add changes

controllers/auth.controller.js

@@ -0,0 +1,288 @@
+const jwt = require('jsonwebtoken');
+const { v4: uuidv4 } = require('uuid');
+const { User, GuestSession, QuizSession, sequelize } = require('../models');
+const config = require('../config/config');
+
+/**
+ * @desc    Register a new user
+ * @route   POST /api/auth/register
+ * @access  Public
+ */
+exports.register = async (req, res) => {
+  const transaction = await sequelize.transaction();
+  
+  try {
+    const { username, email, password, guestSessionId } = req.body;
+
+    // Check if user already exists
+    const existingUser = await User.findOne({
+      where: {
+        [sequelize.Sequelize.Op.or]: [
+          { email: email.toLowerCase() },
+          { username: username.toLowerCase() }
+        ]
+      }
+    });
+
+    if (existingUser) {
+      await transaction.rollback();
+      if (existingUser.email === email.toLowerCase()) {
+        return res.status(400).json({
+          success: false,
+          message: 'Email already registered'
+        });
+      } else {
+        return res.status(400).json({
+          success: false,
+          message: 'Username already taken'
+        });
+      }
+    }
+
+    // Create new user (password will be hashed by beforeCreate hook)
+    const user = await User.create({
+      id: uuidv4(),
+      username: username.toLowerCase(),
+      email: email.toLowerCase(),
+      password: password,
+      role: 'user',
+      is_active: true
+    }, { transaction });
+
+    // Handle guest session migration if provided
+    let migratedData = null;
+    if (guestSessionId) {
+      try {
+        const guestSession = await GuestSession.findOne({
+          where: { guest_id: guestSessionId }
+        });
+
+        if (guestSession && !guestSession.is_converted) {
+          // Migrate quiz sessions from guest to user
+          const migratedSessions = await QuizSession.update(
+            { 
+              user_id: user.id,
+              guest_session_id: null
+            },
+            {
+              where: { guest_session_id: guestSession.id },
+              transaction
+            }
+          );
+
+          // Mark guest session as converted
+          await guestSession.update({
+            is_converted: true,
+            converted_user_id: user.id,
+            converted_at: new Date()
+          }, { transaction });
+
+          // Recalculate user stats from migrated sessions
+          const quizSessions = await QuizSession.findAll({
+            where: { 
+              user_id: user.id,
+              status: 'completed'
+            },
+            transaction
+          });
+
+          let totalQuizzes = quizSessions.length;
+          let quizzesPassed = 0;
+          let totalQuestionsAnswered = 0;
+          let correctAnswers = 0;
+
+          quizSessions.forEach(session => {
+            if (session.is_passed) quizzesPassed++;
+            totalQuestionsAnswered += session.questions_answered || 0;
+            correctAnswers += session.correct_answers || 0;
+          });
+
+          // Update user stats
+          await user.update({
+            total_quizzes: totalQuizzes,
+            quizzes_passed: quizzesPassed,
+            total_questions_answered: totalQuestionsAnswered,
+            correct_answers: correctAnswers
+          }, { transaction });
+
+          migratedData = {
+            quizzes: migratedSessions[0],
+            stats: {
+              totalQuizzes,
+              quizzesPassed,
+              accuracy: totalQuestionsAnswered > 0 
+                ? ((correctAnswers / totalQuestionsAnswered) * 100).toFixed(2)
+                : 0
+            }
+          };
+        }
+      } catch (guestError) {
+        // Log error but don't fail registration
+        console.error('Guest migration error:', guestError.message);
+        // Continue with registration even if migration fails
+      }
+    }
+
+    // Commit transaction before generating JWT
+    await transaction.commit();
+
+    // Generate JWT token (after commit to avoid rollback issues)
+    const token = jwt.sign(
+      { 
+        userId: user.id,
+        email: user.email,
+        username: user.username,
+        role: user.role
+      },
+      config.jwt.secret,
+      { expiresIn: config.jwt.expire }
+    );
+
+    // Return user data (exclude password)
+    const userData = user.toSafeJSON();
