#!/usr/bin/env node
/**
 * Txoko Node - System Metrics Server (v2 — ligero)
 * Expone métricas del sistema via HTTP en localhost.
 *
 * Cambios v2 respecto a v1:
 *  - CPU medida leyendo /proc/stat dos veces con delta (sin spawnear `top`)
 *  - Por-núcleo con uso ACTUAL real (antes era el acumulado desde el arranque)
 *  - RPC de Bitcoin Core por HTTP nativo (sin `curl` → credenciales fuera de `ps`)
 *  - Peers contados con getnetworkinfo (sin getpeerinfo, que es enorme)
 *  - Caché con TTL: mide una vez cada pocos segundos, sirva a N navegadores
 *  - Todo asíncrono: nada bloquea el servidor
 *
 * Setup: ninguno. Sin dependencias — solo Node.js.
 *   node system-metrics.js
 *
 * Acceso: http://127.0.0.1:4082
 */

const { exec } = require("child_process");
const fs = require("fs");
const os = require("os");
const http = require("http");

// ── CONFIGURACIÓN LOCAL ─────────────────────────────────────────────────────
const RPC_HOST = "127.0.0.1";
const RPC_PORT = 8332;
const RPC_USER = "TU_RPC_USER";       // bitcoin.conf → rpcuser
const RPC_PASS = "TU_RPC_PASSWORD";   // bitcoin.conf → rpcpassword

const PORT = 4082;
const HOST = "127.0.0.1";
// ── FIN CONFIGURACIÓN ───────────────────────────────────────────────────────

// ── Helpers asíncronos ──────────────────────────────────────────────────────
const readFile = (path) => {
  try { return fs.readFileSync(path, "utf8").trim(); } catch { return null; }
};

const sh = (cmd) => new Promise((resolve) => {
  exec(cmd, { timeout: 5000 }, (err, stdout) => resolve(err ? null : stdout.toString().trim()));
});

const sleep = (ms) => new Promise(r => setTimeout(r, ms));

// ── Caché con TTL y coalescencia de peticiones ──────────────────────────────
// Mide una sola vez por ventana; si llegan peticiones mientras se calcula,
// esperan a la misma promesa en vez de lanzar otro cálculo.
const cache = new Map(); // key -> {ts, data, inflight}
async function cached(key, ttlMs, fn) {
  const now = Date.now();
  const entry = cache.get(key);
  if (entry) {
    if (entry.inflight) return entry.inflight;
    if (now - entry.ts < ttlMs) return entry.data;
  }
  const inflight = fn().then(data => {
    cache.set(key, { ts: Date.now(), data, inflight: null });
    return data;
  }).catch(err => {
    cache.delete(key);
    throw err;
  });
  cache.set(key, { ts: now, data: entry?.data, inflight });
  return inflight;
}

// ── CPU: /proc/stat con delta entre dos lecturas (sin procesos externos) ────
function readProcStat() {
  const stat = readFile("/proc/stat");
  if (!stat) return null;
  const out = {};
  for (const line of stat.split("\n")) {
    const m = line.match(/^(cpu\d*)\s+(.+)$/);
    if (!m) continue;
    const nums = m[2].trim().split(/\s+/).map(Number);
    const idle = nums[3] + (nums[4] || 0); // idle + iowait
    const total = nums.reduce((a, b) => a + b, 0);
    out[m[1]] = { idle, total };
  }
  return out;
}

async function getCpuUsage() {
  const s1 = readProcStat();
  await sleep(500);
  const s2 = readProcStat();
  if (!s1 || !s2) return { total: 0, cores: [] };

  const usage = (a, b) => {
    const dt = b.total - a.total;
    const di = b.idle - a.idle;
    if (dt <= 0) return 0;
    return Math.min(100, Math.max(0, Math.round(((dt - di) / dt) * 100)));
  };

  const total = usage(s1.cpu, s2.cpu);
  const cores = Object.keys(s2)
    .filter(k => /^cpu\d+$/.test(k))
    .sort((a, b) => parseInt(a.slice(3)) - parseInt(b.slice(3)))
    .map((k, i) => ({ core: i, usage: s1[k] ? usage(s1[k], s2[k]) : 0 }));

  return { total, cores };
}

// ── Temperatura: solo lecturas de /sys (sin `sensors`) ─────────────────────
function getCpuTemp() {
  const paths = [
    "/sys/class/thermal/thermal_zone0/temp",
    "/sys/class/thermal/thermal_zone1/temp",
    "/sys/class/hwmon/hwmon0/temp1_input",
    "/sys/class/hwmon/hwmon1/temp1_input",
    "/sys/class/hwmon/hwmon2/temp1_input",
  ];
  for (const path of paths) {
    const val = readFile(path);
    if (val) {
      const temp = parseInt(val) / 1000;
      if (temp > 0 && temp < 150) return parseFloat(temp.toFixed(1));
    }
  }
  return null;
}

