import { useEffect, useState } from "react";
import { useTranslation } from "react-i18next";
import { useQuery } from "@tanstack/react-query";
import { api, HttpError, type FeedFilters } from "./lib/api";
import { setLanguage, isSupported, type LangCode } from "./i18n";
import {
  applyTheme,
  DEFAULT_THEME,
  loadLocalTheme,
  saveLocalTheme,
  type ThemePrefs,
} from "./lib/theme";
import { hasFilterParams, isPage, paramsToFilters, readPage, stripUrlParams, type Page } from "./lib/urlState";
import {
  loadLayout,
  normalizeLayout,
  saveLayoutLocal,
  type SidebarLayout,
} from "./lib/sidebarLayout";
import { configureNotifications, notify } from "./lib/notifications";
import { setHintsEnabled } from "./lib/hints";
import Login from "./components/Login";
import Header from "./components/Header";
import NavSidebar from "./components/NavSidebar";
import Sidebar from "./components/Sidebar";
import Feed from "./components/Feed";
import Channels, { type ChannelStatusFilter } from "./components/Channels";
import Playlists from "./components/Playlists";
import Stats from "./components/Stats";
import Scheduler from "./components/Scheduler";
import SettingsPanel from "./components/SettingsPanel";
import NotificationsPanel from "./components/NotificationsPanel";
import OnboardingWizard from "./components/OnboardingWizard";
import { shouldAutoOpenOnboarding } from "./lib/onboarding";
import Toaster from "./components/Toaster";
import ErrorDialog from "./components/ErrorDialog";
import About from "./components/About";
import ReleaseNotes from "./components/ReleaseNotes";
import VersionBanner from "./components/VersionBanner";
import DemoBanner from "./components/DemoBanner";
import { CURRENT_VERSION } from "./lib/releaseNotes";

const DEFAULT_FILTERS: FeedFilters = {
  tags: [],
  tagMode: "or",
  q: "",
  sort: "newest",
  scope: "my",
  includeNormal: true,
  includeShorts: false,
  includeLive: false,
  show: "unwatched",
};

const FILTERS_KEY = "subfeed.filters";
const PAGE_KEY = "siftlode.page";

// Page is navigation state, not a filter, but it's also kept out of the address bar — so
// persist it to localStorage to survive a reload. A share link's ?page= still wins.
function loadInitialPage(): Page {
  const params = new URLSearchParams(window.location.search);
  if (params.has("page")) return readPage();
  const stored = localStorage.getItem(PAGE_KEY);
  return isPage(stored) ? stored : "feed";
}

function loadStoredFilters(): FeedFilters {
  try {
    return { ...DEFAULT_FILTERS, ...JSON.parse(localStorage.getItem(FILTERS_KEY) || "{}") };
  } catch {
    return DEFAULT_FILTERS;
  }
}

// URL wins over localStorage so a pasted link reproduces the exact view.
function loadInitialFilters(): FeedFilters {
  const params = new URLSearchParams(window.location.search);
  if (hasFilterParams(params)) return paramsToFilters(params, DEFAULT_FILTERS);
  return loadStoredFilters();
}

export default function App() {
  const { t, i18n } = useTranslation();
  const [theme, setThemeState] = useState<ThemePrefs>(() => loadLocalTheme());
  const [filters, setFiltersState] = useState<FeedFilters>(loadInitialFilters);
  const [view, setView] = useState<"grid" | "list">("grid");
  const [sidebarLayout, setSidebarLayoutState] = useState<SidebarLayout>(loadLayout);
  const [page, setPageState] = useState<Page>(loadInitialPage);
  const [wizardOpen, setWizardOpen] = useState(false);
  const CHANNEL_FILTER_KEY = "siftlode.channelFilter";
  const [channelFilter, setChannelFilterState] = useState<ChannelStatusFilter>(() => {
    const v = localStorage.getItem(CHANNEL_FILTER_KEY);
    return v === "needs_full" || v === "fully_synced" || v === "hidden" || v === "all"
      ? v
      : "all";
  });
  // Persist the channel status chip so a reload (F5) keeps it.
  const setChannelFilter = (f: ChannelStatusFilter) => {
    setChannelFilterState(f);
    localStorage.setItem(CHANNEL_FILTER_KEY, f);
  };
  const [aboutOpen, setAboutOpen] = useState(false);
  const [notesOpen, setNotesOpen] = useState(false);
  const [notesHighlight, setNotesHighlight] = useState<string | undefined>(undefined);
  // "Focus this channel in the manager": jump to the Channels page and seed its name filter
  // so the channel is isolated. Cleared when leaving the page so it doesn't re-apply later.
  const [focusChannelName, setFocusChannelName] = useState<string | null>(null);
  const focusChannel = (name: string) => {
    setFocusChannelName(name);
    setPage("channels");
  };
  useEffect(() => {
    if (page !== "channels") setFocusChannelName(null);
  }, [page]);

