const express = require('express');
const app = express();
const port = process.env.PORT || 3000;

// Middleware
app.use(express.json());

// In-memory data store (in production, you'd use a database)
let users = [
  { id: 1, name: 'John Doe', email: 'john@example.com' },
  { id: 2, name: 'Jane Smith', email: 'jane@example.com' }
];
let nextId = 3;

// Health check endpoint
app.get('/ping', (req, res) => {
  res.json({ status: 'ok', timestamp: new Date().toISOString() });
});

// API Routes
app.get('/api/users', (req, res) => {
  res.json(users);
});

app.get('/api/users/:id', (req, res) => {
  const user = users.find(u => u.id === parseInt(req.params.id));
  if (!user) {
    return res.status(404).json({ error: 'User not found' });
  }
  res.json(user);
});

app.post('/api/users', (req, res) => {
  const { name, email } = req.body;
  if (!name || !email) {
    return res.status(400).json({ error: 'Name and email are required' });
  }
  
  const user = { id: nextId++, name, email };
  users.push(user);
  res.status(201).json(user);
});

app.put('/api/users/:id', (req, res) => {
  const user = users.find(u => u.id === parseInt(req.params.id));
  if (!user) {
    return res.status(404).json({ error: 'User not found' });
  }
  
  const { name, email } = req.body;
  if (name) user.name = name;
  if (email) user.email = email;
  
  res.json(user);
});

app.delete('/api/users/:id', (req, res) => {
  const index = users.findIndex(u => u.id === parseInt(req.params.id));
  if (index === -1) {
    return res.status(404).json({ error: 'User not found' });
  }
  
  users.splice(index, 1);
  res.status(204).send();
});

// Basic documentation endpoint
app.get('/', (req, res) => {
  res.json({
    message: 'Simple API Server',
    endpoints: {
      'GET /api/users': 'Get all users',
      'GET /api/users/:id': 'Get user by ID',
      'POST /api/users': 'Create new user',
      'PUT /api/users/:id': 'Update user by ID',
      'DELETE /api/users/:id': 'Delete user by ID'
    }
  });
});

app.listen(port, () => {
  console.log(`API server running on port ${port}`);
});