From 6b26b5c47fa3c382cd728f9ccb7c05f423f2f567 Mon Sep 17 00:00:00 2001
From: Madeleine Sydney <lomiskiam@gmail.com>
Date: Tue, 6 May 2025 11:35:47 -0600
Subject: [PATCH] feat(git): Use Ediff

---
 modules/home/users/crumb/git.nix | 13 +++++++
 scripts/ediff/ediff              | 59 ++++++++++++++++++++++++++++++++
 2 files changed, 72 insertions(+)
 create mode 100644 scripts/ediff/ediff

diff --git a/modules/home/users/crumb/git.nix b/modules/home/users/crumb/git.nix
index 76da003..93e396f 100644
--- a/modules/home/users/crumb/git.nix
+++ b/modules/home/users/crumb/git.nix
@@ -21,6 +21,19 @@ in {
           enable = true;
           userEmail = my-email;
           userName = my-name;
+          extraConfig = {
+            diff = {
+              tool = "ediff";
+              guitool = "ediff";
+            };
+            difftool.ediff.cmd =
+              "${../../../../scripts/ediff/ediff} $LOCAL $REMOTE $MERGED";
+            merge.tool = "ediff";
+            mergetool.ediff = {
+              cmd = "${../../../../scripts/ediff/ediff} $LOCAL $REMOTE $MERGED";
+              trustExitCode = true;
+            };
+          };
         };
 
         home.shellAliases = {
diff --git a/scripts/ediff/ediff b/scripts/ediff/ediff
new file mode 100644
index 0000000..ff89984
--- /dev/null
+++ b/scripts/ediff/ediff
@@ -0,0 +1,59 @@
+#!/usr/bin/env bash
+
+# Modified from https://github.com/paulotome/emacstool
+
+# test args
+if [ ! ${#} -ge 2 ]; then
+    echo 1>&2 "Usage: ${0} LOCAL REMOTE [MERGED BASE]"
+    echo 1>&2 "       (LOCAL, REMOTE, MERGED, BASE can be provided by \`git mergetool'.)"
+    exit 1
+fi
+
+# tools
+emacsclient=$(which emacsclient)
+basename=$(which basename)
+cp=$(which cp)
+mktemp=$(which mktemp)
+
+# args
+_LOCAL=${1}
+_REMOTE=${2}
+if [ "${3}" ] ; then
+    _MERGED=${3}
+else
+    _MERGED=${_REMOTE}
+fi
+if [ "${4}" ] && [ -r "${4}" ] ; then
+    _BASE=${4}
+    _EDIFF=ediff-merge-files-with-ancestor
+    _EVAL="${_EDIFF} \"${_LOCAL}\" \"${_REMOTE}\" \"${_BASE}\" nil \"${_MERGED}\""
+elif [ "${_REMOTE}" = "${_MERGED}" ] ; then
+    _EDIFF=ediff
+    _EVAL="${_EDIFF} \"${_LOCAL}\" \"${_REMOTE}\""
+else
+    _EDIFF=ediff-merge-files
+    _EVAL="${_EDIFF} \"${_LOCAL}\" \"${_REMOTE}\" nil \"${_MERGED}\""
+fi
+
+# console vs. X
+if [ "${TERM}" = "linux" ]; then
+    unset DISPLAY
+    emacsclientOPTS="-t"
+else
+    emacsclientOPTS="-c"
+fi
+
+# run emacsclient
+${emacsclient} ${emacsclientOPTS} -a "" -e "(${_EVAL})" 2>&1
+
+# check modified file
+if [ ! "$(grep -Ec '^(<<<<<<<|=======|>>>>>>>|####### Ancestor)' "${_MERGED}")" = 0 ]; then
+    _MERGEDSAVE=$(${mktemp} --tmpdir "$(${basename} "${_MERGED}")".XXXXXXXXXX)
+    ${cp} "${_MERGED}" "${_MERGEDSAVE}"
+    echo 1>&2 "Oops! Conflict markers detected in $_MERGED."
+    echo 1>&2 "Saved your changes to ${_MERGEDSAVE}"
+    echo 1>&2 "Exiting with code 1."
+    exit 1
+fi
+
+exit 0