feat: add event reference provider and widget

[mejo-]

Fixes: #7104

Screenshot

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!

[tcitworld]

This should be made backend agnostic, and use OCP\ICalendar\IManager::getCalendarsForPrincipal in the getCalendar method, and OCP\Calendar\ICalendar\search in the getEventData method.

[mejo-]

Can you help me to use ICalendar::search() for finding the event? It seems like it doesn't allow to filter by event URI (e.g. 45C2F160-BA74-4910-B302-79356C24A458.ics). So my best bet would be to search for all events in the calendar and then iterate through them to get the one with the matching URI:

$event = null;
foreach ($calendar->search('') as $result) {
	if (($result['uri'] ?? null) === $eventFile) {
		$event = $result;
		break;
	}
}

This works but doesn't seem a good idea performance-wise. Or is it fine to do it that way?

[tcitworld]

I mistook the object uri and the object uid, sorry about that.

You can call search('', [], ['uid' => $uid]);, but the object uri is not always uid.ics, so this won't work.

I think we could add a modification in the calendar backend to allow to also do search by object uri. I don't know of any implementation using ICalendar::search (or interfaces that extend it) at the moment, so it shouldn't be a problem.
https://github.com/nextcloud/server/blob/7cdbb38d526edc2c32240fffb64b035d5dc0cb35/apps/dav/lib/CalDAV/CalDavBackend.php#L2061-L2063

[mejo-]

Good idea, I did this now: nextcloud/server#59142

Tested with this PR (adjusted the search() parameters) and works well.

[GVodyanov]

Thanks for the contribution!

Please use our CSS variables instead of custom values for padding/margin/gap/etc.

You can check them out here https://docs.nextcloud.com/server/latest/developer_manual/html_css_design/css.html

[mejo-]

I realized another problem: calendar event URLs (e.g. https://nextcloud.local/index.php/apps/calendar/dayGridMonth/now/edit/popover/L3JlbW90ZS5waHAvZGF2L2NhbGVuZGFycy9qYW5lL3BlcnNvbmFsLzQ1QzJGMTYwLUJBNzQtNDkxMC1CMzAyLTc5MzU2QzI0QTQ1OC5pY3M=/1772787600) seem to "expire" in some way. A few hours after I copied them into a document, the preview still renders correctly, but opening the URL just opens the calendar in question with a modal "Event does not exist".

Is this a bug, or are these URLs meant to be ephemeral? Is there something like a persistent URL to an event yet at all?

[tcitworld]

Is this a bug, or are these URLs meant to be ephemeral? Is there something like a persistent URL to an event yet at all?

It might be related to the event occurrence added at the end (/1772787600). Did you try without it?

[mejo-]

It might be related to the event occurrence added at the end (/1772787600). Did you try without it?

There's no route for URLs without the event occurrence part at the end, so unfortunately this leads to "Page not found" 😞