// Serialize feed filters to/from a compact, human-readable URL query string, and build/patch the
// address-bar URL for the whole app's navigation. The query string IS the source of truth for the
// current view (page / channel / plex sub-view / playlist) and the feed filters, so every URL is
// bookmarkable/shareable — the old "Share view" workaround (and the whole-query stripUrlParams) is
// retired. Only non-default values are emitted so URLs stay clean. NOTE: the browser TAB title stays
// the short module/channel name (NavigationProvider owns document.title) — the query never leaks into it.
import { TAG_CATEGORIES, type FeedFilters } from "./api";

export const FEED_KEYS = [
  "q",
  "show",
  "sort",
  "scope",
  "source",
  "normal",
  "shorts",
  "live",
  "tags",
  "tagmode_language",
  "tagmode_topic",
  "tagmode_other",
  "tagmode", // legacy global (topic-only) — still recognised so old shared links resolve
  "notag",
  "channel",
  "maxage",
  "from",
  "to",
  "year",
  "mindur",
  "maxdur",
] as const;
const KEYS = FEED_KEYS;

// The keys the shell itself reads, whatever page is on screen: the page, the channel page (it opens
// over any page), the welcome card's mode and the one-time entry links. No module may declare one of
// these (moduleUrl.contract.test), and a page switch never clears them.
export const SHELL_KEYS = [
  "page",
  "chan",
  "m",
  "link",
  "oauth",
  "admin",
  "account",
  "login",
  "deleted",
  "token",
] as const;

export function filtersToParams(f: FeedFilters): URLSearchParams {
  const p = new URLSearchParams();
  if (f.q) p.set("q", f.q);
  if (f.show && f.show !== "unwatched") p.set("show", f.show);
  if (f.sort && f.sort !== "newest") p.set("sort", f.sort);
  if (f.scope === "all") p.set("scope", "all");
  // Library provenance filter (only meaningful in "all" scope); "organic" is the default.
  if (f.scope === "all" && f.librarySource && f.librarySource !== "organic")
    p.set("source", f.librarySource);
  if (!f.includeNormal) p.set("normal", "0");
  if (f.includeShorts) p.set("shorts", "1");
  if (f.includeLive) p.set("live", "1");
  if (f.tags.length) p.set("tags", f.tags.join(","));
  for (const cat of TAG_CATEGORIES) {
    if (f.tagModes[cat] === "and") p.set(`tagmode_${cat}`, "and");
  }
  if (f.untagged) p.set("notag", "1");
  if (f.channelIds.length) p.set("channel", f.channelIds.join(","));
  if (f.maxAgeDays) p.set("maxage", String(f.maxAgeDays));
  if (f.dateFrom) p.set("from", f.dateFrom);
  if (f.dateTo) p.set("to", f.dateTo);
  if (f.year) p.set("year", String(f.year));
  if (f.minDuration != null) p.set("mindur", String(f.minDuration));
  if (f.maxDuration != null) p.set("maxdur", String(f.maxDuration));
  return p;
}

/** Build the address-bar delta for the feed filters: each recognized filter key mapped to its emitted
 * value, or null to delete it (so switching a filter back to its default clears the key). Pass `null`
 * to clear ALL filter keys — used when leaving the feed, where the localStorage copy still holds them.
 * Feed the result into urlWithParams(). */
export function filterParamUpdates(f: FeedFilters | null): Record<string, string | null> {
  const p = f ? filtersToParams(f) : new URLSearchParams();
  const out: Record<string, string | null> = {};
  for (const k of KEYS) out[k] = p.get(k);
  return out;
}

/** Merge URL params onto a base filter set (typically the defaults). */
export function paramsToFilters(params: URLSearchParams, base: FeedFilters): FeedFilters {
  const f: FeedFilters = { ...base };
  const num = (v: string | null): number | undefined => {
    if (v == null || v === "") return undefined;
    const n = Number(v);
    return Number.isFinite(n) ? n : undefined;
  };

  if (params.has("q")) f.q = params.get("q") ?? "";
  if (params.has("show")) f.show = params.get("show") || "unwatched";
  if (params.has("sort")) f.sort = params.get("sort") || "newest";
  if (params.has("scope")) f.scope = params.get("scope") === "all" ? "all" : "my";
  if (params.has("source")) {
    const s = params.get("source");
    f.librarySource = s === "all" || s === "search" || s === "plex" ? s : "organic";
  }
  if (params.has("normal")) f.includeNormal = params.get("normal") !== "0";
  if (params.has("shorts")) f.includeShorts = params.get("shorts") === "1";
  if (params.has("live")) f.includeLive = params.get("live") === "1";
  if (params.has("tags"))
    f.tags = (params.get("tags") ?? "")
      .split(",")
      .map((s) => Number(s))
      .filter((n) => Number.isInteger(n));
  // Per-category tag match; a legacy global `tagmode=and` (topic-only) migrates into the topic slot.
  f.tagModes = {
    language: params.get("tagmode_language") === "and" ? "and" : "or",
    topic: params.get("tagmode_topic") === "and" || params.get("tagmode") === "and" ? "and" : "or",
    other: params.get("tagmode_other") === "and" ? "and" : "or",
  };
  if (params.has("notag")) f.untagged = params.get("notag") === "1";
  f.channelIds = (params.get("channel") ?? "").split(",").filter(Boolean);
  f.maxAgeDays = num(params.get("maxage"));
  f.dateFrom = params.get("from") || undefined;
  f.dateTo = params.get("to") || undefined;
  f.year = num(params.get("year"));
  f.minDuration = num(params.get("mindur"));
  f.maxDuration = num(params.get("maxdur"));
  return f;
}