+
+    res.status(201).json({
+      success: true,
+      message: 'User registered successfully',
+      data: {
+        user: userData,
+        token,
+        migratedData
+      }
+    });
+
+  } catch (error) {
+    // Only rollback if transaction is still active
+    if (!transaction.finished) {
+      await transaction.rollback();
+    }
+    console.error('Registration error:', error);
+    res.status(500).json({
+      success: false,
+      message: 'Error registering user',
+      error: error.message
+    });
+  }
+};
+
+/**
+ * @desc    Login user
+ * @route   POST /api/auth/login
+ * @access  Public
+ */
+exports.login = async (req, res) => {
+  try {
+    const { email, password } = req.body;
+
+    // Find user by email
+    const user = await User.findOne({
+      where: { 
+        email: email.toLowerCase(),
+        is_active: true
+      }
+    });
+
+    if (!user) {
+      return res.status(401).json({
+        success: false,
+        message: 'Invalid email or password'
+      });
+    }
+
+    // Verify password
+    const isPasswordValid = await user.comparePassword(password);
+    if (!isPasswordValid) {
+      return res.status(401).json({
+        success: false,
+        message: 'Invalid email or password'
+      });
+    }
+
+    // Update last_login
+    await user.update({ last_login: new Date() });
+
+    // Generate JWT token
+    const token = jwt.sign(
+      { 
+        userId: user.id,
+        email: user.email,
+        username: user.username,
+        role: user.role
+      },
+      config.jwt.secret,
+      { expiresIn: config.jwt.expire }
+    );
+
+    // Return user data (exclude password)
+    const userData = user.toSafeJSON();
+
+    res.status(200).json({
+      success: true,
+      message: 'Login successful',
+      data: {
+        user: userData,
+        token
+      }
+    });
+
+  } catch (error) {
+    console.error('Login error:', error);
+    res.status(500).json({
+      success: false,
+      message: 'Error logging in',
+      error: error.message
+    });
+  }
+};
+
+/**
+ * @desc    Logout user (client-side token removal)
+ * @route   POST /api/auth/logout
+ * @access  Public
+ */
+exports.logout = async (req, res) => {
+  // Since we're using JWT (stateless), logout is handled client-side
+  // by removing the token from storage
+  res.status(200).json({
+    success: true,
+    message: 'Logout successful. Please remove token from client storage.'
+  });
+};
+
+/**
+ * @desc    Verify JWT token and return user info
+ * @route   GET /api/auth/verify
+ * @access  Private
+ */
+exports.verifyToken = async (req, res) => {
+  try {
+    // User is already attached to req by verifyToken middleware
+    const user = await User.findByPk(req.user.userId);
+
+    if (!user || !user.isActive) {
+      return res.status(404).json({
+        success: false,
+        message: 'User not found or inactive'
+      });
+    }
+
+    // Return user data (exclude password)
+    const userData = user.toSafeJSON();
+
+    res.status(200).json({
+      success: true,
+      message: 'Token valid',
+      data: {
+        user: userData
+      }
+    });
+
+  } catch (error) {
+    console.error('Token verification error:', error);
+    res.status(500).json({
+      success: false,
+      message: 'Error verifying token',
+      error: error.message
+    });
+  }
+};

controllers/category.controller.js

@@ -0,0 +1,481 @@
+const { Category, Question } = require('../models');
+
+/**
+ * @desc    Get all active categories
+ * @route   GET /api/categories
+ * @access  Public
+ */
+exports.getAllCategories = async (req, res) => {
+  try {
+    // Check if request is from guest or authenticated user
+    const isGuest = !req.user; // If no user attached, it's a guest/public request
+    
+    // Build query conditions
+    const whereConditions = {
+      isActive: true
+    };
+    
+    // If guest, only show guest-accessible categories
+    if (isGuest) {
+      whereConditions.guestAccessible = true;
+    }
+    
+    // Fetch categories
+    const categories = await Category.findAll({
+      where: whereConditions,
+      attributes: [
+        'id',
+        'name',
+        'slug',
+        'description',
+        'icon',
+        'color',
+        'questionCount',
+        'displayOrder',
+        'guestAccessible'
+      ],
+      order: [
+        ['displayOrder', 'ASC'],
+        ['name', 'ASC']
