export const APP_PREFIX = "crupest";
export const APP_NAME = "mailserver";

export function getEnvRequired(key: string, usage: string): string {
  key = `${APP_PREFIX.toUpperCase()}_${APP_NAME.toUpperCase()}_${key}`;
  const value = Deno.env.get(key);
  if (value == null) {
    throw new Error(`Env ${key} does not exist, used for ${usage}.`);
  }
  return value;
}

function getZonedDateTime(instant?: Temporal.Instant | Date) {
  if (instant == null) {
    instant = Temporal.Now.instant();
  } else if (instant instanceof Date) {
    instant = instant.toTemporalInstant();
  }

  return instant.toZonedDateTimeISO("UTC");
}

export function generateTimeStringForFileName(
  instant?: Temporal.Instant | Date,
  dateOnly: boolean = false,
): string {
  const time = getZonedDateTime(instant);

  if (dateOnly) {
    return time.toPlainDate().toString();
  } else {
    return time.toPlainDateTime().toString().replaceAll(/:|\./g, "-");
  }
}