import { writeFile } from 'node:fs/promises';

const BASE_URL = process.env.API_BASE_URL || 'http://localhost:3000';
const USER_COUNT = Number(process.env.SEED_USERS || 20);
const SESSION_COUNT = Number(process.env.SEED_SESSIONS || 50);

const runId = `${Date.now()}`;
const generated = {
  generatedAt: new Date().toISOString(),
  runId,
  teacher: null,
  users: [],
  sessions: [],
};

async function request(path, method = 'GET', body) {
  const response = await fetch(`${BASE_URL}${path}`, {
    method,
    headers: { 'Content-Type': 'application/json' },
    ...(body ? { body: JSON.stringify(body) } : {}),
  });

  const text = await response.text();
  let data;

  try {
    data = JSON.parse(text);
  } catch {
    throw new Error(`${method} ${path}: Invalid JSON response: ${text}`);
  }

  if (!response.ok) {
    throw new Error(
      `${method} ${path} failed (${response.status}): ${JSON.stringify(data)}`
    );
  }

  return data;
}

function entityId(data) {
  const entity = data.result ?? data.data ?? data;
  const id = entity._id ?? entity.id;

  if (!id) {
    throw new Error(`Could not find created record ID: ${JSON.stringify(data)}`);
  }

  return id;
}

async function main() {
  console.log(`Seeding ${BASE_URL}`);

  const teacherResponse = await request('/teachers/', 'POST', {
    fullName: `Load Test Teacher ${runId}`,
    email: `teacher-${runId}@example.invalid`,
    specialization: 'Mathematics',
    experience: '5 years',
  });

  generated.teacher = {
    id: entityId(teacherResponse),
    email: `teacher-${runId}@example.invalid`,
  };

  for (let i = 1; i <= USER_COUNT; i++) {
    const email = `user-${runId}-${i}@example.invalid`;

    const response = await request('/users/', 'POST', {
      fullName: `Load Test User ${i}`,
      email,
      phone: String(9000000000 + i),
    });

    generated.users.push({
      id: entityId(response),
      email,
    });

    if (i % 10 === 0 || i === USER_COUNT) {
      console.log(`Created ${i}/${USER_COUNT} users`);
    }
  }

  // Start tomorrow and spread sessions one hour apart.
  const firstStart = Date.now() + 24 * 60 * 60 * 1000;

  for (let i = 0; i < SESSION_COUNT; i++) {
    const start = new Date(firstStart + i * 60 * 60 * 1000);
    const end = new Date(start.getTime() + 30 * 60 * 1000);

    const response = await request('/sessions/', 'POST', {
      teacherId: generated.teacher.id,
      startTime: start.toISOString(),
      endTime: end.toISOString(),
    });

    generated.sessions.push({
      id: entityId(response),
      startTime: start.toISOString(),
      endTime: end.toISOString(),
      dateTimestamp: start.toISOString(),
    });

    if ((i + 1) % 10 === 0 || i + 1 === SESSION_COUNT) {
      console.log(`Created ${i + 1}/${SESSION_COUNT} sessions`);
    }
  }

  await writeFile(
    new URL('../k6/seed-data.json', import.meta.url),
    JSON.stringify(generated, null, 2) + '\n'
  );

  console.log('\nSeeding completed successfully.');
  console.log(`Teacher: 1`);
  console.log(`Users: ${generated.users.length}`);
  console.log(`Sessions: ${generated.sessions.length}`);
  console.log('Saved IDs to k6/seed-data.json');
}

main().catch((error) => {
  console.error('\nSeeding failed:', error.message);
  process.exitCode = 1;
});