Merge iCal / ICS Files

ics_merge.php

<?php
function merge_ics($token, ...$ics_urls) {
	/**
	* Merge list of ICS files to one ICS file. Use ICS header from first ICS file.
	* Download ICS file from remote server with *file_get_contents*
	*/
	
	$ical_list = "";
	
	foreach($ics_urls as $key => $ics_file) {
		$curl = curl_init();

		curl_setopt($curl, CURLOPT_URL, $ics_file);
		curl_setopt($ch, CURLOPT_HTTPHEADER, ["Authorization: Basic ".$token]);
		curl_setopt($curl, CURLOPT_RETURNTRANSFER, TRUE);

		$ics_data = curl_exec($curl);
		$httpcode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
		
		if($httpcode != 200 || curl_exec($ch) === false) {
			die ('Error for url ' . $ics_file . ': ' . curl_error($ch));
		} else {

			if (count($ics_urls) == 1) return $ics_data;

			$events_begin 	= strpos($ics_data, 'BEGIN:VEVENT');
			$events_end 	= strpos($ics_data, 'END:VCALENDAR');

			if ($key == 0) {
				$ical_header = substr($ics_data, 0, $events_begin);
				$ical_footer = 'END:VCALENDAR';
			}

			$ical_list .= substr($ics_data, $events_begin, $events_end - $events_begin);
		}
	}

	return $ical_header . $ical_list . $ical_footer;
}

ics_merge.py

#!/usr/bin/env python3

import requests

"""
Merge list of ICS files to one ICS file. Use ICS header from first ICS file.
Download ICS file from remote server with *file_get_contents*
"""

def merge_ics(header: dict, **urls: list[str]) -> str:
    ical_list = ""

    for key, ics_file in enumerate(urls):
        try:
            r = requests.get(ics_file, header=header)
            r.raise_for_status()
            ics_data = r.response.content
        except requests.exceptions.HTTPError as err:
            raise SystemExit(err)

        events_begin 	= ics_data.find('BEGIN:VEVENT')
        events_end 	    = ics_data.find('END:VCALENDAR')

        if key == 0:
            ical_header = ics_data[0, events_begin]
            ical_footer = 'END:VCALENDAR'

        ical_list.append(ics_data[events_begin, events_end - events_begin])

    return f"{ical_header}{ical_list}{ical_footer}"