From 126772f08c6a44339a878aa0c6336e54dcb864ab Mon Sep 17 00:00:00 2001
From: carlfriedrich <carlfriedrich@posteo.de>
Date: Thu, 28 Jul 2022 10:16:22 +0200
Subject: [PATCH] Add function forgit::previous_commit

---
 conf.d/forgit.plugin.fish | 21 +++++++++++----------
 forgit.plugin.zsh         | 24 ++++++++++++------------
 2 files changed, 23 insertions(+), 22 deletions(-)

diff --git a/conf.d/forgit.plugin.fish b/conf.d/forgit.plugin.fish
index ab4dda4..c8b9203 100644
--- a/conf.d/forgit.plugin.fish
+++ b/conf.d/forgit.plugin.fish
@@ -21,6 +21,15 @@ function forgit::reverse_lines
     end
 end
 
+function forgit::previous_commit
+    # "SHA~" is invalid when the commit is the first commit, but we can use "--root" instead
+    if test (git rev-parse $argv) = (git rev-list --max-parents=0 HEAD)
+        echo "--root"
+    else
+        echo "$argv~"
+    end
+end
+
 # extract the first git sha occuring in the input and strip trailing newline
 set -g forgit_extract_sha  "grep -Eo '[a-f0-9]+' | head -1 | tr -d '[:space:]'"
 
@@ -399,11 +408,7 @@ function forgit::fixup -d "git fixup"
     set target_commit (eval "$cmd" | FZF_DEFAULT_OPTS="$opts" fzf | eval "$forgit_extract_sha")
 
     if test -n "$target_commit" && git commit --fixup "$target_commit"
-        # "$target_commit~" is invalid when the commit is the first commit, but we can use "--root" instead
-        set prev_commit "$target_commit~"
-        if test "(git rev-parse '$target_commit')" = "(git rev-list --max-parents=0 HEAD)"
-            set prev_commit "--root"
-        end
+        set prev_commit (forgit::previous_commit $target_commit)
 
         GIT_SEQUENCE_EDITOR=: git rebase --autostash -i --autosquash "$prev_commit"
     end
@@ -440,11 +445,7 @@ function forgit::rebase -d "git rebase"
     set target_commit (eval "$cmd" | FZF_DEFAULT_OPTS="$opts" fzf | eval "$forgit_extract_sha")
 
     if test $target_commit
-        # "$target_commit~" is invalid when the commit is the first commit, but we can use "--root" instead
-        set prev_commit "$target_commit~"
-        if test "(git rev-parse '$target_commit')" = "(git rev-list --max-parents=0 HEAD)"
-            set prev_commit "--root"
-        end
+        set prev_commit (forgit::previous_commit $target_commit)
 
         git rebase -i "$prev_commit"
     end
diff --git a/forgit.plugin.zsh b/forgit.plugin.zsh
index 606c23b..9e0e301 100755
--- a/forgit.plugin.zsh
+++ b/forgit.plugin.zsh
@@ -6,6 +6,15 @@ forgit::inside_work_tree() { git rev-parse --is-inside-work-tree >/dev/null; }
 # tac is not available on OSX, tail -r is not available on Linux, so we use either of them
 forgit::reverse_lines() { tac 2> /dev/null || tail -r; }
 
+forgit::previous_commit() {
+    # "SHA~" is invalid when the commit is the first commit, but we can use "--root" instead
+    if [[ "$(git rev-parse "$1")" == "$(git rev-list --max-parents=0 HEAD)" ]]; then
+        echo "--root"
+    else
+        echo "$1~"
+    fi
+}
+
 # optional render emoji characters (https://github.com/wfxr/emoji-cli)
 hash emojify &>/dev/null && forgit_emojify='|emojify'
 
@@ -192,12 +201,8 @@ forgit::rebase() {
     "
     target_commit=$(eval "$cmd" | FZF_DEFAULT_OPTS="$opts" fzf | eval "$forgit_extract_sha")
     if [[ -n "$target_commit" ]]; then
-        # "$target_commit~" is invalid when the commit is the first commit, but we can use "--root" instead
-        if [[ "$(git rev-parse "$target_commit")" == "$(git rev-list --max-parents=0 HEAD)" ]]; then
-            prev_commit="--root"
-        else
-            prev_commit="$target_commit~"
-        fi
+        prev_commit=$(forgit::previous_commit $target_commit)
+
         git rebase -i "$prev_commit"
     fi
 }
@@ -220,12 +225,7 @@ forgit::fixup() {
     "
     target_commit=$(eval "$cmd" | FZF_DEFAULT_OPTS="$opts" fzf | eval "$forgit_extract_sha")
     if [[ -n "$target_commit" ]] && git commit --fixup "$target_commit"; then
-        # "$target_commit~" is invalid when the commit is the first commit, but we can use "--root" instead
-        if [[ "$(git rev-parse "$target_commit")" == "$(git rev-list --max-parents=0 HEAD)" ]]; then
-            prev_commit="--root"
-        else
-            prev_commit="$target_commit~"
-        fi
+        prev_commit=$(forgit::previous_commit $target_commit)
         # rebase will fail if there are unstaged changes so --autostash is needed to temporarily stash them
         # GIT_SEQUENCE_EDITOR=: is needed to skip the editor
         GIT_SEQUENCE_EDITOR=: git rebase --autostash -i --autosquash "$prev_commit"