// ── RAM desde /proc/meminfo ─────────────────────────────────────────────────
function getRam() {
  try {
    const meminfo = readFile("/proc/meminfo");
    if (!meminfo) throw new Error("no meminfo");
    const get = key => {
      const m = meminfo.match(new RegExp(`^${key}:\\s+(\\d+)`, "m"));
      return m ? parseInt(m[1]) * 1024 : 0;
    };
    const total = get("MemTotal");
    const free = get("MemFree");
    const buffers = get("Buffers");
    const cached_ = get("Cached");
    const reclaimable = get("SReclaimable");
    const swapTotal = get("SwapTotal");
    const swapFree = get("SwapFree");
    const used = total - free - buffers - cached_ - reclaimable;
    const swapUsed = swapTotal - swapFree;
    const gb = v => parseFloat((v / 1e9).toFixed(1));
    return {
      total_gb: gb(total), used_gb: gb(used), free_gb: gb(free),
      cached_gb: gb(cached_ + buffers + reclaimable),
      percent: Math.round((used / total) * 100),
      swap_total_gb: gb(swapTotal), swap_used_gb: gb(swapUsed),
      swap_percent: swapTotal > 0 ? Math.round((swapUsed / swapTotal) * 100) : 0,
    };
  } catch {
    const total = os.totalmem(), free = os.freemem(), used = total - free;
    return {
      total_gb: parseFloat((total / 1e9).toFixed(1)),
      used_gb: parseFloat((used / 1e9).toFixed(1)),
      free_gb: parseFloat((free / 1e9).toFixed(1)),
      percent: Math.round((used / total) * 100),
    };
  }
}

// ── Disco ───────────────────────────────────────────────────────────────────
async function getDisk() {
  const result = await sh("df -h / | tail -1");
  if (!result) return null;
  const parts = result.split(/\s+/);
  return { total: parts[1], used: parts[2], free: parts[3], percent: parts[4] };
}

// ── Procesos destacados (nombre limpio del binario) ────────────────────────
async function getProcesses() {
  const result = await sh("ps aux --no-headers --sort=-%mem | head -8");
  if (!result) return [];
  return result.split("\n").map(line => {
    const parts = line.trim().split(/\s+/);
    // Nombre limpio: basename del ejecutable; si es un intérprete (node,
    // python...), añade el basename del script que ejecuta.
    const exe = (parts[10] || "").split("/").pop();
    const interp = /^(node|python\d?|bash|sh|perl|ruby|java)$/.test(exe);
    let command = exe;
    if (interp) {
      // Saltar flags (--max-old-space-size=…, -e, etc.) y quedarse con el
      // primer argumento "real": el script (suele acabar en .js/.py o ser ruta)
      const args = parts.slice(11);
      const script = args.find(a => a && !a.startsWith("-"));
      if (script) {
        const name = script.split("/").pop();
        command = `${exe} (${name})`;
      }
    }
    command = command.slice(0, 24);
    return {
      user: parts[0],
      cpu: parseFloat(parts[2]),
      mem: parseFloat(parts[3]),
      command,
    };
  }).filter(p => p.mem > 0.5);
}

// ── Load / Uptime ───────────────────────────────────────────────────────────
function getLoad() {
  const load = os.loadavg();
  return { "1m": load[0].toFixed(2), "5m": load[1].toFixed(2), "15m": load[2].toFixed(2) };
}
function getUptime() {
  const s = os.uptime();
  return `${Math.floor(s / 86400)}d ${Math.floor((s % 86400) / 3600)}h ${Math.floor((s % 3600) / 60)}m`;
}

// ── Bitcoin Core RPC por HTTP nativo (sin curl, sin credenciales en ps) ────
function rpcCall(method, params = []) {
  const body = JSON.stringify({ jsonrpc: "1.0", id: "txoko", method, params });
  const auth = Buffer.from(`${RPC_USER}:${RPC_PASS}`).toString("base64");
  return new Promise((resolve, reject) => {
    const req = http.request({
      host: RPC_HOST, port: RPC_PORT, method: "POST",
      headers: { "Content-Type": "application/json", "Authorization": `Basic ${auth}` },
      timeout: 8000,
    }, res => {
      let data = "";
      res.on("data", c => data += c);
      res.on("end", () => {
        try {
          const parsed = JSON.parse(data);
          if (parsed.error) reject(new Error(parsed.error.message || "RPC error"));
          else resolve(parsed.result);
        } catch (e) { reject(e); }
      });
    });
    req.on("error", reject);
    req.on("timeout", () => { req.destroy(); reject(new Error("RPC timeout")); });
    req.write(body);
    req.end();
  });
}

