import http from 'k6/http';
import { check, group, sleep } from 'k6';
import { SharedArray } from 'k6/data';
import { Counter, Rate, Trend } from 'k6/metrics';

// ---------------------------------------------------------------------------
// Custom metrics
// ---------------------------------------------------------------------------
const loginDuration     = new Trend('login_duration', true);
const refreshDuration   = new Trend('refresh_duration', true);
const dashboardDuration = new Trend('dashboard_duration', true);
const profileDuration   = new Trend('profile_duration', true);
const loginFailures     = new Counter('login_failures');
const authErrors        = new Rate('auth_error_rate');

// ---------------------------------------------------------------------------
// Test user pool – parameterized from CSV
// ---------------------------------------------------------------------------
const users = new SharedArray('users', function () {
  const lines = open('../config/user-pool.csv').split('\n').slice(1); // skip header
  return lines
    .filter((l) => l.trim().length > 0)
    .map((line) => {
      const [email, password, orgId, role] = line.split(',');
      return { email: email.trim(), password: password.trim(), orgId: orgId.trim(), role: role.trim() };
    });
});

// ---------------------------------------------------------------------------
// Environment config
// ---------------------------------------------------------------------------
const ENV  = JSON.parse(open('../config/environments.json'));
const CONF = ENV[__ENV.TARGET_ENV || 'staging'];
const BASE = CONF.baseUrl;

// ---------------------------------------------------------------------------
// k6 options – ramp-up / steady / ramp-down
// ---------------------------------------------------------------------------
export const options = {
  scenarios: {
    auth_dashboard: {
      executor: 'ramping-vus',
      startVUs: 0,
      stages: [
        { duration: '1m',  target: CONF.stages.rampUp   },  // ramp-up
        { duration: '5m',  target: CONF.stages.steady    },  // steady state
        { duration: '1m',  target: 0                     },  // ramp-down
      ],
      gracefulStop: '30s',
    },
  },
  thresholds: {
    http_req_duration:   [`p(95)<${CONF.thresholds.http_req_duration_p95}`],
    login_duration:      [`p(95)<${CONF.thresholds.login_p95}`],
    dashboard_duration:  [`p(95)<${CONF.thresholds.dashboard_p95}`],
    auth_error_rate:     [`rate<${CONF.thresholds.error_rate}`],
    http_req_failed:     [`rate<${CONF.thresholds.error_rate}`],
  },
};

// ---------------------------------------------------------------------------
// Helpers
// ---------------------------------------------------------------------------
function authHeaders(accessToken) {
  return {
    headers: {
      Authorization: `Bearer ${accessToken}`,
      'Content-Type': 'application/json',
    },
  };
}

function jsonPost(url, body, params = {}) {
  return http.post(url, JSON.stringify(body), {
    headers: { 'Content-Type': 'application/json', ...((params.headers) || {}) },
    tags: params.tags || {},
  });
}

// ---------------------------------------------------------------------------
// Default VU function – login → dashboard journey
// ---------------------------------------------------------------------------
export default function () {
  const user = users[__VU % users.length];

  let accessToken = null;

  // ── 1. Login ─────────────────────────────────────────────────────────
  group('01_login', () => {
    const res = jsonPost(`${BASE}/api/auth/login`, {
      email: user.email,
      password: user.password,
    }, { tags: { name: 'POST /api/auth/login' } });

    loginDuration.add(res.timings.duration);

    const ok = check(res, {
      'login status 200|201': (r) => r.status === 200 || r.status === 201,
      'login returns accessToken': (r) => {
        try { return !!JSON.parse(r.body).accessToken; } catch { return false; }
      },
    });

    if (!ok) {
      loginFailures.add(1);
      authErrors.add(1);
      return; // abort journey – cannot continue without token
    }
    authErrors.add(0);

    const body = JSON.parse(res.body);
    accessToken = body.accessToken;
  });

  if (!accessToken) return; // guard

  sleep(0.5); // think-time between login and dashboard load

  // ── 2. Fetch profile ────────────────────────────────────────────────
  group('02_profile', () => {
    const res = http.get(`${BASE}/api/auth/profile`, authHeaders(accessToken));
    profileDuration.add(res.timings.duration);
    check(res, {
      'profile status 200': (r) => r.status === 200,
    });
  });

  sleep(0.3);

  // ── 3. Dashboard KPIs ───────────────────────────────────────────────
  group('03_dashboard', () => {
    const res = http.get(`${BASE}/api/reports/dashboard`, authHeaders(accessToken));
    dashboardDuration.add(res.timings.duration);
    check(res, {
      'dashboard status 200': (r) => r.status === 200,
    });
  });

  sleep(0.3);

  // ── 4. Parallel dashboard widgets (batch) ───────────────────────────
  group('04_dashboard_widgets', () => {
    const now      = new Date();
    const year     = now.getFullYear();
    const fromDate = `${year}-01-01`;
    const toDate   = now.toISOString().slice(0, 10);

    const responses = http.batch([
      ['GET', `${BASE}/api/accounts?fundType=operating`,       null, authHeaders(accessToken)],
      ['GET', `${BASE}/api/reports/income-statement?from=${fromDate}&to=${toDate}`, null, authHeaders(accessToken)],
      ['GET', `${BASE}/api/reports/balance-sheet?as_of=${toDate}`, null, authHeaders(accessToken)],
      ['GET', `${BASE}/api/reports/aging`,                     null, authHeaders(accessToken)],
      ['GET', `${BASE}/api/health-scores/latest`,              null, authHeaders(accessToken)],
      ['GET', `${BASE}/api/onboarding/progress`,               null, authHeaders(accessToken)],
    ]);

    responses.forEach((res, i) => {
      check(res, {
        [`widget_${i} status 200`]: (r) => r.status === 200,
      });
    });
  });

  sleep(0.5);

  // ── 5. Refresh token ───────────────────────────────────────────────
  group('05_refresh_token', () => {
    const res = http.post(`${BASE}/api/auth/refresh`, null, {
      headers: { 'Content-Type': 'application/json' },
      tags: { name: 'POST /api/auth/refresh' },
    });
    refreshDuration.add(res.timings.duration);
    check(res, {
      'refresh status 200|201': (r) => r.status === 200 || r.status === 201,
    });
  });

  sleep(0.5);

  // ── 6. Logout ──────────────────────────────────────────────────────
  group('06_logout', () => {
    const res = http.post(`${BASE}/api/auth/logout`, null, authHeaders(accessToken));
    check(res, {
      'logout status 200|201': (r) => r.status === 200 || r.status === 201,
    });
  });

  sleep(1); // pacing between iterations
}