  function openReleaseNotes(highlight?: string) {
    setNotesHighlight(highlight);
    setNotesOpen(true);
  }

  function setFilters(next: FeedFilters) {
    setFiltersState(next);
    localStorage.setItem(FILTERS_KEY, JSON.stringify(next));
  }

  function setPage(next: Page) {
    if (next === page) return;
    setPageState(next);
    localStorage.setItem(PAGE_KEY, next);
    // Push an in-app history entry so the browser/mouse Back button steps through pages
    // instead of leaving the app (e.g. back to the OAuth redirect). The URL stays clean —
    // the page rides in history.state, not the query string (filters never go in the URL).
    window.history.pushState({ ...window.history.state, sfPage: next }, "");
  }

  function setSidebarLayout(next: SidebarLayout) {
    setSidebarLayoutState(next);
    saveLayoutLocal(next);
    api.savePrefs({ sidebarLayout: next }).catch(() => {});
  }

  useEffect(() => applyTheme(theme), [theme]);

  // Filters live in localStorage, not the address bar. If we arrived via a "Share view"
  // link, its params have already hydrated the initial state — persist them and strip the
  // query so the URL stays clean from here on.
  useEffect(() => {
    const params = new URLSearchParams(window.location.search);
    if (hasFilterParams(params) || params.has("page")) {
      localStorage.setItem(FILTERS_KEY, JSON.stringify(filters));
      stripUrlParams();
    }
  }, []); // eslint-disable-line react-hooks/exhaustive-deps

  // In-app Back/Forward: stamp the initial entry with the current page, then sync `page`
  // from history.state on popstate. Runs after the strip-params effect above (which resets
  // history.state to null), so the initial stamp isn't clobbered.
  useEffect(() => {
    window.history.replaceState(
      { ...window.history.state, sfPage: page },
      ""
    );
    function onPop(e: PopStateEvent) {
      const p = (e.state?.sfPage as Page) ?? "feed";
      setPageState(p);
      localStorage.setItem(PAGE_KEY, p);
    }
    window.addEventListener("popstate", onPop);
    return () => window.removeEventListener("popstate", onPop);
  }, []); // eslint-disable-line react-hooks/exhaustive-deps

  const meQuery = useQuery({ queryKey: ["me"], queryFn: api.me });

  // First-login onboarding: prompt the user to connect YouTube (and resume the flow after
  // each consent redirect). Derived from granted scopes + storage flags so it's stable
  // across the full-page OAuth round-trip; dismissible and reopenable from Settings.
  useEffect(() => {
    if (meQuery.data && shouldAutoOpenOnboarding(meQuery.data)) setWizardOpen(true);
  }, [meQuery.data?.id, meQuery.data?.can_read, meQuery.data?.can_write]);

  // On login, adopt server-stored preferences.
  useEffect(() => {
    const prefs = meQuery.data?.preferences;
    if (!prefs) return;
    if (prefs.theme) {
      const merged = { ...DEFAULT_THEME, ...prefs.theme };
      setThemeState(merged);
      saveLocalTheme(merged);
    }
    if (prefs.view === "grid" || prefs.view === "list") setView(prefs.view);
    if (prefs.sidebarLayout) {
      const l = normalizeLayout(prefs.sidebarLayout);
      setSidebarLayoutState(l);
      saveLayoutLocal(l);
    }
    if (isSupported(prefs.language)) setLanguage(prefs.language);
    if (prefs.notifications) configureNotifications(prefs.notifications);
    if (typeof prefs.hints === "boolean") setHintsEnabled(prefs.hints);
    if (typeof prefs.performanceMode === "boolean")
      document.documentElement.dataset.perf = prefs.performanceMode ? "1" : "";
    // Nudge admins when access requests are waiting (in lieu of a server-push bell).
    const pending = meQuery.data?.pending_invites ?? 0;
    if (meQuery.data?.role === "admin" && pending > 0) {
      notify({
        level: "warning",
        title: t("common.accessRequestsTitle"),
        message: t("common.accessRequestsMessage", { count: pending }),
      });
    }
    // The demo account is shared: there are no subscriptions, so default it to the whole
    // library (the "my" feed would be empty). The communal-state warning is a permanent
    // banner (see DemoBanner below), not a toast that re-pops on every reload.
    if (meQuery.data?.is_demo) {
      setFilters({ ...loadStoredFilters(), scope: "all" });
    }
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [meQuery.data?.id]);

