# -*- indent-tabs-mode: t; -*-
#+title: Git
#+setupfile: headers
#+PROPERTY: header-args :exports code :tangle no
#+PROPERTY: header-args:conf-unix :mkdirp yes :tangle no :exports code :noweb yes

* Git
** Basic configuration
Just to make Emacs follow the convention in terms of indentation, I’m
forcing it to use tabs.
#+begin_src conf-unix
# -*- indent-tabs-mode: t; -*-
#+end_src

*** Setting Up Personal Information and Preferences
Let’s set some of my personal information, namely my name, my email,
and which GPG key I sign my commits with.
#+begin_src conf-unix
[user]
	email = lucien@phundrak.com
	name = Lucien Cartier-Tilet
	signingkey = ~/.ssh/id_ed25519.pub
#+end_src

In terms of core configuration, I simply set Emacs as my default Git
editor. I also have my global gitignore file, described below in
[[file:./git.md#global-gitignore-file][Global gitignore file]].
#+begin_src conf-unix
[core]
	editor = emacsclient -c -a emacs
	excludesfile = ~/.config/git/global-ignore
#+end_src

Let’s not forget to tell Git to use the =main= branch by default.
#+begin_src conf-unix
[init]
	defaultBranch = main
#+end_src

This is entirely a matter of personal preferences, but I like to use
[[https://zen-browser.app/][Zen]], a Firefox fork with really nice features.
#+begin_src conf-unix
[web]
	browser = zen-browser
#+end_src

*** Better Diffing
Git’s diffing algorithm evolved and improved over time, but its
default algorithm did not. Take this example, from [[https://blog.gitbutler.com/how-git-core-devs-configure-git/][this Gitbutler article]]:

#+html: <ImgFigure src="/img/git/diff-default.png">Default git diff output</ImgFigure>

Not really readable, I think you’ll agree. I mean, you can sort of see
what happens, but really, we just moved the =h2= styling below the
=.event= styling. Git seems to think otherwise. However, let’s turn on
the =histogram= algorithm on:

#+html: <ImgFigure src="/img/git/diff-histogram.png">git diff output with histogram algorithm</ImgFigure>

Immediately, we have a much clearer picture of what happened! But I’ll
let you on another secret: you can make it even clearer by using the
=colorMoved= option to color differently lines that were moved from
lines that were actually modified!

#+html: <ImgFigure src="/img/git/diff-moved.png">git diff output with histogram algorithm and specific colours for moved blocks</ImgFigure>

I’ll also add a configuration to make it easier to see what is being
compared using =mnemonicPrefix=. As per =man git-config=:
#+begin_src text
git diff
    compares the (i)ndex and the (w)ork tree;

git diff HEAD
    compares a (c)ommit and the (w)ork tree;

git diff --cached
    compares a (c)ommit and the (i)ndex;

git diff HEAD:<file1> <file2>
    compares an (o)bject and a (w)ork tree entity;

git diff --no-index <a> <b>
    compares two non-git things <a> and <b>.
#+end_src

That means you can see I was comparing to objects not tracked by git
in my screenshot above.

Finally, =renames= set to =copies= not only better detects file renames,
but also file copies.

#+begin_src conf-unix
[diff]
	algorithm = histogram
	colorMoved = plain
	mnemonicPrefix = true
	renames = copy
#+end_src

*** Better Fetching, Pulling, Rebasing, and Pushing
By default, when I pull new commits, I do not want to create a merge
commit, but rather to rebase my commits on what’s new upstream.
#+begin_src conf-unix
[pull]
	rebase = true
#+end_src

However, there is a problem with git’s default behaviour: it wont
allow me to pull changes or perform a rebase as long as my worktree is
dirty. I either have to commit or stash my changes before I can do
something. And you know what? Git can auto stash your changes for you
before performing a rebase. In fact, while we’re at it, let’s also
automatically squash commits that need to be squashed, and update all
refs.
#+begin_src conf-unix
[rebase]
	autoSquash = true
	autoStash = true
	updateRefs = true
#+end_src

And oh, buggers, you have a merge conflict! I’m used to it, but since
git 2.3, there is a new feature that adds some context to git
conflicts: =zdiff3= (which stands for /zealous diff3/). Not only will it
show you the conflicting incoming and HEAD changes, but it will also
show you what the code was before either modified the conflicting
area. Not a must-have feature, but a nice one to have. Compare this:

#+html: <ImgFigure src="/img/git/merge-default.png">Default appearance of a git conflict during a merge</ImgFigure>

To this:

#+html: <ImgFigure src="/img/git/merge-zdiff3.png">Same git conflict but with zdiff3</ImgFigure>

We have a new line beginning with =|||||||= with the original line
below. Also, it’s nice to see Emacs supports this syntax out of the
box!

