import { useCallback, useEffect, useRef, useState } from 'react';
import { useClient } from 'hooks/useClient';
import { useFofosChanged } from './channel';

/**
 * Is this plugin ready to be USED — that is, may anything but Administration be opened?
 *
 * ── One condition, read in two places ──
 *
 * The nav decides whether a section is clickable and the detail panel decides what to render. Those
 * are two answers to the same question, and a nav that lets you click a row the panel then refuses is
 * worse than one that does not offer it. So the condition lives here and both panels read it, rather
 * than each deciding for itself — the panels are siblings and neither may own the other.
 *
 * ── It is a GATE, not a hint ──
 *
 * Not ready means the site sections cannot be reached at all, by clicking or by typing `?section=` in
 * the address bar. Every one of them is a window onto fofos, and without a working connection there is
 * nothing behind any of them; offering nine doors onto the same "not connected" message taught nobody
 * anything and made a setup step look like nine faults.
 *
 * ── Hardcoded false, deliberately, for now ──
 *
 * The shape is real and the plumbing is real: it asks `/status`, it re-asks whenever the connection
 * changes, and it reports while it is still asking. Only the final verdict is pinned, so turning the
 * gate on is one line rather than a feature.
 *
 * ── Both panels call this, so `/status` is fetched twice ──
 *
 * Known and accepted for now: two cheap GETs that answer the same question, kept in step because both
 * re-run on the same `useFofosChanged` signal. The alternative is a context provider around the two
 * panels, which is a shared-state boundary this does not yet need — and the duplication is visible
 * here rather than hidden in a wrapper. If the condition grows expensive, that is the moment to fix
 * it, not before.
 *
 * What it will become is roughly `configured && lastProbeOk` — the connection is stored AND the last
 * probe reached fofos — but "all the info needed in Administration" is not settled yet and will grow
 * past those two. That is why this returns a single boolean and not the parts: callers must not start
 * assembling their own version of the condition out of the pieces.
 */

type Status = { configured: boolean; lastProbeOk: boolean | null; rootSet: boolean };

export type Readiness = {
  /** The fofos connection works. Gates every section that READS the site. */
  ready: boolean;
  /**
   * A root location has been chosen.
   *
   * Separate from `ready` because the two are genuinely different questions and one section depends on
   * each. Media needs a folder on this machine; it never speaks to fofos, and gating it behind a
   * connection it does not use was the bug that made this distinction necessary.
   */
  rootSet: boolean;
  /** Still asking. Callers should render nothing rather than guess — see below. */
  loading: boolean;
};

export const useReady = (): Readiness => {
  const client = useClient();
  const clientRef = useRef(client);
  clientRef.current = client;

  const [status, setStatus] = useState<Status | null>(null);
  const [signal] = useFofosChanged();

  const check = useCallback(async () => {
    try {
      setStatus(await clientRef.current.get<Status>('/fofos-admin/status'));
    } catch {
      /*
        Cannot tell. Treated as CONFIGURED rather than not — a transient failure must never present as
        "you have not set this up", which is a far more alarming thing to be told and invites somebody
        to re-enter a connection that was never the problem.
      */
      setStatus({ configured: true, lastProbeOk: null, rootSet: false });
    }
  }, []);

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

  // ────────────────────────────────────────────────────────────────────────────────────────────────
  // The gate. Replace `false` with the real condition — nothing else here has to change.
  // ────────────────────────────────────────────────────────────────────────────────────────────────
  const ready = false;

  return { ready, rootSet: status?.rootSet ?? false, loading: status === null };
};