import { useCallback, useEffect, useRef, useState } from 'react';
import { FolderOpen, TriangleAlert } from 'lucide-react';
import { FileBrowserApp } from 'officerdev';
import { useClient } from 'hooks/useClient';

/**
 * The site's own media, browsed in place.
 *
 * ── It embeds the platform's file browser rather than reimplementing one ──
 *
 * Upload, delete, rename, move, thumbnails, the context menu and every task that hangs off it already
 * exist and are maintained in one place. A plugin drawing its own file list would be a second one to
 * keep in step, and it would arrive without any of that.
 *
 * ── `basePath` is a jail, not a starting folder ──
 *
 * `useFileBrowserApp` resets `currentPath` whenever it leaves `basePath`, so pointing it at
 * `<root>/media/originals` means the breadcrumb stops there and `derived/` is not reachable by
 * navigating. That is the behaviour the owner asked for: people work in originals, and derived is made
 * for them.
 *
 * **It is a guardrail, not a permission boundary, and the difference matters.** The file-browser API is
 * unchanged and still addresses the whole home — somebody with file access can reach `derived/` through
 * the Files screen or by hand. Confining it properly would mean scoping the API per user, which is a
 * platform change and a much larger one. What this prevents is an accident, not a determined person.
 *
 * ── Nothing here is fofos-specific ──
 *
 * The root is a setting, `media/originals` is the layout this plugin creates, and the panel reads both
 * from the API. Another site's admin plugin built from this one changes the label and nothing else.
 */

type Settings = { rootPath: string; rootRelative: string | null; isSet: boolean };

/** Where the uploads live, relative to the root. The other half, `derived/`, is deliberately not shown. */
const ORIGINALS = 'media/originals';

export const MediaPanel = () => {
  const client = useClient();
  const clientRef = useRef(client);
  clientRef.current = client;

  const [settings, setSettings] = useState<Settings | null>(null);
  const [denied, setDenied] = useState(false);

  const load = useCallback(async () => {
    try {
      setSettings(await clientRef.current.get<Settings>('/fofos-admin/_config/root'));
    } catch (failure) {
      // The root is owner-only. A member sees the section and is told why rather than an empty browser.
      if ((failure as { status?: number })?.status === 403) setDenied(true);
      else setSettings({ rootPath: '', rootRelative: null, isSet: false });
    }
  }, []);

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

  if (denied) {
    return <Notice icon={TriangleAlert}>Only the owner can see where the site's media lives.</Notice>;
  }

  if (!settings) {
    return <Notice icon={FolderOpen}>Loading…</Notice>;
  }

  /*
    A root outside the owner's home is a legitimate setting and the file browser cannot address it —
    everything it does is relative to `home`. Said plainly here rather than rendering an empty folder,
    which would read as "there is nothing in your media".
  */
  if (!settings.rootRelative) {
    return (
      <Notice icon={TriangleAlert}>
        The root location is outside your home directory, so the file browser cannot show it. Move it under your home in
        Administration, or use the Files screen.
      </Notice>
    );
  }

  const base = `${settings.rootRelative === '/' ? '' : settings.rootRelative}/${ORIGINALS}`;

  /*
    Just the browser. No banner explaining `derived/`.

    The people using this upload photographs; the two-folder split is the machine's business, not
    theirs. A line at the top of every visit is a permanent tax paid by everyone to answer a question
    almost nobody asks — and it is written properly in the affordance and the plugin's docs.

    `rootLabel` so the breadcrumb reads "Media" rather than "originals": the folder's name on disk is
    an implementation detail of how this plugin lays out a root, and the section is called Media.

    `panelId` so the folder somebody is in survives a reload — without it every refresh drops them
    back at the top, however deep they were.
  */
  return <FileBrowserApp basePath={base} rootLabel="Media" panelId="fofos-admin-media" />;
};

const Notice = ({ icon: Icon, children }: { icon: typeof FolderOpen; children: React.ReactNode }) => (
  <div className="flex size-full flex-col items-center justify-center gap-2 p-6 text-center">
    <Icon className="size-6 text-muted-foreground/60" />
    <p className="max-w-sm text-sm text-muted-foreground">{children}</p>
  </div>
);