/**
 * Recognises links to this site's own pages. The self provider previews them
 * from the database, and remote/fetch.ts accepts them as dump links even on a
 * private host such as localhost.
 *
 * @module
 */

import { FRONTEND_URL, PUBLIC_URL } from "../config.ts";

const SELF_HOSTS = new Set(
  [PUBLIC_URL, FRONTEND_URL].flatMap((u) => {
    try {
      return [new URL(u).host.toLowerCase()];
    } catch {
      return [];
    }
  }),
);

const SELF_PATH_RE = /^\/(dumps|users|playlists)\/[^/]+$/;

/**
 * Checks whether `url` links to one of this site's own dump, user or playlist
 * pages. Matched on the host as well as the path: `/users/bob` on some other
 * site is someone else's page, not ours.
 */
export function isSelfUrl(url: URL): boolean {
  return SELF_HOSTS.has(url.host.toLowerCase()) &&
    SELF_PATH_RE.test(url.pathname);
}