async function getBitcoinInfo() {
  try {
    const [info, netinfo, uptime] = await Promise.all([
      rpcCall("getblockchaininfo"),
      rpcCall("getnetworkinfo"),
      rpcCall("uptime"),
    ]);
    if (!info || !netinfo) return null;
    // connections_in/out existen desde Core 0.21; fallback a getpeerinfo si no
    let inbound = netinfo.connections_in;
    let outbound = netinfo.connections_out;
    if (inbound === undefined || outbound === undefined) {
      const peers = await rpcCall("getpeerinfo").catch(() => null);
      inbound = peers ? peers.filter(p => p.inbound).length : 0;
      outbound = peers ? peers.filter(p => !p.inbound).length : 0;
    }
    return {
      version: `v${Math.floor(netinfo.version / 10000)}.${Math.floor((netinfo.version % 10000) / 100)}.${netinfo.version % 100}`,
      blocks: info.blocks,
      headers: info.headers,
      synced: info.verificationprogress > 0.9999,
      progress: (info.verificationprogress * 100).toFixed(2),
      size_gb: (info.size_on_disk / 1e9).toFixed(1),
      peers: netinfo.connections,
      inbound, outbound,
      uptime_sec: uptime,
      chain: info.chain,
    };
  } catch { return null; }
}

// ── Logs ────────────────────────────────────────────────────────────────────
async function getLogs(service, lines = 50) {
  const result = await sh(`journalctl -u ${service} -n ${lines} --no-pager --output=short-iso 2>/dev/null`);
  if (!result) return [];
  return result.split("\n").filter(Boolean).reverse().map(line => {
    let level = "info";
    if (/error/i.test(line)) level = "error";
    else if (/warn/i.test(line)) level = "warn";
    return { line, level };
  });
}

// ── Handlers (caché por ruta: el trabajo se hace 1 vez por ventana) ────────
const routes = {

  "/system/info": async () => cached("info", 3000, async () => {
    const [cpu, disk, processes] = await Promise.all([
      getCpuUsage(), getDisk(), getProcesses(),
    ]);
    return {
      cpu: {
        usage: cpu.total,
        cores: cpu.cores,
        temp: getCpuTemp(),
        count: os.cpus().length,
        model: os.cpus()[0]?.model?.trim() || "—",
      },
      ram: getRam(),
      disk,
      load: getLoad(),
      processes,
      uptime: getUptime(),
      os: `${os.type()} ${os.release()}`,
    };
  }),

  "/system/bitcoin": async () => {
    const info = await cached("bitcoin", 5000, getBitcoinInfo);
    if (!info) return { __status: 503, error: "No se pudo conectar a Bitcoin Core" };
    return info;
  },

  "/system/logs/bitcoin": async (query) => {
    const lines = parseInt(query.get("lines")) || 50;
    const logs = await cached(`logs-btc-${lines}`, 10000, () => getLogs("bitcoind", lines));
    return { logs };
  },

  "/system/logs/fulcrum": async (query) => {
    const lines = parseInt(query.get("lines")) || 50;
    const logs = await cached(`logs-ful-${lines}`, 10000, () => getLogs("fulcrum", lines));
    return { logs };
  },

  "/system/health": async () => ({ status: "ok", timestamp: Date.now() }),
};

// ── Servidor HTTP nativo (sin dependencias) ─────────────────────────────────
const server = http.createServer(async (req, res) => {
  res.setHeader("Access-Control-Allow-Origin", "*");
  res.setHeader("Access-Control-Allow-Methods", "GET");
  res.setHeader("Content-Type", "application/json");

  const url = new URL(req.url, `http://${req.headers.host || "localhost"}`);
  const handler = routes[url.pathname];

  if (!handler) {
    res.writeHead(404);
    return res.end(JSON.stringify({ error: "Not found" }));
  }

  try {
    const data = await handler(url.searchParams);
    if (data && data.__status) {
      const { __status, ...body } = data;
      res.writeHead(__status);
      return res.end(JSON.stringify(body));
    }
    res.writeHead(200);
    res.end(JSON.stringify(data));
  } catch (e) {
    res.writeHead(500);
    res.end(JSON.stringify({ error: e.message || "Internal error" }));
  }
});

// ── Start ───────────────────────────────────────────────────────────────────
server.listen(PORT, HOST, () => {
  console.log(`
  ₿ Txoko System Metrics v2
  ─────────────────────────────────
  Escuchando en http://${HOST}:${PORT}
  Solo accesible desde localhost
  Caché: info 3s · bitcoin 5s · logs 10s
  ─────────────────────────────────
  GET /system/info          → CPU, RAM, disco, procesos
  GET /system/bitcoin       → Bitcoin Core info
  GET /system/logs/bitcoin  → logs bitcoind
  GET /system/logs/fulcrum  → logs fulcrum
  `);
});