+      ]
+    });
+    
+    res.status(200).json({
+      success: true,
+      count: categories.length,
+      data: categories,
+      message: isGuest 
+        ? `${categories.length} guest-accessible categories available`
+        : `${categories.length} categories available`
+    });
+    
+  } catch (error) {
+    console.error('Error fetching categories:', error);
+    res.status(500).json({
+      success: false,
+      message: 'Error fetching categories',
+      error: error.message
+    });
+  }
+};
+
+/**
+ * @desc    Get category details by ID
+ * @route   GET /api/categories/:id
+ * @access  Public (with optional auth for access control)
+ */
+exports.getCategoryById = async (req, res) => {
+  try {
+    const { id } = req.params;
+    const isGuest = !req.user;
+    
+    // Validate ID (accepts UUID or numeric)
+    if (!id) {
+      return res.status(400).json({
+        success: false,
+        message: 'Invalid category ID'
+      });
+    }
+    
+    // UUID format validation (basic check)
+    const isUUID = /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/i.test(id);
+    const isNumeric = !isNaN(id) && Number.isInteger(Number(id));
+    
+    if (!isUUID && !isNumeric) {
+      return res.status(400).json({
+        success: false,
+        message: 'Invalid category ID format'
+      });
+    }
+    
+    // Find category
+    const category = await Category.findByPk(id, {
+      attributes: [
+        'id',
+        'name',
+        'slug',
+        'description',
+        'icon',
+        'color',
+        'questionCount',
+        'displayOrder',
+        'guestAccessible',
+        'isActive'
+      ]
+    });
+    
+    // Check if category exists
+    if (!category) {
+      return res.status(404).json({
+        success: false,
+        message: 'Category not found'
+      });
+    }
+    
+    // Check if category is active
+    if (!category.isActive) {
+      return res.status(404).json({
+        success: false,
+        message: 'Category not found'
+      });
+    }
+    
+    // Check guest access
+    if (isGuest && !category.guestAccessible) {
+      return res.status(403).json({
+        success: false,
+        message: 'This category requires authentication. Please register or login to access.',
+        requiresAuth: true
+      });
+    }
+    
+    // Get question preview (first 5 questions)
+    const questionPreview = await Question.findAll({
+      where: {
+        categoryId: id,
+        isActive: true
+      },
+      attributes: [
+        'id',
+        'questionText',
+        'questionType',
+        'difficulty',
+        'points',
+        'timesAttempted',
+        'timesCorrect'
+      ],
+      order: [['createdAt', 'ASC']],
+      limit: 5
+    });
+    
+    // Calculate category stats
+    const allQuestions = await Question.findAll({
+      where: {
+        categoryId: id,
+        isActive: true
+      },
+      attributes: ['difficulty', 'timesAttempted', 'timesCorrect']
+    });
+    
+    const stats = {
+      totalQuestions: allQuestions.length,
+      questionsByDifficulty: {
+        easy: allQuestions.filter(q => q.difficulty === 'easy').length,
+        medium: allQuestions.filter(q => q.difficulty === 'medium').length,
+        hard: allQuestions.filter(q => q.difficulty === 'hard').length
+      },
+      totalAttempts: allQuestions.reduce((sum, q) => sum + (q.timesAttempted || 0), 0),
+      totalCorrect: allQuestions.reduce((sum, q) => sum + (q.timesCorrect || 0), 0)
+    };
+    
+    // Calculate average accuracy
+    stats.averageAccuracy = stats.totalAttempts > 0 
+      ? Math.round((stats.totalCorrect / stats.totalAttempts) * 100) 
+      : 0;
+    
+    // Prepare response
+    const categoryData = {
+      id: category.id,
+      name: category.name,
+      slug: category.slug,
+      description: category.description,
+      icon: category.icon,
+      color: category.color,
+      questionCount: category.questionCount,
+      displayOrder: category.displayOrder,
+      guestAccessible: category.guestAccessible
+    };
+    
+    res.status(200).json({
+      success: true,
+      data: {
+        category: categoryData,
+        questionPreview: questionPreview.map(q => ({
+          id: q.id,
+          questionText: q.questionText,
+          questionType: q.questionType,
+          difficulty: q.difficulty,
+          points: q.points,
