import type { Metadata } from "next";
import { Toaster } from "sonner";
import { ThemeProvider } from "@/components/theme-provider";
import { FaviconUpdater } from "@/components/favicon-updater";
import { ImageDeliveryOptimizer } from "@/components/image-delivery-optimizer";
import { getSiteSettings } from "@/lib/db/queries";

import "./globals.css";
import { SessionProvider } from "next-auth/react";

const metadataBase = resolveMetadataBase();

export async function generateMetadata(): Promise<Metadata> {
  const settings = await getSiteSettings().catch(() => null);
  const siteName = String(settings?.siteName || "").trim() || "AI Chatbot";

  return {
    metadataBase,
    title: {
      template: `%s | ${siteName}`,
      default: siteName,
    },
    description:
      "AI design workspace for Canvas, Agent workflows, image editing, 3D/CAD, and local AI operations.",
    icons: {
      icon: [
        {
          url: "/api/favicon",
          sizes: "any",
        },
      ],
      apple: "/api/favicon",
      shortcut: "/api/favicon",
    },
  };
}

function resolveMetadataBase() {
  const candidate =
    process.env.NEXT_PUBLIC_APP_URL || process.env.AUTH_URL || process.env.NEXTAUTH_URL;

  if (candidate) {
    try {
      return new URL(candidate);
    } catch {
      // Keep metadata generation resilient when local env files contain placeholders.
    }
  }

  return new URL("http://localhost:3000");
}

export const viewport = {
  maximumScale: 1, // Disable auto-zoom on mobile Safari
};

const LIGHT_THEME_COLOR = "hsl(0 0% 100%)";
const DARK_THEME_COLOR = "hsl(240deg 10% 3.92%)";
const THEME_COLOR_SCRIPT = `\
(function() {
  var html = document.documentElement;
  var meta = document.querySelector('meta[name="theme-color"]');
  if (!meta) {
    meta = document.createElement('meta');
    meta.setAttribute('name', 'theme-color');
    document.head.appendChild(meta);
  }
  function updateThemeColor() {
    var isDark = html.classList.contains('dark');
    meta.setAttribute('content', isDark ? '${DARK_THEME_COLOR}' : '${LIGHT_THEME_COLOR}');
  }
  var observer = new MutationObserver(updateThemeColor);
  observer.observe(html, { attributes: true, attributeFilter: ['class'] });
  updateThemeColor();
})();`;

const CHUNK_ERROR_RECOVERY_SCRIPT = `\
(function() {
  // 安全地访问sessionStorage（某些浏览器设置可能禁止访问）
  function safeGetSessionStorage(key) {
    try {
      return sessionStorage.getItem(key);
    } catch (e) {
      return null;
    }
  }
  
  function safeSetSessionStorage(key, value) {
    try {
      sessionStorage.setItem(key, value);
      return true;
    } catch (e) {
      return false;
    }
  }
  
  // Keep one attempt per route for the browser session. A cooldown alone can
  // turn a recurring editor exception into an endless reload cycle.
  var RECOVERY_KEY = 'chunk-reload-attempted-v3:' + window.location.pathname;
  var lastReloadAt = Number(safeGetSessionStorage(RECOVERY_KEY) || '0') || 0;
  var recoveryNoticeShown = false;

  function isFlowBoardEditing() {
    var path = window.location.pathname;
    return path === '/flow-board' || path.indexOf('/flow-board/') === 0;
  }

  function showManualRecoveryNotice() {
    if (recoveryNoticeShown) return;
    recoveryNoticeShown = true;
    function show() {
      if (!document.body || !isFlowBoardEditing()) return;
      var notice = document.createElement('div');
      notice.setAttribute('role', 'alert');
      notice.setAttribute('data-runtime-recovery-notice', 'true');
      notice.style.cssText = 'position:fixed;bottom:24px;left:50%;transform:translateX(-50%);z-index:2147483647;max-width:calc(100vw - 32px);padding:12px 16px;border:1px solid var(--border,#e4e4e7);border-radius:12px;background:var(--background,#fff);color:var(--foreground,#27272a);box-shadow:0 4px 20px #0002;font:14px/1.5 system-ui;';
      notice.textContent = '部分页面资源加载失败，请先保存白板后手动刷新页面。';
      document.body.appendChild(notice);
    }
    if (document.body) show();
    else window.addEventListener('DOMContentLoaded', show, { once: true });
  }

  function shouldAutoRecover(message) {
    if (!message) return false;
    var normalized = String(message).toLowerCase();
    return (
      normalized.indexOf('chunkloaderror') !== -1 ||
      normalized.indexOf('failed to load chunk') !== -1 ||
      normalized.indexOf('loading chunk') !== -1 ||
      normalized.indexOf('failed to fetch dynamically imported module') !== -1 ||
      normalized.indexOf('error loading dynamically imported module') !== -1 ||
      normalized.indexOf('importing a module script failed') !== -1 ||
      normalized.indexOf('module script load failed') !== -1 ||
      normalized.indexOf('failed to find server action') !== -1
    );
  }
  
  function triggerAutoRecover(reason) {
    if (isFlowBoardEditing()) {
      showManualRecoveryNotice();
      return;
    }
    if (lastReloadAt) return;
    var now = Date.now();
    // If storage is blocked, a reload cannot remember its attempt and must not run.
    if (!safeSetSessionStorage(RECOVERY_KEY, String(now))) return;
    lastReloadAt = now;
    console.warn('[RuntimeRecover] 检测到页面资源加载失败，尝试恢复一次...', reason || '');
    setTimeout(function() {
      if (isFlowBoardEditing()) {
        showManualRecoveryNotice();
        return;
      }
      window.location.reload();
    }, 800);
  }

  window.addEventListener('error', function(event) {
    var message = '';
    if (event && event.message) message += event.message;
    if (event && event.error && event.error.message) {
      message += ' ' + event.error.message;
    }
    if (shouldAutoRecover(message)) {
      triggerAutoRecover(message);
    }
  }, true);
  
  window.addEventListener('unhandledrejection', function(event) {
    var reason = event && event.reason;
    var reasonText = '';
    if (typeof reason === 'string') reasonText = reason;
    else if (reason && typeof reason.message === 'string') reasonText = reason.message;
    if (shouldAutoRecover(reasonText)) {
      triggerAutoRecover(reasonText);
    }
  });
  
})();`;

export default function RootLayout({
  children,
}: Readonly<{
  children: React.ReactNode;
}>) {
  return (
    <html
      // `next-themes` injects an extra classname to the body element to avoid
      // visual flicker before hydration. Hence the `suppressHydrationWarning`
      // prop is necessary to avoid the React hydration mismatch warning.
      // https://github.com/pacocoursey/next-themes?tab=readme-ov-file#with-app
      lang="zh-CN"
      suppressHydrationWarning
    >
      <head>
        <script
          dangerouslySetInnerHTML={{
            __html: THEME_COLOR_SCRIPT,
          }}
        />
        <script
          dangerouslySetInnerHTML={{
            __html: CHUNK_ERROR_RECOVERY_SCRIPT,
          }}
        />
      </head>
      <body className="antialiased">
        <FaviconUpdater />
        <ImageDeliveryOptimizer />
        <ThemeProvider
          attribute="class"
          defaultTheme="system"
          disableTransitionOnChange
          enableSystem
        >
          <Toaster position="top-center" />
          <SessionProvider>{children}</SessionProvider>
        </ThemeProvider>
      </body>
    </html>
  );
}