"use client";

import { useEffect, useState, useCallback } from "react";
import { authFetch } from "@/lib/auth";
import { useAuth } from "@/lib/auth";
import Link from "next/link";

interface PM2Proc {
  name: string;
  status: string;
  cpu: number;
  memory_mb: number;
  restarts: number;
  uptime_ms: number;
  pid: number;
}

interface ServerStatus {
  timestamp: number;
  cpu: { percent: number; cores: number };
  memory: { total_gb: number; used_gb: number; percent: number; swap_percent: number };
  disk: { total_gb: number; used_gb: number; free_gb: number; percent: number };
  load: { load1: number; load5: number; load15: number };
  uptime_hours: number;
  network: { bytes_sent_gb: number; bytes_recv_gb: number };
  pm2: PM2Proc[];
  postgres: {
    db_size_mb: number;
    agg_trades_count: number;
    rate_snapshots_count: number;
    symbols: Record<string, { latest_ms: number; earliest_ms: number; span_hours: number }>;
  };
  backfill_running: boolean;
}

function bjtStr(ms: number) {
  const d = new Date(ms + 8 * 3600 * 1000);
  return `${String(d.getUTCMonth()+1).padStart(2,"0")}-${String(d.getUTCDate()).padStart(2,"0")} ${String(d.getUTCHours()).padStart(2,"0")}:${String(d.getUTCMinutes()).padStart(2,"0")}`;
}

function uptimeStr(ms: number) {
  if (!ms) return "-";
  const now = Date.now();
  const diff = now - ms;
  const h = Math.floor(diff / 3600000);
  const m = Math.floor((diff % 3600000) / 60000);
  if (h > 24) return `${Math.floor(h/24)}d ${h%24}h`;
  if (h > 0) return `${h}h ${m}m`;
  return `${m}m`;
}

function ProgressBar({ percent }: { percent: number }) {
  const color = percent > 90 ? "bg-red-500" : percent > 70 ? "bg-amber-500" : "bg-blue-500";
  return (
    <div className="w-full bg-slate-100 rounded-full h-2 overflow-hidden">
      <div className={`h-full rounded-full transition-all duration-500 ${color}`} style={{ width: `${Math.min(percent, 100)}%` }} />
    </div>
  );
}

function numberFmt(n: number) {
  return n.toLocaleString("en-US");
}

export default function ServerPage() {
  const { isLoggedIn } = useAuth();
  const [data, setData] = useState<ServerStatus | null>(null);
  const [loading, setLoading] = useState(true);

  const fetchData = useCallback(async () => {
    try {
      const res = await authFetch("/api/server/status");
      if (!res.ok) return;
      const json = await res.json();
      setData(json);
    } catch (e) {
      // ignore
    } finally {
      setLoading(false);
    }
  }, []);

  useEffect(() => {
    if (!isLoggedIn) return;
    fetchData();
    const iv = setInterval(fetchData, 10000);
    return () => clearInterval(iv);
  }, [isLoggedIn, fetchData]);

  if (!isLoggedIn) {
    return (
      <div className="flex flex-col items-center justify-center h-64 gap-3">
        <p className="text-slate-500 text-sm">请先登录查看服务器状态</p>
        <div className="flex gap-2">
          <Link href="/login" className="bg-blue-600 text-white px-4 py-2 rounded-lg text-sm">登录</Link>
          <Link href="/register" className="border border-slate-300 text-slate-600 px-4 py-2 rounded-lg text-sm">注册</Link>
        </div>
      </div>
    );
  }

  return (
    <div className="space-y-5">
      {/* 标题 */}
      <div className="flex items-center justify-between flex-wrap gap-2">
        <div>
          <h1 className="text-xl font-bold text-slate-900">服务器监控</h1>
          <p className="text-slate-500 text-xs mt-0.5">GCP asia-northeast1-b · 每10秒自动刷新</p>
        </div>
        {data?.backfill_running && (
          <span className="inline-flex items-center gap-1.5 px-3 py-1 rounded-full bg-blue-50 border border-blue-200 text-xs text-blue-700 font-medium">
            <span className="w-1.5 h-1.5 rounded-full bg-blue-500 animate-pulse" />
            回补运行中
          </span>
        )}
      </div>

