import type { Metadata } from "next";
import Link from "next/link";
import { cookies } from "next/headers";
import {
  Users,
  PenLine,
  MessageCircle,
  Activity,
  Megaphone,
  Palette,
  ChevronRight,
  UserPlus,
  LayoutGrid,
} from "lucide-react";
import { fetchOverview, type OverviewResponse } from "@/lib/api";
import { authCookieHeader } from "@/lib/cookies";
import { getMeCached } from "@/lib/serverData";
import Avatar from "@/components/Avatar";
import { formatRelative } from "@/lib/format";

export const metadata: Metadata = {
  title: "管理仪表盘",
};

// 精确千分位（管理员视角需要真实数值，不用首页的紧凑 K/M）
const fmt = (n: number) => n.toLocaleString("zh-CN");

function greeting(hour: number) {
  if (hour < 6) return "凌晨好";
  if (hour < 12) return "上午好";
  if (hour < 14) return "中午好";
  if (hour < 18) return "下午好";
  return "晚上好";
}

// 统计 Bento 卡：总量 + 今日增量，语义色与全站令牌一致
function StatCard({
  label,
  value,
  foot,
  icon,
  color,
  soft,
}: {
  label: string;
  value: string;
  foot: string;
  icon: React.ReactNode;
  color: string;
  soft: string;
}) {
  return (
    <div className="panel p-4 sm:p-5">
      <div className="flex items-start justify-between gap-2">
        <p className="text-[12.5px] font-semibold" style={{ color: "var(--ink-3)" }}>
          {label}
        </p>
        <span
          className="w-8 h-8 rounded-lg flex items-center justify-center shrink-0"
          style={{ background: soft, color }}
          aria-hidden="true"
        >
          {icon}
        </span>
      </div>
      <p
        className="mt-3 text-[26px] sm:text-[30px] font-extrabold tabular-nums leading-none tracking-tight"
        style={{ color: "var(--ink)" }}
      >
        {value}
      </p>
      <p className="mt-2 text-[11.5px] sm:text-[12px] font-semibold" style={{ color: "var(--ink-3)" }}>
        {foot}
      </p>
    </div>
  );
}

// 快捷管理入口：整卡可点（stretch-link），图标 + 标题 + 描述 + 箭头
function QuickLink({
  href,
  icon,
  title,
  desc,
  soft,
  color,
}: {
  href: string;
  icon: React.ReactNode;
  title: string;
  desc: string;
  soft: string;
  color: string;
}) {
  return (
    <Link href={href} className="panel hover-lift relative block p-5 group">
      <div className="flex items-start gap-3.5">
        <span
          className="w-10 h-10 rounded-xl flex items-center justify-center shrink-0"
          style={{ background: soft, color }}
          aria-hidden="true"
        >
          {icon}
        </span>
        <div className="min-w-0 flex-1">
          <p className="text-[15px] font-extrabold" style={{ color: "var(--ink)" }}>
            {title}
          </p>
          <p className="meta mt-1 text-[12.5px] leading-relaxed">{desc}</p>
        </div>
        <ChevronRight
          size={17}
          className="shrink-0 mt-1 transition-transform group-hover:translate-x-0.5"
          style={{ color: "var(--ink-3)" }}
        />
      </div>
    </Link>
  );
}

function PanelHead({ title, extra }: { title: string; extra?: string }) {
  return (
    <div
      className="px-4 sm:px-5 py-3.5 flex items-center justify-between gap-2"
      style={{ borderBottom: "1px solid var(--line)" }}
    >
      <span className="font-bold text-[15px]" style={{ color: "var(--ink)" }}>
        {title}
      </span>
      {extra && (
        <span className="meta text-[12px] tabular-nums" style={{ color: "var(--ink-3)" }}>
          {extra}
        </span>
      )}
    </div>
  );
}

export default async function AdminDashboardPage() {
  const cookie = authCookieHeader(await cookies());
  // 与 layout 的 /me 请求共享 React cache；概览失败降级，不阻塞仪表盘骨架
  const [me, overview] = await Promise.all([
    getMeCached(cookie || undefined),
    fetchOverview(cookie).catch(() => null),
  ]);

  const now = new Date();
  const dateLabel = new Intl.DateTimeFormat("zh-CN", {
    year: "numeric",
    month: "long",
    day: "numeric",
    weekday: "long",
  }).format(now);

  const stats = overview?.stats;
  const boards = overview?.boards ?? [];
  const newUsers = overview?.new_users ?? [];
  const topBoards = [...boards].sort((a, b) => b.post_count - a.post_count).slice(0, 6);
  const maxBoardCount = Math.max(1, ...topBoards.map((b) => b.post_count));

  return (
    <div>
      {/* 页头 */}
      <div className="mb-5">
        <h1 className="text-[22px] sm:text-[26px] font-extrabold tracking-tight" style={{ color: "var(--ink)" }}>
          {greeting(now.getHours())}，{me.user?.nickname}
        </h1>
        <p className="meta mt-1.5 text-[12.5px]">{dateLabel} · 这里是站点运营全貌</p>
      </div>

