[BUG] temporary file for cog commit -e should have fixed extension

[brainplot]

Describe the bug
The temporary file that cog commit -e opens in order to compose a new commit message should have a fixed extension so that it can be associated with a file format in a text editor.

My text editor of choice is neovim and whenever I run git commit normally, it knows how to enable the correct syntax highlighting and a few extra custom options by virtue of the fact the file being edited is COMMIT_MSG.

This does not happen when I run cog commit -e because the file cocogitto opens under the hood is a temporary file with a name such as .tmpGjG8hc. That doesn't mean anything for my text editor, nor does it have a useful extension I can associate with a Git commit message file type.

Right now all I can do is run :setfiletype gitcommit whenever a new temporary buffer opens up, which is not ideal.

If you agree that this is something worth fixing, I can attempt a PR!

[oknozor]

That's definitely worth fixing, please go ahead and make a PR !

[brainplot]

Thank you. I can attempt fixing this over the weekend. In the meantime, what do you think the new format for the file name should be?

[oknozor]

No need for a custom filename, COMMIT_EDITMSG should be recognized by any editor.
The current issue is that we use a temp file to edit the commit message here:

cocogitto/src/bin/cog/commit.rs

Lines 32 to 37 in 891d55b

	pub fn edit_message<P: AsRef<Path>>(
	path: P,
	breaking: bool,
	) -> Result<(Option<String>, Option<String>, bool)> {
	let template = fs::read_to_string(path.as_ref())?;
	let edited = edit::edit(template)?;

Instead we should use edit::edit_file to directly edit COMMIT_EDITMSG file then, read it back so it can be parsed as a conventional commit. The remaining COMMIT_EDITMSG file should then be removed so it's not picked by later git commit usage.

Also a nice addition would be to generate a git like commit message template containing the current changes:

# Please enter the commit message for your changes. Lines starting
# with '#' will be ignored, and an empty message aborts the commit.
#
# On branch main
# Your branch is up to date with 'origin/main'.
#
# Changes to be committed:
#	new file:   package-lock.json
#	new file:   package.json
#	modified:   web/nami/src/lib/index.ts
#

[brainplot]

Yes, I was indeed asking myself why cocogitto didn't use COMMIT_EDITMSG in the first place and what the purpose of the temporary file actually was. I can try to implement this change.

As for your second point, leaving the COMMIT_EDITMSG file, to my knowledge and from what I have observed using Git, shouldn't be an issue since Git will clean it up and overwrite it, before letting you edit it. However, I would like to confirm this by reading Git's source code.