Mattermost-server: Limit the number of reactions that can be added to posts on the web/desktop apps to match mobile app

[mattermod]

Environment: 5.18-rc1 and 1.26 build 249

This ticket is created as a follow up to MM-17838

The number of reactions on the web and desktop app should be limited to 40 to match the mobile app.
Currently, additional reactions added from the webapp are breaking the mobile app UI. See attached image.

Expected: Reactions to be capped at 40. When 40 reactions are added:

• Remove the emoji icon in the post hover menu
• Remove the "+" button in the list of reactions

Some work was started here on this issue already: https://github.com/mattermost/mattermost-webapp/pull/5222#issuecomment-705079131

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JIRA: https://mattermost.atlassian.net/browse/MM-21061

[rakhi2104]

I want to take this up.

[rakhi2104]

Remove the "+:emoji: typed into the reply input field

Why is this necessary?

[hanzei]

@esethna Could you please take a look at the questions about?

[esethna]

@rakhi2104 we only want to remove this functionality ("+:emoji:" in the reply input area) when there are >40 reactions. Otherwise it would allow users to add more reactions when the number of reactions should be capped.

[rakhi2104]

@esethna, I didn't know the "+:emoji" shortcut. I'll try to handle this as well

[esethna]

Work started here to reference but anyone can feel free to take on this ticket again now: https://github.com/mattermost/mattermost-webapp/pull/5222#issuecomment-705079131

[vaibhav-stpl]

I want to take this up !

[sudheerDev]

@vaibhav-stpl 👍 Thank you!

[vaibhav-stpl]

Here I just observed a bug on mobile app, meanwhile I was trying to reproduce the user story. So in mobile the emoji reaction icon goes away after 40 reactions, but users are still able to add reaction manually using keyboard shortcut "+:emoji" ?
Let me know if this behaviour should persist in web app too or this is a bug ?

[esethna]

^ @vaibhav-stpl good catch, this is a bug and should not be allowed on mobile or webapp. See this approach to how we want to solve this: https://github.com/mattermost/mattermost-webapp/pull/5222#issuecomment-606611607

ie show an error message when the post is submitted that states: "Reaction limit exceeded for this message"