import fs from 'fs';

const API_BASE = 'http://localhost:3001/api';

async function login(email, password) {
  const res = await fetch(`${API_BASE}/auth/login`, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ email, password })
  });
  const data = await res.json();
  if (!res.ok || !data.success) throw new Error(`Login failed: ${JSON.stringify(data)}`);
  return data.data.token;
}

async function register(email, password) {
  const res = await fetch(`${API_BASE}/auth/register`, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ email, password, emailCode: '123456' })
  });
  const data = await res.json();
  if (!res.ok || !data.success) {
    if (data.message === 'User already exists') {
      return await login(email, password);
    }
    throw new Error(`Register failed: ${JSON.stringify(data)}`);
  }
  return data.data.token;
}

async function createCourse(token, index) {
  const res = await fetch(`${API_BASE}/admin/courses`, {
    method: 'POST',
    headers: { 
      'Content-Type': 'application/json',
      'Authorization': `Bearer ${token}`
    },
    body: JSON.stringify({
      title: `Stress Test Course ${index}`,
      description: `A course created for load testing ${index}`,
      coverImage: 'https://via.placeholder.com/150',
      driveLink: 'https://drive.google.com/example',
      price: 9.99,
      category: 'Testing'
    })
  });
  const data = await res.json();
  if (!res.ok) throw new Error(`Create course failed: ${JSON.stringify(data)}`);
  return data.data.id;
}

async function createOrder(token, courseId, price) {
  const res = await fetch(`${API_BASE}/orders/create`, {
    method: 'POST',
    headers: { 
      'Content-Type': 'application/json',
      'Authorization': `Bearer ${token}`
    },
    body: JSON.stringify({ courseId, price })
  });
  const data = await res.json();
  if (!res.ok) throw new Error(`Create order failed: ${JSON.stringify(data)}`);
  return data.data.orderId;
}

async function preparePayment(token, orderId) {
  const res = await fetch(`${API_BASE}/payment/prepare`, {
    method: 'POST',
    headers: { 
      'Content-Type': 'application/json',
      'Authorization': `Bearer ${token}`
    },
    body: JSON.stringify({ orderId: String(orderId), payType: 'wechat' })
  });
  const data = await res.json();
  if (!res.ok) throw new Error(`Prepare payment failed: ${JSON.stringify(data)}`);
  return data.data;
}

async function runTest() {
  console.log('Starting Load Test...');
  
  // 1. Admin login
  console.log('Logging in as admin...');
  const adminToken = await login('admin@example.com', '123456');
  
  // 2. Create courses
  const NUM_COURSES = 10;
  console.log(`Creating ${NUM_COURSES} courses...`);
  const courseIds = [];
  for (let i = 1; i <= NUM_COURSES; i++) {
    const id = await createCourse(adminToken, i);
    courseIds.push(id);
  }
  console.log(`Created course IDs: ${courseIds.join(', ')}`);

  // 3. Create users
  const NUM_USERS = 50;
  console.log(`Creating ${NUM_USERS} users...`);
  const userTokens = [];
  for (let i = 1; i <= NUM_USERS; i++) {
    const email = `loadtestuser${Date.now()}_${i}@example.com`;
    const token = await register(email, '123456');
    userTokens.push(token);
  }

  // 4. Stress test: all users try to buy all courses concurrently
  console.log(`Starting concurrent purchase stress test for ${NUM_USERS * NUM_COURSES} requests...`);
  const startTime = Date.now();
  let successCount = 0;
  let failCount = 0;
  
  const tasks = [];
  
  for (const token of userTokens) {
    for (const courseId of courseIds) {
      tasks.push((async () => {
        try {
          const orderId = await createOrder(token, courseId, 9.99);
          await preparePayment(token, orderId);
          successCount++;
        } catch (e) {
          failCount++;
          console.error(e.message);
        }
      })());
    }
  }

  await Promise.all(tasks);
  
  const endTime = Date.now();
  console.log('\n--- Stress Test Completed ---');
  console.log(`Total Purchase Tasks: ${tasks.length}`);
  console.log(`Success: ${successCount}`);
  console.log(`Failed: ${failCount}`);
  console.log(`Time taken: ${endTime - startTime} ms`);
  console.log(`Requests per second: ${((tasks.length * 2) / ((endTime - startTime) / 1000)).toFixed(2)} req/s (2 API calls per task)`);
}

runTest().catch(console.error);