#+begin_src conf-unix
[merge]
	conflictstyle = zdiff3
#+end_src

Finally, once we’re good to go, we may want to push our changes to the
remote repository. Sometimes, git is confused and isn’t sure where it
should push your branch. Let’s tell it to simply push your current
branch to the branch with the same name on the remote with
=push.default=. If the upstream branch is not set yet, you can
automatically set it up with =push.autoSetupRemote=. Finally, I don’t
want to push separately my tags, so let’s push them with any other
push.
#+begin_src conf-unix
[push]
	default = simple
	autoSetupRemote = true
	followTags = true
#+end_src

*** Making Git Look Better
First, let’s activate colors in git by default when we are in a terminal.
#+begin_src conf-unix
[color]
	ui = auto
#+end_src

Getting a raw list of things –branches, tags, …– is *not nice*. So,
let’s make it a bit nicer and split these lists in columns.
#+begin_src conf-unix
[column]
	ui = auto
#+end_src

Simply using the =column.ui= option sets everything to use columns when
using a terminal. If you want more granularity, you can instead use
=column.branch=, =column.status=, etc... Look up =man git-config= for more
info.

*** Better Sorting Branches and Tags
By default, branches are sorted alphabetically. This may be fine for
most people, but I prefer something else: sorting them by how recently
they were comitted to. This is actually quite easy to configure:
#+begin_src conf-unix
[branch]
	sort = -committerdate
#+end_src

Sorting tags is not nice by default. For instance, git will show you
version 11 before version 2, because 11 is technically before 2
alphabetically speaking. Let’s fix that.
#+begin_src conf-unix
[tag]
	sort = version:refname
#+end_src

*** Did You Mean "Commit"?
Sometimes, I fat finger my git commands and white a subcommand that
does not exist, like =git pul= or =git comitt=. By default, git will
simply tell you that, no, that subcommand does not exist, but will be
kind enough to suggest a few commands that may be what you are looking
for. Let’s make git not only suggest these, but also ask you if you
want to run the one you most likely wanted to run.
#+begin_src conf-unix
[help]
	autocorrect = prompt
#+end_src

** Aliases
#+name: git-add-abbrev
| abbreviation | equivalent                                     |
|--------------+------------------------------------------------|
| =a=            | =add --all=                                      |
| =aca=          | =!git add --all && git commit --amend=           |
| =acan=         | =!git add --all && git commit --amend --no-edit= |

#+name: abbrev-gen
#+begin_src emacs-lisp :tangle no :exports none :var abbrevs=git-push-abbrev :wrap "src conf-unix :tangle no"
(mapconcat (lambda (abbreviation)
	     (replace-regexp-in-string
	      (concat (regexp-quote "\\vert") (rx (? "{}")))
	      "|"
	      (concat "\t"
		      (string-replace "=" "" (car abbreviation))
		      " = "
		      (string-replace "=" "" (cadr abbreviation)))))
	   abbrevs
	   "\n")
#+end_src

#+RESULTS: abbrev-gen
#+begin_src conf-unix :tangle no
	ps = push
	psf = push --force-with-lease
	pso = push origin
	psfo = push --force-with-lease origin
	pushall = !git remote | xargs -L1 git push
	psl = !git remote | xargs -L1 git push
	pullall = !git remote | xargs -L1 git pull
	pll = !git remote | xargs -L1 git pull
#+end_src

#+name: git-branch-abbrev
| abbreviation | equivalent |
|--------------+------------|
| =b=            | =branch=     |
| =bd=           | =branch -d=  |
| =bdd=          | =branch -D=  |

#+name: git-commit-abbrev
| abbreviation | equivalent           |
|--------------+----------------------|
| =c=            | =commit -S=            |
| =ca=           | =commit -Sa=           |
| =can=          | =commit -Sa --no-edit= |
| =cm=           | =commit -Sm=           |
| =cam=          | =commit -Sam=          |

