import type { Metadata } from "next";
import { cookies } from "next/headers";
import { Plus_Jakarta_Sans, Noto_Sans_SC, JetBrains_Mono } from "next/font/google";
import "./globals.css";
import Header from "@/components/Header";
import Footer from "@/components/Footer";
import Toaster from "@/components/Toaster";
import { fetchMe, fetchUnreadCount, type User } from "@/lib/api";

// 构建期下载并自托管字体：同源加载 + 自动 preload + fallback 度量校正，
// 消除 F5 时 Google CDN 字体到达后整页"由粗变细"的 FOUT 闪动
const jakarta = Plus_Jakarta_Sans({
  subsets: ["latin"],
  weight: ["400", "500", "600", "700", "800"],
  variable: "--font-jakarta",
  display: "swap",
});

const notoSC = Noto_Sans_SC({
  weight: ["400", "500", "700", "900"],
  variable: "--font-noto-sc",
  display: "swap",
});

const jetbrainsMono = JetBrains_Mono({
  subsets: ["latin"],
  weight: ["400", "500", "700"],
  variable: "--font-jetbrains",
  display: "swap",
});

export const metadata: Metadata = {
  title: {
    default: "姜十三论坛 · J13 FORUM",
    template: "%s · 姜十三论坛",
  },
  description: "姜十三论坛 - 技术分享与讨论社区",
  openGraph: {
    title: "姜十三论坛 · J13 FORUM",
    description: "姜十三论坛 - 技术分享与讨论社区",
    type: "website",
  },
};

export default async function RootLayout({
  children,
}: {
  children: React.ReactNode;
}) {
  const cookieStore = await cookies();
  // 浅色优先的设计系统，仅在显式选择暗色时挂 .dark
  const theme = cookieStore.get("j13-theme")?.value === "dark" ? "dark" : "light";

  // SSR 直出登录态（access 过期时 middleware 已先行轮转，见 middleware.ts），
  // 保证 F5 初始 HTML 中的右上角就是正确的用户区，而非先闪"登录/注册"
  const cookieHeader = cookieStore.toString();
  let user: User | null = null;
  let unread = 0;
  if (cookieStore.get("j13_refresh")?.value) {
    try {
      const [me, count] = await Promise.all([
        fetchMe(cookieHeader),
        fetchUnreadCount(cookieHeader),
      ]);
      user = me.user;
      unread = count;
    } catch {
      // 后端不可用时降级为游客视图，不阻塞页面渲染
    }
  }

  return (
    <html
      lang="zh-CN"
      className={`${theme === "dark" ? "dark" : ""} ${jakarta.variable} ${notoSC.variable} ${jetbrainsMono.variable}`}
    >
      <body className="min-h-screen flex flex-col">
        <a href="#main" className="skip-link">
          跳到主要内容
        </a>
        <Header initialUser={user} initialUnread={unread} initialTheme={theme} />
        <main
          id="main"
          tabIndex={-1}
          className="flex-1 w-full max-w-6xl mx-auto px-4 sm:px-6 py-7 sm:py-9 outline-none"
        >
          {children}
        </main>
        <Footer />
        <Toaster />
      </body>
    </html>
  );
}