#!/usr/bin/env bash
set -euo pipefail

if [ "${1:-}" = "--help" ] || [ "${1:-}" = "-h" ]; then
  cat <<'USAGE'
Purpose: Print the next free flat AC identifier (AC-N) for a spec.
Usage:   bash scripts/next-ac-id.sh <spec-file>
Output:  One AC id (AC-{max+1}) on stdout.
Exits:   0 ok | 2 usage error
Note:    Flat AC-N only. The freeze parser reads flat ids; a dotted
USAGE
  exit 0
fi

if [ -z "${1:-}" ]; then
  printf 'usage: bash scripts/next-ac-id.sh <spec-file>\n' >&2
  exit 2
fi

spec="$1"

if [ ! -f "$spec" ]; then
  printf 'error: spec not found: %s\n' "$spec" >&2
  exit 2
fi

next=$( { grep -Eo 'AC-[0-9]+(\.[0-9]+)?' "$spec" || true; } \
  | { grep -Ev '\.' || true; } \
  | awk -F- '{print $2}' \
  | LC_ALL=C sort -n \
  | tail -1)
next=$(( ${next:-0} + 1 ))
printf 'AC-%s\n' "$next"