+          accuracy: q.timesAttempted > 0 
+            ? Math.round((q.timesCorrect / q.timesAttempted) * 100) 
+            : 0
+        })),
+        stats
+      },
+      message: `Category details retrieved successfully`
+    });
+    
+  } catch (error) {
+    console.error('Error fetching category details:', error);
+    res.status(500).json({
+      success: false,
+      message: 'Error fetching category details',
+      error: error.message
+    });
+  }
+};
+
+/**
+ * @desc    Create new category (Admin only)
+ * @route   POST /api/categories
+ * @access  Private/Admin
+ */
+exports.createCategory = async (req, res) => {
+  try {
+    const {
+      name,
+      slug,
+      description,
+      icon,
+      color,
+      guestAccessible,
+      displayOrder
+    } = req.body;
+    
+    // Validate required fields
+    if (!name) {
+      return res.status(400).json({
+        success: false,
+        message: 'Category name is required'
+      });
+    }
+    
+    // Check if category with same name exists
+    const existingByName = await Category.findOne({
+      where: { name }
+    });
+    
+    if (existingByName) {
+      return res.status(400).json({
+        success: false,
+        message: 'A category with this name already exists'
+      });
+    }
+    
+    // Check if custom slug provided and if it exists
+    if (slug) {
+      const existingBySlug = await Category.findOne({
+        where: { slug }
+      });
+      
+      if (existingBySlug) {
+        return res.status(400).json({
+          success: false,
+          message: 'A category with this slug already exists'
+        });
+      }
+    }
+    
+    // Create category (slug will be auto-generated by model hook if not provided)
+    const category = await Category.create({
+      name,
+      slug,
+      description: description || null,
+      icon: icon || null,
+      color: color || '#3B82F6',
+      guestAccessible: guestAccessible !== undefined ? guestAccessible : false,
+      displayOrder: displayOrder || 0,
+      isActive: true,
+      questionCount: 0,
+      quizCount: 0
+    });
+    
+    res.status(201).json({
+      success: true,
+      data: {
+        id: category.id,
+        name: category.name,
+        slug: category.slug,
+        description: category.description,
+        icon: category.icon,
+        color: category.color,
+        guestAccessible: category.guestAccessible,
+        displayOrder: category.displayOrder,
+        questionCount: category.questionCount,
+        isActive: category.isActive
+      },
+      message: 'Category created successfully'
+    });
+    
+  } catch (error) {
+    console.error('Error creating category:', error);
+    res.status(500).json({
+      success: false,
+      message: 'Error creating category',
+      error: error.message
+    });
+  }
+};
+
+/**
+ * @desc    Update category (Admin only)
+ * @route   PUT /api/categories/:id
+ * @access  Private/Admin
+ */
+exports.updateCategory = async (req, res) => {
+  try {
+    const { id } = req.params;
+    const {
+      name,
+      slug,
+      description,
+      icon,
+      color,
+      guestAccessible,
+      displayOrder,
+      isActive
+    } = req.body;
+    
+    // Validate ID
+    if (!id) {
+      return res.status(400).json({
+        success: false,
+        message: 'Category ID is required'
+      });
+    }
+    
+    // Find category
+    const category = await Category.findByPk(id);
+    
+    if (!category) {
+      return res.status(404).json({
+        success: false,
+        message: 'Category not found'
+      });
+    }
+    
+    // Check if new name conflicts with existing category
+    if (name && name !== category.name) {
+      const existingByName = await Category.findOne({
+        where: { name }
+      });
+      
+      if (existingByName) {
+        return res.status(400).json({
+          success: false,
+          message: 'A category with this name already exists'
+        });
+      }
+    }
+    
+    // Check if new slug conflicts with existing category
+    if (slug && slug !== category.slug) {
+      const existingBySlug = await Category.findOne({
+        where: { slug }
+      });
+      
+      if (existingBySlug) {
+        return res.status(400).json({
+          success: false,
+          message: 'A category with this slug already exists'
+        });
+      }
+    }
+    
