#!/usr/bin/env node
// Collect server metrics — called by cron every minute
// Appends JSON lines to analytics.jsonl

const { Rcon } = require("rcon-client");
const { execSync } = require("child_process");
const { appendFileSync, readFileSync, writeFileSync } = require("fs");

const ANALYTICS_FILE = "/home/minecraft/server/analytics.jsonl";
const RCON_HOST = "127.0.0.1";
const RCON_PORT = 25575;
const RCON_PASS = "23991818cc169249f181436f2a29a013";

async function main() {
  // Check if server is running
  try {
    const active = execSync("systemctl is-active minecraft.service", { encoding: "utf8" }).trim();
    if (active !== "active") process.exit(0);
  } catch {
    process.exit(0);
  }

  // Get MC PID
  let mcPid = "";
  try {
    mcPid = execSync("pgrep -f 'java.*forge' | head -1", { encoding: "utf8" }).trim();
  } catch {}

  let tps = 0;
  let playersOnline = 0;
  let players = [];

  // RCON queries
  try {
    const rcon = await Rcon.connect({ host: RCON_HOST, port: RCON_PORT, password: RCON_PASS });

    // TPS
    try {
      const tpsRaw = await rcon.send("forge tps");
      const match = tpsRaw.match(/Overall.*Mean TPS:\s*(\d+\.?\d*)/i) || tpsRaw.match(/Mean TPS:\s*(\d+\.?\d*)/);
      if (match) tps = parseFloat(match[1]);
    } catch {}

    // Players
    try {
      const listRaw = await rcon.send("list");
      const countMatch = listRaw.match(/(\d+)\s+of/);
      if (countMatch) playersOnline = parseInt(countMatch[1]);
      if (playersOnline > 0) {
        const namesStr = listRaw.split(":").pop() || "";
        players = namesStr.split(",").map(n => n.trim()).filter(Boolean);
      }
    } catch {}

    rcon.end();
  } catch {
    // RCON not available
  }

  // RAM
  let ramUsedMB = 0;
  const ramTotalMB = 8192;
  if (mcPid) {
    try {
      const status = readFileSync(`/proc/${mcPid}/status`, "utf8");
      const match = status.match(/VmRSS:\s+(\d+)/);
      if (match) ramUsedMB = Math.round(parseInt(match[1]) / 1024);
    } catch {}
  }

  // CPU (normalize to total system CPU — ps reports per-core)
  let cpuPercent = 0;
  const numCpus = parseInt(execSync("nproc", { encoding: "utf8" }).trim()) || 1;
  if (mcPid) {
    try {
      const cpu = execSync(`ps -p ${mcPid} -o %cpu --no-headers`, { encoding: "utf8" }).trim();
      cpuPercent = (parseFloat(cpu) || 0) / numCpus;
    } catch {}
  }

  // Write
  const entry = {
    ts: new Date().toISOString(),
    tps: Math.round(tps * 10) / 10,
    ramUsedMB,
    ramTotalMB,
    cpuPercent: Math.round(cpuPercent * 10) / 10,
    playersOnline,
    players,
  };

  appendFileSync(ANALYTICS_FILE, JSON.stringify(entry) + "\n");

  // Prune to last 2880 lines (48h)
  try {
    const lines = readFileSync(ANALYTICS_FILE, "utf8").split("\n").filter(Boolean);
    if (lines.length > 3000) {
      writeFileSync(ANALYTICS_FILE, lines.slice(-2880).join("\n") + "\n");
    }
  } catch {}
}

main().catch(() => process.exit(0));