Update rabbitmq integration to report which user in a shared calendar made a change.

[RileyMathews]

Hey there! I've been following Radicale for quite a while as a potential way for me to replace my families calendar with a self hosted option. The one feature that my wife especially has as a requirement is that currently apple's calendar apps will notify the other person when someone makes a change to the calendar and we both really like that as a way to keep on top of changes to our schedule.

Seeing the shared calendar feature recently added was a huge step towards me adopting this app in my homelab. But from looking at the rabbitmq code it seems like it doesn't report which user made a change. If it did I could write a simple downstream consumer to ping everyone other than the actor that caused the event with something like ntfy.

This seems like it wouldn't be too much work to add and I'm definitely willing to open a PR for this. Just wanted to check in first to see if this is something that ya'll are open to accepting.

Thanks for all the work with this app!

[pbiering]

downstream consumer to ping everyone other than the actor that caused the event with something like ntfy.

One need to investigate whether at the step the hook is triggered, the original login user is available at all and in case of a 1:N share the backtracing to other share users lookup in the sharing database is anyhow required (also honoring owner+user "Enabled"). Feel free to create a prototype and then submit a PR.

[RileyMathews]

I'm honestly thinking for me I would hardcode the list of 'all users' just in my downstream consumer and have it just filter out the user from the rabbitmq message for notifications. For my use case it wouldn't be expected that it would change a whole lot but I could also explore dynamically populating information about the 'share' model as well on the rabbitmq message.

From my initial investigation it seems like the specific user variable is mutated by the time the hook fires but I think we could just populate a second 'actor' variable before that mutation happens to preserve the original actor. I'll get a minimal prototype working with that when I next have time and then we can discuss specifics around share edge cases with a PR to point at and annotate.

[RileyMathews]

I was able to work on this some last night and just made a PR here with the work so far. #2115