import si from "systeminformation";
import type { SystemResult } from "@/lib/types/system-result";

const CACHE_MS = 1_000;

let lastSample: { data: SystemResult; ts: number } | null = null;
let inFlight: Promise<SystemResult> | null = null;

function pickDisk(disks: si.Systeminformation.FsSizeData[]): si.Systeminformation.FsSizeData | undefined {
  return disks.find((disk) => disk.mount === "/") ?? disks.sort((a, b) => b.size - a.size)[0];
}

async function sample(): Promise<SystemResult> {
  const [load, mem, disks, net] = await Promise.all([
    si.currentLoad(),
    si.mem(),
    si.fsSize(),
    si.networkStats(),
  ]);

  const disk = pickDisk(disks);
  const primaryNet = net[0];

  return {
    cpuPercent: load.currentLoad,
    memUsedBytes: mem.active,
    memTotalBytes: mem.total,
    diskUsedBytes: disk?.used ?? 0,
    diskTotalBytes: disk?.size ?? 0,
    netRxBytesPerSec: primaryNet?.rx_sec ?? 0,
    netTxBytesPerSec: primaryNet?.tx_sec ?? 0,
  };
}

export async function collectSystem(): Promise<SystemResult> {
  const now = Date.now();
  if (lastSample && now - lastSample.ts < CACHE_MS) {
    return lastSample.data;
  }
  if (inFlight) return inFlight;

  inFlight = sample()
    .then((data) => {
      lastSample = { data, ts: Date.now() };
      return data;
    })
    .finally(() => {
      inFlight = null;
    });

  return inFlight;
}