+    // Update category
+    const updateData = {};
+    if (name !== undefined) updateData.name = name;
+    if (slug !== undefined) updateData.slug = slug;
+    if (description !== undefined) updateData.description = description;
+    if (icon !== undefined) updateData.icon = icon;
+    if (color !== undefined) updateData.color = color;
+    if (guestAccessible !== undefined) updateData.guestAccessible = guestAccessible;
+    if (displayOrder !== undefined) updateData.displayOrder = displayOrder;
+    if (isActive !== undefined) updateData.isActive = isActive;
+    
+    await category.update(updateData);
+    
+    res.status(200).json({
+      success: true,
+      data: {
+        id: category.id,
+        name: category.name,
+        slug: category.slug,
+        description: category.description,
+        icon: category.icon,
+        color: category.color,
+        guestAccessible: category.guestAccessible,
+        displayOrder: category.displayOrder,
+        questionCount: category.questionCount,
+        isActive: category.isActive
+      },
+      message: 'Category updated successfully'
+    });
+    
+  } catch (error) {
+    console.error('Error updating category:', error);
+    res.status(500).json({
+      success: false,
+      message: 'Error updating category',
+      error: error.message
+    });
+  }
+};
+
+/**
+ * @desc    Delete category (soft delete - Admin only)
+ * @route   DELETE /api/categories/:id
+ * @access  Private/Admin
+ */
+exports.deleteCategory = async (req, res) => {
+  try {
+    const { id } = req.params;
+    
+    // Validate ID
+    if (!id) {
+      return res.status(400).json({
+        success: false,
+        message: 'Category ID is required'
+      });
+    }
+    
+    // Find category
+    const category = await Category.findByPk(id);
+    
+    if (!category) {
+      return res.status(404).json({
+        success: false,
+        message: 'Category not found'
+      });
+    }
+    
+    // Check if already deleted
+    if (!category.isActive) {
+      return res.status(400).json({
+        success: false,
+        message: 'Category is already deleted'
+      });
+    }
+    
+    // Check if category has questions
+    const questionCount = await Question.count({
+      where: {
+        categoryId: id,
+        isActive: true
+      }
+    });
+    
+    // Soft delete - set isActive to false
+    await category.update({ isActive: false });
+    
+    res.status(200).json({
+      success: true,
+      data: {
+        id: category.id,
+        name: category.name,
+        questionCount: questionCount
+      },
+      message: questionCount > 0 
+        ? `Category deleted successfully. ${questionCount} questions are still associated with this category.`
+        : 'Category deleted successfully'
+    });
+    
+  } catch (error) {
+    console.error('Error deleting category:', error);
+    res.status(500).json({
+      success: false,
+      message: 'Error deleting category',
+      error: error.message
+    });
+  }
+};

controllers/guest.controller.js

@@ -0,0 +1,447 @@
+const { GuestSession, Category, User, QuizSession, sequelize } = require('../models');
+const { v4: uuidv4 } = require('uuid');
+const jwt = require('jsonwebtoken');
+const config = require('../config/config');
+
+/**
+ * @desc    Start a new guest session
+ * @route   POST /api/guest/start-session
+ * @access  Public
+ */
+exports.startGuestSession = async (req, res) => {
+  try {
+    const { deviceId } = req.body;
+    
+    // Get IP address
+    const ipAddress = req.ip || req.connection.remoteAddress || 'unknown';
+    
+    // Get user agent
+    const userAgent = req.headers['user-agent'] || 'unknown';
+    
+    // Generate unique guest_id
+    const timestamp = Date.now();
+    const randomString = Math.random().toString(36).substring(2, 10);
+    const guestId = `guest_${timestamp}_${randomString}`;
+    
+    // Calculate expiry (24 hours from now by default)
+    const expiryHours = parseInt(config.guest.sessionExpireHours) || 24;
+    const expiresAt = new Date(Date.now() + expiryHours * 60 * 60 * 1000);
+    const maxQuizzes = parseInt(config.guest.maxQuizzes) || 3;
+    
+    // Generate session token (JWT) before creating session
+    const sessionToken = jwt.sign(
+      { guestId },
+      config.jwt.secret,
+      { expiresIn: `${expiryHours}h` }
+    );
+    
+    // Create guest session
