import https from "https";

const HOST  = process.env.FORTIGATE_HOST;
const TOKEN = process.env.FORTIGATE_API_TOKEN;

const POLL_INTERVAL_MS = 2 * 60 * 1000; // 2 minutes

let cached = null;

function fetchJson(urlStr, headers) {
  return new Promise((resolve, reject) => {
    const url = new URL(urlStr);
    const req = https.request(
      {
        hostname: url.hostname,
        port: url.port || 443,
        path: url.pathname + url.search,
        method: "GET",
        headers,
        rejectUnauthorized: false,
      },
      (res) => {
        let body = "";
        res.on("data", (chunk) => (body += chunk));
        res.on("end", () => {
          if (res.statusCode < 200 || res.statusCode >= 300) {
            reject(new Error(`HTTP ${res.statusCode}`));
          } else {
            try { resolve(JSON.parse(body)); }
            catch { reject(new Error("Invalid JSON in response")); }
          }
        });
      }
    );
    req.on("error", reject);
    req.end();
  });
}

function formatUptime(seconds) {
  const d = Math.floor(seconds / 86400);
  const h = Math.floor((seconds % 86400) / 3600);
  const m = Math.floor((seconds % 3600) / 60);
  if (d > 0) return `${d}d ${h}h`;
  if (h > 0) return `${h}h ${m}m`;
  return `${m}m`;
}

async function poll() {
  const headers = { Authorization: `Bearer ${TOKEN}` };
  const base = `https://${HOST}`;

  const [statusData, resourceData] = await Promise.all([
    fetchJson(`${base}/api/v2/monitor/system/status`, headers),
    fetchJson(`${base}/api/v2/monitor/system/resource/usage`, headers),
  ]);

  const r = statusData.results ?? {};
  const nowSec = Math.floor(Date.now() / 1000);
  const uptimeSec = r.utc_last_reboot
    ? nowSec - r.utc_last_reboot
    : null;

  const cpuPct = resourceData.results?.cpu?.[0]?.current ?? null;
  const memPct = resourceData.results?.mem?.[0]?.current ?? null;

  cached = {
    hostname:      r.hostname ?? "FortiGate",
    model:         r.model_number ?? "1800F",
    version:       statusData.version ?? "—",
    uptimeSeconds: uptimeSec,
    uptimeLabel:   uptimeSec !== null ? formatUptime(uptimeSec) : "—",
    cpuPct,
    memPct,
    lastUpdated:   new Date().toISOString(),
  };
}

export function getHealth() {
  return cached;
}

export function startPolling() {
  if (!HOST || !TOKEN) {
    console.warn("[fg-health] FORTIGATE_HOST or FORTIGATE_API_TOKEN not set — health polling disabled.");
    return;
  }
  poll().catch((err) =>
    console.error("[fg-health] Initial poll failed:", err.message)
  );
  setInterval(
    () => poll().catch((err) =>
      console.error("[fg-health] Poll failed:", err.message)
    ),
    POLL_INTERVAL_MS
  );
}