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('crud_login_duration', true);
const createDuration  = new Trend('crud_create_duration', true);
const readDuration    = new Trend('crud_read_duration', true);
const updateDuration  = new Trend('crud_update_duration', true);
const deleteDuration  = new Trend('crud_delete_duration', true);
const listDuration    = new Trend('crud_list_duration', true);
const crudErrors      = new Rate('crud_error_rate');

// ---------------------------------------------------------------------------
// Test user pool
// ---------------------------------------------------------------------------
const users = new SharedArray('users', function () {
  const lines = open('../config/user-pool.csv').split('\n').slice(1);
  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
// ---------------------------------------------------------------------------
export const options = {
  scenarios: {
    crud_flow: {
      executor: 'ramping-vus',
      startVUs: 0,
      stages: [
        { duration: '1m',  target: CONF.stages.rampUp },
        { duration: '5m',  target: CONF.stages.steady  },
        { duration: '1m',  target: 0                   },
      ],
      gracefulStop: '30s',
    },
  },
  thresholds: {
    http_req_duration:     [`p(95)<${CONF.thresholds.http_req_duration_p95}`],
    crud_create_duration:  [`p(95)<${CONF.thresholds.crud_write_p95}`],
    crud_update_duration:  [`p(95)<${CONF.thresholds.crud_write_p95}`],
    crud_read_duration:    [`p(95)<${CONF.thresholds.crud_read_p95}`],
    crud_list_duration:    [`p(95)<${CONF.thresholds.crud_read_p95}`],
    crud_error_rate:       [`rate<${CONF.thresholds.error_rate}`],
    http_req_failed:       [`rate<${CONF.thresholds.error_rate}`],
  },
};

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

function jsonPost(url, body, token, tags) {
  return http.post(url, JSON.stringify(body), {
    headers: {
      Authorization: `Bearer ${token}`,
      'Content-Type': 'application/json',
    },
    tags: tags || {},
  });
}

function jsonPut(url, body, token, tags) {
  return http.put(url, JSON.stringify(body), {
    headers: {
      Authorization: `Bearer ${token}`,
      'Content-Type': 'application/json',
    },
    tags: tags || {},
  });
}

function login(user) {
  const res = http.post(
    `${BASE}/api/auth/login`,
    JSON.stringify({ email: user.email, password: user.password }),
    { headers: { 'Content-Type': 'application/json' }, tags: { name: 'POST /api/auth/login' } },
  );
  loginDuration.add(res.timings.duration);
  if (res.status !== 200 && res.status !== 201) return null;
  try { return JSON.parse(res.body).accessToken; } catch { return null; }
}

// ---------------------------------------------------------------------------
// VU function – CRUD journey across core entities
// ---------------------------------------------------------------------------
export default function () {
  const user = users[__VU % users.length];

  // ── 1. Login ─────────────────────────────────────────────────────────
  const accessToken = login(user);
  if (!accessToken) {
    crudErrors.add(1);
    return;
  }
  crudErrors.add(0);
  sleep(0.5);

  // ── 2. Units CRUD ───────────────────────────────────────────────────
  let unitId = null;
  group('units_crud', () => {
    // List
    group('list_units', () => {
      const res = http.get(`${BASE}/api/units`, authHeaders(accessToken));
      listDuration.add(res.timings.duration);
      check(res, { 'list units 200': (r) => r.status === 200 });
    });
    sleep(0.3);

    // Create
    group('create_unit', () => {
      const payload = {
        unitNumber: `LT-${__VU}-${Date.now()}`,
        address: `${__VU} Load Test Lane`,
        ownerName: `Load Tester ${__VU}`,
        ownerEmail: `lt-${__VU}@loadtest.local`,
        squareFeet: 1200,
      };
      const res = jsonPost(`${BASE}/api/units`, payload, accessToken, { name: 'POST /api/units' });
      createDuration.add(res.timings.duration);
      const ok = check(res, {
        'create unit 200|201': (r) => r.status === 200 || r.status === 201,
      });
      if (ok) {
        try { unitId = JSON.parse(res.body).id; } catch { /* noop */ }
      }
    });
    sleep(0.3);

