/** @see execShellLine — nounset violations surface as exit status 1 */
export const BARE_OS_SHELL_NOUNSET_ERROR = 'BARE_OS_SHELL_NOUNSET'

/**
 * @param {Record<string, string> | null | undefined} env
 */
export function shellNounsetEnvOn(env) {
  return (
    env &&
    (env.BARE_OS_SHELL_NOUNSET === '1' || env.BARE_OS_SHELL_NOUNSET === 'true')
  )
}

/**
 * @param {string} name
 * @param {Record<string, string>} env
 */
export function shellCheckUnboundParam(name, env) {
  if (!shellNounsetEnvOn(env) || !name) return
  const n = name.trim()
  if (n === '?' || /^\d+$/.test(n)) return
  if (!/^[A-Za-z_][A-Za-z0-9_]*$/.test(n)) return
  if (!Object.prototype.hasOwnProperty.call(env, n)) {
    const e = new Error(`unbound variable: ${n}`)
    e.code = BARE_OS_SHELL_NOUNSET_ERROR
    throw e
  }
}