import type { Metadata } from "next";
import { cookies } from "next/headers";
import Link from "next/link";
import { PenSquare, SearchX, MessagesSquare } from "lucide-react";
import {
  fetchPosts,
  fetchOverview,
  fetchBoardSidebar,
  type OverviewResponse,
  type BoardSidebarResponse,
} from "@/lib/api";
import { authCookieHeader } from "@/lib/cookies";
import { getMeCached } from "@/lib/serverData";
import Pagination from "@/components/Pagination";
import PostRow from "@/components/PostRow";
import FeedTabs, { type FeedSort } from "@/components/home/FeedTabs";
import FeedNewTip from "@/components/home/FeedNewTip";
import { WorkspaceNav, WorkspaceNavMobile } from "@/components/home/WorkspaceNav";
import { CommunityPanels, CommunityPanelsMobile } from "@/components/home/CommunityPanels";
import {
  BoardPanels,
  BoardPanelsMobile,
  BoardMissingPanel,
} from "@/components/home/BoardPanels";

export const metadata: Metadata = {
  title: "姜十三论坛 · 技术讨论社区",
  description: "姜十三论坛，分享技术、讨论问题、交流心得的社区",
};

interface HomePageProps {
  searchParams: Promise<{ q?: string; page?: string; sort?: string; board?: string }>;
}

function normalizeSort(v?: string): FeedSort {
  if (v === "new" || v === "recommended") return v;
  return "latest";
}

// 空结果面板（无帖 / 无搜索结果）
function EmptyState({ keyword }: { keyword: string }) {
  return (
    <div className="text-center py-20 px-6">
      <span
        className="inline-flex w-14 h-14 rounded-full items-center justify-center mb-4"
        style={{ background: "var(--accent-soft)", color: "var(--accent)" }}
      >
        {keyword ? <SearchX size={26} /> : <MessagesSquare size={26} />}
      </span>
      <p className="font-bold text-lg" style={{ color: "var(--ink)" }}>
        {keyword ? "没有找到相关帖子" : "还没有帖子"}
      </p>
      <p className="meta mt-1.5">
        {keyword ? `换个关键词试试，或者发起“${keyword}”相关的话题` : "成为第一个发起讨论的人吧"}
      </p>
      {keyword ? (
        <div className="flex items-center justify-center gap-3 mt-6">
          <Link href="/" className="btn btn-line">
            清除搜索
          </Link>
          <Link href="/compose" className="btn btn-primary">
            <PenSquare size={15} /> 发起这个话题
          </Link>
        </div>
      ) : (
        <Link href="/compose" className="btn btn-primary mt-6">
          <PenSquare size={15} /> 写新帖
        </Link>
      )}
    </div>
  );
}

export default async function HomePage({ searchParams }: HomePageProps) {
  const sp = await searchParams;
  const keyword = sp.q?.trim() || "";
  const page = Math.max(1, parseInt(sp.page || "1", 10) || 1);
  const sort = normalizeSort(sp.sort);
  const boardId = Math.max(0, parseInt(sp.board || "0", 10) || 0);
  const isSearch = keyword.length > 0;

  const cookie = authCookieHeader(await cookies());
  // 与 layout 共享同一份 /me 请求（React cache 去重）
  const mePromise = getMeCached(cookie || undefined);
  const postsPromise = fetchPosts(
    page,
    20,
    isSearch || boardId <= 0 ? undefined : boardId,
    sort,
    keyword,
    sort === "recommended",
    cookie
  );
  // 聚合面板失败不阻塞帖子流
  const overviewPromise: Promise<OverviewResponse | null> = fetchOverview(cookie).catch(() => null);
  const boardSidebarPromise: Promise<BoardSidebarResponse | null> =
    boardId > 0 && !isSearch
      ? fetchBoardSidebar(boardId, cookie).catch(() => null)
      : Promise.resolve(null);

  const [me, postsData, overview, boardSidebar] = await Promise.all([
    mePromise,
    postsPromise,
    overviewPromise,
    boardSidebarPromise,
  ]);
  const user = me.user;
  const boards = overview?.boards ?? [];
  const activeBoard = boards.find((b) => b.id === boardId) || boardSidebar?.board || null;
  const showBoardPanels = boardId > 0 && !isSearch;
  // boardId 有效但接口失败 → 显示简卡；成功则板级右栏；否则全站右栏
  const boardPanelsMissing = showBoardPanels && !boardSidebar;

