/**
 * @file App.tsx
 * @description Top-level React tree for the AgentHub dashboard.
 * Wires together routing, real-time WebSocket ingestion, browser notifications,
 * and the splash screen shown on cold load.
 *
 * ## Data flow
 * 1. {@link useWebSocket} connects to the server's `/ws` endpoint.
 * 2. Each inbound {@link WSMessage} is published on the in-memory
 *    {@link eventBus} so any page can subscribe without prop drilling.
 * 3. {@link useNotifications} listens for alert-worthy events and surfaces OS
 *    notifications when permitted.
 *
 * ## Routing
 * All feature pages nest under {@link Layout}, which owns the sidebar and
 * passes `wsConnected` for the connection badge. Unknown paths fall through to
 * {@link NotFound}.
 *
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */
/* =============================================================================
 * MODULE_GUIDE — extended in-file reference (comments only; safe to read, never executed)
 * =============================================================================
 * **Purpose:** Dashboard module consumed by the React client, MCP tools, or desktop shell depending on deployment mode.
 *
 * ## Design constraints
 * - Local-first: no telemetry leaves the machine unless the user configures webhooks.
 * - Fail-safe hooks path on the server must never block Claude Code; UI mirrors that
 *   philosophy by degrading gracefully (empty states, stale badges, reconnect loops).
 * - Destructive flows stay behind explicit confirmation modals and server-side gates.
 * - Internationalization: user-visible strings belong in i18n JSON, not literals here.
 *
 * ## Remote data & SSH
 * Remote Data Sources let operators aggregate multiple machines. SSH entries describe
 * how to reach a peer dashboard; the global data scope (`dataScope.ts`) narrows every
 * scoped GET via `?sources=`. Health checks and import history surface in Settings.
 *
 * ## Internal dependencies
 * - `./components/Layout`
 * - `./components/SplashScreen`
 * - `./pages/Dashboard` (lazy)
 * - `./pages/History` (lazy)
 * - `./pages/SessionDetail` (lazy)
 * - `./pages/SettingsHub` (lazy)
 * - `./pages/Workspace` (lazy)
 *
 * ## Testing pointers
 * - Prefer colocated `__tests__` with Vitest + Testing Library for UI.
 * - Server contract changes require `npm run test:server` and OpenAPI sync.
 *
 * ## Related docs
 * - `ARCHITECTURE.md` — hooks → API → SQLite → WebSocket → UI pipeline.
 * - `docs/API.md` — REST reference.
 * - `skills/file-headers/` — mandatory `@author` header policy.
 * ============================================================================= */

import { BrowserRouter, Routes, Route, Navigate, useParams, useLocation } from "react-router-dom";
import { lazy, Suspense, useCallback, useEffect, type ReactNode } from "react";
import { useTranslation } from "react-i18next";
import { Layout } from "./components/Layout";
import { DocumentTitle } from "./components/DocumentTitle";
import { SplashScreen } from "./components/SplashScreen";
import { GlobalTooltip } from "./components/Tooltip";
import { Toaster } from "./components/Toaster";
import { ConfirmHost } from "./components/ConfirmHost";
import { RouteErrorBoundary, reloadOnce } from "./components/RouteErrorBoundary";
import { usePermissions } from "./components/AuthGate";
import { NotFound } from "./pages/NotFound";
import { useWebSocket } from "./hooks/useWebSocket";
import { useNotifications } from "./hooks/useNotifications";
import { eventBus } from "./lib/eventBus";
import { copyOnCtrlShiftC } from "./lib/keys";
import { reloadOnNewBuild } from "./lib/newBuildReload";
import type { WSMessage } from "./lib/types";

// The heavy pages (xterm, the diff viewer, the settings editors) load on first
// visit instead of in the initial bundle — the Dashboard and History too, so the
// entry chunk holds only the shell.
const Dashboard = lazy(() => import("./pages/Dashboard").then((m) => ({ default: m.Dashboard })));
const History = lazy(() => import("./pages/History").then((m) => ({ default: m.History })));
const Workspace = lazy(() => import("./pages/Workspace").then((m) => ({ default: m.Workspace })));
const SettingsHub = lazy(() =>
  import("./pages/SettingsHub").then((m) => ({ default: m.SettingsHub }))
);
const SessionDetail = lazy(() =>
  import("./pages/SessionDetail").then((m) => ({ default: m.SessionDetail }))
);
const SnapshotView = lazy(() =>
  import("./pages/SnapshotView").then((m) => ({ default: m.SnapshotView }))
);
const FilesPage = lazy(() => import("./pages/FilesPage").then((m) => ({ default: m.FilesPage })));
const Users = lazy(() => import("./pages/Users").then((m) => ({ default: m.Users })));
const Artifacts = lazy(() => import("./pages/Artifacts").then((m) => ({ default: m.Artifacts })));

