const express = require('express');
const router = express.Router();
const db = require('../config/database');
const { requireAuth, requireRole } = require('../middleware/auth');

// 获取学生成绩
router.get('/grades', requireAuth, requireRole(['student']), async (req, res) => {
    try {
        const userId = req.session.user.id;
        
        // 获取学生信息
        const students = await db.pool.execute(
            'SELECT id FROM students WHERE user_id = ?',
            [userId]
        );
        
        if (students[0].length === 0) {
            return res.status(404).json({ 
                success: false, 
                message: '学生信息不存在' 
            });
        }
        
        const studentId = students[0][0].id;
        
        // 获取成绩信息
        const grades = await db.pool.execute(`
            SELECT s.*, c.course_code, c.course_name, c.credit,
                   u.name as teacher_name
            FROM scores s
            JOIN courses c ON s.course_id = c.id
            JOIN users u ON s.teacher_id = u.id
            WHERE s.student_id = ?
            ORDER BY s.exam_date DESC
        `, [studentId]);
        
        // 计算统计信息
        let totalCredits = 0;
        let totalGradePoints = 0;
        let totalCourses = grades.length;
        
        grades.forEach(grade => {
            totalCredits += parseFloat(grade.credit);
            if (grade.grade_point) {
                totalGradePoints += parseFloat(grade.grade_point) * parseFloat(grade.credit);
            }
        });
        
        const gpa = totalCredits > 0 ? (totalGradePoints / totalCredits).toFixed(2) : 0;
        
        res.json({
            success: true,
            grades,
            statistics: {
                totalCourses,
                totalCredits,
                gpa,
                averageScore: totalCourses > 0 ? 
                    (grades.reduce((sum, g) => sum + parseFloat(g.score || 0), 0) / totalCourses).toFixed(1) : 0
            }
        });
        
    } catch (error) {
        console.error('获取成绩错误:', error);
        res.status(500).json({ 
            success: false, 
            message: '服务器错误' 
        });
    }
});

// 获取成绩详情
router.get('/grades/:id', requireAuth, requireRole(['student']), async (req, res) => {
    try {
        const gradeId = req.params.id;
        const userId = req.session.user.id;
        
        const grades = await db.pool.execute(`
            SELECT s.*, c.course_code, c.course_name, c.credit, c.semester,
                   u.full_name as teacher_name, u.email as teacher_email,
                   st.student_id as student_number, st.class_name, st.major
            FROM scores s
            JOIN courses c ON s.course_id = c.id
            JOIN users u ON s.teacher_id = u.id
            JOIN students st ON s.student_id = st.id
            WHERE s.id = ? AND st.user_id = ?
        `, [gradeId, userId]);
        
        if (grades[0].length === 0) {
            return res.status(404).json({ 
                success: false, 
                message: '成绩不存在' 
            });
        }
        
        res.json({
            success: true,
            grade: grades[0]
        });
        
    } catch (error) {
        console.error('获取成绩详情错误:', error);
        res.status(500).json({ 
            success: false, 
            message: '服务器错误' 
        });
    }
});

// 获取学生个人信息
router.get('/profile', requireAuth, requireRole(['student']), async (req, res) => {
    try {
        const userId = req.session.user.id;
        
        const students = await db.pool.execute(`
            SELECT s.*, u.username, u.email, u.created_at as account_created
            FROM students s
            JOIN users u ON s.user_id = u.id
            WHERE u.id = ?
        `, [userId]);
        
        if (students[0].length === 0) {
            return res.status(404).json({ 
                success: false, 
                message: '学生信息不存在' 
            });
        }
        
        res.json({
            success: true,
            profile: students[0]
        });
        
    } catch (error) {
        console.error('获取个人信息错误:', error);
        res.status(500).json({ 
            success: false, 
            message: '服务器错误' 
        });
    }
});

module.exports = router;