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

services=("$@")

service_exists() {
  local service="$1"
  systemctl list-unit-files "${service}.service" --no-legend 2>/dev/null | awk '{print $1}' | grep -qx "${service}.service"
}

pick_default_scheduler() {
  if service_exists cron; then
    printf 'cron'
  elif service_exists crond; then
    printf 'crond'
  else
    printf 'cron'
  fi
}

pick_default_ssh() {
  if service_exists sshd; then
    printf 'sshd'
  elif service_exists ssh; then
    printf 'ssh'
  else
    printf 'sshd'
  fi
}

if ! command -v systemctl >/dev/null 2>&1; then
  printf 'CRITICAL: systemctl command not available; cannot check services\n' >&2
  exit 1
fi

if (( ${#services[@]} == 0 )); then
  services=("$(pick_default_ssh)" "$(pick_default_scheduler)")
fi

status=0

for service in "${services[@]}"; do
  if ! service_exists "$service"; then
    printf 'CRITICAL: %s service not found\n' "$service"
    status=1
    continue
  fi

  if systemctl is-active --quiet "$service"; then
    printf 'OK: %s is active\n' "$service"
  else
    state="$(systemctl is-active "$service" 2>/dev/null || true)"
    printf 'CRITICAL: %s is %s\n' "$service" "${state:-unknown}"
    status=1
  fi
done

exit "$status"