# Conventional commits, matching this repository's existing log
# (feat:, fix:, docs:, refactor:, chore:, test:, style:, ci:).
#
# Deliberately a plain regex rather than a commitlint dependency: this project's
# thesis is having no unnecessary dependencies, and one regex is legible to
# every agent that has to satisfy it.

message_file=$1
first_line=$(head -n1 "$message_file")

# Allow merge and revert commits through untouched.
case "$first_line" in
  "Merge "*|"Revert "*) exit 0 ;;
esac

if ! printf '%s' "$first_line" | grep -qE '^(feat|fix|docs|refactor|chore|test|style|ci|perf|build)(\([a-z0-9 -]+\))?: .{1,}$'; then
  echo "commit-msg: subject must be '<type>: <subject>' (lowercase type)." >&2
  echo "  types: feat fix docs refactor chore test style ci perf build" >&2
  echo "  got:   $first_line" >&2
  exit 1
fi

if [ "${#first_line}" -gt 72 ]; then
  echo "commit-msg: subject is ${#first_line} chars; keep it under 72." >&2
  exit 1
fi