server/routes/courses.js

const express = require('express');
const Course = require('../models/Course');
const auth = require('../middleware/auth');
const router = express.Router();

// Get all courses
router.get('/', async (req, res) => {
  try {
    const { category, level, featured } = req.query;
    const query = {};
    
    if (category) query.category = category;
    if (level) query.level = level;
    if (featured) query.isFeatured = featured === 'true';

    const courses = await Course.find(query)
      .populate('instructor', 'username profile.fullName')
      .sort({ createdAt: -1 });

    res.json(courses);
  } catch (err) {
    res.status(500).json({ message: 'Server error' });
  }
});

// Get single course
router.get('/:id', async (req, res) => {
  try {
    const course = await Course.findById(req.params.id)
      .populate('instructor', 'username profile.fullName profile.bio profile.avatar')
      .populate('lessons.quiz');

    if (!course) return res.status(404).json({ message: 'Course not found' });

    res.json(course);
  } catch (err) {
    res.status(500).json({ message: 'Server error' });
  }
});

// Create course (admin/instructor only)
router.post('/', auth, async (req, res) => {
  try {
    if (req.user.role !== 'admin' && req.user.role !== 'instructor') {
      return res.status(403).json({ message: 'Not authorized' });
    }

    const course = new Course({
      ...req.body,
      instructor: req.user.id
    });

    await course.save();
    res.status(201).json(course);
  } catch (err) {
    res.status(500).json({ message: 'Server error' });
  }
});

module.exports = router;