import { useEffect, useMemo, useState } from "react";
import { TopBar } from "./components/TopBar";
import { Sidebar, MobileNav } from "./components/Nav";
import { ModeRouter } from "./modes/ModeRouter";
import { AdminApp } from "./admin/AdminApp";
import { Login } from "./components/Login";
import { parseAdminRoute, readAdminEntry, subscribeAdminRoute } from "./admin/router";
import { connectWs, disconnectWs } from "./lib/ws";
import { useWsResync } from "./lib/useWsResync";
import { markSessionOpenedRead } from "./lib/sessionRead";
import { initTheme } from "./lib/theme";
import {
  fetchMessages,
  fetchPersonas,
  fetchSessions,
  getAuthToken,
} from "./lib/api";
import type { SessionMeta } from "./lib/types";
import { useAppStore } from "./store/useAppStore";
import { personaMoodSeed } from "./store/personaSelectors";

export default function App(): React.ReactNode {
  // Apply the persisted (dark-first) theme and open the realtime channel only
  // when we hold a token — otherwise the gateway rejects the handshake with 401.
  //
  // 管理面板是**安全入口**（裁决 1.6 / 16.4.7，design/07 §0.2）：入口前缀由后端
  // 按 .env 的 ADMIN_PATH 注入到面板那一份 index.html
  // （`window.__CYRENE_ADMIN_ENTRY__`，见 internal/services/gateway/routes.go）。
  // 用户端页面没有这个全局量，因此这里的 route.admin 恒为 false —— 用户端
  // 既不含入口链接、也解析不出面板路由。面板模块切换走 history（不再读 hash，
  // hash 只留给渠道页的子页）。
  const entry = useMemo(readAdminEntry, []);
  const [route, setRoute] = useState(() => parseAdminRoute(window.location.pathname, entry));
  const [menuOpen, setMenuOpen] = useState(false);
  const setPersonas = useAppStore((s) => s.setPersonas);
  const seedMoods = useAppStore((s) => s.seedMoods);
  // WS 重连后重跑本页的引导读取（切片 P0 的顺带件）：握手 history 回放只补**消息**，
  // 会话列表 / 角色目录 / 消息页这些初始 GET 在断线窗口里的变化没人补，页面会一直
  // 停在旧态。这里只递增一个世代号，下面的加载副作用把它列进依赖即可（首次连接不触发，
  // 页面挂载时的初始加载已经做过一遍）。
  const [resyncNonce, setResyncNonce] = useState(0);
  useWsResync(() => setResyncNonce((n) => n + 1));

  useEffect(() => {
    initTheme();
    if (getAuthToken()) connectWs();
    const onRoute = () => setRoute(parseAdminRoute(window.location.pathname, entry));
    const unsubscribe = subscribeAdminRoute(onRoute);
    return () => {
      disconnectWs();
      unsubscribe();
    };
  }, [entry]);

  // Load the role catalog (design/22 §4.6). The rendered role is no longer one
  // global value: it is derived per active session from this catalog plus that
  // session's own `personaId` (see store/personaSelectors), so this fetch only has
  // to fill the catalog. It must not hinge on a single mount-time
  // request: a token may appear (login) after mount, or the fetch may transiently
  // fail — in which case the avatar/name would stay on the neutral placeholder. We
  // re-run when the token appears, and retry on failure. The catalog is persisted
  // by useAppStore, so a refresh renders the right role before the fetch returns.
  //
  // The catalog also carries each role's *role-level* mood (design/01 §2: emotion
  // follows the role), which seeds the mood bucket of every role it names — that is
  // what stops the 心情 badge from flashing empty after a refresh. Seeding merges
  // (see `seedMoods`): a role the backend reports no mood for is skipped, so a WS
  // `mood` frame that landed first is never cleared.
  const token = getAuthToken();
  useEffect(() => {
    if (!token) return;
    let cancelled = false;
    let retry: number | null = null;

