to cut from the beginning
    Example:
    >>> splitAndCutDates("Di. 08.01.Di. 22.01.Di. 05.02.", 10, 4)
    ['08.01.', '22.01.', '05.02.']
    """
    return [s[i + c: i + l] for i in range(0, len(s), l)]


def getDay(s):
    """extract and return the day of a string like '21.04.' as integer
    Examples:
    >>> getDay("21.04.")
    21
    >>> getDay("01.12.")
    1
    """
    return int(s[0: 2])


def getMonth(s):
    """extract and return the month of a string like '21.04.' as integer
    Examples:
    >>> getMonth("21.04.")
    4
    >>> getMonth("01.12.")
    12
    """
    return int(s[3: 5])


def createIcalEvent(summary, dayAndMonth, year, description):
    """Create and return an ical event"""
    event = Event()
    event.add('summary', summary)
    event.add('dtstart', datetime(year,
                                  getMonth(dayAndMonth),
                                  getDay(dayAndMonth),
                                  16, 0, 0, 0)-timedelta(days=1))
    event.add('dtend', datetime(year,
                                getMonth(dayAndMonth),
                                getDay(dayAndMonth),
                                16, 0, 0, 0))
    event.add('dtstamp', datetime.now())
    event.add('description', description)
    event.add('uid', uuid4())
    return event


if __name__ == '__main__':
    # Create array of dates
    muelltermine = splitAndCutDates(muelltermine,
                                    len("Di. 08.01."),
                                    len("Di. "))
    papiertermine = splitAndCutDates(papiertermine,
                                     len("Di. 08.01."),
                                     len("Di. "))

    # Create calendar
    cal = Calendar()
    cal.add('prodid', 'https://icalendar.readthedocs.io')
    cal.add('version', '2.0')

    # Create one entry per date
    for x in muelltermine:
        cal.add_component(
            createIcalEvent("Muelltonne",
                            x,
                            2019,
                            "BEGIN:Info_Muelltonne:ON\n"
                            "END:Info_Muelltonne:OFF"))
    for x in papiertermine:
        cal.add_component(
            createIcalEvent("Papiertonne",
                            x,
                            2019,
                            "BEGIN:Info_Papiertonne:ON\n"
                            "END:Info_Papiertonne:OFF"))

    # Write file
    f = open('entsorgungsdaten.ics', 'wb')
    f.write(cal.to_ical())
    f.close()