Handling BASE_URLs in Vercel env

constants.ts

const { CI, PORT = 3000, VERCEL_ENV, NEXT_PUBLIC_VERCEL_ENV, VERCEL_URL, NEXT_PUBLIC_VERCEL_URL } = process.env;

export const ENVIRONMENT = VERCEL_ENV || NEXT_PUBLIC_VERCEL_ENV;

const baseDomainSource = CI ? VERCEL_URL : NEXT_PUBLIC_VERCEL_URL;
const baseDomain = baseDomainSource;

let BASE_URL: string;

if (ENVIRONMENT === 'preview') {
  BASE_URL = `https://${baseDomain}`;
} else if (ENVIRONMENT === 'production') {
  BASE_URL = baseDomain!;
} else {
  BASE_URL = `http://localhost:${PORT}`;
}