/**
 * EN: k6 load test — Order creation endpoint (POST /api/v1/orders).
 * VI: k6 load test — endpoint tạo đơn hàng (POST /api/v1/orders).
 *
 * Usage:
 *   k6 run tests/load/k6/order-creation.js
 *   k6 run --env BASE_URL=http://api.staging.goodgo.vn tests/load/k6/order-creation.js
 *
 * Thresholds:
 *   - 95th-percentile response time < 500ms
 *   - Error rate < 1%
 */
import http from 'k6/http';
import { check, sleep } from 'k6';
import { Rate, Trend } from 'k6/metrics';

// ---------------------------------------------------------------------------
// Custom metrics
// ---------------------------------------------------------------------------
const orderCreationErrors = new Rate('order_creation_errors');
const orderCreationDuration = new Trend('order_creation_duration', true);

// ---------------------------------------------------------------------------
// Test options
// ---------------------------------------------------------------------------
export const options = {
  stages: [
    // EN: Ramp up to 20 VUs over 30s / VI: Tăng lên 20 VUs trong 30s
    { duration: '30s', target: 20 },
    // EN: Hold at 20 VUs for 1 minute / VI: Duy trì 20 VUs trong 1 phút
    { duration: '1m', target: 20 },
    // EN: Spike to 50 VUs for 30s / VI: Tăng đột biến lên 50 VUs trong 30s
    { duration: '30s', target: 50 },
    // EN: Ramp down / VI: Giảm dần
    { duration: '30s', target: 0 },
  ],
  thresholds: {
    // EN: 95% of requests must complete below 500ms / VI: 95% requests phải hoàn thành dưới 500ms
    http_req_duration: ['p(95)<500'],
    // EN: Error rate must stay below 1% / VI: Tỷ lệ lỗi phải dưới 1%
    order_creation_errors: ['rate<0.01'],
    // EN: Custom trend threshold / VI: Ngưỡng trend tùy chỉnh
    order_creation_duration: ['p(99)<1000'],
  },
};

// ---------------------------------------------------------------------------
// Config
// ---------------------------------------------------------------------------
const BASE_URL = __ENV.BASE_URL || 'http://localhost:5010';
const JWT_TOKEN = __ENV.JWT_TOKEN || 'test-bearer-token';

const SHOP_ID = __ENV.SHOP_ID || '00000000-0000-0000-0000-000000000001';
const PRODUCT_ID = __ENV.PRODUCT_ID || '00000000-0000-0000-0000-000000000002';

const headers = {
  'Content-Type': 'application/json',
  Authorization: `Bearer ${JWT_TOKEN}`,
  'X-Shop-Id': SHOP_ID,
};

// ---------------------------------------------------------------------------
// Helper — generate a random order payload
// ---------------------------------------------------------------------------
function buildOrderPayload() {
  const tableNumber = Math.floor(Math.random() * 20) + 1;
  const qty = Math.floor(Math.random() * 3) + 1;
  return JSON.stringify({
    shopId: SHOP_ID,
    tableNumber: `T${tableNumber}`,
    orderType: 'dine_in',
    items: [
      {
        productId: PRODUCT_ID,
        quantity: qty,
        unitPrice: 35000,
        note: '',
      },
    ],
    note: `k6-load-test-${Date.now()}`,
  });
}

// ---------------------------------------------------------------------------
// Default function — executed per VU iteration
// ---------------------------------------------------------------------------
export default function () {
  const payload = buildOrderPayload();
  const startTime = Date.now();

  const res = http.post(`${BASE_URL}/api/v1/orders`, payload, { headers });

  const duration = Date.now() - startTime;
  orderCreationDuration.add(duration);

  const success = check(res, {
    // EN: Status is 201 Created / VI: Status là 201 Created
    'status is 201': (r) => r.status === 201,
    // EN: Response body has success=true / VI: Body phản hồi có success=true
    'body has success:true': (r) => {
      try {
        return JSON.parse(r.body).success === true;
      } catch {
        return false;
      }
    },
    // EN: Response time below 500ms / VI: Thời gian phản hồi dưới 500ms
    'response time < 500ms': (r) => r.timings.duration < 500,
  });

  if (!success) {
    orderCreationErrors.add(1);
  } else {
    orderCreationErrors.add(0);
  }

  // EN: Think time between requests (0.5–1.5s) / VI: Thời gian nghỉ giữa các request
  sleep(0.5 + Math.random());
}