import "server-only";
import { cookies, headers } from "next/headers";
import { getPaths } from "yt-dlp-transcript-common/lib/paths";
import { listSiteIds } from "yt-dlp-transcript-common/lib/site";
import {
  activeSiteCookieName,
  resolveActiveSiteFrom,
  type ResolvedActiveSite,
} from "./activeSite";

// THE ONE READ of the active site on the server (see ./activeSite.ts). The root
// layout calls it with no param (a layout has no searchParams) and hands the
// result to SiteScopeProvider; Dashboard and Channels call it with their
// `searchParams.site`, which wins for that request when it names a site or
// "__all__". Nothing is written here: a server component cannot set a cookie,
// and only setActiveSiteAction does.
export type ActiveSiteRead = ResolvedActiveSite & {
  // The cookie's raw value, or null when the request carried none — which is
  // what tells the provider a visitor may still have the old localStorage key.
  stored: string | null;
};

// The request's own cookie name (per port; see activeSiteCookieName).
export async function activeSiteCookieForRequest(): Promise<string> {
  return activeSiteCookieName((await headers()).get("host"));
}

export async function readActiveSite(
  param?: string | null,
  siteIds: string[] = listSiteIds(getPaths()),
): Promise<ActiveSiteRead> {
  const name = await activeSiteCookieForRequest();
  const stored = (await cookies()).get(name)?.value ?? null;
  return { ...resolveActiveSiteFrom([param, stored], siteIds), stored };
}