Add dialing/ringing state to CallViewModel (callPickupState$)

[toger5]

This adds a new public behavior to the call view model that represents the current waiting state when this client initiated the call. This state is described in the doc comment:

/**
   * The current call pickup state of the call.
   *  - "ringing": The call is ringing on other devices in this room (This client should give audiovisual feedback that this is happening).
   *  - "unknown": The client has not yet sent the notification event. We don't know if it will because it first needs to send its own membership.
   *     Then we can conclude if we were the first one to join or not.
   *  - "timeout": No-one picked up in the defined time this call should be ringing on others devices.
   *     The call failed. If desired this can be used as a trigger to exit the call.
   *  - "success": Someone else joined. The call is in a normal state. Stop audiovisual feedback.
   *  - null: EC is configured to never show any waiting for answer state.
   */

It will be used by the view to render a "waiting" screen and play a "dialing/waiting sound" (not part of this PR)

It is missing any decline state which will be added in a seperate PR.

Signed-off-by: Timo K toger5@hotmail.de

[BillCarsonFr]

This is hard to find a correct naming for that :/
If I get it right it is when I start a call that will ring on the other side. And we want like a phone call experience, it should show the other user avatar/name, should give a ringing feedback, and gave up after a timeput

[robintown]

Right. A nitpick: we could simplify the name to waitForCallPickup. Or to clarify that the ringing is happening on the other side, perhaps waitForRemoteAnswer.

[robintown]

I pushed a commit changing this to waitForCallPickup for now. If anyone has a preference for something else, let me know.

[BillCarsonFr]

Not sure to understand that, what does this mean "expires on the recevievers side?" Like the receiver should send some expiration signal?? Or is it a local timeout for when to stop trying to call?

[robintown]

My understanding is that it's a local timeout - we get to specify a duration when sending the calling event, so if we assume that the receiver respects it, we can use a local timer to approximate when their ringing stops and we should give up.

[robintown]

Here's my initial review - still need to look at the newly added behaviors in more detail.

[robintown]

My understanding is that it's a local timeout - we get to specify a duration when sending the calling event, so if we assume that the receiver respects it, we can use a local timer to approximate when their ringing stops and we should give up.

[robintown]

Right. A nitpick: we could simplify the name to waitForCallPickup. Or to clarify that the ringing is happening on the other side, perhaps waitForRemoteAnswer.

[robintown]

The new behaviors look correct, though I'd like to try my hand at rewriting them into a slightly more idiomatic RxJS style. Some notes on the tests as well.

[robintown]

Since Timo is out, I fixed up my own comments. @BillCarsonFr Would you like to review again, or do we just consider this done?

[BillCarsonFr]

If you can clarify the behavior change on the raise hand test