"use client";

import { useEffect, useLayoutEffect, useRef, useState } from "react";
import { usePathname } from "next/navigation";
import Header from "@/components/Header";
import Footer from "@/components/Footer";
import BackToTop from "@/components/BackToTop";
import type { User } from "@/lib/api";

function pathIsAdmin(pathname: string | null) {
  if (!pathname) return false;
  return pathname === "/admin" || pathname.startsWith("/admin/");
}

function pathIsChat(pathname: string | null) {
  if (!pathname) return false;
  return pathname === "/chat" || pathname.startsWith("/chat/");
}

function pathIsComposeStudio(pathname: string | null) {
  if (!pathname) return false;
  return pathname === "/compose" || /^\/post\/[^/]+\/edit\/?$/.test(pathname);
}

/** 帖子详情（非 edit）移动端有底栏，回顶需抬高 */
function pathIsPostDetail(pathname: string | null) {
  if (!pathname) return false;
  return /^\/post\/[^/]+$/.test(pathname);
}

/**
 * 公开站 chrome 闸门：/admin 不渲染 Header/Footer/1440 main。
 * 首屏用 middleware 的 x-pathname 初值保证 hydration 一致；
 * 挂载后同步跟 usePathname（渲染期判定，避免 useEffect 晚一拍闪框）。
 */
export default function SiteChrome({
  initialIsAdmin,
  user,
  unread,
  chatUnread,
  theme,
  siteName,
  allowRegister,
  children,
}: {
  initialIsAdmin: boolean;
  user: User | null;
  unread: number;
  chatUnread: number;
  theme: "light" | "dark";
  siteName: string;
  allowRegister: boolean;
  children: React.ReactNode;
}) {
  const pathname = usePathname();
  const [mounted, setMounted] = useState(false);
  const isFirstPath = useRef(true);

  useEffect(() => {
    setMounted(true);
  }, []);

  // Next.js App Router：新页顶若仍在视口内会跳过滚顶。sticky Header 把
  // 「微滚后的页顶」判成已可见，软导航就会停在资料卡上沿。父级 layoutEffect
  // 晚于 Next.js 子级滚动处理，且不影响 F5 / 带 hash 的定位。
  useLayoutEffect(() => {
    if (isFirstPath.current) {
      isFirstPath.current = false;
      return;
    }
    if (pathIsAdmin(pathname)) return;
    if (window.location.hash) return;
    window.scrollTo({ top: 0, left: 0, behavior: "auto" });
  }, [pathname]);

  // 首屏跟 SSR；之后在渲染期直接读 pathname，软导航无 Header 闪动
  const isAdmin = mounted ? pathIsAdmin(pathname) : initialIsAdmin;

  if (isAdmin) {
    return <>{children}</>;
  }

  // 聊天 / 发帖工作台锁视口，窗口回顶无意义
  const showBackToTop = !pathIsChat(pathname) && !pathIsComposeStudio(pathname);

  return (
    <>
      <Header
        initialUser={user}
        initialUnread={unread}
        initialChatUnread={chatUnread}
        initialTheme={theme}
        siteName={siteName}
        allowRegister={allowRegister}
      />
      <main
        id="main"
        tabIndex={-1}
        className="flex-1 w-full max-w-[1440px] mx-auto px-4 sm:px-6 py-7 sm:py-[var(--main-pad-y)] outline-none"
      >
        {children}
      </main>
      <Footer siteName={siteName} />
      {showBackToTop ? (
        <BackToTop liftForMobileBar={pathIsPostDetail(pathname)} />
      ) : null}
    </>
  );
}