compose: Allow ctrl + enter to send in preview mode as well.

[N-Shar-ma]

When the user chose to send the composebox message on pressing ctrl +
enter instead of just enter, it only worked in writing mode but not
the preview mode.

This change makes ctrl + enter send the message even in preview mode,
when that setting is chosen.

Fixes: #21670.

Self-review checklist

• Self-reviewed the changes for clarity and maintainability
  (variable names, code reuse, readability, etc.).

Communicate decisions, questions, and potential concerns.

• Explains differences from previous plans (e.g., issue description).
• Highlights technical choices and bugs encountered.
• Calls out remaining decisions and concerns.
• Automated tests verify logic where appropriate.

Individual commits are ready for review (see commit discipline).

• Each commit is a coherent idea.
• Commit message(s) explain reasoning and motivation for changes.

Completed manual review and testing of the following:

• Visual appearance of the changes.
• Responsiveness and internationalization.
• Strings and tooltips.
• End-to-end functionality of buttons, interactions and flows.
• Corner cases, error conditions, and easily imagined bugs.

[zulipbot]

Hello @zulip/server-compose members, this pull request was labeled with the "area: compose" label, so you may want to check it out!

[timabbott]

We already have this function:

export function enter_with_preview_open() {                                           
    if (user_settings.enter_sends) {                                                  
        // If enter_sends is enabled, we attempt to send the message                  
        finish();                                                                     
    } else {                                                                          
        // Otherwise, we return to the compose box and focus it                       
        $("#compose-textarea").trigger("focus");                                      
    }                                                                                 
}                                                                                     

So the question is why that code isn't handling this; we shouldn't add a duplicate.

[timabbott]

Oh, but this is Ctrl+Enter. Well, that still presents the question of what we think should happen if user_settings.enter_sends is false; I think probably we want basically the opposite of the above function?

[timabbott]

We're generally trying to avoid new use of rewire; is this necessary?

[N-Shar-ma]

@timabbott Thank you for the feedback! I was initially trying to use the enter_with_preview_open function for ctrl+enter as well, and overcomplicated things by using the should_enter_send function.

Anyway, I thought through it all again and have a much smaller and simpler PR now, using that 1 function only, just with an optional parameter and more specific conditions. The original tests remain untouched.

Please have another look, and let me know if anything else can be improved!

[timabbott]

This seemed to not work for me -- when I hit Ctrl+Enter in preview mode with "Enter sends" enabled. But I figured out the bug was, and possibly the situation changed with the merge of d6d3683 earlier today; I've added a commit that fixes it.

I also changed it back to a simple else statement, since I think we Ctrl+Enter and Enter to have their behavior swap when the "Enter sends" setting is toggled.

Merged with those changes, thanks @N-Shar-ma!