import { useSearchParams } from 'react-router';
import { DEFAULT_SECTION, isSectionKey, sectionFor, sectionOpen, type SectionKey } from './sections';
import { AdministrationPanel } from './AdministrationPanel';
import { MediaPanel } from './MediaPanel';
import { MessagesPanel } from './MessagesPanel';
import { PlannedSection } from './PlannedSection';
import { useReady } from './useReady';

/**
 * The right column: whichever section the nav has selected.
 *
 * It reads `?section=` from the URL rather than being handed it — the two panels are siblings in a
 * workspace and neither owns the other.
 *
 * ── There used to be a `?config=1` ──
 *
 * The connection form was an overlay reached from a link in this header, because it was not one of the
 * sections. Now it IS one — Administration — so the overlay is gone and so is the link. A second route
 * to the same screen is a second thing to keep correct, and the two disagreed the moment a section was
 * selected underneath a form that covered it.
 *
 * ── Not ready means Administration, whatever the URL says ──
 *
 * The gate is `useReady`, shared with the nav so the two cannot disagree. Enforced HERE and not only
 * there, because the nav can only decline to offer a link — `?section=gallery` typed into the address
 * bar, or a bookmark from before the connection was forgotten, arrives without going through it. A
 * nav that hides a door is a courtesy; this is the lock.
 */

/**
 * Which component renders which section.
 *
 * A map rather than a conditional on `built`. The version of this that read
 * `built ? <MessagesPanel/> : <Planned/>` was correct only while exactly one section existed — the
 * second one to be finished would have rendered Messages under its own name, which is the kind of bug
 * that looks like a data problem for an hour. A key with no entry here falls through to Planned, so
 * marking a section `built` in sections.ts without writing its panel fails visibly rather than
 * silently showing somebody else's.
 */
const PANELS: Partial<Record<SectionKey, () => React.JSX.Element>> = {
  messages: MessagesPanel,
  administration: AdministrationPanel,
  media: MediaPanel,
};

export const DetailPanel = () => {
  const [params] = useSearchParams();
  const raw = params.get('section');
  const selected: SectionKey = isSectionKey(raw) ? raw : DEFAULT_SECTION;

  const { ready, rootSet, loading } = useReady();

  if (loading) {
    return <div className="flex size-full items-center justify-center p-6 text-sm text-muted-foreground">Loading…</div>;
  }

  /*
    Not ready, so Administration regardless of what the URL asked for. The header then NAMES it, which
    is the part the old overlay could not do: the form used to appear under whichever row happened to
    be highlighted, so it read as that section being broken rather than as one step not done yet.
  */
  /*
    A section that cannot be opened sends you to Administration, because that is where every requirement
    is satisfied. Asked per section rather than by one flag: Media is reachable the moment a root
    location exists, long before fofos is connected.
  */
  const wanted = sectionFor(selected);
  const current = sectionOpen(wanted, { ready, rootSet }) ? wanted : sectionFor('administration');

  const Panel = current.built ? PANELS[current.key] : undefined;

  return (
    <div className="flex size-full flex-col overflow-hidden">
      <div className="min-h-0 flex-1">{Panel ? <Panel /> : <PlannedSection section={current} />}</div>
    </div>
  );
};