Make ics events recurring

README.md

ETH myStudies ics Script

This script is intended to be used with the ics files outputted by myStudies, to make importing your schedule into your calendar easier.

myStudies does not export recurring events, but instead individual events for every date. This makes it hard if you want to edit them, because you can't edit them as a series.

Usage

Call this script with these arguments:

1. input ics file
2. output ics file name
3. start date of events to be considered (choose exactly one week, all events in the given timeframe will be kept with the added weekly recurrence rule)
4. end date of events to be considered

the dates should be in the YYYYMMDD format for the script to work. (no separators) important: myStudies only gives events for the future. so choose a start and end week that lies in the future (ideally just next week)

This script requires Python 3 (tested with 3.11) and no other dependencies

script.py

import sys
import os
import re

def read_ics_file(file_path):
    with open(file_path, 'r', encoding='utf-8') as file:
        lines = file.readlines()
    return lines

def write_ics_file(file_path, lines):
    with open(file_path, 'w', encoding='utf-8') as file:
        file.writelines(lines)

def parse_datetime_to_ics(date_str, time_str="000000"):
    return f"{date_str}T{time_str}Z"

def process_events(lines, start_datetime_ics, end_datetime_ics):
    in_event = False
    event_lines = []
    processed_events = []
    for line in lines:
        if line.startswith('BEGIN:VEVENT'):
            in_event = True
        elif line.startswith('END:VEVENT'):
            in_event = False
            processed_events.extend(process_event(event_lines, start_datetime_ics, end_datetime_ics))
        elif in_event:
            event_lines.append(line.strip())
        else:
            processed_events.append(line)
    return processed_events

def process_event(event_lines, start_datetime_ics, end_datetime_ics):
    event_info = {}
    description = []
    for line in event_lines:
        if line.startswith(' '):  # Continuation line
            description.append(line.strip())
        else:
            if description:
                event_info['DESCRIPTION'] = ''.join(description)
                description = []
            key, value = parse_line(line)
            if key:
                event_info[key] = value

    if 'DTSTART' in event_info and event_info['DTSTART'] >= start_datetime_ics and event_info['DTSTART'] <= end_datetime_ics:
        event_info['RRULE'] = 'FREQ=WEEKLY'
        return generate_event(event_info)
    else:
        return []

def parse_line(line):
    match = re.match(r'([^:]+):(.+)', line)
    if match:
        return match.group(1), match.group(2).strip()
    return None, None

def generate_event(event_info):
    event_lines = ['BEGIN:VEVENT']
    for key in event_info:
        if key == 'DESCRIPTION':
            # Wrap long descriptions
            desc = event_info[key]
            for i in range(0, len(desc), 75):
                part = desc[i:i+75]
                if i > 0:
                    part = ' ' + part
                event_lines.append(f'{key}:{part}')
        else:
            event_lines.append(f'{key}:{event_info[key]}')
    event_lines.append('END:VEVENT')
    return [line+'\n' for line in event_lines]

if __name__ == '__main__':
    if len(sys.argv) != 5:
        print("Usage: python make_weekly_recurring.py <input.ics> <output.ics> <start_date> <end_date>")
        sys.exit(1)

    input_file_path = sys.argv[1]
    output_file_path = sys.argv[2]
    start_date = sys.argv[3]
    end_date = sys.argv[4]

    if not os.path.exists(input_file_path):
        print(f"The input file {input_file_path} does not exist.")
        sys.exit(1)

    start_datetime_ics = parse_datetime_to_ics(start_date)
    end_datetime_ics = parse_datetime_to_ics(end_date)

    ics_lines = read_ics_file(input_file_path)
    processed_lines = process_events(ics_lines, start_datetime_ics, end_datetime_ics)
    write_ics_file(output_file_path, processed_lines)

    print(f"Processed events have been written to {output_file_path}")