      {loading ? (
        <div className="flex items-center justify-center h-48 text-slate-400 text-sm">加载中...</div>
      ) : !data ? (
        <div className="flex items-center justify-center h-48 text-red-500 text-sm">获取失败</div>
      ) : (
        <>
          {/* 系统概览 4卡片 */}
          <div className="grid grid-cols-2 lg:grid-cols-4 gap-4">
            {/* CPU */}
            <div className="rounded-xl border border-slate-200 bg-white shadow-sm p-4">
              <div className="flex items-center justify-between mb-3">
                <span className="text-xs text-slate-500 font-medium">CPU</span>
                <span className="text-xs text-slate-400">{data.cpu.cores} 核</span>
              </div>
              <div className="text-2xl font-bold text-slate-900 mb-2">{data.cpu.percent}%</div>
              <ProgressBar percent={data.cpu.percent} />
              <p className="mt-2 text-xs text-slate-400">
                负载 {data.load.load1} / {data.load.load5} / {data.load.load15}
              </p>
            </div>

            {/* 内存 */}
            <div className="rounded-xl border border-slate-200 bg-white shadow-sm p-4">
              <div className="flex items-center justify-between mb-3">
                <span className="text-xs text-slate-500 font-medium">内存</span>
                <span className="text-xs text-slate-400">{data.memory.used_gb}G / {data.memory.total_gb}G</span>
              </div>
              <div className="text-2xl font-bold text-slate-900 mb-2">{data.memory.percent}%</div>
              <ProgressBar percent={data.memory.percent} />
              {data.memory.swap_percent > 0 && (
                <p className="mt-2 text-xs text-amber-600">Swap {data.memory.swap_percent}%</p>
              )}
            </div>

            {/* 硬盘 */}
            <div className="rounded-xl border border-slate-200 bg-white shadow-sm p-4">
              <div className="flex items-center justify-between mb-3">
                <span className="text-xs text-slate-500 font-medium">硬盘</span>
                <span className="text-xs text-slate-400">{data.disk.free_gb}G 可用</span>
              </div>
              <div className="text-2xl font-bold text-slate-900 mb-2">{data.disk.percent}%</div>
              <ProgressBar percent={data.disk.percent} />
              <p className="mt-2 text-xs text-slate-400">{data.disk.used_gb}G / {data.disk.total_gb}G</p>
            </div>

            {/* 运行时间 & 网络 */}
            <div className="rounded-xl border border-slate-200 bg-white shadow-sm p-4">
              <div className="flex items-center justify-between mb-3">
                <span className="text-xs text-slate-500 font-medium">系统</span>
              </div>
              <div className="text-2xl font-bold text-slate-900 mb-2">
                {data.uptime_hours > 24 ? `${Math.floor(data.uptime_hours/24)}天` : `${data.uptime_hours}h`}
              </div>
              <div className="text-xs text-slate-400 space-y-0.5">
                <p>↑ 发送 {data.network.bytes_sent_gb} GB</p>
                <p>↓ 接收 {data.network.bytes_recv_gb} GB</p>
              </div>
            </div>
          </div>

