// k6 equivalent of KneeStepsSimulation: open model, 30 -> 240 requests/s in 8 steps,
// each held 6 s and separated by 2 s ramps. Every request is tagged with the step it was sent in.
import http from 'k6/http';
import exec from 'k6/execution';
import { check } from 'k6';
import { SharedArray } from 'k6/data';

const BASE = __ENV.APP_URL || 'http://localhost:18300';
const STEPS = 8, RATE_STEP = 30, HOLD_S = 6, RAMP_S = 2;

// the feeder: same CSV Gatling reads
const symbols = new SharedArray('symbols', () =>
  open('../src/test/resources/data/symbols.csv').trim().split('\n').slice(1));

// k6 treats only these statuses as success, so a 503 counts in http_req_failed
http.setResponseCallback(http.expectedStatuses(200));

const stages = [];
for (let i = 0; i < STEPS; i++) {
  if (i > 0) stages.push({ duration: `${RAMP_S}s`, target: RATE_STEP * (i + 1) });
  stages.push({ duration: `${HOLD_S}s`, target: RATE_STEP * (i + 1) });
}

export const options = {
  scenarios: {
    knee: {
      executor: 'ramping-arrival-rate',   // open model: iterations start on a schedule
      startRate: RATE_STEP,
      timeUnit: '1s',
      preAllocatedVUs: 200,
      maxVUs: 1000,
      stages,
    },
  },
};

function stepLabel() {
  const elapsed = Date.now() - exec.scenario.startTime;
  const slot = Math.floor(elapsed / ((HOLD_S + RAMP_S) * 1000));
  const into = elapsed % ((HOLD_S + RAMP_S) * 1000);
  if (into >= HOLD_S * 1000 || slot >= STEPS) return 'ramp';
  return `rate ${String(RATE_STEP * (slot + 1)).padStart(3, '0')}/s`;
}

export default function () {
  const symbol = symbols[Math.floor(Math.random() * symbols.length)];
  const res = http.get(`${BASE}/api/quote/${symbol}`, { tags: { step: stepLabel() } });
  check(res, { 'status is 200': (r) => r.status === 200 });
}