Merge branch 'describe-with-content-diff'

* Branch commit log:
  jj-fzf: commit: --message fixup
  jj-fzf: echo_commit_msg: skip signoff if no files changed
  jj-fzf: add ui.default-description to commit messages
  jj-fzf: use JJ_EDITOR to really override th JJ editor settings
  jj-fzf: honor the JJ_EDITOR precedence
	The JJ docs describe the precedence:
	$JJ_EDITOR > ui.editor > $VISUAL > $EDITOR > pico
	https://jj-vcs.github.io/jj/latest/config/#editor
  jj-fzf: show content diff when editing commit message
	Show the first few thausand lines of the content diff during
	commit message creation, inspired by git commit --verbose

Signed-off-by: Tim Janik <[email protected]>

jj-fzf

@@ -371,6 +371,7 @@ echo_commit_msg()
 	gsed '/^\([A-Z][a-z0-9-]*-by\|Cc\):/d' | # strip Signed-off-by:
 	gsed '/^$/d ; s/^/\t/ ; s/^\t\f$/  (no description)/ ; s/^\t\f/  /'
     done
+    echo_signoff
   else # Commit message based on files
     # start with file name prefixes
     cd "$JJROOT" # create root relative file names
@@ -379,25 +380,40 @@ echo_commit_msg()
     test ${#FILES[@]} -gt 0 &&
       printf "%s: \n" "${FILES[@]}" ||
 	echo ""
+    jj config --no-pager get 'ui.default-description' 2>/dev/null || :
+    test ${#FILES[@]} -le 0 ||
+      echo_signoff
   fi
-  # ensure signoff
-  echo_signoff
 )
-# Run user editor: user_editor_on_var <FILE> <VARIABLE>
+# Run user editor: user_editor_on_var <FILE> <VARIABLE> [COMMIT]
 user_editor_on_var()
 {
-  local FILE="$1" N=
+  local FILE="$1" COMMIT="${3:-}" N=
   declare -n _ueovMSG="$2"			# <VARIABLE> alias
   # create msg file
   temp_dir
   local TEMPFILE="$TEMPD/$FILE"
   cat >"$TEMPFILE" <<<"$_ueovMSG"
+  test -z "$COMMIT" || {
+    jj diff --ignore-working-copy --no-pager --color=never -r "$COMMIT" |
+      head -n 4000 > "$TEMPFILE.diff"
+    test -s "$TEMPFILE.diff" && {
+      echo
+      echo '# -------- >8 -------- >8 -------- 8< -------- 8< --------'
+      echo '# Everything below the snippet mark will be ignored'
+      echo '#'
+      echo '# Content diff of this revision:'
+      cat "$TEMPFILE.diff"
+    }
+    rm -f "$TEMPFILE.diff"
+  } >> "$TEMPFILE"
   # edit commit msg
-  JJ_EDITOR="$(jj config get ui.editor 2>/dev/null || echo "${EDITOR:-pico}")"
+  test -n "${JJ_EDITOR:-}" || # https://jj-vcs.github.io/jj/latest/config/#editor
+    JJ_EDITOR="$(jj config get ui.editor 2>/dev/null || echo "${VISUAL:-${EDITOR:-pico}}")"
   $JJ_EDITOR "$TEMPFILE" &&
     N="$(cat "$TEMPFILE")" && {
       test "$_ueovMSG" != "$N" &&
-	_ueovMSG="$(cat "$TEMPFILE")"
+	_ueovMSG="$(gsed -r '/^# -+ >8 -+ >8 -+ 8< -+ 8< -+/Q' < "$TEMPFILE")"
       rm -f "$TEMPFILE"
       return 0
     }
@@ -547,20 +563,20 @@ commit()
   MSG="$(echo_commit_msg "$R")"
   O="$MSG"
   if test "$R" == "$W" -a "$IMMU" != true ; then
-    user_editor_on_var "COMMIT-$R.txt" MSG &&
+    user_editor_on_var "COMMIT-$R.txt" MSG "$R" &&
       test "$O" != "$MSG" ||
