User Typing indicator API

[shiqimei]

What? ⛵

Added a new type indicator API:

typing(options: ITypingOptions): Promise<() => Promise<void>>;

Why? 🤔

Closes #330
Closes #303

Links 🌎

RFC: https://forums.rocket.chat/t/rfc-30-apps-engine-add-support-for-user-typing-indicator/8684 (private)

PS 👀

[shiqimei]

Implementation in the RocketChat side: RocketChat/Rocket.Chat#19228

[d-gubert]

Very good overall!

One thing I'm thinking is that we may leave the "setTimeout pattern" for the public API, but keep the bridge simply passing data around. This would mean having the bridge method receive the options saying whether the user is still typing, and having the Notifier accessor make the return cancellation-function in the typing method.

The reason for this is that we keep communication between the Engine and Rocket.Chat transferring simple data types (strings, objects, maybe even Buffers) instead of a complex construct like a function or an instance of a specific class, which hold more than simple data. Think about how you can't reliably serialize a function in order to transfer it over the network, if it was necessary.

@thassiov @sampaiodiego would like your opinions here too :)

[thassiov]

I agree. Passing functions around can make it a bit more difficult to reason about the functionality, too (at least in my head it does). But it works, so 👍

[codecov]

Codecov Report

Merging #332 into alpha will decrease coverage by 2.06%.
The diff coverage is 12.50%.

@@            Coverage Diff             @@
##            alpha     #332      +/-   ##
==========================================
- Coverage   52.76%   50.69%   -2.07%     
==========================================
  Files          83       75       -8     
  Lines        2968     2858     -110     
  Branches      433      436       +3     
==========================================
- Hits         1566     1449     -117     
- Misses       1402     1409       +7     

Impacted Files	Coverage Δ
src/server/accessors/Notifier.ts	56.00% <12.50%> (-20.48%)	⬇️
src/server/marketplace/license/index.ts
src/server/storage/index.ts
src/server/bridges/index.ts
src/server/managers/index.ts
src/server/errors/index.ts
src/server/compiler/index.ts
src/server/accessors/index.ts
src/server/logging/index.ts

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[shiqimei]

Very good overall!

One thing I'm thinking is that we may leave the "setTimeout pattern" for the public API, but keep the bridge simply passing data around. This would mean having the bridge method receive the options saying whether the user is still typing, and having the Notifier accessor make the return cancellation-function in the typing method.

The reason for this is that we keep communication between the Engine and Rocket.Chat transferring simple data types (strings, objects, maybe even Buffers) instead of a complex construct like a function or an instance of a specific class, which hold more than simple data. Think about how you can't reliably serialize a function in order to transfer it over the network, if it was necessary.

@thassiov @sampaiodiego would like your opinions here too :)

Thanks for the inputs :) It does make sense. I've made changes, please take another review.