calendar/packages/lib/dayjs/timeZone.schema.ts

import { z } from "zod";

import { isSupportedTimeZone } from "./index";

// Schema for validating IANA timezone strings compatible with Intl.DateTimeFormat
// Browserstack and some automations return +00:00 as the timezone which isn't a valid IANA timezone
// @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DateTimeFormat/resolvedOptions#timezone
export const timeZoneSchema = z
  .string()
  .refine(
    (timeZone) => {
      // Allow +00:00 as a special case - it will be transformed to UTC
      if (timeZone === "+00:00") {
        return true;
      }
      return isSupportedTimeZone(timeZone);
    },
    { message: "Invalid timezone. Must be a valid IANA timezone string." }
  )
  .transform((timeZone) => (timeZone === "+00:00" ? "UTC" : timeZone));