#!/usr/bin/env node
/**
 * Lightweight soak/load probe for staging (Phase 3).
 * Does not require k6 — uses Node fetch against /health, /ready, /metrics.
 *
 * Usage:
 *   API_BASE=https://staging.example.com node scripts/load/soak-probe.mjs
 *   DURATION_SEC=60 CONCURRENCY=8 node scripts/load/soak-probe.mjs
 */
const base = (process.env.API_BASE ?? 'http://127.0.0.1:4000').replace(/\/$/, '')
const durationSec = Number(process.env.DURATION_SEC ?? 30)
const concurrency = Number(process.env.CONCURRENCY ?? 4)
const paths = (process.env.SOAK_PATHS ?? '/health,/ready,/metrics').split(',').map((p) => p.trim())

const stats = {
  ok: 0,
  fail: 0,
  statuses: /** @type {Record<string, number>} */ ({}),
  latencies: /** @type {number[]} */ ([]),
}

async function oneRequest(path) {
  const started = Date.now()
  try {
    const res = await fetch(`${base}${path}`, { method: 'GET' })
    const ms = Date.now() - started
    stats.latencies.push(ms)
    const key = String(res.status)
    stats.statuses[key] = (stats.statuses[key] ?? 0) + 1
    if (res.status >= 200 && res.status < 400) stats.ok += 1
    else stats.fail += 1
  } catch {
    stats.fail += 1
    stats.statuses.error = (stats.statuses.error ?? 0) + 1
  }
}

async function worker(deadline) {
  let i = 0
  while (Date.now() < deadline) {
    const path = paths[i % paths.length]
    i += 1
    await oneRequest(path)
  }
}

function percentile(sorted, p) {
  if (!sorted.length) return 0
  const idx = Math.min(sorted.length - 1, Math.max(0, Math.ceil((p / 100) * sorted.length) - 1))
  return sorted[idx]
}

const deadline = Date.now() + durationSec * 1000
console.log(`Soak probe ${base} duration=${durationSec}s concurrency=${concurrency} paths=${paths.join(',')}`)

await Promise.all(Array.from({ length: concurrency }, () => worker(deadline)))

const sorted = [...stats.latencies].sort((a, b) => a - b)
const total = stats.ok + stats.fail
console.log(JSON.stringify({
  total,
  ok: stats.ok,
  fail: stats.fail,
  errorRate: total ? Number((stats.fail / total).toFixed(4)) : 0,
  p50_ms: percentile(sorted, 50),
  p95_ms: percentile(sorted, 95),
  p99_ms: percentile(sorted, 99),
  statuses: stats.statuses,
}, null, 2))

if (stats.fail / Math.max(total, 1) > Number(process.env.MAX_ERROR_RATE ?? 0.05)) {
  console.error('Soak probe FAILED: error rate above MAX_ERROR_RATE')
  process.exit(1)
}
console.log('Soak probe PASSED')