#!/usr/bin/env bash
set -euo pipefail
umask 077
entry="$(cd "$(dirname "$0")" && pwd -P)/gate-lane.mjs"
verb="${1:-run}"
if [ "$verb" = status ]; then exec node "$entry" "$@"; fi
state="$(node "$entry" lock-dir "$@")"
lane=a
exclusive=0
args=("$@")
for ((i=0;i<${#args[@]};i++)); do
  case "${args[i]}" in
    --lane) lane="${args[i+1]:-}" ;;
    --exclusive) exclusive=1 ;;
  esac
done
case "$verb" in recover|prepare-image) exclusive=1;; esac
case "$lane" in a|b) ;; *) echo 'gate-lane: refused: invalid lane' >&2; exit 2;; esac
if [ "$exclusive" = 1 ]; then
  exec 3>>"$state/a.lock" 4>>"$state/b.lock" 5>>"$state/image.lock"
  flock -n 3 && flock -n 4 && flock -n -x 5 || { echo 'gate-lane: refused: lane or image lock busy' >&2; exit 2; }
else
  exec 3>>"$state/$lane.lock" 5>>"$state/image.lock"
  flock -n 3 && flock -n -s 5 || { echo 'gate-lane: refused: lane or image lock busy' >&2; exit 2; }
fi
exec node "$entry" --locked "$@"