      {/* 统计 Bento */}
      <div className="grid grid-cols-2 lg:grid-cols-4 gap-3 sm:gap-4">
        <StatCard
          label="注册用户"
          value={stats ? fmt(stats.users) : "—"}
          foot={stats ? `今日新增 +${fmt(stats.today_users)}` : "统计暂不可用"}
          icon={<Users size={16} />}
          color="var(--accent)"
          soft="var(--accent-soft)"
        />
        <StatCard
          label="话题总数"
          value={stats ? fmt(stats.posts) : "—"}
          foot={stats ? `今日新发 +${fmt(stats.today_posts)}` : "统计暂不可用"}
          icon={<PenLine size={16} />}
          color="var(--clay)"
          soft="var(--clay-soft)"
        />
        <StatCard
          label="回复总数"
          value={stats ? fmt(stats.comments) : "—"}
          foot={stats ? `今日新增 +${fmt(stats.today_comments)}` : "统计暂不可用"}
          icon={<MessageCircle size={16} />}
          color="var(--ok)"
          soft="var(--ok-soft)"
        />
        <StatCard
          label="在线用户"
          value={stats ? fmt(stats.online) : "—"}
          foot={stats ? `近 5 分钟活跃 · 峰值 ${fmt(stats.peak_online)}` : "统计暂不可用"}
          icon={<Activity size={16} />}
          color="var(--gold)"
          soft="var(--gold-soft)"
        />
      </div>

      {/* 快捷入口 */}
      <h2 className="sr-only">快捷管理</h2>
      <div className="grid sm:grid-cols-2 xl:grid-cols-3 gap-3 sm:gap-4 mt-4">
        <QuickLink
          href="/admin/users"
          icon={<Users size={18} />}
          title="用户管理"
          desc="查看全站成员，授予管理员权限或封禁违规账号"
          soft="var(--accent-soft)"
          color="var(--accent)"
        />
        <QuickLink
          href="/admin/announcements"
          icon={<Megaphone size={18} />}
          title="公告管理"
          desc="发布、编辑与下线站点公告，支持标签颜色与草稿状态"
          soft="var(--clay-soft)"
          color="var(--clay)"
        />
        <QuickLink
          href="/admin/appearance"
          icon={<Palette size={18} />}
          title="外观设置"
          desc="配置全站主题强调色，实时预览后保存并对所有用户生效"
          soft="var(--gold-soft)"
          color="var(--gold)"
        />
      </div>

      {/* 成员与板块 */}
      <div className="grid lg:grid-cols-2 gap-4 mt-4 items-start">
        {/* 最新注册成员 */}
        <div className="panel overflow-hidden">
          <PanelHead title="最新注册成员" extra={stats ? `共 ${fmt(stats.users)} 人` : undefined} />
          {newUsers.length === 0 ? (
            <p className="meta text-center py-14 text-[13px]">暂无成员数据</p>
          ) : (
            newUsers.slice(0, 6).map((u) => (
              <Link
                key={u.id}
                href={`/u/${u.id}`}
                className="flex items-center gap-3 px-4 sm:px-5 py-3 transition-colors hover:bg-[var(--panel-2)]"
                style={{ borderTop: "1px solid var(--line)" }}
              >
                <Avatar name={u.nickname || u.username} src={u.avatar || undefined} size={34} />
                <span className="min-w-0 flex-1 leading-tight">
                  <span className="block text-[13.5px] font-bold truncate" style={{ color: "var(--ink)" }}>
                    {u.nickname}
                  </span>
                  <span className="block text-[11.5px] truncate" style={{ color: "var(--ink-3)" }}>
                    @{u.username}
                  </span>
                </span>
                <span
                  className="shrink-0 inline-flex items-center gap-1 text-[11.5px] font-semibold"
                  style={{ color: "var(--ink-3)" }}
                >
                  <UserPlus size={12} aria-hidden="true" />
                  {formatRelative(u.created_at)}加入
                </span>
              </Link>
            ))
          )}
        </div>

        {/* 板块分布 */}
        <div className="panel overflow-hidden">
          <PanelHead title="板块话题分布" extra={`${boards.length} 个板块`} />
          {topBoards.length === 0 ? (
            <p className="meta text-center py-14 text-[13px]">暂无板块数据</p>
          ) : (
            topBoards.map((b) => (
              <Link
                key={b.id}
                href={`/?board=${b.id}`}
                className="flex items-center gap-3 px-4 sm:px-5 py-3 transition-colors hover:bg-[var(--panel-2)]"
                style={{ borderTop: "1px solid var(--line)" }}
              >
                <span
                  className="w-8 h-8 rounded-lg flex items-center justify-center shrink-0"
                  style={{ background: "var(--panel-2)", color: "var(--accent)" }}
                  aria-hidden="true"
                >
                  <LayoutGrid size={14} />
                </span>
                <span className="min-w-0 flex-1">
                  <span className="flex items-center justify-between gap-2">
                    <span className="text-[13.5px] font-bold truncate" style={{ color: "var(--ink)" }}>
                      {b.name}
                    </span>
                    <span className="text-[12px] font-bold tabular-nums shrink-0" style={{ color: "var(--ink-2)" }}>
                      {fmt(b.post_count)}
                    </span>
                  </span>
                  {/* 相对占比迷你条（纯装饰） */}
                  <span
                    className="block mt-1.5 h-1 rounded-full overflow-hidden"
                    style={{ background: "var(--tint)" }}
                    aria-hidden="true"
                  >
                    <span
                      className="block h-full rounded-full"
                      style={{
                        width: `${Math.max(4, Math.round((b.post_count / maxBoardCount) * 100))}%`,
                        background: "var(--accent)",
                      }}
                    />
                  </span>
                </span>
              </Link>
            ))
          )}
        </div>
      </div>
    </div>
  );
}