 	ERROR "Commit cancelled by user"
       ( set -x
-	jj commit -m "$MSG"
+	jj commit --message="$MSG"
       ) || sleep 1
-  else # R is @ and mutable
+  else # R is not @, may be immutable
     [[ $IMMU =~ ^true ]] || {
-      user_editor_on_var "COMMIT-$R.txt" MSG &&
+      user_editor_on_var "COMMIT-$R.txt" MSG "$R" &&
 	test "$O" != "$MSG" ||
 	  ERROR "Commit cancelled by user"
       test "$O" != "$MSG" &&
 	( set -x
-	  jj describe --no-edit -r "$R" -m "$MSG"
+	  jj describe --no-edit -r "$R" --message="$MSG"
 	) || sleep 1
     }
     # open new empty working copy commit
@@ -638,7 +654,7 @@ describe()
   R="$(xrev_or_commit "${1:-@}")"
   MSG="$(echo_commit_msg "$R")"
   O="$MSG"
-  user_editor_on_var "CHANGE-$R.txt" MSG ||
+  user_editor_on_var "CHANGE-$R.txt" MSG "$R" ||
     ERROR "Describe cancelled by user"
   test "$O" != "$MSG" ||
     return
@@ -684,8 +700,7 @@ DOC['split-interactive']='Use `jj split` to interactively select content diff hu
 split-interactive()
 (
   R="$(xrev "${1:-@}")"
-  # Override ui.editor to implement --split-with-no-description: truncate the first
-  # (original) description, then keep the other description for subsequent edits
+  # To avoid message editing, truncate all but the first (original) description
   temp_dir
   cat > $TEMPD/noeditor <<-\__EOF__
 	#!/usr/bin/env bash
@@ -695,8 +710,9 @@ split-interactive()
 	gsed 's/TRUNCATE=./TRUNCATE=y/' -i "$0"
 	__EOF__
   chmod +x $TEMPD/noeditor
+  export JJ_EDITOR="$TEMPD/noeditor" # Override ui.editor to implement --split-with-no-description
   ( set -x
-    jj split --interactive -r "$R" --config-toml "ui.editor='$TEMPD/noeditor'"
+    jj split --interactive -r "$R"
   ) || ERROR
 )
 KEYBINDINGS["Alt-I"]="split-interactive"
@@ -1034,9 +1050,9 @@ split-files()
   # create n-1 new commits from n files
   while [[ ${#MAPFILE[@]} -gt 1 ]] ; do
     unset 'MAPFILE[-1]' # unset 'MAPFILE[${#MAPFILE[@]}-1]'
-    # Override ui.editor to implement --split-with-no-description
+    export JJ_EDITOR='true' # Override ui.editor to implement --split-with-no-description
     ( set -x
-      jj split --config-toml 'ui.editor="true"' -r "$R" -- "${MAPFILE[@]}"
+      jj split -r "$R" -- "${MAPFILE[@]}"
     ) || ERROR
   done
 )
@@ -1346,10 +1362,10 @@ vivifydivergent()
   test "$COMMIT" == "$WCOPY" && NOEDIT= || NOEDIT=--no-edit
   echo "# $SELF vivifydivergent $COMMIT" >&2
   jj --no-pager log --no-graph -T builtin_log_oneline -r "$COMMIT" # --ignore-working-copy
-  # Override ui.editor to implement --squash-with-no-description
+  export JJ_EDITOR='true' # Override ui.editor to implement --squash-with-no-description
   ( set -x
     jj new --insert-after "$COMMIT" $NOEDIT
-    jj squash --from "$COMMIT" --into "$COMMIT+" --config-toml 'ui.editor="true"'
+    jj squash --from "$COMMIT" --into "$COMMIT+"
   ) || ERROR
 )
 KEYBINDINGS["Alt-V"]="vivifydivergent"	NEXTS="$NEXTS vivifydivergent"