Fix #31: .ICS attachment Convert DateTimeImmutable before formatting it

[dalgwen]

closes #31

[JodliDev]

Hello
Thank you so much for your fix. I have two concerns though:
-) Unfortunately DateTime::createFromImmutable is not available before PHP 7.3 and the original project still has php 5.5 as their minimal requirement and I would like to stay as close as possible to their project to be able to incorporate future updates easily. A solution for that problem is to just recreate the object by using the timestamp (as I did here: https://github.com/JodliDev/libcalendaring/blob/f96299dbd7fd26599c01c4e64183a90f69bed645/libcalendaring.php#L199)

-) But more importantly: I have a feeling that we are trying to fix an underlying issue in https://github.com/JodliDev/libcalendaring
As far as I can see, your changes correct a faulty output from either load_events()

calendar/drivers/caldav/caldav_driver.php

Line 1374 in f0a90df

public function load_events($start, $end, $query = null, $calendars = null, $virtual = 1, $modifiedsince = null)

or (which I think is the culprit here) get_mail_ical_objects() in libcalendaring
https://github.com/JodliDev/libcalendaring/blob/f96299dbd7fd26599c01c4e64183a90f69bed645/libcalendaring.php#L1172

If I am not mistaken, the output from load_events() is coming from the database, so it should not be Immutable - meaning we dont have to correct it. So in theory, if we fix get_mail_ical_objects() everything should work as expected. I will continue to investigate and see if my theory is correct.

[dalgwen]

OK, I see what you mean and why you would like to fix it at the source.
I try to read the code of get_mail_ical_objects() in libcalendaring but php is DEFINITELY not my type 😅
Let me know if I can help you.