Deletes events from an ics file based on regex filter.

ics-filter.py

import re
import sys

def print_usage():
    print("Usage: python3 ./ics-filter.py [file] [regex_filter]")

n = len(sys.argv)
if n < 2:
    print("No ics file provided")
    print_usage()
    exit(1)
if n < 3:
    print("No filter provided")
    print_usage()
    exit(1)

filename = sys.argv[1]
event_filter = re.compile(sys.argv[2])

def should_add_event(event_data: str, filter: re.Pattern) -> bool:
    return filter.search(event_data) is None

new_file_contents = ""
with open(filename, encoding="utf-8") as f:
    read_data = f.read()
    current_event_data = []
    is_reading_event_data = False

    new_file_contents_list = []
    for line in read_data.split("\n"):
        if line == "BEGIN:VEVENT":
            is_reading_event_data = True

        if is_reading_event_data:
            current_event_data.append(line)
        else:
            new_file_contents_list.append(line)

        if line == "END:VEVENT":
            joined_current_event_data = "\n".join(current_event_data)
            if should_add_event(joined_current_event_data, event_filter):
                new_file_contents_list.append(joined_current_event_data)
            current_event_data = []
            is_reading_event_data = False
    new_file_contents = "\n".join(new_file_contents_list)

    with open(filename + ".bkp", mode="w", encoding="utf-8") as f_bkp:
        f_bkp.write(read_data)

with open(filename, mode="w", encoding="utf-8") as f:
    f.write(new_file_contents)