[Bug]: Hashtags autocompletion / keyword popularity statistics popover breaks when editing a hashtag that is followed by regular words

[nekohayo]

Describe the bug

This is the 2024 Edition™ follow-up to #660 :)

The hashtags autocompletion+stats widget can still break under some circumstances: It does not like me changing my mind and using backspace + rewriting an existing hashtag in a draft. This occurs frequently when trying to iteratively figure out the best hashtag to use while drafting.

Symptoms (as observed in the video below):

• Most of the time the autocompletion stats widget does not show up at all
• Sometimes it also erronously parses adjacent words into it

Steps To Reproduce

See demonstration video below. Basically:

1. Type out a hashtag
2. Type some non-hashtag words afterwards
3. Go back to the end of your hashtag word, backspace and try to change the hashtag to something else

Logs and/or Screenshots

breaking.tuba.autocompletion.by.editing.2024.edition.webm

Instance Backend

Mastodon

Operating System

Fedora 39

Package

Flatpak

Troubleshooting information

os: GNOME 46 (Flatpak runtime)
prefix: /app
flatpak: true
version: 0.7.2 (production)
gtk: 4.14.1 (4.14.1)
libadwaita: 1.5.0 (1.5.0)
libsoup: 3.4.4 (3.4.4)
libgtksourceview: 5.12.0 (5.12.0)

Additional Context

No response

[nekohayo]

"overwriting" (i.e. ctrl+shift+left to select the whole word, then just type a replacement) also breaks in new and exciting ways ;)

breaking.tuba.autocompletion.by.editing.2024.edition.part.2.webm

[GeopJr]

What did past me mean by this:

		// If end is ':', everything until
		// a newline will be treated as a word
		if (end.get_char () != ':')
			end.forward_word_end ();

[GeopJr]

the comment is wrong, the comment doesnt even tell me why

[GeopJr]

The main issue is that i'm fighting both the completionprovider and pango,
pango treats foo#bar as 2 words, foo and bar, supposedly # being the word break
then completionprovider bounds are from the pango word start until the cursor, so if you have abc#defgh and your cursor is between f and g, it will return def 😩

I'm going to rewrite this again, but any input would be appreciated:
We'll get the word bounds, then move backwards until we find a space, then move one forward and check if it's a provider trigger e.g. #, @, :. Then from the end, move forward until we find a space (and move one back) or word end. That will return the full word.

When replacing, we'll add a space at the end if there's not one already

Hopefully it won't have too much of a performance impact