"use client";

import { useState, useTransition } from "react";
import Link from "next/link";
import { ChevronRight, Eye, UserPlus, Users } from "lucide-react";
import {
  apiAdminAnalytics,
  type AnalyticsOverview,
  type NewUser,
} from "@/lib/api";
import { postTypeLabel } from "@/lib/postMeta";
import { formatRelative } from "@/lib/format";
import { postPath, userPath } from "@/lib/urlStyle";
import Avatar from "@/components/Avatar";
import { useUrlStyle } from "@/components/SiteBrandProvider";
import { AdminSegmented } from "@/components/admin";
import {
  AdminChartCard,
  DualLineChart,
  NamedBarChart,
  NamedPieChart,
  SingleAreaChart,
  VisitTrendChart,
} from "@/components/admin/charts";

type RangeKey = "7d" | "30d";

const fmt = (n: number) => n.toLocaleString("zh-CN");

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-medium text-[15px]" style={{ color: "var(--ink)" }}>
        {title}
      </span>
      {extra && (
        <span className="meta text-[12px] tabular-nums" style={{ color: "var(--ink-3)" }}>
          {extra}
        </span>
      )}
    </div>
  );
}

function mergePostCommentSeries(data: AnalyticsOverview) {
  const map = new Map<string, { date: string; posts: number; comments: number }>();
  for (const row of data.posts_series) {
    map.set(row.date, { date: row.date, posts: row.count, comments: 0 });
  }
  for (const row of data.comments_series) {
    const prev = map.get(row.date);
    if (prev) prev.comments = row.count;
    else map.set(row.date, { date: row.date, posts: 0, comments: row.count });
  }
  return [...map.values()].sort((a, b) => a.date.localeCompare(b.date));
}

export default function DashboardClient({
  initialAnalytics,
  newUsers,
  totalUsers,
  canUsers,
}: {
  initialAnalytics: AnalyticsOverview;
  newUsers: NewUser[];
  totalUsers?: number;
  canUsers: boolean;
}) {
  const urlStyle = useUrlStyle();
  const [range, setRange] = useState<RangeKey>("7d");
  const [data, setData] = useState(initialAnalytics);
  const [error, setError] = useState<string | null>(null);
  const [pending, startTransition] = useTransition();

  const switchRange = (next: RangeKey) => {
    if (next === range || pending) return;
    setRange(next);
    setError(null);
    startTransition(async () => {
      try {
        const res = await apiAdminAnalytics(next);
        setData(res);
      } catch {
        setError("趋势数据加载失败，请稍后重试");
      }
    });
  };

  const activitySeries = mergePostCommentSeries(data);
  const registerSeries = data.registers_series.map((r) => ({
    date: r.date,
    count: r.count,
  }));
  const boardBars = data.boards.map((b) => ({
    label: b.label || b.key,
    count: b.count,
  }));
  const typeSlices = data.post_types.map((t) => ({
    label: postTypeLabel(t.key),
    count: t.count,
  }));

  return (
    <div className="space-y-4">
      <div className="flex items-center justify-between gap-3 flex-wrap">
        <p className="meta text-[12.5px]" style={{ color: "var(--ink-3)" }}>
          {pending ? "正在切换区间…" : `近 ${data.range_days} 日趋势`}
        </p>
        <AdminSegmented<RangeKey>
          ariaLabel="分析时间范围"
          size="sm"
          role="group"
          value={range}
          onChange={switchRange}
          options={[
            { key: "7d", label: "近 7 日" },
            { key: "30d", label: "近 30 日" },
          ]}
        />
      </div>

      {error && (
        <p className="text-[13px] px-1" style={{ color: "var(--danger)" }} role="alert">
          {error}
        </p>
      )}

      <AdminChartCard title="访问趋势" hint="页面浏览量（PV）与独立访客（UV）">
        <VisitTrendChart data={data.visits} />
      </AdminChartCard>

      <div className="grid grid-cols-1 lg:grid-cols-2 gap-4">
        <AdminChartCard title="发帖与评论" hint="按日新增">
          <DualLineChart
            data={activitySeries}
            aKey="posts"
            bKey="comments"
            aName="发帖"
            bName="评论"
          />
        </AdminChartCard>
        <AdminChartCard title="新注册" hint="按日新增成员">
          <SingleAreaChart data={registerSeries} dataKey="count" name="注册" color="var(--ok)" />
        </AdminChartCard>
        <AdminChartCard title="板块发帖分布" hint="区间内发帖量">
          <NamedBarChart data={boardBars} layout="horizontal" />
        </AdminChartCard>
        <AdminChartCard title="帖子类型" hint="区间内发帖构成">
          <NamedPieChart data={typeSlices} />
        </AdminChartCard>
      </div>

      <div className="grid lg:grid-cols-2 gap-4 items-start">
        <div className="panel overflow-hidden">
          <PanelHead
            title="最新注册成员"
            extra={totalUsers != null ? `共 ${fmt(totalUsers)} 人` : undefined}
          />
          {newUsers.length === 0 ? (
            <p className="meta text-center py-14 text-[13px]">暂无成员数据</p>
          ) : (
            newUsers.slice(0, 8).map((u) => (
              <Link
                key={u.id}
                href={userPath(urlStyle, 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] 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]"
                  style={{ color: "var(--ink-3)" }}
                >
                  <UserPlus size={12} aria-hidden />
                  {formatRelative(u.created_at)}加入
                </span>
              </Link>
            ))
          )}
          {canUsers && (
            <Link
              href="/admin/users"
              className="flex items-center justify-center gap-1.5 px-4 py-3 text-[13px] transition-colors hover:bg-[var(--panel-2)]"
              style={{
                borderTop: "1px solid var(--line)",
                color: "var(--accent)",
              }}
            >
              <Users size={14} aria-hidden />
              前往用户管理
              <ChevronRight size={14} aria-hidden />
            </Link>
          )}
        </div>

        <div className="panel overflow-hidden">
          <PanelHead title="热门浏览" extra={`近 ${data.range_days} 日`} />
          {data.top_viewed.length === 0 ? (
            <p className="meta text-center py-14 text-[13px]">暂无浏览数据</p>
          ) : (
            data.top_viewed.map((p, i) => (
              <Link
                key={p.id}
                href={postPath(urlStyle, p.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-7 h-7 rounded-md flex items-center justify-center shrink-0 text-[12px] font-bold tabular-nums"
                  style={{ background: "var(--panel-2)", color: "var(--ink-3)" }}
                  aria-hidden
                >
                  {i + 1}
                </span>
                <span className="min-w-0 flex-1 text-[13.5px] truncate" style={{ color: "var(--ink)" }}>
                  {p.title}
                </span>
                <span
                  className="shrink-0 inline-flex items-center gap-1 text-[12px] tabular-nums"
                  style={{ color: "var(--ink-3)" }}
                >
                  <Eye size={13} aria-hidden />
                  {fmt(p.view_count)}
                </span>
              </Link>
            ))
          )}
        </div>
      </div>
    </div>
  );
}