#+name: git-checkout-abbrev
| abbreviation | equivalent       |
|--------------+------------------|
| =co=           | =checkout=         |
| =cob=          | =checkout -b=      |
| =cod=          | =checkout develop= |

#+name: git-clone-abbrev
| abbreviation | equivalent      |
|--------------+-----------------|
| =cl=           | =clone=           |
| =cl1=          | =clone --depth 1= |

#+name: git-fetch-abbrev
| abbreviation | equivalent    |
|--------------+---------------|
| =f=            | =fetch=         |
| =fp=           | =fetch --prune= |

#+name: git-push-abbrev
| abbreviation | equivalent                       |
|--------------+----------------------------------|
| =ps=           | =push=                             |
| =psf=          | =push --force-with-lease=          |
| =pso=          | =push origin=                      |
| =psfo=         | =push --force-with-lease origin=   |
| =pushall=      | =!git remote \vert{} xargs -L1 git push= |
| =psl=          | =!git remote \vert{} xargs -L1 git push= |
| =pullall=      | =!git remote \vert{} xargs -L1 git pull= |
| =pll=          | =!git remote \vert{} xargs -L1 git pull= |

#+name: git-pull-abbrev
| abbreviation | equivalent    |
|--------------+---------------|
| =pl=           | =pull=          |
| =pb=           | =pull --rebase= |

#+name: git-rebase-abbrev
| abbreviation | equivalent        |
|--------------+-------------------|
| =r=            | =rebase=            |
| =ra=           | =rebase --abort=    |
| =rc=           | =rebase --continue= |
| =rd=           | =rebase develop=    |
| =ri=           | =rebase -i=         |

#+name: git-rm-abbrev
| abbreviation | equivalent |
|--------------+------------|
| =rmf=          | =rm -f=      |
| =rmd=          | =rm -r=      |
| =rmdf=         | =rm -rf=     |

#+name: git-submodule-abbrev
| abbreviation | equivalent                          |
|--------------+-------------------------------------|
| =sm=           | =submodule=                           |
| =sms=          | =submodule status=                    |
| =sma=          | =submodule add=                       |
| =smu=          | =submodule update=                    |
| =smui=         | =submodule update --init=             |
| =smuir=        | =submodule update --init --recursive= |

#+name: git-stash-abbrev
| abbreviation | equivalent  |
|--------------+-------------|
| =st=           | =stash=       |
| =stc=          | =stash clear= |
| =stp=          | =stash pop=   |
| =stw=          | =stash show=  |

#+name: git-unstage-abbrev
| abbreviation | equivalent |
|--------------+------------|
| =u=            | =reset --=   |
| =unstage=      | =reset --=   |

#+name: git-single-abbrev
| abbreviation | equivalent                       |
|--------------+----------------------------------|
| =d=            | =diff -w=                          |
| =l=            | =log --oneline --graph --decorate= |
| =s=            | =status=                           |
| =staged=       | =diff --cached=                    |

#+RESULTS:
:       a = add --all
:       aca = !git add --all && git commit --amend
:       acan = !git add --all && git commit --amend --no-edit

#+begin_src conf-unix
[alias]
<<abbrev-gen(abbrevs=git-add-abbrev)>>
<<abbrev-gen(abbrevs=git-branch-abbrev)>>
<<abbrev-gen(abbrevs=git-commit-abbrev)>>
<<abbrev-gen(abbrevs=git-checkout-abbrev)>>
<<abbrev-gen(abbrevs=git-clone-abbrev)>>
<<abbrev-gen(abbrevs=git-fetch-abbrev)>>
<<abbrev-gen(abbrevs=git-push-abbrev)>>
<<abbrev-gen(abbrevs=git-pull-abbrev)>>
<<abbrev-gen(abbrevs=git-rebase-abbrev)>>
<<abbrev-gen(abbrevs=git-rm-abbrev)>>
<<abbrev-gen(abbrevs=git-submodule-abbrev)>>
<<abbrev-gen(abbrevs=git-stash-abbrev)>>
<<abbrev-gen(abbrevs=git-unstage-abbrev)>>
<<abbrev-gen(abbrevs=git-single-abbrev)>>
#+end_src