    // Read
    if (unitId) {
      group('read_unit', () => {
        const res = http.get(`${BASE}/api/units/${unitId}`, authHeaders(accessToken));
        readDuration.add(res.timings.duration);
        check(res, { 'read unit 200': (r) => r.status === 200 });
      });
      sleep(0.3);

      // Update
      group('update_unit', () => {
        const res = jsonPut(`${BASE}/api/units/${unitId}`, {
          ownerName: `Updated Tester ${__VU}`,
        }, accessToken, { name: 'PUT /api/units/:id' });
        updateDuration.add(res.timings.duration);
        check(res, { 'update unit 200': (r) => r.status === 200 });
      });
      sleep(0.3);

      // Delete
      group('delete_unit', () => {
        const res = http.del(`${BASE}/api/units/${unitId}`, null, authHeaders(accessToken));
        deleteDuration.add(res.timings.duration);
        check(res, { 'delete unit 200': (r) => r.status === 200 });
      });
    }
  });

  sleep(0.5);

  // ── 3. Vendors CRUD ─────────────────────────────────────────────────
  let vendorId = null;
  group('vendors_crud', () => {
    group('list_vendors', () => {
      const res = http.get(`${BASE}/api/vendors`, authHeaders(accessToken));
      listDuration.add(res.timings.duration);
      check(res, { 'list vendors 200': (r) => r.status === 200 });
    });
    sleep(0.3);

    group('create_vendor', () => {
      const payload = {
        name: `LT Vendor ${__VU}-${Date.now()}`,
        email: `vendor-${__VU}@loadtest.local`,
        phone: '555-0100',
        category: 'maintenance',
      };
      const res = jsonPost(`${BASE}/api/vendors`, payload, accessToken, { name: 'POST /api/vendors' });
      createDuration.add(res.timings.duration);
      const ok = check(res, {
        'create vendor 200|201': (r) => r.status === 200 || r.status === 201,
      });
      if (ok) {
        try { vendorId = JSON.parse(res.body).id; } catch { /* noop */ }
      }
    });
    sleep(0.3);

    if (vendorId) {
      group('read_vendor', () => {
        const res = http.get(`${BASE}/api/vendors/${vendorId}`, authHeaders(accessToken));
        readDuration.add(res.timings.duration);
        check(res, { 'read vendor 200': (r) => r.status === 200 });
      });
      sleep(0.3);

      group('update_vendor', () => {
        const res = jsonPut(`${BASE}/api/vendors/${vendorId}`, {
          name: `Updated Vendor ${__VU}`,
        }, accessToken, { name: 'PUT /api/vendors/:id' });
        updateDuration.add(res.timings.duration);
        check(res, { 'update vendor 200': (r) => r.status === 200 });
      });
    }
  });

  sleep(0.5);

  // ── 4. Journal Entries workflow ─────────────────────────────────────
  let journalEntryId = null;
  group('journal_entries', () => {
    group('list_journal_entries', () => {
      const res = http.get(`${BASE}/api/journal-entries`, authHeaders(accessToken));
      listDuration.add(res.timings.duration);
      check(res, { 'list JE 200': (r) => r.status === 200 });
    });
    sleep(0.3);

    // Fetch accounts first so we can build a valid entry
    let accounts = [];
    group('fetch_accounts_for_je', () => {
      const res = http.get(`${BASE}/api/accounts`, authHeaders(accessToken));
      check(res, { 'list accounts 200': (r) => r.status === 200 });
      try { accounts = JSON.parse(res.body); } catch { /* noop */ }
    });
    sleep(0.3);

    if (Array.isArray(accounts) && accounts.length >= 2) {
      group('create_journal_entry', () => {
        const payload = {
          date: new Date().toISOString().slice(0, 10),
          memo: `Load test JE VU-${__VU}`,
          type: 'standard',
          lines: [
            { accountId: accounts[0].id, debit: 100, credit: 0, memo: 'debit leg' },
            { accountId: accounts[1].id, debit: 0, credit: 100, memo: 'credit leg' },
          ],
        };
        const res = jsonPost(`${BASE}/api/journal-entries`, payload, accessToken, { name: 'POST /api/journal-entries' });
        createDuration.add(res.timings.duration);
        const ok = check(res, {
          'create JE 200|201': (r) => r.status === 200 || r.status === 201,
        });
        if (ok) {
          try { journalEntryId = JSON.parse(res.body).id; } catch { /* noop */ }
        }
      });
      sleep(0.3);

      if (journalEntryId) {
        group('read_journal_entry', () => {
          const res = http.get(`${BASE}/api/journal-entries/${journalEntryId}`, authHeaders(accessToken));
          readDuration.add(res.timings.duration);
          check(res, { 'read JE 200': (r) => r.status === 200 });
        });
        sleep(0.3);