          {/* PM2 进程 */}
          <div className="rounded-xl border border-slate-200 bg-white shadow-sm overflow-hidden">
            <div className="px-4 py-3 border-b border-slate-100">
              <h3 className="font-semibold text-sm text-slate-800">PM2 进程</h3>
            </div>
            <div className="overflow-x-auto">
              <table className="w-full text-xs">
                <thead>
                  <tr className="text-slate-400 border-b border-slate-100 text-left">
                    <th className="px-4 py-2.5 font-medium">名称</th>
                    <th className="px-4 py-2.5 font-medium text-center">状态</th>
                    <th className="px-4 py-2.5 font-medium text-right">CPU</th>
                    <th className="px-4 py-2.5 font-medium text-right">内存</th>
                    <th className="px-4 py-2.5 font-medium text-right">重启</th>
                    <th className="px-4 py-2.5 font-medium text-right">运行时间</th>
                  </tr>
                </thead>
                <tbody>
                  {data.pm2.map((p, i) => (
                    <tr key={i} className="border-b border-slate-50 hover:bg-slate-50/50">
                      <td className="px-4 py-2.5 font-mono text-slate-800">{p.name}</td>
                      <td className="px-4 py-2.5 text-center">
                        <span className={`inline-flex items-center gap-1 px-2 py-0.5 rounded-full text-xs font-medium ${
                          p.status === "online"
                            ? "bg-emerald-50 text-emerald-700 border border-emerald-200"
                            : "bg-red-50 text-red-700 border border-red-200"
                        }`}>
                          <span className={`w-1.5 h-1.5 rounded-full ${p.status === "online" ? "bg-emerald-500" : "bg-red-500"}`} />
                          {p.status}
                        </span>
                      </td>
                      <td className="px-4 py-2.5 text-right font-mono text-slate-600">{p.cpu}%</td>
                      <td className="px-4 py-2.5 text-right font-mono text-slate-600">{p.memory_mb} MB</td>
                      <td className="px-4 py-2.5 text-right font-mono text-slate-600">{p.restarts}</td>
                      <td className="px-4 py-2.5 text-right text-slate-400">{uptimeStr(p.uptime_ms)}</td>
                    </tr>
                  ))}
                </tbody>
              </table>
            </div>
          </div>

          {/* PostgreSQL */}
          <div className="rounded-xl border border-slate-200 bg-white shadow-sm overflow-hidden">
            <div className="px-4 py-3 border-b border-slate-100">
              <h3 className="font-semibold text-sm text-slate-800">PostgreSQL</h3>
            </div>
            <div className="p-4 grid grid-cols-2 lg:grid-cols-4 gap-4">
              <div>
                <p className="text-xs text-slate-400 mb-1">数据库大小</p>
                <p className="text-lg font-bold text-slate-900">
                  {data.postgres.db_size_mb > 1024
                    ? `${(data.postgres.db_size_mb / 1024).toFixed(1)} GB`
                    : `${data.postgres.db_size_mb} MB`}
                </p>
              </div>
              <div>
                <p className="text-xs text-slate-400 mb-1">aggTrades</p>
                <p className="text-lg font-bold text-blue-600">{numberFmt(data.postgres.agg_trades_count)}</p>
              </div>
              <div>
                <p className="text-xs text-slate-400 mb-1">费率快照</p>
                <p className="text-lg font-bold text-slate-900">{numberFmt(data.postgres.rate_snapshots_count)}</p>
              </div>
              <div>
                <p className="text-xs text-slate-400 mb-1">回补状态</p>
                <p className={`text-lg font-bold ${data.backfill_running ? "text-blue-600" : "text-slate-400"}`}>
                  {data.backfill_running ? "运行中" : "已停止"}
                </p>
              </div>
            </div>

            {/* 数据覆盖范围 */}
            {data.postgres.symbols && Object.keys(data.postgres.symbols).length > 0 && (
              <div className="px-4 pb-4">
                <p className="text-xs text-slate-400 mb-2">数据覆盖范围</p>
                <div className="grid grid-cols-1 lg:grid-cols-2 gap-2">
                  {Object.entries(data.postgres.symbols).map(([sym, info]) => (
                    <div key={sym} className="flex items-center justify-between bg-slate-50 rounded-lg px-3 py-2 border border-slate-100">
                      <span className="font-mono text-sm font-medium text-slate-800">{sym}</span>
                      <div className="text-xs text-slate-500 text-right">
                        <p>{bjtStr(info.earliest_ms)} → {bjtStr(info.latest_ms)}</p>
                        <p className="text-blue-600 font-medium">
                          {info.span_hours > 24 ? `${(info.span_hours/24).toFixed(1)} 天` : `${info.span_hours.toFixed(1)} 小时`}
                        </p>
                      </div>
                    </div>
                  ))}
                </div>
              </div>
            )}
          </div>

          {/* 说明 */}
          <div className="rounded-lg border border-blue-100 bg-blue-50 px-4 py-3 text-xs text-slate-600">
            <span className="text-blue-600 font-medium">说明：</span>数据每10秒自动刷新。PM2进程状态实时反映服务运行情况，回补运行中时CPU和网络负载会偏高属正常现象。
          </div>
        </>
      )}
    </div>
  );
}