import {
  Check,
  Grid2X2,
  LayoutDashboard,
  Settings as SettingsIcon,
} from "lucide-react";
import {
  useCallback,
  useEffect,
  useLayoutEffect,
  useRef,
  useState,
} from "react";
import type { DashboardPayload } from "../shared/contracts";
import { api } from "./api";
import { persistSortOrder, type SortableEntity } from "./persist-sort-order";
import { Dashboard, DashboardSkeleton } from "./components/Dashboard";
import { Settings, type SettingsSection } from "./components/Settings";
import { Brand } from "./components/Brand";

type Page = "dashboard" | "settings";

export function App() {
  const [page, setPage] = useState<Page>("dashboard");
  const [settingsSection, setSettingsSection] =
    useState<SettingsSection>("apps");
  const [data, setData] = useState<DashboardPayload | null>(null);
  const [error, setError] = useState<string | null>(null);
  const [syncing, setSyncing] = useState(false);
  const [toast, setToast] = useState<string | null>(null);
  const toastTimerRef = useRef<number | undefined>(undefined);
  const syncInFlightRef = useRef<Promise<void> | null>(null);
  const theme = data?.preferences.theme;
  const accent = data?.preferences.accent;
  const density = data?.preferences.density;
  const contentWidth = data?.preferences.contentWidth;
  const backgroundStyle = data?.preferences.backgroundStyle;
  const reducedMotion = data?.preferences.reducedMotion;
  const pollingIntervalMs = data
    ? Math.min(
        data.preferences.pollingIntervalMs,
        ...data.apps
          .filter((app) => app.widgetEnabled)
          .map((app) => app.widgetRefreshIntervalMs),
      )
    : undefined;

  const load = useCallback(async () => {
    try {
      const payload = await api.dashboard();
      setData(payload);
      setError(null);
    } catch (loadError) {
      setError(
        loadError instanceof Error
          ? loadError.message
          : "DockDeck is niet bereikbaar.",
      );
    }
  }, []);

  const sync = useCallback(async () => {
    if (syncInFlightRef.current) return syncInFlightRef.current;
    const request = (async () => {
      setSyncing(true);
      try {
        await api.sync();
        await load();
      } catch (syncError) {
        setError(
          syncError instanceof Error
            ? syncError.message
            : "De actuele status kon niet worden vernieuwd.",
        );
      } finally {
        setSyncing(false);
        syncInFlightRef.current = null;
      }
    })();
    syncInFlightRef.current = request;
    return request;
  }, [load]);

  useEffect(() => {
    void load().then(sync);
  }, [load, sync]);

  useLayoutEffect(() => {
    if (!theme || !accent || !density || !contentWidth || !backgroundStyle)
      return;
    const root = document.documentElement;
    root.dataset.theme = theme;
    root.dataset.accent = accent;
    root.dataset.density = density;
    root.dataset.contentWidth = contentWidth;
    root.dataset.background = backgroundStyle;
    root.dataset.reducedMotion = String(Boolean(reducedMotion));
  }, [accent, backgroundStyle, contentWidth, density, reducedMotion, theme]);

  useEffect(() => {
    if (!pollingIntervalMs) return;
    const refreshWhenVisible = () => {
      if (document.visibilityState === "visible") void sync();
    };
    const timer = window.setInterval(refreshWhenVisible, pollingIntervalMs);
    document.addEventListener("visibilitychange", refreshWhenVisible);
    window.addEventListener("online", refreshWhenVisible);
    return () => {
      window.clearInterval(timer);
      document.removeEventListener("visibilitychange", refreshWhenVisible);
      window.removeEventListener("online", refreshWhenVisible);
    };
  }, [pollingIntervalMs, sync]);

  const notify = (message: string) => {
    window.clearTimeout(toastTimerRef.current);
    setToast(message);
    toastTimerRef.current = window.setTimeout(() => setToast(null), 2400);
  };

  const reorderDashboardItems = async (
    entity: SortableEntity,
    items: readonly { id: string }[],
  ) => {
    try {
      await persistSortOrder(entity, items);
      await load();
      notify(
        entity === "app"
          ? "Appvolgorde bijgewerkt"
          : entity === "category"
            ? "Categorievolgorde bijgewerkt"
            : "Favorietenvolgorde bijgewerkt",
      );
      return true;
    } catch (reorderError) {
      await load();
      notify(
        reorderError instanceof Error
          ? reorderError.message
          : "De nieuwe volgorde kon niet worden opgeslagen.",
      );
      return false;
    }
  };

  useEffect(
    () => () => {
      window.clearTimeout(toastTimerRef.current);
    },
    [],
  );

  if (!data && !error) return <DashboardSkeleton />;
  if (!data && error)
    return (
      <div className="fatal-state">
        <Brand />
        <p className="eyebrow">VERBINDING VERBROKEN</p>
        <h1>DockDeck is even niet bereikbaar.</h1>
        <p>{error}</p>
        <button className="primary-button" onClick={() => void load()}>
          Opnieuw proberen
        </button>
      </div>
    );
  if (!data) return null;

  return (
    <div className="app-shell">
      <a className="skip-link" href="#main-content">
        Naar inhoud
      </a>
      {page === "dashboard" ? (
        <Dashboard
          data={data}
          syncing={syncing}
          onSync={sync}
          onReorder={reorderDashboardItems}
          onSettings={(section = "apps") => {
            setSettingsSection(section);
            setPage("settings");
          }}
        />
      ) : (
        <Settings
          data={data}
          initialSection={settingsSection}
          onBack={() => setPage("dashboard")}
          syncing={syncing}
          onSync={sync}
          onChanged={load}
          notify={notify}
        />
      )}
      {toast && (
        <div className="toast" role="status">
          <Check size={16} />
          {toast}
        </div>
      )}
      <nav className="mobile-nav" aria-label="Mobiele navigatie">
        <button
          className={page === "dashboard" ? "active" : ""}
          aria-current={page === "dashboard" ? "page" : undefined}
          onClick={() => setPage("dashboard")}
        >
          <LayoutDashboard size={20} />
          <span>Dashboard</span>
        </button>
        <button
          className=""
          onClick={() => {
            setPage("dashboard");
            window.setTimeout(
              () =>
                document
                  .getElementById("category-navigation")
                  ?.scrollIntoView({ behavior: "smooth" }),
              0,
            );
          }}
        >
          <Grid2X2 size={20} />
          <span>Categorieën</span>
        </button>
        <button
          className={page === "settings" ? "active" : ""}
          aria-current={page === "settings" ? "page" : undefined}
          onClick={() => setPage("settings")}
        >
          <SettingsIcon size={20} />
          <span>Instellingen</span>
        </button>
      </nav>
    </div>
  );
}