        // Post (finalize) the journal entry
        group('post_journal_entry', () => {
          const res = http.post(`${BASE}/api/journal-entries/${journalEntryId}/post`, null, authHeaders(accessToken));
          updateDuration.add(res.timings.duration);
          check(res, { 'post JE 200': (r) => r.status === 200 });
        });
        sleep(0.3);

        // Void the journal entry (cleanup)
        group('void_journal_entry', () => {
          const res = http.post(`${BASE}/api/journal-entries/${journalEntryId}/void`, null, authHeaders(accessToken));
          deleteDuration.add(res.timings.duration);
          check(res, { 'void JE 200': (r) => r.status === 200 });
        });
      }
    }
  });

  sleep(0.5);

  // ── 5. Payments CRUD ────────────────────────────────────────────────
  let paymentId = null;
  group('payments_crud', () => {
    group('list_payments', () => {
      const res = http.get(`${BASE}/api/payments`, authHeaders(accessToken));
      listDuration.add(res.timings.duration);
      check(res, { 'list payments 200': (r) => r.status === 200 });
    });
    sleep(0.3);

    group('create_payment', () => {
      const payload = {
        amount: 150.00,
        date: new Date().toISOString().slice(0, 10),
        method: 'check',
        memo: `Load test payment VU-${__VU}`,
      };
      const res = jsonPost(`${BASE}/api/payments`, payload, accessToken, { name: 'POST /api/payments' });
      createDuration.add(res.timings.duration);
      const ok = check(res, {
        'create payment 200|201': (r) => r.status === 200 || r.status === 201,
      });
      if (ok) {
        try { paymentId = JSON.parse(res.body).id; } catch { /* noop */ }
      }
    });
    sleep(0.3);

    if (paymentId) {
      group('read_payment', () => {
        const res = http.get(`${BASE}/api/payments/${paymentId}`, authHeaders(accessToken));
        readDuration.add(res.timings.duration);
        check(res, { 'read payment 200': (r) => r.status === 200 });
      });
      sleep(0.3);

      group('update_payment', () => {
        const res = jsonPut(`${BASE}/api/payments/${paymentId}`, {
          memo: `Updated payment VU-${__VU}`,
        }, accessToken, { name: 'PUT /api/payments/:id' });
        updateDuration.add(res.timings.duration);
        check(res, { 'update payment 200': (r) => r.status === 200 });
      });
      sleep(0.3);

      group('delete_payment', () => {
        const res = http.del(`${BASE}/api/payments/${paymentId}`, null, authHeaders(accessToken));
        deleteDuration.add(res.timings.duration);
        check(res, { 'delete payment 200': (r) => r.status === 200 });
      });
    }
  });

  sleep(0.5);

  // ── 6. Reports (read-heavy) ─────────────────────────────────────────
  group('reports_read', () => {
    const now      = new Date();
    const year     = now.getFullYear();
    const toDate   = now.toISOString().slice(0, 10);
    const fromDate = `${year}-01-01`;

    const responses = http.batch([
      ['GET', `${BASE}/api/reports/balance-sheet?as_of=${toDate}`,                null, authHeaders(accessToken)],
      ['GET', `${BASE}/api/reports/income-statement?from=${fromDate}&to=${toDate}`, null, authHeaders(accessToken)],
      ['GET', `${BASE}/api/reports/aging`,                                         null, authHeaders(accessToken)],
      ['GET', `${BASE}/api/reports/cash-flow?from=${fromDate}&to=${toDate}`,       null, authHeaders(accessToken)],
      ['GET', `${BASE}/api/accounts/trial-balance?asOfDate=${toDate}`,             null, authHeaders(accessToken)],
    ]);

    responses.forEach((res, i) => {
      readDuration.add(res.timings.duration);
      check(res, { [`report_${i} status 200`]: (r) => r.status === 200 });
    });
  });

  sleep(1); // pacing
}