Function validateCronExpression

apps/sim/lib/workflows/schedules/utils.ts:15–51

(
  cronExpression: string,
  timezone?: string
)

 * @returns Validation result with isValid flag, error message, and next run date
 */
export function validateCronExpression(
  cronExpression: string,
  timezone?: string
): {
  isValid: boolean
  error?: string
  nextRun?: Date
} {
  if (!cronExpression?.trim()) {
    return {
      isValid: false,
      error: 'Cron expression cannot be empty',
    }
  }

  try {
    const cron = new Cron(cronExpression, timezone ? { timezone } : undefined)
    const nextRun = cron.nextRun()

    if (!nextRun) {
      return {
        isValid: false,
        error: 'Cron expression produces no future occurrences',
      }
    }

    return {
      isValid: true,
      nextRun,
    }
  } catch (error) {
    return {
      isValid: false,
      error: getErrorMessage(error, 'Invalid cron expression syntax'),
    }
  }
}

/** Upper bound on how many excluded occurrences the next-run search skips before giving up. */
const MAX_OCCURRENCE_SKIP = 1000