add new changes

backend/controllers/question.controller.js

@@ -1,6 +1,209 @@
 const { Question, Category, sequelize } = require('../models');
 const { Op } = require('sequelize');
 
+/**
+ * Get single question by ID (Admin only)
+ * GET /api/admin/questions/:id
+ * Returns complete question data including correctAnswer
+ */
+exports.getQuestionByIdAdmin = async (req, res) => {
+  try {
+    const { id } = req.params;
+
+    // Validate UUID format
+    const uuidRegex = /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/i;
+    if (!uuidRegex.test(id)) {
+      return res.status(400).json({
+        success: false,
+        message: 'Invalid question ID format'
+      });
+    }
+
+    // Query question with category info (including inactive questions for admin)
+    const question = await Question.findOne({
+      where: { id },
+      attributes: [
+        'id',
+        'questionText',
+        'questionType',
+        'options',
+        'correctAnswer',
+        'difficulty',
+        'points',
+        'timesAttempted',
+        'timesCorrect',
+        'explanation',
+        'tags',
+        'keywords',
+        'isActive',
+        'createdAt',
+        'updatedAt'
+      ],
+      include: [
+        {
+          model: Category,
+          as: 'category',
+          attributes: ['id', 'name', 'slug', 'icon', 'color', 'guestAccessible', 'isActive']
+        }
+      ]
+    });
+
+    // Check if question exists
+    if (!question) {
+      return res.status(404).json({
+        success: false,
+        message: 'Question not found'
+      });
+    }
+
+    // Convert to JSON and add calculated fields
+    const questionData = question.toJSON();
+    
+    // Calculate accuracy
+    questionData.accuracy = question.timesAttempted > 0
+      ? Math.round((question.timesCorrect / question.timesAttempted) * 100)
+      : 0;
+
+    res.status(200).json({
+      success: true,
+      data: questionData,
+      message: 'Question retrieved successfully'
+    });
+
+  } catch (error) {
+    console.error('Error in getQuestionByIdAdmin:', error);
+    res.status(500).json({
+      success: false,
+      message: 'An error occurred while retrieving the question',
+      error: process.env.NODE_ENV === 'development' ? error.message : undefined
+    });
+  }
+};
+
+/**
+ * Get all questions with pagination, filtering and search (Admin only)
+ * GET /api/admin/questions?page=1&limit=10&search=javascript&category=uuid&difficulty=easy&sortBy=createdAt&order=DESC
+ */
+exports.getAllQuestions = async (req, res) => {
+  try {
+    const {
+      page = 1,
+      limit = 10,
+      search = '',
+      category = '',
+      difficulty = '',
+      sortBy = 'createdAt',
+      order = 'DESC'
+    } = req.query;
+
+    // Validate and parse pagination
+    const pageNumber = Math.max(parseInt(page, 10) || 1, 1);
+    const pageSize = Math.min(Math.max(parseInt(limit, 10) || 10, 1), 100);
+    const offset = (pageNumber - 1) * pageSize;
+
+    // Build where conditions for questions
+    const whereConditions = {};
+
+    // Search filter (question text or explanation)
+    if (search && search.trim().length > 0) {
+      whereConditions[Op.or] = [
+        { questionText: { [Op.like]: `%${search.trim()}%` } },
+        { explanation: { [Op.like]: `%${search.trim()}%` } },
+        { tags: { [Op.like]: `%${search.trim()}%` } }
+      ];
+    }
+
+    // Difficulty filter
+    if (difficulty && ['easy', 'medium', 'hard'].includes(difficulty.toLowerCase())) {
+      whereConditions.difficulty = difficulty.toLowerCase();
+    }
+
+    // Category filter
+    if (category) {
+      const uuidRegex = /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/i;
+      if (uuidRegex.test(category)) {
+        whereConditions.categoryId = category;
+      }
+    }
+
+    // Validate sort field
+    const validSortFields = ['createdAt', 'updatedAt', 'questionText', 'difficulty', 'points', 'timesAttempted'];
+    const sortField = validSortFields.includes(sortBy) ? sortBy : 'createdAt';
+    const sortOrder = order.toUpperCase() === 'ASC' ? 'ASC' : 'DESC';
+
+    // Query questions with pagination
+    const { count, rows: questions } = await Question.findAndCountAll({
+      where: whereConditions,
+      attributes: [
+        'id',
+        'questionText',
+        'questionType',
+        'options',
+        'difficulty',
+        'points',
+        'explanation',
+        'tags',
+        'keywords',
+        'timesAttempted',
+        'timesCorrect',
+        'isActive',
+        'createdAt',
+        'updatedAt'
+      ],
+      include: [
+        {
+          model: Category,
+          as: 'category',
+          attributes: ['id', 'name', 'slug', 'icon', 'color', 'guestAccessible']
+        }
+      ],
+      order: [[sortField, sortOrder]],
+      limit: pageSize,
+      offset: offset
+    });
+
+    // Calculate accuracy for each question
+    const questionsWithAccuracy = questions.map(question => {
+      const questionData = question.toJSON();
+      questionData.accuracy = question.timesAttempted > 0
+        ? Math.round((question.timesCorrect / question.timesAttempted) * 100)
+        : 0;
+      
+      // Keep correctAnswer for admin
+      return questionData;
+    });
+
+    // Calculate pagination metadata
+    const totalPages = Math.ceil(count / pageSize);
+
+    res.status(200).json({
+      success: true,
+      count: questionsWithAccuracy.length,
+      total: count,
+      page: pageNumber,
+      totalPages,
+      limit: pageSize,
+      filters: {
+        search: search || null,
+        category: category || null,
+        difficulty: difficulty || null,
+        sortBy: sortField,
+        order: sortOrder
+      },
+      data: questionsWithAccuracy,
+      message: `Retrieved ${questionsWithAccuracy.length} of ${count} questions`
+    });
+
+  } catch (error) {
+    console.error('Error in getAllQuestions:', error);
+    res.status(500).json({
+      success: false,
+      message: 'An error occurred while retrieving questions',
+      error: process.env.NODE_ENV === 'development' ? error.message : undefined
+    });
+  }
+};
+
 /**
  * Get questions by category with filtering and pagination
  * GET /api/questions/category/:categoryId?difficulty=easy&limit=10&random=true