import { NextRequest, NextResponse } from "next/server";
import { auth } from "@/lib/auth";
import { mcProcessManager } from "@/lib/minecraft/process";
import { checkRateLimit, getClientIp } from "@/lib/security/rateLimit";
import * as os from "node:os";

export async function GET(req: NextRequest) {
  const session = await auth.api.getSession({ headers: req.headers });
  if (!session) return NextResponse.json({ error: "Unauthorized" }, { status: 401 });

  const ip = getClientIp(req);
  const { allowed } = checkRateLimit(ip);
  if (!allowed) return NextResponse.json({ error: "Too many requests" }, { status: 429 });

  const totalMemMb = Math.round(os.totalmem() / 1024 / 1024);
  const freeMemMb = Math.round(os.freemem() / 1024 / 1024);
  const usedMemMb = totalMemMb - freeMemMb;

  // CPU usage (average across all cores, sampled over 100ms)
  const cpuPercent = await getCpuPercent();

  const serverStatus = mcProcessManager.getStatus();

  return NextResponse.json({
    system: {
      cpuPercent,
      totalMemMb,
      usedMemMb,
      freeMemMb,
      loadAvg: os.loadavg(),
      uptime: os.uptime(),
      platform: os.platform(),
      arch: os.arch(),
    },
    server: serverStatus,
    timestamp: Date.now(),
  });
}

function getCpuPercent(): Promise<number> {
  return new Promise((resolve) => {
    const cpus1 = os.cpus();
    setTimeout(() => {
      const cpus2 = os.cpus();
      let totalIdle = 0;
      let totalTick = 0;

      for (let i = 0; i < cpus1.length; i++) {
        const cpu1 = cpus1[i].times;
        const cpu2 = cpus2[i].times;
        const idle = cpu2.idle - cpu1.idle;
        const total =
          (cpu2.user - cpu1.user) +
          (cpu2.nice - cpu1.nice) +
          (cpu2.sys - cpu1.sys) +
          (cpu2.idle - cpu1.idle) +
          ((cpu2.irq ?? 0) - (cpu1.irq ?? 0));
        totalIdle += idle;
        totalTick += total;
      }

      const percent = totalTick === 0 ? 0 : Math.round(((totalTick - totalIdle) / totalTick) * 100);
      resolve(percent);
    }, 100);
  });
}