There are two possible fixes for this bug, and they differ in behavior when
rewording a commit. The one I chose here always splits at the first line feed,
which means that for an improperly formatted commit message such as this one:
This is a very long multi-line subject,
which you shouldn't really use in git.
And this is the body (we call it "description" in lazygit).
we split after the first line instead of after the first paragraph. This is
arguably not what the original author meant, but splitting after the first
paragraph doesn't really work well in lazygit, because we would try to put both
lines into the one-line subject field of the message panel, and you'd only see
the second and not even know that there are more.
The other potential fix would have been to join subject and description with two
line feeds instead of one in JoinCommitMessageAndDescription; this would have
fixed our bug in the same way, but would result in splitting the above message
after the second line instead of the first. I think that's worse, so I decided
for the first fix.
While we're at it, simplify the code a little bit; strings.Cut is documented to
return (s, "") when the separator is not found, so there's no need to do this on
our side.
We do have to trim spaces on the description now, to support the regular reword
case where subject and body are separated by a blank line.
This is useful for when you begin to type the message in lazygit's commit panel,
and then realize that you'd rather use your editor's more powerful editing
capabilities. Pressing <c-o> will take you right there.
Previously we used a single-line prompt for a tag annotation. Now we're using the commit message
prompt.
I've had to update other uses of that prompt to allow the summary and description labels to
be passed in
When cycling history, we want to make it so that upon returning to the original prompt, you get your text back.
Importantly, we don't want to use the existing preservedMessage field for that because that's only for preserving
a NEW commit message, and we don't want the history stuff of the commit reword flow to overwrite that.
When we use the one panel for the entire commit message, its tricky to have a keybinding both for adding a newline and submitting.
By having two panels: one for the summary line and one for the description, we allow for 'enter' to submit the message when done from the summary panel,
and 'enter' to add a newline when done from the description panel. Alt-enter, for those who can use that key combo, also works for submitting the message
from the description panel. For those who can't use that key combo, and don't want to remap the keybinding, they can hit tab to go back to the summary panel
and then 'enter' to submit the message.
We have some awkwardness in that both contexts (i.e. panels) need to appear and disappear in tandem and we don't have a great way of handling that concept,
so we just push both contexts one after the other, and likewise remove both contexts when we escape.
