import type { Metadata } from "next";
import Link from "next/link";
import { Megaphone } from "lucide-react";
import { fetchAnnouncementsPage, fetchOverview, type Announcement } from "@/lib/api";
import { getPublicSettingsCached } from "@/lib/serverData";
import { formatDate } from "@/lib/format";
import Pagination from "@/components/Pagination";
import {
  SiteDocShell,
  SiteDocIdentity,
  SiteDocPageNav,
  SiteDocBreadcrumb,
} from "@/components/site-doc";

export const metadata: Metadata = {
  title: "站点公告",
  description: "站点公告与通知列表",
};

interface PageProps {
  searchParams: Promise<{ page?: string }>;
}

/** 粗略去掉 Markdown，取摘要 */
function plainSummary(md: string, max = 120): string {
  const text = md
    .replace(/```[\s\S]*?```/g, " ")
    .replace(/!\[[^\]]*\]\([^)]+\)/g, " ")
    .replace(/\[([^\]]+)\]\([^)]+\)/g, "$1")
    .replace(/[#>*_`~\-|=]/g, "")
    .replace(/\s+/g, " ")
    .trim();
  return text.length > max ? `${text.slice(0, max)}…` : text;
}

function FeaturedAnnouncement({ a }: { a: Announcement }) {
  const summary = plainSummary(a.content, 180);
  return (
    <Link
      href={`/announcement/${a.id}`}
      className="block px-5 sm:px-6 pt-5 sm:pt-6 pb-5 transition-colors hover:bg-[var(--accent-soft)] focus-visible:bg-[var(--accent-soft)]"
    >
      <div className="flex items-center gap-2 flex-wrap mb-3">
        <span
          className="inline-flex items-center rounded-full px-2.5 py-0.5 text-[11.5px] font-semibold tracking-wide"
          style={{ background: "var(--accent-soft)", color: "var(--accent)" }}
        >
          置顶公告
        </span>
        {a.pinned ? <span className="badge-pin">置顶</span> : null}
        <span className={`j13-anno-tag is-${a.tag_color}`}>{a.tag}</span>
        <time className="meta text-[12px] tabular-nums ml-auto" dateTime={a.created_at}>
          {formatDate(a.created_at)}
        </time>
      </div>
      <h2
        className="text-[22px] sm:text-[26px] font-extrabold leading-snug tracking-tight"
        style={{ color: "var(--ink)" }}
      >
        {a.title}
      </h2>
      {summary ? (
        <p className="mt-3 text-[14.5px] leading-relaxed line-clamp-3" style={{ color: "var(--ink-2)" }}>
          {summary}
        </p>
      ) : null}
    </Link>
  );
}

function AnnouncementRow({ a, showDivider }: { a: Announcement; showDivider: boolean }) {
  const summary = plainSummary(a.content);
  return (
    <Link
      href={`/announcement/${a.id}`}
      className="block px-5 sm:px-6 py-4 sm:py-5 transition-colors hover:bg-[var(--accent-soft)] focus-visible:bg-[var(--accent-soft)]"
      style={showDivider ? { borderTop: "1px solid var(--line)" } : undefined}
    >
      <div className="flex items-center gap-2 flex-wrap">
        {a.pinned ? <span className="badge-pin">置顶</span> : null}
        <span className={`j13-anno-tag is-${a.tag_color}`}>{a.tag}</span>
        <time className="meta text-[12px] tabular-nums ml-auto" dateTime={a.created_at}>
          {formatDate(a.created_at)}
        </time>
      </div>
      <h2
        className="mt-2 text-[16px] sm:text-[17px] font-semibold leading-snug tracking-tight"
        style={{ color: "var(--ink)" }}
      >
        {a.title}
      </h2>
      {summary ? (
        <p className="mt-1.5 text-[13.5px] leading-relaxed line-clamp-2" style={{ color: "var(--ink-2)" }}>
          {summary}
        </p>
      ) : null}
    </Link>
  );
}

export default async function AnnouncementsListPage({ searchParams }: PageProps) {
  const sp = await searchParams;
  const page = Math.max(1, parseInt(sp.page || "1", 10) || 1);
  const size = 20;

  let announcements: Announcement[] = [];
  let total = 0;
  let error = "";
  try {
    const res = await fetchAnnouncementsPage(page, size);
    announcements = res.announcements ?? [];
    total = res.total ?? 0;
  } catch (e) {
    error = e instanceof Error ? e.message : "加载公告失败";
  }

  const [overview, settings] = await Promise.all([
    fetchOverview().catch(() => null),
    getPublicSettingsCached(),
  ]);
  const sidebarPages = overview?.sidebar_pages ?? [];
  const siteLead = settings.site_description?.trim() || undefined;

  // 首页置顶条目作头图；其余走列表行（置顶已在头图时不再重复）
  const featured = page === 1 ? announcements.find((a) => a.pinned) : undefined;
  const rest = featured ? announcements.filter((a) => a.id !== featured.id) : announcements;

  const left = <SiteDocIdentity kind="announcements" lead={siteLead} />;
  const right = <SiteDocPageNav pages={sidebarPages} title="关于本站" />;

  return (
    <SiteDocShell
      left={left}
      right={right}
      mobileExtras={<SiteDocPageNav pages={sidebarPages} title="关于本站" />}
    >
      <SiteDocBreadcrumb
        items={[
          { href: "/", label: "首页" },
          { label: "站点公告" },
        ]}
      />

      <header className="mb-5">
        <h1
          className="text-[24px] sm:text-[28px] font-extrabold tracking-tight flex items-center gap-2"
          style={{ color: "var(--ink)" }}
        >
          <Megaphone size={26} style={{ color: "var(--accent)" }} aria-hidden />
          站点公告
        </h1>
        <p className="meta mt-2">
          {error ? "加载失败" : total > 0 ? `共 ${total} 条官方通知` : "站点通知与运营公告"}
        </p>
      </header>

      {error ? (
        <p className="alert-error">{error}</p>
      ) : announcements.length === 0 ? (
        <div className="panel p-10 text-center">
          <p className="font-medium" style={{ color: "var(--ink)" }}>
            暂无公告
          </p>
          <p className="meta mt-1.5">有新消息时会显示在这里</p>
        </div>
      ) : (
        <div className="panel overflow-hidden">
          {featured ? <FeaturedAnnouncement a={featured} /> : null}
          {rest.map((a, i) => (
            <AnnouncementRow key={a.id} a={a} showDivider={!!featured || i > 0} />
          ))}
        </div>
      )}

      {!error ? (
        <Pagination total={total} page={page} size={size} basePath="/announcements" />
      ) : null}
    </SiteDocShell>
  );
}