const $ = (id) => document.getElementById(id);
const HISTORY = { cpu: [], mem: [] };
const MAX_HISTORY = 60;

const DEMO = () => {
  const rnd = (a, b) => Math.round(a + Math.random() * (b - a));
  const memPct = rnd(35, 55);
  return {
    hostname: "demo-server", os: "linux", release: "6.x", arch: "x64",
    uptime: 3 * 86400 + 7 * 3600 + 42 * 60,
    loadavg: [0.4, 0.3, 0.2],
    cpu: { usage: rnd(5, 25), model: "Пример данных (Предпросмотр)", cores: 8, speed: 2.4 },
    mem: { total: 16 * 1024 ** 3, used: Math.round(memPct / 100 * 16 * 1024 ** 3), free: Math.round((100 - memPct) / 100 * 16 * 1024 ** 3), percent: memPct },
    disk: { total: 100 * 1024 ** 3, used: 64 * 1024 ** 3, free: 36 * 1024 ** 3, percent: 64 },
    network: "1.2 Гбит/с",
    processes: [
      { pid: 1234, name: "node", cpu: 12.3, mem: 4.2 },
      { pid: 5678, name: "nginx", cpu: 3.1, mem: 1.0 },
      { pid: 9012, name: "python3", cpu: 2.4, mem: 5.7 },
      { pid: 3456, name: "postgres", cpu: 1.8, mem: 12.5 },
      { pid: 7890, name: "redis", cpu: 0.9, mem: 0.8 },
      { pid: 1112, name: "docker", cpu: 0.6, mem: 1.4 },
    ],
  };
};

function fmtBytes(n) {
  if (n == null || isNaN(n)) return "—";
  const u = ["Б", "КБ", "МБ", "ГБ", "ТБ"];
  let i = 0;
  while (n >= 1024 && i < u.length - 1) { n /= 1024; i++; }
  return n.toFixed(i >= 2 ? 1 : 0) + " " + u[i];
}

function fmtUptime(sec) {
  if (sec == null) return "—";
  const d = Math.floor(sec / 86400);
  const h = Math.floor((sec % 86400) / 3600);
  const m = Math.floor((sec % 3600) / 60);
  let s = m + " мин";
  if (h > 0) s = h + " ч " + s;
  if (d > 0) s = d + " дн " + s;
  return s;
}

function level(p) {
  if (p >= 90) return { c: "bad", w: "bad" };
  if (p >= 70) return { c: "warn", w: "warn" };
  return { c: "ok", w: "" };
}

function spark(id, arr) {
  const el = $(id);
  if (!arr.length) return;
  const w = 100, h = 30, pad = 2;
  const min = Math.min(...arr), max = Math.max(...arr);
  const rng = max - min || 1;
  const pts = arr.map((v, i) => {
    const x = pad + (i / (arr.length - 1)) * (w - pad * 2);
    const y = h - pad - ((v - min) / rng) * (h - pad * 2);
    return x + "," + y;
  });
  const path = "M" + pts.join(" L");
  const last = pts[pts.length - 1].split(",");
  el.innerHTML = '<path d="' + path + '"/>' +
    '<circle cx="' + last[0] + '" cy="' + last[1] + '" r="2"/>';
}

function pushHistory(m) {
  HISTORY.cpu.push(m.cpu.usage);
  HISTORY.mem.push(m.mem.percent);
  if (HISTORY.cpu.length > MAX_HISTORY) { HISTORY.cpu.shift(); HISTORY.mem.shift(); }
}

function render(m) {
  const status = m.status || "ok";
  const dot = $("statusDot");
  dot.className = "dot " + status;
  $("hostname").textContent = m.hostname || "—";
  $("osinfo").textContent = (m.os || "") + " " + (m.release || "") + " · " + (m.arch || "");
  $("lastUpd").textContent = "последнее обновление: " + new Date().toLocaleTimeString("ru-RU");

  $("cpuPct").textContent = Math.round(m.cpu.usage);
  $("cpuBar").style.width = Math.min(100, m.cpu.usage) + "%";
  $("cpuBar").className = level(m.cpu.usage).w;
  $("cpuSub").textContent = m.cpu.cores + " ядер" + (m.cpu.speed > 0 ? " · " + m.cpu.speed + " ГГц" : "");
  $("cpuModel").textContent = m.cpu.model || "—";
  $("cpuCard").classList.toggle("dim", false);
  $("cpuSpark").style.display = "block";
  spark("cpuSpark", HISTORY.cpu);

  $("memPct").textContent = Math.round(m.mem.percent);
  $("memBar").style.width = Math.min(100, m.mem.percent) + "%";
  $("memBar").className = level(m.mem.percent).w;
  $("memSub").textContent = "использовано " + fmtBytes(m.mem.used) + " из " + fmtBytes(m.mem.total);
  spark("memSpark", HISTORY.mem);

  $("diskPct").textContent = Math.round(m.disk.percent);
  $("diskBar").style.width = Math.min(100, m.disk.percent) + "%";
  $("diskBar").className = level(m.disk.percent).w;
  $("diskSub").textContent = "свободно " + fmtBytes(m.disk.free) + " из " + fmtBytes(m.disk.total);

  $("uptime").textContent = fmtUptime(m.uptime);
  $("loadavg").textContent = (m.loadavg || []).map((x) => x.toFixed ? x.toFixed(2) : x).join(" / ");
  $("network").textContent = m.network || "—";
  $("cores").textContent = (m.cpu.cores || "—") + " · " + (m.arch || "—");

  const body = $("procBody");
  if (!m.processes || !m.processes.length) {
    body.innerHTML = '<tr><td colspan="4" class="muted">нет данных</td></tr>';
    return;
  }
  body.innerHTML = m.processes.map((p) =>
    '<tr>' +
      '<td class="pid">' + p.pid + '</td>' +
      '<td>' + p.name + '</td>' +
      '<td class="num-cell"><span class="cpu-cell"><span class="minibar"><i style="width:' + Math.min(100, p.cpu) + '%"></i></span>' + Number(p.cpu).toFixed(1) + '%</span></td>' +
      '<td class="num-cell">' + Number(p.mem).toFixed(1) + '%</td>' +
    '</tr>'
  ).join("");
}

async function load() {
  let m;
  try {
    const r = await fetch("/api/metrics", { cache: "no-store" });
    if (!r.ok) throw new Error("http " + r.status);
    m = await r.json();
  } catch (e) {
    m = DEMO();
    $("cpuModel").textContent = "Сервер не запущен — показаны демо-данные";
    $("statusDot").className = "dot warn";
  }
  pushHistory(m);
  render(m);
}

load();
setInterval(load, 3000);