#!/usr/bin/env bash
# Ensure the RCS backend is running (intended for user crontab every minute).
# Does not rebuild the binary — run `make build` first.
set -euo pipefail

REPO="$(cd "$(dirname "$0")/.." && pwd)"
BIN="${RCS_BIN:-$REPO/bin/rcs}"
DATA_DIR="${RCS_DATA_DIR_OVERRIDE:-$REPO/data}"
PIDFILE="${RCS_PIDFILE:-$DATA_DIR/rcs.pid}"
LOG="${RCS_LOG:-$DATA_DIR/rcs.log}"
ENVFILE="${RCS_ENV_FILE:-$DATA_DIR/rcs.env}"
LOCKFILE="${RCS_LOCKFILE:-$DATA_DIR/rcs.watchdog.lock}"

mkdir -p "$DATA_DIR"

exec 9>"$LOCKFILE"
if ! flock -n 9; then
  # Another watchdog instance is starting the process.
  exit 0
fi

log_msg() {
  local line="[$(date -Iseconds)] $*"
  echo "$line" >>"$LOG"
}

if [[ ! -x "$BIN" ]]; then
  log_msg "ERROR: binary missing or not executable: $BIN (run: make build)"
  echo "rcs-watchdog: binary missing: $BIN" >&2
  exit 1
fi

if [[ -f "$PIDFILE" ]]; then
  old_pid="$(tr -d '[:space:]' <"$PIDFILE" || true)"
  if [[ -n "${old_pid:-}" ]] && kill -0 "$old_pid" 2>/dev/null; then
    exit 0
  fi
  rm -f "$PIDFILE"
fi

# Absolute data dir so cron cwd ($HOME) does not matter.
export RCS_DATA_DIR="$DATA_DIR"

if [[ -f "$ENVFILE" ]]; then
  # shellcheck disable=SC1090
  set -a
  # shellcheck disable=SC1090
  source "$ENVFILE"
  set +a
  # Keep data under the repo unless the env file overrides with an absolute path.
  if [[ -z "${RCS_DATA_DIR:-}" || "${RCS_DATA_DIR}" == "data" || "${RCS_DATA_DIR}" == "./data" ]]; then
    export RCS_DATA_DIR="$DATA_DIR"
  fi
fi

cd "$REPO"
nohup "$BIN" >>"$LOG" 2>&1 &
new_pid=$!
echo "$new_pid" >"$PIDFILE"
log_msg "started $BIN pid=$new_pid"
exit 0