+    const guestSession = await GuestSession.create({
+      guestId: guestId,
+      sessionToken: sessionToken,
+      deviceId: deviceId || null,
+      ipAddress: ipAddress,
+      userAgent: userAgent,
+      expiresAt: expiresAt,
+      maxQuizzes: maxQuizzes,
+      quizzesAttempted: 0,
+      isConverted: false
+    });
+    
+    // Get guest-accessible categories
+    const categories = await Category.findAll({
+      where: {
+        isActive: true,
+        guestAccessible: true
+      },
+      attributes: ['id', 'name', 'slug', 'description', 'icon', 'color', 'questionCount'],
+      order: [['displayOrder', 'ASC'], ['name', 'ASC']]
+    });
+    
+    // Return response
+    res.status(201).json({
+      success: true,
+      message: 'Guest session created successfully',
+      data: {
+        guestId: guestSession.guestId,
+        sessionToken,
+        expiresAt: guestSession.expiresAt,
+        expiresIn: `${expiryHours} hours`,
+        restrictions: {
+          maxQuizzes: guestSession.maxQuizzes,
+          quizzesRemaining: guestSession.maxQuizzes - guestSession.quizzesAttempted,
+          features: {
+            canTakeQuizzes: true,
+            canViewResults: true,
+            canBookmarkQuestions: false,
+            canTrackProgress: false,
+            canEarnAchievements: false
+          }
+        },
+        availableCategories: categories,
+        upgradeMessage: 'Sign up to unlock unlimited quizzes, track progress, and earn achievements!'
+      }
+    });
+    
+  } catch (error) {
+    console.error('Error creating guest session:', error);
+    res.status(500).json({
+      success: false,
+      message: 'Error creating guest session',
+      error: error.message
+    });
+  }
+};
+
+/**
+ * @desc    Get guest session details
+ * @route   GET /api/guest/session/:guestId
+ * @access  Public
+ */
+exports.getGuestSession = async (req, res) => {
+  try {
+    const { guestId } = req.params;
+    
+    // Find guest session
+    const guestSession = await GuestSession.findOne({
+      where: { guestId: guestId }
+    });
+    
+    if (!guestSession) {
+      return res.status(404).json({
+        success: false,
+        message: 'Guest session not found'
+      });
+    }
+    
+    // Check if session is expired
+    if (guestSession.isExpired()) {
+      return res.status(410).json({
+        success: false,
+        message: 'Guest session has expired. Please start a new session.',
+        expired: true
+      });
+    }
+    
+    // Check if session is converted
+    if (guestSession.isConverted) {
+      return res.status(410).json({
+        success: false,
+        message: 'This guest session has been converted to a user account',
+        converted: true,
+        userId: guestSession.convertedUserId
+      });
+    }
+    
+    // Get guest-accessible categories
+    const categories = await Category.findAll({
+      where: {
+        isActive: true,
+        guestAccessible: true
+      },
+      attributes: ['id', 'name', 'slug', 'description', 'icon', 'color', 'questionCount'],
+      order: [['displayOrder', 'ASC'], ['name', 'ASC']]
+    });
+    
+    // Calculate time until expiry
+    const now = new Date();
+    const expiresAt = new Date(guestSession.expiresAt);
+    const hoursRemaining = Math.max(0, Math.floor((expiresAt - now) / (1000 * 60 * 60)));
+    const minutesRemaining = Math.max(0, Math.floor(((expiresAt - now) % (1000 * 60 * 60)) / (1000 * 60)));
+    
+    // Return session details
+    res.status(200).json({
+      success: true,
+      data: {
+        guestId: guestSession.guestId,
+        expiresAt: guestSession.expiresAt,
+        expiresIn: `${hoursRemaining}h ${minutesRemaining}m`,
+        isExpired: false,
+        restrictions: {
+          maxQuizzes: guestSession.maxQuizzes,
+          quizzesAttempted: guestSession.quizzesAttempted,
+          quizzesRemaining: Math.max(0, guestSession.maxQuizzes - guestSession.quizzesAttempted),
+          features: {
+            canTakeQuizzes: guestSession.quizzesAttempted < guestSession.maxQuizzes,
+            canViewResults: true,
+            canBookmarkQuestions: false,
+            canTrackProgress: false,
+            canEarnAchievements: false
+          }
+        },
+        availableCategories: categories,
+        upgradeMessage: 'Sign up to unlock unlimited quizzes, track progress, and earn achievements!'
