Homarr/packages/common/src/url.ts

import type { ReadonlyHeaders } from "next/dist/server/web/spec-extension/adapters/headers";

export const appendPath = (url: URL | string, path: string) => {
  const newUrl = new URL(url);
  newUrl.pathname = removeTrailingSlash(newUrl.pathname) + path;
  return newUrl;
};

const removeTrailingSlash = (path: string) => {
  return path.at(-1) === "/" ? path.substring(0, path.length - 1) : path;
};

export const extractBaseUrlFromHeaders = (headers: ReadonlyHeaders): `${string}://${string}` => {
  let protocol = headers.get("x-forwarded-proto") ?? "http";

  // @see https://support.glitch.com/t/x-forwarded-proto-contains-multiple-protocols/17219
  if (protocol.includes(",")) {
    protocol = protocol.includes("https") ? "https" : "http";
  }

  const host = headers.get("x-forwarded-host") ?? headers.get("host");

  return `${protocol}://${host}`;
};