import { useEffect, useState } from 'react';
import { createRoot } from 'react-dom/client';
import './styles/fonts.css';
import './styles/tokens.css';
import './styles/app.css';
import './styles/landing.css';
import { ThemeProvider } from './theme/ThemeProvider';
import { I18nProvider } from './i18n/I18nProvider';
import { Landing } from './Landing';
import { Workspace } from './App';
import { Admin } from './Admin';
import { ProfilePage } from './ProfilePage';
import { PhotosPage } from './PhotosPage';
import { Library } from './Library';
import { go } from './nav';
import { ErrorBoundary } from './ui/ErrorBoundary';
import { OtherWindowNotice, TakenBar, useSingleWindow } from './ui/SingleTab';
import { InstallPrompt } from './ui/InstallPrompt';
import { OfflineBar } from './ui/OfflineBar';
import { installTracking } from './track';

// Six routes, no router: the landing page, the workspace, the strip moderation
// screen, the member's own profile, the member's photo folder and the local
// catalogue of folders on the visitor's own disk. nginx serves index.html for
// all of them (SPA fallback), so this is a pathname check.
//
// The pages that are not the two heavy screens: they read no catalogue and boot
// no renderer, so they are drawn straight from the route and nothing is kept.
function page(route: string) {
  return route.startsWith('/admin') ? (
    <Admin />
  ) : route.startsWith('/photos') ? (
    <PhotosPage />
  ) : route.startsWith('/profile') ? (
    <ProfilePage />
  ) : (
    <Landing />
  );
}

// The studio and the library are the two screens worth a boot: ~20MB of CanvasKit
// under one and the whole catalogue under the other. Both used to be mounted for
// every visit, which is the 20MB and the read on a page that was shown neither,
// and it is what a machine short of memory took for a crash. A route mounts its
// screen the first time it is asked for and stays mounted after that, so coming
// back from the studio is a screen opening rather than a page loading.
const heavy = (route: string) => (route.startsWith('/app') ? 'app' : route.startsWith('/library') ? 'library' : 'other');

function Shell() {
  const [route, setRoute] = useState(() => window.location.pathname + window.location.search);

  useEffect(() => {
    const onClick = (e: MouseEvent) => {
      if (e.defaultPrevented || e.button !== 0 || e.metaKey || e.ctrlKey || e.shiftKey || e.altKey) return;
      const target = e.target as Element | null;
      const link = target?.closest?.('a');
      if (!(link instanceof HTMLAnchorElement)) return;
      if (link.target || link.hasAttribute('download')) return;
      const url = new URL(link.href, window.location.href);
      const here = window.location.pathname + window.location.search;
      if (url.origin !== window.location.origin || url.hash) return;
      if (url.pathname + url.search === here) return;
      e.preventDefault();
      go(url.pathname + url.search);
    };
    const onPop = () => setRoute(window.location.pathname + window.location.search);
    document.addEventListener('click', onClick);
    window.addEventListener('popstate', onPop);
    return () => {
      document.removeEventListener('click', onClick);
      window.removeEventListener('popstate', onPop);
    };
  }, []);

  const kind = heavy(route);
  const [seen, setSeen] = useState(() => new Set([kind]));
  useEffect(() => {
    setSeen((prev) => (prev.has(kind) ? prev : new Set(prev).add(kind)));
  }, [kind]);

  // One window at a time, decided before either heavy screen is mounted — see
  // `useSingleWindow`. `null` is the question still being out: nothing is drawn
  // for it, because drawing the app and then taking it away is worse than the
  // fraction of a second the answer takes.
  const { held, taken, take } = useSingleWindow(kind !== 'other');
  const blocked = kind !== 'other' && held !== false;

  return (
    <>
      {blocked ? (
        held ? (
          <OtherWindowNotice onUse={take} />
        ) : null
      ) : (
        <>
          {seen.has('app') ? (
            <div style={{ display: kind === 'app' ? 'block' : 'none', height: '100%' }}>
              <Workspace />
            </div>
          ) : null}
          {seen.has('library') ? (
            <div style={{ display: kind === 'library' ? 'block' : 'none', height: '100%' }}>
              <Library />
            </div>
          ) : null}
          {kind === 'other' ? page(route) : null}
        </>
      )}
      {taken ? <TakenBar onTake={take} /> : null}
    </>
  );
}

const root = document.getElementById('root');
if (!root) throw new Error('#root missing');

// The traffic counter records this page and then any click on a `data-key`
// control, for the life of the page.
installTracking();

// No StrictMode: it double-invokes effects, which would load CanvasKit twice and
// run the render pipeline twice on every mount. The install offer hangs off the
// i18n provider because its copy comes from the dictionaries. The boundary is
// the whole app's: an error on the way to the screen used to be a white page.
createRoot(root).render(
  <ThemeProvider>
    <I18nProvider>
      <ErrorBoundary>
        <Shell />
      </ErrorBoundary>
      <InstallPrompt />
      <OfflineBar />
    </I18nProvider>
  </ThemeProvider>
);

// Service worker, production only: in dev it would answer the browser with the
// last build's shell instead of vite's modules. Registered after `load` so its
// precache does not race the studio's own 20MB of wasm for the connection, and a
// browser that refuses it (private mode, a plain-http origin) just loses the
// offline shell — nothing else depends on it.
if (import.meta.env.PROD && 'serviceWorker' in navigator) {
  window.addEventListener('load', () => {
    navigator.serviceWorker.register('/sw.js').catch(() => {});
  });
}