+      }
+    });
+    
+  } catch (error) {
+    console.error('Error getting guest session:', error);
+    res.status(500).json({
+      success: false,
+      message: 'Error retrieving guest session',
+      error: error.message
+    });
+  }
+};
+
+/**
+ * @desc    Check guest quiz limit
+ * @route   GET /api/guest/quiz-limit
+ * @access  Protected (Guest Token Required)
+ */
+exports.checkQuizLimit = async (req, res) => {
+  try {
+    // Guest session is already verified and attached by middleware
+    const guestSession = req.guestSession;
+    
+    // Calculate remaining quizzes
+    const quizzesRemaining = guestSession.maxQuizzes - guestSession.quizzesAttempted;
+    const hasReachedLimit = quizzesRemaining <= 0;
+    
+    // Calculate time until reset (session expiry)
+    const now = new Date();
+    const expiresAt = new Date(guestSession.expiresAt);
+    const timeRemainingMs = expiresAt - now;
+    const hoursRemaining = Math.floor(timeRemainingMs / (1000 * 60 * 60));
+    const minutesRemaining = Math.floor((timeRemainingMs % (1000 * 60 * 60)) / (1000 * 60));
+    
+    // Format reset time
+    let resetTime;
+    if (hoursRemaining > 0) {
+      resetTime = `${hoursRemaining}h ${minutesRemaining}m`;
+    } else {
+      resetTime = `${minutesRemaining}m`;
+    }
+    
+    // Prepare response
+    const response = {
+      success: true,
+      data: {
+        guestId: guestSession.guestId,
+        quizLimit: {
+          maxQuizzes: guestSession.maxQuizzes,
+          quizzesAttempted: guestSession.quizzesAttempted,
+          quizzesRemaining: Math.max(0, quizzesRemaining),
+          hasReachedLimit: hasReachedLimit
+        },
+        session: {
+          expiresAt: guestSession.expiresAt,
+          timeRemaining: resetTime,
+          resetTime: resetTime
+        }
+      }
+    };
+    
+    // Add upgrade prompt if limit reached
+    if (hasReachedLimit) {
+      response.data.upgradePrompt = {
+        message: 'You have reached your quiz limit!',
+        benefits: [
+          'Unlimited quizzes',
+          'Track your progress over time',
+          'Earn achievements and badges',
+          'Bookmark questions for review',
+          'Compete on leaderboards'
+        ],
+        callToAction: 'Sign up now to continue learning!'