  // 搜索态：单栏占满，无 Tabs/侧栏
  if (isSearch) {
    return (
      <div className="max-w-3xl mx-auto">
        <div className="mb-5">
          <h1 className="text-[24px] sm:text-[28px] font-extrabold tracking-tight" style={{ color: "var(--ink)" }}>
            搜索“<span style={{ color: "var(--accent)" }}>{keyword}</span>”
          </h1>
          <p className="meta mt-2">共 {postsData.total} 篇结果 · 按相关度与时间排序</p>
        </div>
        <div className="panel overflow-hidden">
          {postsData.posts.length > 0 ? (
            postsData.posts.map((post, i) => (
              <PostRow key={post.id} post={post} boardHref index={i} showViews={false} showLike={false} />
            ))
          ) : (
            <EmptyState keyword={keyword} />
          )}
        </div>
        <Pagination
          total={postsData.total}
          page={page}
          size={20}
          basePath="/"
          query={{ q: keyword }}
        />
      </div>
    );
  }

  // 置顶帖直接按后端 pinned DESC 顺序并入统一信息流；标题仅供屏幕阅读器
  const heading = activeBoard
    ? activeBoard.name
    : sort === "new"
      ? "最新发布"
      : sort === "recommended"
        ? "推荐帖"
        : "最新讨论";

  const pageQuery: Record<string, string> = {};
  if (boardId > 0) pageQuery.board = String(boardId);
  if (sort !== "latest") pageQuery.sort = sort;

  return (
    <div>
      <WorkspaceNavMobile boards={boards} user={user} />

      <div className="flex items-start gap-6 xl:gap-7 mt-5 lg:mt-0">
        <WorkspaceNav boards={boards} user={user} />

        {/* 中栏：tab 栏与帖子流为同一个整体卡片（左栏切板块只替换这一列） */}
        <div className="flex-1 min-w-0">
          <h1 className="sr-only">{heading}</h1>

          <div className="panel overflow-hidden">
            <div className="flex items-center justify-between gap-2 px-3 sm:px-4 pt-3 pb-2.5">
              <FeedTabs current={sort} boardId={boardId} />
              <span className="meta shrink-0 text-[12px] tabular-nums">
                共 {postsData.total} 篇
              </span>
            </div>
            {user && (
              <FeedNewTip
                sort={sort}
                boardId={boardId}
                page={page}
                userId={user.id}
              />
            )}
            {postsData.posts.length > 0 ? (
              postsData.posts.map((post, i) => (
                <PostRow
                  key={post.id}
                  post={post}
                  boardHref={!activeBoard}
                  compact
                  index={i}
                  showViews={false}
                  showLike={false}
                />
              ))
            ) : (
              <EmptyState keyword="" />
            )}
          </div>

          <Pagination
            total={postsData.total}
            page={page}
            size={20}
            basePath="/"
            query={Object.keys(pageQuery).length > 0 ? pageQuery : undefined}
          />
        </div>

        {/* 右栏：选中板块时切板级面板，否则全站社区面板 */}
        {showBoardPanels ? (
          boardSidebar ? (
            <BoardPanels
              board={boardSidebar.board}
              moderators={boardSidebar.moderators}
              stats={boardSidebar.stats}
              hot={boardSidebar.hot}
              activeUsers={boardSidebar.active_users}
              checkin={boardSidebar.checkin ?? undefined}
            />
          ) : boardPanelsMissing ? (
            <BoardMissingPanel />
          ) : null
        ) : (
          overview && (
            <CommunityPanels
              stats={overview.stats}
              hot={overview.hot}
              activeUsers={overview.active_users}
              announcements={overview.announcements}
              newUsers={overview.new_users}
              checkin={overview.checkin ?? undefined}
            />
          )
        )}
      </div>

      {/* 窄屏：面板下沉到帖子流之后 */}
      {showBoardPanels ? (
        boardSidebar ? (
          <div className="mt-6">
            <BoardPanelsMobile
              board={boardSidebar.board}
              moderators={boardSidebar.moderators}
              stats={boardSidebar.stats}
              hot={boardSidebar.hot}
              activeUsers={boardSidebar.active_users}
              checkin={boardSidebar.checkin ?? undefined}
            />
          </div>
        ) : null
      ) : (
        overview && (
          <div className="mt-6">
            <CommunityPanelsMobile
              stats={overview.stats}
              hot={overview.hot}
              activeUsers={overview.active_users}
              announcements={overview.announcements}
              newUsers={overview.new_users}
              checkin={overview.checkin ?? undefined}
            />
          </div>
        )
      )}
    </div>
  );
}