// URL-derived navigation seeds, split out of NavigationProvider so they stay unit-testable AND the
// provider file keeps react-refresh happy (component-only exports). `loadInitialPage` picks the landing
// module from a bookmark's params; `channelViewFrom` is the shared _chan/?chan resolver behind BOTH the
// channelView seed and the onPop handler.
import { hasFilterParams, isPage, readPage, type Page } from "../lib/urlState";
import { getAccountRaw, LS } from "../lib/storage";

export const PAGE_KEY = LS.page;
// Module-local: the Settings toggle writes `LS.startOnHome` directly, so exporting this alias would
// only be a second name for the same key.
const START_HOME_KEY = LS.startOnHome;

/** The two stored values of the landing preference (raw strings, via useAccountPersistedState).
 *  Settings → Appearance → Startup writes them and `loadInitialPage` reads them, so they are defined
 *  ONCE: the same magic string spelled out in a writer and a reader is precisely the drift that has
 *  bitten this codebase before (`cancelled` vs `canceled`). */
export const START_ON_HOME = { on: "1", off: "0" } as const;

export interface ChannelView {
  id: string;
  name?: string;
}

export function loadInitialPage(): Page {
  const params = new URLSearchParams(window.location.search);
  if (params.has("page")) return readPage();
  // A view-specific param implies its page, so a bookmarked deep link lands on the right module even
  // without an explicit ?page. Feed filters (or a channel overlay) imply the feed.
  if (params.has("v")) return "plex";
  if (params.has("pl")) return "playlists";
  if (hasFilterParams(params) || params.has("chan")) return "feed";
  // A bare URL → Home (E24), the surface whose whole job is to answer "what should I watch" before
  // the user has to decide anything. It deliberately OVERRIDES the remembered last module: landing
  // on whatever you happened to close the app on is the behaviour the anti-paralysis epic exists to
  // replace. The account can opt out (Settings → Appearance → Startup) and get the remembered
  // module back.
  if (getAccountRaw(START_HOME_KEY) !== START_ON_HOME.off) return "home";
  const stored = getAccountRaw(PAGE_KEY);
  return isPage(stored) ? stored : "feed";
}

/** Resolve the open channel page from a landed history entry: the in-app `_chan` id (with its optional
 *  `_chanName`), else the ?chan URL param — a fresh ?chan bookmark's entry is URL-only. The seed AND
 *  the popstate handler share this ONE resolver so a popstate that lands on a bookmark entry (no
 *  `_chan`) restores the channel from the URL instead of wrongly closing it. */
export function channelViewFrom(
  state: { _chan?: unknown; _chanName?: unknown } | null | undefined,
  search: string,
): ChannelView | null {
  const id =
    (state?._chan as string | undefined) ?? new URLSearchParams(search).get("chan") ?? undefined;
  return id ? { id, name: (state?._chanName as string) ?? undefined } : null;
}