+      };
+      response.message = 'Quiz limit reached. Sign up to continue!';
+    } else {
+      response.message = `You have ${quizzesRemaining} quiz${quizzesRemaining === 1 ? '' : 'zes'} remaining`;
+    }
+    
+    res.status(200).json(response);
+    
+  } catch (error) {
+    console.error('Error checking quiz limit:', error);
+    res.status(500).json({
+      success: false,
+      message: 'Error checking quiz limit',
+      error: error.message
+    });
+  }
+};
+
+/**
+ * @desc    Convert guest session to registered user account
+ * @route   POST /api/guest/convert
+ * @access  Protected (Guest Token Required)
+ */
+exports.convertGuestToUser = async (req, res) => {
+  const transaction = await sequelize.transaction();
+  
+  try {
+    const { username, email, password } = req.body;
+    const guestSession = req.guestSession; // Attached by middleware
+    
+    // Validate required fields
+    if (!username || !email || !password) {
+      await transaction.rollback();
+      return res.status(400).json({
+        success: false,
+        message: 'Username, email, and password are required'
+      });
+    }
+    
+    // Validate username length
+    if (username.length < 3 || username.length > 50) {
+      await transaction.rollback();
+      return res.status(400).json({
+        success: false,
+        message: 'Username must be between 3 and 50 characters'
+      });
+    }
+    
+    // Validate email format
+    const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
+    if (!emailRegex.test(email)) {
+      await transaction.rollback();
+      return res.status(400).json({
+        success: false,
+        message: 'Invalid email format'
+      });
+    }
+    
+    // Validate password strength
+    if (password.length < 8) {
+      await transaction.rollback();
+      return res.status(400).json({
+        success: false,
+        message: 'Password must be at least 8 characters long'
+      });
+    }
+    
+    // Check if email already exists
+    const existingEmail = await User.findOne({
+      where: { email: email.toLowerCase() },
+      transaction
+    });
+    
+    if (existingEmail) {
+      await transaction.rollback();
+      return res.status(400).json({
+        success: false,
+        message: 'Email already registered'
+      });
+    }
+    
+    // Check if username already exists
+    const existingUsername = await User.findOne({
+      where: { username },
+      transaction
+    });
+    
+    if (existingUsername) {
+      await transaction.rollback();
+      return res.status(400).json({
+        success: false,
+        message: 'Username already taken'
+      });
+    }
+    
+    // Create new user account (password will be hashed by User model hook)
+    const user = await User.create({
+      username,
+      email: email.toLowerCase(),
+      password,
+      role: 'user'
+    }, { transaction });
+    
+    // Migrate quiz sessions from guest to user
+    const migratedSessions = await QuizSession.update(
+      { 
+        userId: user.id,
+        guestSessionId: null
+      },
+      {
+        where: { guestSessionId: guestSession.id },
+        transaction
+      }
+    );
+    
+    // Mark guest session as converted
+    await guestSession.update({
+      isConverted: true,
+      convertedUserId: user.id
+    }, { transaction });
+    
+    // Recalculate user stats from migrated sessions
+    const quizSessions = await QuizSession.findAll({
+      where: { 
+        userId: user.id,
+        status: 'completed'
+      },
+      transaction
+    });
+    
+    let totalQuizzes = quizSessions.length;
+    let quizzesPassed = 0;
+    let totalQuestionsAnswered = 0;
+    let correctAnswers = 0;
+    
+    quizSessions.forEach(session => {
+      if (session.isPassed) quizzesPassed++;
+      totalQuestionsAnswered += session.questionsAnswered || 0;
+      correctAnswers += session.correctAnswers || 0;
+    });
+    
+    // Update user stats
+    await user.update({
+      totalQuizzes,
+      quizzesPassed,
+      totalQuestionsAnswered,
+      correctAnswers
+    }, { transaction });
+    
+    // Commit transaction
+    await transaction.commit();
+    
+    // Generate JWT token for the new user
+    const token = jwt.sign(
+      {
+        userId: user.id,
+        email: user.email,
+        username: user.username,
+        role: user.role
+      },
+      config.jwt.secret,
+      { expiresIn: config.jwt.expire }
+    );
+    
+    // Return response
+    res.status(201).json({
+      success: true,
+      message: 'Guest account successfully converted to registered user',
+      data: {
+        user: user.toSafeJSON(),
+        token,
+        migration: {
+          quizzesTransferred: migratedSessions[0],
+          stats: {
+            totalQuizzes,
+            quizzesPassed,
+            totalQuestionsAnswered,
+            correctAnswers,
+            accuracy: totalQuestionsAnswered > 0 
+              ? ((correctAnswers / totalQuestionsAnswered) * 100).toFixed(2)
+              : 0
+          }
+        }
+      }
+    });
+    
+  } catch (error) {
+    if (!transaction.finished) {
+      await transaction.rollback();
+    }
+    
+    console.error('Error converting guest to user:', error);
+    console.error('Error stack:', error.stack);
+    res.status(500).json({
+      success: false,
+      message: 'Error converting guest account',
+      error: error.message,
+      stack: process.env.NODE_ENV === 'development' ? error.stack : undefined
+    });
+  }
+};