feat: 实现教师资料更新、操作日志和系统设置功能

新增教师资料更新功能，包括个人信息修改和密码更新
添加操作日志记录系统，记录用户关键操作
实现系统设置模块，支持动态配置系统参数
重构数据库模型，新增教师表和系统设置表
优化成绩录入逻辑，支持平时分、期中和期末成绩计算
添加数据导出功能，支持学生、教师和成绩数据导出
完善管理员后台，增加统计图表和操作日志查看

backend/services/teacherService.js

@@ -7,8 +7,39 @@ class TeacherService {
         return await Course.findByTeacherId(teacherId);
     }
 
+    static async getClasses() {
+        return await Course.getClasses();
+    }
+
+    static async getTeacherClasses(teacherId) {
+        const sql = `SELECT * FROM classes WHERE teacher_id = ?`;
+        const db = require('../config/database');
+        return await db.query(sql, [teacherId]);
+    }
+
+    static async createCourse(teacherId, courseData) {
+        return await Course.create({ ...courseData, teacher_id: teacherId });
+    }
+
+    static async updateCourse(teacherId, courseId, courseData) {
+        // Verify ownership
+        const course = await Course.findById(courseId);
+        if (!course || course.teacher_id != teacherId) {
+            throw new Error('无权修改该课程或课程不存在');
+        }
+        return await Course.update(courseId, courseData);
+    }
+
+    static async getGrades(teacherId, filters) {
+        if (filters.courseId) {
+            return await Score.findCourseStudentsWithGrades(filters.courseId, teacherId);
+        } else {
+            return await Score.findByTeacher(teacherId, filters);
+        }
+    }
+
     static async addScore(teacherId, scoreData) {
-        const { studentId, courseId, score } = scoreData;
+        let { studentId, courseId, score, usual_score, midterm_score, final_score } = scoreData;
 
         // 验证学生
         const student = await Student.findById(studentId);
@@ -16,13 +47,12 @@ class TeacherService {
             throw new Error('学生不存在');
         }
 
-        // 验证课程（可选：验证是否是该教师的课程）
-        // const course = await Course.findById(courseId);
-        
-        // 检查重复
-        const existingScore = await Score.findByStudentAndCourse(studentId, courseId);
-        if (existingScore) {
-            throw new Error('该学生此课程成绩已存在');
+        // 如果没有总分但有平时/期中/期末分，尝试计算总分 (30% + 30% + 40%)
+        if ((score === undefined || score === '') && (usual_score || midterm_score || final_score)) {
+            const u = parseFloat(usual_score) || 0;
+            const m = parseFloat(midterm_score) || 0;
+            const f = parseFloat(final_score) || 0;
+            score = (u * 0.3 + m * 0.3 + f * 0.4).toFixed(1);
         }
 
         // 计算绩点和等级
@@ -30,19 +60,33 @@ class TeacherService {
         let gradePoint = 0;
         let gradeLevel = 'F';
 
-        if (numericScore >= 90) { gradePoint = 4.0; gradeLevel = 'A'; }
-        else if (numericScore >= 80) { gradePoint = 3.0; gradeLevel = 'B'; }
-        else if (numericScore >= 70) { gradePoint = 2.0; gradeLevel = 'C'; }
-        else if (numericScore >= 60) { gradePoint = 1.0; gradeLevel = 'D'; }
+        if (!isNaN(numericScore)) {
+            if (numericScore >= 90) { gradePoint = 4.0; gradeLevel = 'A'; }
+            else if (numericScore >= 85) { gradePoint = 3.7; gradeLevel = 'A-'; }
+            else if (numericScore >= 82) { gradePoint = 3.3; gradeLevel = 'B+'; }
+            else if (numericScore >= 78) { gradePoint = 3.0; gradeLevel = 'B'; }
+            else if (numericScore >= 75) { gradePoint = 2.7; gradeLevel = 'B-'; }
+            else if (numericScore >= 72) { gradePoint = 2.3; gradeLevel = 'C+'; }
+            else if (numericScore >= 68) { gradePoint = 2.0; gradeLevel = 'C'; }
+            else if (numericScore >= 64) { gradePoint = 1.5; gradeLevel = 'C-'; }
+            else if (numericScore >= 60) { gradePoint = 1.0; gradeLevel = 'D'; }
+        } else {
+            gradePoint = null;
+            gradeLevel = null;
+        }
 
         const fullScoreData = {
             ...scoreData,
+            score, // 更新后的总分
             teacherId,
             gradePoint,
-            gradeLevel
+            gradeLevel,
+            usual_score, 
+            midterm_score, 
+            final_score
         };
 
-        const gradeId = await Score.create(fullScoreData);
+        const gradeId = await Score.upsert(fullScoreData);
         return gradeId;
     }
 }