/**
 * Monitors docker container CPU/memory during a stress test.
 *
 * Usage (run in parallel with run-stress-test.js):
 *   node stress/monitor-docker.js --containers pdf-test --interval 1000 --duration 300000 --out stress/results/monitor.json
 */

const { spawnSync } = require('child_process');
const fs = require('fs');
const path = require('path');

function parseArgs(argv) {
  const args = { containers: 'pdf-test,pdf-prod', interval: 1000, duration: 300000, out: '' };
  for (let i = 0; i < argv.length; i++) {
    const m = argv[i].match(/^--([^=]+)(?:=(.*))?$/);
    if (!m) continue;
    if (m[2] !== undefined) {
      args[m[1]] = m[2];
    } else if (i + 1 < argv.length && !argv[i + 1].startsWith('--')) {
      args[m[1]] = argv[++i];
    } else {
      args[m[1]] = true;
    }
  }
  return args;
}

function sample(containers) {
  try {
    // Use spawnSync with an args array (no shell) to avoid Windows quoting bugs.
    const res = spawnSync('docker', ['stats', '--no-stream', '--format', '{{json .}}', '--', ...containers], { encoding: 'utf8', timeout: 10000 });
    if (res.status !== 0 || !res.stdout) return {};
    const rows = {};
    for (const line of res.stdout.split('\n').filter(Boolean)) {
      let obj;
      try { obj = JSON.parse(line); } catch (e) { continue; }
      const name = obj.Name;
      if (!name) continue;
      rows[name] = {
        cpuPerc: parseFloat(obj.CPUPerc) || 0,
        memUsedGiB: parseGiB(obj.MemUsage),
        memTotalGiB: 0,
        memPerc: parseFloat(obj.MemPerc) || 0,
      };
    }
    return rows;
  } catch (e) {
    return {};
  }
}

function parseGiB(memUsageStr) {
  if (!memUsageStr) return 0;
  const m = memUsageStr.match(/^([\d.]+)\s*(\w+)\s*\/\s*([\d.]+)\s*(\w+)$/);
  if (!m) return 0;
  const used = parseFloat(m[1]);
  const unit = m[2];
  if (unit === 'GiB') return used;
  if (unit === 'MiB') return used / 1024;
  if (unit === 'KiB') return used / (1024 * 1024);
  return used;
}

async function main() {
  const args = parseArgs(process.argv.slice(2));
  const containers = args.containers.split(',');
  const interval = parseInt(args.interval, 10);
  const duration = parseInt(args.duration, 10);
  const outFile = args.out || path.join(__dirname, 'results', `monitor-${Date.now()}.json`);

  const samples = [];
  const started = Date.now();
  console.log(`Monitoring ${containers.join(',')} for ${duration}ms...`);
  while (Date.now() - started < duration) {
    const rows = sample(containers);
    samples.push({ t: Date.now() - started, rows });
    process.stdout.write(`\rt=${Date.now() - started}ms  ` + containers.map((c) => {
      const r = rows[c];
      return r ? `${c}: cpu=${r.cpuPerc.toFixed(1)}% mem=${r.memUsedGiB.toFixed(2)}GiB` : `${c}: n/a`;
    }).join('  '));
    await new Promise((r) => setTimeout(r, interval));
  }
  process.stdout.write('\n');

  const summary = {};
  for (const c of containers) {
    const vals = samples.map((s) => s.rows[c]).filter(Boolean);
    if (!vals.length) { summary[c] = null; continue; }
    const cpu = vals.map((v) => v.cpuPerc).sort((a, b) => a - b);
    const mem = vals.map((v) => v.memUsedGiB).sort((a, b) => a - b);
    summary[c] = {
      cpuPerc: { avg: +(cpu.reduce((a, b) => a + b, 0) / cpu.length).toFixed(1), peak: Math.round(cpu[cpu.length - 1]) },
      memUsedGiB: { avg: +(mem.reduce((a, b) => a + b, 0) / mem.length).toFixed(2), peak: +mem[mem.length - 1].toFixed(2) },
    };
  }
  const report = { started, duration, interval, containers, summary, samples };
  fs.writeFileSync(outFile, JSON.stringify(report, null, 2));
  console.log(`\nMonitor report saved: ${outFile}`);
  console.log(JSON.stringify(summary, null, 2));
}

main().catch((e) => {
  console.error(e);
  process.exit(1);
});