server/models/User.js

const mongoose = require('mongoose');
const bcrypt = require('bcryptjs');

const userSchema = new mongoose.Schema({
  username: { type: String, required: true, unique: true },
  email: { type: String, required: true, unique: true },
  password: { type: String, required: true },
  role: { type: String, enum: ['student', 'instructor', 'admin'], default: 'student' },
  enrolledCourses: [{ type: mongoose.Schema.Types.ObjectId, ref: 'Course' }],
  completedLessons: [{ 
    course: { type: mongoose.Schema.Types.ObjectId, ref: 'Course' },
    lesson: { type: mongoose.Schema.Types.ObjectId, ref: 'Lesson' }
  }],
  profile: {
    fullName: String,
    bio: String,
    avatar: String,
    skills: [String]
  },
  createdAt: { type: Date, default: Date.now }
});

userSchema.pre('save', async function(next) {
  if (!this.isModified('password')) return next();
  this.password = await bcrypt.hash(this.password, 12);
  next();
});

userSchema.methods.comparePassword = async function(candidatePassword) {
  return await bcrypt.compare(candidatePassword, this.password);
};

module.exports = mongoose.model('User', userSchema);