** Tools
*** Sendemail
With git, it is possible to directly send commits as patches to a
mailing list by email. However, it needs to know how. I’ll just
configure my mail server here.
#+begin_src conf-unix
[sendemail]
	smtpserver = mail.phundrak.com
	smtpuser = lucien@phundrak.com
	smtpencryption = tls
	smtpserverport = 587
#+end_src

Git also needs to know my password for my email address. Obviously, I
won’t share it here, but I am using a helper which will itself return
my password to git.
#+begin_src conf-unix
[credentials "smtp://lucien@phundrak.com@mail.phundrak.com:587"]
	helper = "secret-tool lookup password email_lucien-phundrak-com"
#+end_src

*** Magit
This configuration is specific for what I consider to be the best git
client out there, [[https://magit.vc/][Magit]]. Not just because it is an Emacs git client,
but also because it is quite transparent in terms of what happens with
the command line, but it also lets you see so much more easily what
happens with so many niceties. Rebases, including interactive rebases,
are a breeze with Magit.

I also can interact with some Git forges, including GitHub. Here are
some configurations recommended by Magit for Git.
#+begin_src conf-unix
[magithub]
	online = true
[magithub "status"]
	includeStatusHeader = true
	includePullRequestsSection = true
	includeIssuesSection = true
#+end_src

*** GPG
#+begin_src conf-unix
[gpg]
	format = ssh
[gpg "ssh"]
	allowedSignersFile = "~/.ssh/allowed_signers"
[commit]
	gpgsign = true
#+end_src

*** Merge
I like to use Emacs for everything (is it surprising?). Let’s declare
the merge tool =ediff= and use it in my git configuration.

#+begin_src conf-unix
[merge]
	tool = ediff
#+end_src

#+begin_src conf-unix
[mergetool.ediff]
	cmd = emacs --eval \" (progn (defun ediff-write-merge-buffer () (let ((file ediff-merge-store-file)) (set-buffer ediff-buffer-C) (write-region (point-min) (point-max) file) (message \\\"Merge buffer saved in: %s\\\" file) (set-buffer-modified-p nil) (sit-for 1))) (setq ediff-quit-hook 'kill-emacs ediff-quit-merge-hook 'ediff-write-merge-buffer) (ediff-merge-files-with-ancestor \\\"$LOCAL\\\" \\\"$REMOTE\\\" \\\"$BASE\\\" nil \\\"$MERGED\\\"))\"
#+end_src

*** Git forges
#+begin_src conf-unix
[github]
	user = phundrak
#+end_src

#+begin_src conf-unix
[url "https://phundrak@github.com"]
	insteadOf = https://github.com

[url "https://phundrak@labs.phundrak.com"]
	insteadOf = https://labs.phundrak.com

[url "https://github.com/RustSec/advisory-db"]
    insteadOf = https://github.com/RustSec/advisory-db
#+end_src

*** LFS
#+begin_src conf-unix
[filter "lfs"]
	required = true
	clean = git-lfs clean -- %f
	smudge = git-lfs smudge -- %f
	process = git-lfs filter-process
#+end_src

** Global gitignore file
:PROPERTIES:
:HEADER-ARGS: :mkdirp yes :tangle ~/.config/git/global-ignore
:END:
This is my global gitignore file, specifying files that will always be
ignored by Git, as described in [[file:./git.md#basic-configuration][Basic configuration]].

You may see some lines beginning with =,*=. Just read it as a simple =*=,
this is done in order to avoid org-mode being confused by a
line-initial =*= usually marking headings.

First, let’s just ignore dotenv files and direnv’s directories.
#+begin_src gitignore
.env
.direnv/
#+end_src

Now, let’s ignore files generated by Emacs.
#+begin_src gitignore
,*~
\#*\#
,*.elc
auto-save-list
.\#*
,*_flymake.*
/auto/
.projectile
.dir-locals.el

# Org mode files
.org-id-locations
,*_archive
#+end_src

Finally, let’s ignore some files we generally do not want.
#+begin_src text
,*.out
,*.o
,*.so

# Archives
,*.7zz
,*.dmg
,*.gz
,*.iso
,*.jar
,*.rar
,*.tar
,*.zip

,*.log
,*.sqlite

dist/
#+end_src