function PageFallback() {
  const { t } = useTranslation();
  return (
    <div role="status" className="flex items-center justify-center py-20 text-sm text-fg-muted">
      {t("common:loading")}
    </div>
  );
}

function Page({ children }: { children: ReactNode }) {
  const { pathname } = useLocation();
  return (
    <RouteErrorBoundary resetKey={pathname}>
      <Suspense fallback={<PageFallback />}>{children}</Suspense>
    </RouteErrorBoundary>
  );
}

/** A page only a shared server needs (the File Explorer): local mode goes home. */
function ServerOnly({ children }: { children: ReactNode }) {
  return usePermissions().local ? <Navigate to="/" replace /> : <>{children}</>;
}

/** Keyed by the id so moving to another session starts from fresh state. */
function SessionDetailRoute() {
  const { id } = useParams();
  return <SessionDetail key={id} />;
}

/**
 * Application root component mounted by {@link main.tsx}.
 * @returns Routed dashboard UI inside `BrowserRouter`.
 */
export default function App() {
  const onMessage = useCallback((msg: WSMessage) => {
    eventBus.publish(msg);
  }, []);

  const { connected } = useWebSocket(onMessage);
  useNotifications();

  // A self-update replaced the hashed assets this tab still references: Vite
  // reports the failed preload here; reload once (guarded against loops).
  useEffect(() => {
    const onPreloadError = (e: Event) => {
      if (reloadOnce()) e.preventDefault();
    };
    window.addEventListener("vite:preloadError", onPreloadError);
    return () => window.removeEventListener("vite:preloadError", onPreloadError);
  }, []);

  // The server came back as a newer version (any tab, any way it was updated):
  // load its UI build instead of leaving the user to press F5.
  useEffect(() => reloadOnNewBuild(), []);

  // Ctrl+Shift+C is copy here (Linux terminal habit), not the browser's inspector.
  useEffect(() => {
    window.addEventListener("keydown", copyOnCtrlShiftC, true);
    return () => window.removeEventListener("keydown", copyOnCtrlShiftC, true);
  }, []);

  return (
    <>
      <SplashScreen />
      {/* One renderer gives every `title` in the app the designed bubble —
          see components/Tooltip.tsx for why it is not a wrapper component. */}
      <GlobalTooltip />
      {/* App-wide toasts and promise-based confirms: lib/toast.ts, lib/confirm.ts. */}
      <Toaster />
      <ConfirmHost />
      <BrowserRouter>
        <DocumentTitle />
        <Routes>
          <Route element={<Layout wsConnected={connected} />}>
            <Route
              index
              element={
                <Page>
                  <Dashboard />
                </Page>
              }
            />
            <Route
              path="sessions"
              element={
                <Page>
                  <History />
                </Page>
              }
            />
            <Route
              path="sessions/:id"
              element={
                <Page>
                  <SessionDetailRoute />
                </Page>
              }
            />
            <Route
              path="snapshot/:token"
              element={
                <Page>
                  <SnapshotView />
                </Page>
              }
            />
            <Route path="query" element={<Navigate to="/sessions?view=agents" replace />} />
            <Route path="activity" element={<Navigate to="/sessions?view=events" replace />} />
            <Route
              path="workflows"
              element={<Navigate to="/?tab=analytics&sub=workflow" replace />}
            />
            <Route path="lanes" element={<Navigate to="/workspace" replace />} />
            <Route
              path="cc-config"
              element={<Navigate to="/settings/agents/claude-code" replace />}
            />
            <Route path="run" element={<Navigate to="/workspace" replace />} />
            <Route
              path="workspace"
              element={
                <Page>
                  <Workspace />
                </Page>
              }
            />
            <Route
              path="artifacts"
              element={
                <Page>
                  <Artifacts />
                </Page>
              }
            />
            <Route
              path="files"
              element={
                <ServerOnly>
                  <Page>
                    <FilesPage />
                  </Page>
                </ServerOnly>
              }
            />
            <Route
              path="users"
              element={
                <Page>
                  <Users />
                </Page>
              }
            />
            <Route
              path="settings/*"
              element={
                <Page>
                  <SettingsHub />
                </Page>
              }
            />
            <Route path="*" element={<NotFound />} />
          </Route>
        </Routes>
      </BrowserRouter>
    </>
  );
}