Ensure proper footer sorting of footer

When no trailer was configured in git configuration, TRAILERS_BY_REGEX
remained empty. This caused the subsequent match condition to always
evaluate to true, leading to incorrect footer sorting regardless of
their content. To address this issue, the update ensures that when the
configuration is empty, default terms are used to initialize
TRAILERS_BY_REGEX. The sorting mechanism is then adjusted to prioritize
other footers, configured trailers, and the change-id.

Co-authored-by: EricccTaiwan <[email protected]>
Change-Id: I6df5438b7ec6c85f5438f869b44cd14589c03339

Refactor commit trailer regex

Refactor commit trailer regex by renaming default_trailers_by to
DEFAULT_TRAILERS_BY to follow the naming convention for global
variables.Then refine build_commit_trailer_regex by reusing the array.

Co-authored-by: EricccTaiwan <[email protected]>
Change-Id: I7c7e9367f59a6da0ff84605904d08343ad558f42

Author: charliechiou

scripts/commit-msg.hook

@@ -130,6 +130,16 @@ get_all_match_positions() {
   done <<< "$targets"
 }
 
+KNOWN_TRAILERS_BY=(
+  'Signed-off-by'
+  'Reviewed-by'
+  'Co-authored-by'
+  'Acked-by'
+  'Suggested-by'
+  'Tested-by'
+  'Reported-by'
+)
+
 # Build regex for detecting commit trailers.
 build_commit_trailer_regex() {
   local -a keys specials standalones trailers
@@ -145,12 +155,17 @@ build_commit_trailer_regex() {
     'Signed-off-by' 'Suggested-by' 'Tested-by'
   )
 
+  trailers_test=(
+    'CC' 'Change-Id' 'Closes'
+    "${KNOWN_TRAILERS_BY[@]}"
+  )
   # Standalone keys (those that do not require a value).
   standalones=(
     '(Doc|Upgrade|Security)Impact'
     "Git-Dch[$separators] (Ignore|Short|Full)"
   )
 
+
   # Read custom trailer keys from git config and add them either to specials or trailers.
   # This loop reads lines matching 'trailer.*.key'.
   while read -r _ key; do
@@ -170,6 +185,10 @@ build_commit_trailer_regex() {
     fi
   done < <(git config --get-regexp 'trailer.*.key')
 
+  if [[ ${#trailers_by[@]} -eq 0 ]]; then
+    trailers_by=("${DEFAULT_TRAILERS_BY[@]}")
+  fi
+
   # Possible trailers :
   # - Acked-by
   # - Co-authored-by
@@ -178,8 +197,7 @@ build_commit_trailer_regex() {
   # - Signed-off-by
   # - Suggested-by
   # - Tested-by
-  TRAILERS_BY_REGEX="^($(IFS='|'; echo "${trailers_by[*]}")):"
-
+  TRAILERS_BY_REGEX="/($(IFS='|'; echo "${trailers_by[*]}" | tr '[:upper:]' '[:lower:]'))/"
   # Begin constructing the regex.
   TRAILER_REGEX='^('
 
@@ -610,7 +628,7 @@ add_change_id() {
     other_footer = ""
 
     for (line = 1; line <= numlines; line++) {
-      if (match(tolower(footer[line]), TRAILERS_BY_REGEX)) {
+      if (match(tolower(footer[line]), '"$TRAILERS_BY_REGEX"')) {
         trailers = trailers footer[line] "\n"
       } else {
         other_footer = other_footer footer[line] "\n"