ADD file via upload

exams.js

@@ -0,0 +1,111 @@
+const Exam = require('../models/Exam');
+
+// 获取所有考试
+exports.getExams = async (req, res, next) => {
+    try {
+        const exams = await Exam.find({ isActive: true })
+            .select('-questions.answer') // 不返回答案
+            .populate('createdBy', 'username');
+
+        res.json(exams);
+    } catch (err) {
+        next(err);
+    }
+};
+
+// 获取单个考试详情
+exports.getExam = async (req, res, next) => {
+    try {
+        const exam = await Exam.findById(req.params.id)
+            .select('-questions.answer') // 不返回答案
+            .populate('createdBy', 'username');
+
+        if (!exam) {
+            return res.status(404).json({ message: 'Exam not found' });
+        }
+
+        res.json(exam);
+    } catch (err) {
+        next(err);
+    }
+};
+
+// 创建新考试 (教师/管理员)
+exports.createExam = async (req, res, next) => {
+    try {
+        const { title, description, duration, questions } = req.body;
+
+        const exam = new Exam({
+            title,
+            description,
+            duration,
+            questions,
+            createdBy: req.user.id
+        });
+
+        await exam.save();
+
+        res.status(201).json(exam);
+    } catch (err) {
+        next(err);
+    }
+};
+
+// 验证考试答案
+exports.validateAnswers = async (req, res, next) => {
+    try {
+        const { answers } = req.body;
+
+        // 获取考试(包含正确答案)
+        const exam = await Exam.findById(req.params.id);
+        if (!exam) {
+            return res.status(404).json({ message: 'Exam not found' });
+        }
+
+        // 计算分数
+        let totalScore = 0;
+        const results = exam.questions.map(question => {
+            const userAnswer = answers[question._id];
+            let isCorrect = false;
+            let score = 0;
+
+            if (question.type === 'text') {
+                // 简答题默认给一半分
+                if (userAnswer && userAnswer.trim().length > 0) {
+                    isCorrect = true;
+                    score = question.score / 2;
+                }
+            } else if (Array.isArray(question.answer)) {
+                // 多选题
+                const correctAnswers = [...question.answer].sort().toString();
+                const userAns = [...userAnswer].sort().toString();
+                isCorrect = correctAnswers === userAns;
+                score = isCorrect ? question.score : 0;
+            } else {
+                // 单选题
+                isCorrect = userAnswer === question.answer;
+                score = isCorrect ? question.score : 0;
+            }
+
+            totalScore += score;
+
+            return {
+                questionId: question._id,
+                question: question.question,
+                userAnswer,
+                correctAnswer: question.answer,
+                isCorrect,
+                score
+            };
+        });
+
+        res.json({
+            examId: exam._id,
+            totalScore,
+            maxScore: exam.questions.reduce((sum, q) => sum + q.score, 0),
+            results
+        });
+    } catch (err) {
+        next(err);
+    }
+};