    const load = () => {
      if (cancelled) return;
      fetchPersonas()
        .then((list) => {
          if (cancelled) return;
          setPersonas(list);
          seedMoods(personaMoodSeed(list));
        })
        .catch(() => {
          // Transient failure — retry rather than leaving the placeholder forever.
          if (!cancelled) retry = window.setTimeout(load, 3000);
        });
    };
    load();

    return () => {
      cancelled = true;
      if (retry !== null) window.clearTimeout(retry);
    };
  }, [token, setPersonas, seedMoods, resyncNonce]);

  const sessions = useAppStore((s) => s.sessions);
  const activeSessionId = useAppStore((s) => s.activeSessionId);
  const setSessions = useAppStore((s) => s.setSessions);
  const setActiveSession = useAppStore((s) => s.setActiveSession);
  const setMessages = useAppStore((s) => s.setMessages);

  // Load the session list once we hold a token, then focus a session: a persisted
  // (still-present) session id, else the main session (design/16 §4.1). The main
  // session has `type === "main"`; fall back to the first entry, then clear.
  useEffect(() => {
    if (!token) return;
    let cancelled = false;
    fetchSessions()
      .then((list) => {
        if (cancelled) return;
        const byId = Object.fromEntries(
          list.map((s) => [s.id, s] as const)
        ) as Record<string, SessionMeta>;
        setSessions(list);
        const main = list.find((s) => s.type === "main") ?? list[0];
        const next =
          activeSessionId && byId[activeSessionId] ? activeSessionId : main?.id;
        setActiveSession(next ?? "");
      })
      .catch(() => {
        // Backend not wired yet — leave the shell in its untouched state.
      });
    return () => {
      cancelled = true;
    };
  }, [token, setSessions, setActiveSession, resyncNonce]);

  // Whenever the focused session changes (switch, new, or first load) and it is
  // a session we know about, pull its initial page of history into the panel, then
  // advance that session's read cursor (协同 B3/D4) — *after* the page lands, so the
  // cursor never passes messages the user was never shown. The effect hinges on
  // *whether* the session is known rather than on the list's identity: clearing the
  // unread badge rewrites `sessions`, and keying on it would re-fetch history (and
  // so double every session switch) for a metadata-only change.
  const activeSessionKnown = Boolean(sessions[activeSessionId]);
  useEffect(() => {
    if (!activeSessionId || !activeSessionKnown) return;
    let cancelled = false;
    fetchMessages(activeSessionId, undefined, 50)
      .then((list) => {
        if (cancelled) return;
        setMessages(list);
        markSessionOpenedRead(activeSessionId);
      })
      .catch(() => {
        if (!cancelled) setMessages([]);
      });
    return () => {
      cancelled = true;
    };
  }, [activeSessionId, activeSessionKnown, setMessages, resyncNonce]);

  // The M9 modal UI and the admin subsystem (design/10) are two separate shells.
  // 面板由安全入口路径进入（见上方 route 注释），每个模块是前缀下的一段路径。
  if (route.admin) {
    return <AdminApp section={route.section} />;
  }

  // No credential: never render the chat shell (it would silently show an
  // "未登录" shell with no way in). Show the user-side login card instead; its
  // onSuccess reloads the page so connectWs + session/persona effects re-run
  // with the fresh token. Admin shell keeps its own LoginGate.
  if (!getAuthToken()) {
    return <Login onSuccess={() => window.location.reload()} />;
  }

  return (
    <div className="flex h-full flex-col">
      <TopBar onMenu={() => setMenuOpen(true)} />
      <div className="flex min-h-0 flex-1">
        <Sidebar />
        <main className="relative min-h-0 flex-1 overflow-y-auto">
          <ModeRouter />
        </main>
      </div>
      <MobileNav open={menuOpen} onClose={() => setMenuOpen(false)} />
    </div>
  );
}