/**
 * Recognises links to this site's own pages. The self provider previews them
 * from the database, remote/fetch.ts accepts them as dump links even on a
 * private host such as localhost, and migration 0021 rewrote the v3 ones in
 * stored text.
 *
 * @module
 */

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

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

/**
 * Checks whether `host` (with its port, as `URL.host` gives it) is where this
 * site is served, at its public URL or its frontend's.
 */
export function isSelfHost(host: string): boolean {
  return SELF_HOSTS.has(host.toLowerCase());
}

/**
 * Checks whether `url` links to one of this site's own dump, user or playlist
 * pages, by `parsePagePath`; a dump's editor doesn't count. Matched on the
 * host as well as the path: `/@bob` on some other site is someone else's
 * page, not ours.
 */
export function isSelfUrl(url: URL): boolean {
  if (!isSelfHost(url.host)) return false;
  const page = parsePagePath(url.pathname);
  return !!page && !(page.kind === "dump" && page.edit);
}