add caldav sync for events app about asteroidossync

[FlorentRevest]

The "calendar-test" branch of asteroid-btsyncd is also a good place to start: AsteroidOS/asteroid-btsyncd@cdd3bcf
You'd probably need to make yourself familiar with BLE first https://asteroidos.org/wiki/ble-profiles/
And finish to bridge jrtberlin's branch of AsteroidOSSync and my branch of asteroid-btsyncd.

I have very limited time but I'd be glad to help out as well.

[jrtberlin]

Hi, currently there is no calendar sync at all.
As discussed in #19 the project will probably use Androids Calendar Provider API.
According to @Rudloff, this would make it compatible with every application that uses this API (Google Agenda, DAVDroid, etc.).
I'm a nextcloud user myself and would love to have good integration.

However, there is not much work done on this feature. I started working on it but didn't had much time since. If you have a bit of time to spare feel free to contribute.

[wgahnagl]

I would love to help!
Was there anything particularly hard that you ran into while trying to implement it, or was it just a lack of time to get it done?

[jrtberlin]

It was more or less lack of time. I started working on it in the calendar branch of my fork . Maybe that's a good starting point. I have a bit of time in the next week, so if you need help just ask.

[wgahnagl]

groovy!
Is there any good way to get in touch with you guys while I'm figuring it out, like a matrix chat or something?

[jrtberlin]

We have an IRC channel on freenode called asteroid.
You can reach me via email if you have questions regarding my codebase. You can find my email on my webpage including my pgp key under legal. (I don't post it here to avoid spam, it's just two clicks)

[Foxite]

I've updated jrtberlin's work to compile in the current AsteroidOSSync codebase and serialize calendar data to ICS, but I haven't tested any of it yet. btsyncd's calendar branch is similarly outdated, but I can't update it with my lack of C++ skills. So going to create an issue there.