Enable undo in the current prompt area

[bobrowadam]

This will allow user to undo changes on the current prompt and context areas but not on any of the previous chat buffer
areas.

Addresses:
#64

[ericdallo]

@bobrowadam thanks for the try, but still cause issues if one try to undo after chat has messages

[ericdallo]

Also I felt in a case where I undo the context but it was still in there in the eca variables, so it was not visually there but was used which is dangerous

[bobrowadam]

can you explain how? the undo would work only on the user current prompt, not previous chat messages. do you notice a different behavior?

[ericdallo]

Send any hello message, wait until the LLM reply, than in prompt type u to undo, you will see it will undo the content LLM outputed

[bobrowadam]

@ericdallo
I did some more changes that should handle all the edge cases, yet the code is not nice and adding more components that edit the chat buffer would probably break this.
It would be best if we only insert text using a dedicated function/macro that is always handling the undo state and not using insert directly, but this might be a considerably big refactor. WDYT?

[ericdallo]

@bobrowadam I like that, I'm ok with creating a eca-chat--insert for that, are you willing to do that?
Let's be as concise as possible in the changes though for the review

[bobrowadam]

@bobrowadam I like that, I'm ok with creating a eca-chat--insert for that, are you willing to do that? Let's be as concise as possible in the changes though for the review

Yes. I'll give that a try

[ericdallo]

Hey @bobrowadam I just went ahead and followed with your idea, commenting in the issue, but feel free to change anything or test/fix if you find any problems, thanks for the help so far, I believe we could close this one and open a new one if needed

[bobrowadam]

OH nice!
Found a small bug that I'm trying to fix:
If you insert some text in the prompt, then add context (for instance, moving the cursor), the undo history will be erased while you are still in the middle of editing your prompt.
Also, we are not handling delete-region, which we probably need to.

[ericdallo]

Hum makes sense, I kinda replaced all inserts with our internal function, we would need to remove some of them and maybe rename to eca-chat--insert-cleaning-undo