/** True if the query string carries any filter param we recognize. */
export function hasFilterParams(params: URLSearchParams): boolean {
  return KEYS.some((k) => params.has(k));
}

// The single source of truth for valid page ids; `Page` and the runtime validator both
// derive from it, so adding a page is a one-line change (no parallel allowlists to keep in
// sync). "feed" is the default/fallback.
export const PAGES = [
  "home",
  "feed",
  "channels",
  "stats",
  "playlists",
  "settings",
  "scheduler",
  "config",
  "users",
  "activity",
  "notifications",
  "files",
  "plex",
] as const;

export type Page = (typeof PAGES)[number];

/** Narrow an arbitrary string to a known Page (else null). */
function isPage(p: string | null | undefined): p is Page {
  return !!p && (PAGES as readonly string[]).includes(p);
}

// A page this build no longer has, the page that took its place, and the params that open its part
// of that page — from the old link's own params. A bookmark, the remembered last page and an old
// history entry can still name one; all three resolve through `resolvePage`, so a retired page lands
// where its content went instead of on the feed, and the navigation provider writes `params` into the
// address bar as it rewrites the page (a null clears a key the old page owned).
type Updates = Record<string, string | null>;
const RETIRED: Readonly<
  Record<string, { page: Page; params?: (old: URLSearchParams) => Updates }>
> = {
  // The download queue became the tray; what it downloaded lives in Files.
  downloads: { page: "files" },
  // The audit log and the server log became tabs of the activity page (its `at` key).
  audit: { page: "activity", params: () => ({ at: "admin" }) },
  // The server log's own account, text and range became the page's shared filters; a link without
  // a range meant the log's default then, 24 hours.
  logs: {
    page: "activity",
    params: (old) => ({
      at: "logs",
      au: old.get("lu"),
      aq: old.get("lq"),
      aw: old.get("lwin") ?? "24h",
      lu: null,
      lq: null,
      lwin: null,
    }),
  },
};

const retired = (p: string | null | undefined) =>
  p && Object.prototype.hasOwnProperty.call(RETIRED, p) ? RETIRED[p]! : null;

/** A page id as stored or linked: a live page, a retired page's successor, else null. */
export function resolvePage(p: string | null | undefined): Page | null {
  if (isPage(p)) return p;
  return retired(p)?.page ?? null;
}

/** The params that open a retired page's part of its successor, read from the old link's `params`
 *  (none for a live page). */
export function retiredParams(
  p: string | null | undefined,
  params = new URLSearchParams(window.location.search),
): Updates {
  return isPage(p) ? {} : (retired(p)?.params?.(params) ?? {});
}

export function readPage(): Page {
  return resolvePage(new URLSearchParams(window.location.search).get("page")) ?? "feed";
}

/** Build a URL (path + query + fragment) from the CURRENT location with `updates` applied to the query —
 * a null value deletes that key, any other string sets it. Lets each provider own its own nav key(s) —
 * page / chan / v / pl / the feed-filter keys — and update the address bar without clobbering the others
 * (read-modify-write on the live query). The caller decides pushState vs replaceState with the string.
 *
 * ⚠️ The FRAGMENT must be carried over. The one-time auth tokens ride it (`#verify=…` / `#reset=…`, SB3),
 * and the providers that mirror nav params (useUrlMirror in FeedFilters/Playlists/Plex/Channels) sit ABOVE
 * the lazily-loaded <App> in main.tsx — their mount effect replaceState's this URL before the auth card's
 * chunk has even loaded. Dropping the hash here silently ate the token: the verification link opened a
 * bare sign-in page and the account could never be verified. */
export function urlWithParams(updates: Record<string, string | null>): string {
  const params = new URLSearchParams(window.location.search);
  for (const [k, v] of Object.entries(updates)) {
    if (v == null) params.delete(k);
    else params.set(k, v);
  }
  return hrefHere(params);
}

/** This page's address with its query replaced by `query` and its fragment by `hash` — what every
 * address-bar writer hands to `history`. Built on the URL itself, never by gluing `pathname` in front:
 * a path opened as `//evil.com/x` would read as a link to ANOTHER host, `history.replaceState` refuses
 * that (SecurityError), and the first nav mirror to write threw the whole app into its crash screen.
 * Relative where that is safe, so the address stays as it was typed; the full href when the path
 * starts with `//`. */
export function hrefHere(query: URLSearchParams, hash: string = window.location.hash): string {
  const url = new URL(window.location.href);
  url.search = query.toString();
  url.hash = hash;
  return url.pathname.startsWith("//") ? url.href : `${url.pathname}${url.search}${url.hash}`;
}

/** Remove specific TRANSIENT params (one-time auth/admin links: ?link, ?oauth, ?admin, ?access, ?verify,
 * ?reset) from the address bar once they've been read, WITHOUT touching the nav/filter params that now
 * live there. Preserves history.state. Replaces the old whole-query stripUrlParams, which is unsafe now
 * that the query is the source of truth for navigation. No-op when none of the keys are present. */
export function clearParams(...keys: string[]): void {
  const params = new URLSearchParams(window.location.search);
  let changed = false;
  for (const k of keys) {
    if (params.has(k)) {
      params.delete(k);
      changed = true;
    }
  }
  if (!changed) return;
  // Same fragment rule as urlWithParams: this strips QUERY keys only, so a `#verify=…`/`#reset=…`
  // token that has not been consumed yet must survive. Welcome's own cleanup is what clears it.
  window.history.replaceState(window.history.state, "", hrefHere(params));
}