import { isValidHostLabel } from "@smithy/util-endpoints";
const validRegions = new Set();
export const checkRegion = (region, check = isValidHostLabel) => {
    if (!validRegions.has(region) && !check(region)) {
        if (region === "*") {
            console.warn(`@smithy/config-resolver WARN - Please use the caller region instead of "*". See "sigv4a" in https://github.com/aws/aws-sdk-js-v3/blob/main/supplemental-docs/CLIENTS.md.`);
        }
        else {
            throw new Error(`Region not accepted: region="${region}" is not a valid hostname component.`);
        }
    }
    else {
        validRegions.add(region);
    }
};