  function setTheme(next: ThemePrefs) {
    setThemeState(next);
    saveLocalTheme(next);
    api.savePrefs({ theme: next }).catch(() => {});
  }
  function changeView(v: "grid" | "list") {
    setView(v);
    api.savePrefs({ view: v }).catch(() => {});
  }
  function changeLanguage(code: LangCode) {
    setLanguage(code);
    api.savePrefs({ language: code }).catch(() => {});
  }

  if (meQuery.isLoading)
    return (
      <div className="min-h-screen grid place-items-center text-muted">{t("common.loading")}</div>
    );
  if (meQuery.error instanceof HttpError && meQuery.error.status === 401)
    return <Login />;
  if (meQuery.error)
    return (
      <div className="min-h-screen grid place-items-center text-muted">
        {t("common.somethingWrong")}
      </div>
    );

  return (
    <div className="h-screen flex bg-bg text-fg">
      <NavSidebar
        me={meQuery.data!}
        page={page}
        setPage={setPage}
        onOpenAbout={() => setAboutOpen(true)}
        onChangeLanguage={changeLanguage}
        language={i18n.language as LangCode}
        filters={filters}
        setFilters={setFilters}
      />
      <div className="relative flex-1 min-w-0 flex flex-col">
        <Header
          me={meQuery.data!}
          filters={filters}
          setFilters={setFilters}
          page={page}
          onGoToFullHistory={() => {
            setChannelFilter("needs_full");
            setPage("channels");
          }}
        />
        {meQuery.data!.is_demo && <DemoBanner />}
        <VersionBanner onOpen={() => openReleaseNotes(CURRENT_VERSION)} />
        <div className="flex flex-1 min-h-0">
          {page === "feed" && (
            <Sidebar
              filters={filters}
              setFilters={setFilters}
              layout={sidebarLayout}
              setLayout={setSidebarLayout}
              onFocusChannel={focusChannel}
            />
          )}
          <main className="flex-1 min-w-0 overflow-y-auto">
          {page === "channels" ? (
            <Channels
              canWrite={meQuery.data!.can_write}
              isAdmin={meQuery.data!.role === "admin"}
              focusChannelName={focusChannelName}
              onFocusChannel={focusChannel}
              statusFilter={channelFilter}
              setStatusFilter={setChannelFilter}
              onOpenWizard={() => setWizardOpen(true)}
              onViewChannel={(id, name) => {
                setFilters({ ...filters, channelId: id, channelName: name, show: "all" });
                setPage("feed");
              }}
              onFilterByTag={(tagId, name) => {
                setFilters({ ...filters, tags: [tagId], channelId: undefined, channelName: undefined });
                setPage("feed");
                notify({ level: "info", message: t("channels.notify.filteredByTag", { name }) });
              }}
            />
          ) : page === "stats" && meQuery.data!.role === "admin" ? (
            <Stats />
          ) : page === "scheduler" && meQuery.data!.role === "admin" ? (
            <Scheduler />
          ) : page === "playlists" ? (
            <Playlists canWrite={meQuery.data!.can_write} />
          ) : page === "notifications" ? (
            <NotificationsPanel />
          ) : page === "settings" ? (
            <SettingsPanel
              me={meQuery.data!}
              theme={theme}
              setTheme={setTheme}
              view={view}
              setView={changeView}
              onOpenWizard={() => setWizardOpen(true)}
            />
          ) : (
            <Feed
              filters={filters}
              setFilters={setFilters}
              view={view}
              canRead={meQuery.data!.can_read}
              isDemo={meQuery.data!.is_demo}
              onOpenWizard={() => setWizardOpen(true)}
            />
          )}
          </main>
        </div>
        {/* Toasts rise from the bottom-left, by the notification bell in the nav rail.
            Anchored inside the content column so they clear the sidebar automatically
            (collapsed or expanded) without tracking its width. */}
        <Toaster />
      </div>
      {wizardOpen && meQuery.data && !meQuery.data.is_demo && (
        <OnboardingWizard me={meQuery.data} onClose={() => setWizardOpen(false)} />
      )}
      {aboutOpen && (
        <About
          onClose={() => setAboutOpen(false)}
          onOpenReleaseNotes={() => {
            setAboutOpen(false);
            openReleaseNotes();
          }}
        />
      )}
      {notesOpen && (
        <ReleaseNotes onClose={() => setNotesOpen(false)} highlight={notesHighlight} />
      )}
      <ErrorDialog />
    </div>
  );
}