添加每日一练功能（未完成排行榜前端）

后端功能：
- 添加Exam模型is_system字段标识系统试卷
- 创建每日一练服务，使用PostgreSQL分布式锁
- 集成cron定时任务，每天凌晨1点自动生成试卷
- 自动分享给所有用户（批量插入）
- API权限控制：系统试卷禁止删除和再次分享
- 添加GetDailyExamRanking API返回排行榜

前端功能：
- 添加is_system类型定义
- 系统试卷显示"系统"标签
- 系统试卷隐藏删除和分享按钮
- 添加getDailyExamRanking API方法

技术亮点：
- 使用PostgreSQL Advisory Lock实现分布式锁
- 使用robfig/cron/v3调度定时任务
- 批量插入提升分享性能

待完成：首页添加每日一练排行榜组件

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

go.mod

@@ -41,6 +41,7 @@ require (
 	github.com/pelletier/go-toml/v2 v2.2.4 // indirect
 	github.com/quic-go/qpack v0.5.1 // indirect
 	github.com/quic-go/quic-go v0.55.0 // indirect
+	github.com/robfig/cron/v3 v3.0.1 // indirect
 	github.com/sashabaranov/go-openai v1.41.2 // indirect
 	github.com/twitchyliquid64/golang-asm v0.15.1 // indirect
 	github.com/ugorji/go/codec v1.3.1 // indirect

go.sum

@@ -74,6 +74,8 @@ github.com/quic-go/qpack v0.5.1 h1:giqksBPnT/HDtZ6VhtFKgoLOWmlyo9Ei6u9PqzIMbhI=
 github.com/quic-go/qpack v0.5.1/go.mod h1:+PC4XFrEskIVkcLzpEkbLqq1uCoxPhQuvK5rH1ZgaEg=
 github.com/quic-go/quic-go v0.55.0 h1:zccPQIqYCXDt5NmcEabyYvOnomjs8Tlwl7tISjJh9Mk=
 github.com/quic-go/quic-go v0.55.0/go.mod h1:DR51ilwU1uE164KuWXhinFcKWGlEjzys2l8zUl5Ss1U=
+github.com/robfig/cron/v3 v3.0.1 h1:WdRxkvbJztn8LMz/QEvLN5sBU+xKpSqwwUO1Pjr4qDs=
+github.com/robfig/cron/v3 v3.0.1/go.mod h1:eQICP3HwyT7UooqI/z+Ov+PtYAWygg1TEWWzGIFLtro=
 github.com/sashabaranov/go-openai v1.41.2 h1:vfPRBZNMpnqu8ELsclWcAvF19lDNgh1t6TVfFFOPiSM=
 github.com/sashabaranov/go-openai v1.41.2/go.mod h1:lj5b/K+zjTSFxVLijLSTDZuP7adOgerWeFyZLUhAKRg=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=

internal/handlers/exam_handler.go

@@ -734,6 +734,15 @@ func DeleteExam(c *gin.Context) {
 		return
 	}
 
+	// 检查是否为系统试卷
+	if exam.IsSystem {
+		c.JSON(http.StatusForbidden, gin.H{
+			"success": false,
+			"message": "系统试卷不允许删除",
+		})
+		return
+	}
+
 	// 软删除
 	if err := db.Delete(&exam).Error; err != nil {
 		log.Printf("删除试卷失败: %v", err)
@@ -951,6 +960,15 @@ func ShareExam(c *gin.Context) {
 		return
 	}
 
+	// 检查是否为系统试卷
+	if exam.IsSystem {
+		c.JSON(http.StatusForbidden, gin.H{
+			"success": false,
+			"message": "系统试卷不允许再次分享",
+		})
+		return
+	}
+
 	// 开始事务
 	tx := db.Begin()
 	defer func() {
@@ -1011,3 +1029,84 @@ func ShareExam(c *gin.Context) {
 		},
 	})
 }
+
+// GetDailyExamRanking 获取每日一练排行榜
+func GetDailyExamRanking(c *gin.Context) {
+	_, exists := c.Get("user_id")
+	if !exists {
+		c.JSON(http.StatusUnauthorized, gin.H{"success": false, "message": "未登录"})
+		return
+	}
+
+	db := database.GetDB()
+
+	// 获取今天的每日一练试卷
+	today := time.Now()
+	title := fmt.Sprintf("%d年%02d月%02d日的每日一练",
+		today.Year(), today.Month(), today.Day())
+
+	var exam models.Exam
+	err := db.Where("is_system = ? AND title = ?", true, title).First(&exam).Error
+	if err != nil {
+		c.JSON(http.StatusNotFound, gin.H{
+			"success": false,
+			"message": "今日每日一练尚未生成",
+		})
+		return
+	}
+
+	// 查询该试卷的成绩排行榜（取最高分）
+	type RankingItem struct {
+		UserID    uint    `json:"user_id"`
+		Username  string  `json:"username"`
+		Nickname  string  `json:"nickname"`
+		Avatar    string  `json:"avatar"`
+		Score     float64 `json:"score"`
+		TimeSpent int     `json:"time_spent"` // 答题用时
+		Rank      int     `json:"rank"`
+	}
+
+	var rankings []RankingItem
+
+	// SQL查询：每个用户的最高分
+	err = db.Table("exam_records").
+		Select(`
+			exam_records.user_id,
+			users.username,
+			users.nickname,
+			users.avatar,
+			MAX(exam_records.score) as score,
+			MIN(exam_records.time_spent) as time_spent
+		`).
+		Joins("JOIN users ON users.id = exam_records.user_id").
+		Where("exam_records.exam_id = ? AND exam_records.status = ?", exam.ID, "graded").
+		Group("exam_records.user_id, users.username, users.nickname, users.avatar").
+		Order("score DESC, time_spent ASC").
+		Limit(50). // 显示前50名
+		Find(&rankings).Error
+
+	if err != nil {
+		log.Printf("查询排行榜失败: %v", err)
+		c.JSON(http.StatusInternalServerError, gin.H{
+			"success": false,
+			"message": "查询排行榜失败",
+		})
+		return
+	}
+
+	// 添加排名
+	for i := range rankings {
+		rankings[i].Rank = i + 1
+	}
+
+	c.JSON(http.StatusOK, gin.H{
+		"success": true,
+		"data": gin.H{
+			"exam_id":    exam.ID,
+			"exam_title": exam.Title,
+			"rankings":   rankings,
+			"total":      len(rankings),
+		},
+	})
+}
+

internal/models/exam.go

@@ -20,6 +20,7 @@ type Exam struct {
 	PassScore   int            `gorm:"not null;default:60" json:"pass_score"`                    // 及格分数
 	QuestionIDs datatypes.JSON `gorm:"type:json" json:"question_ids"`                            // 题目ID列表 (JSON数组)
 	Status      string         `gorm:"type:varchar(20);not null;default:'active'" json:"status"` // 状态: active, archived
+	IsSystem    bool           `gorm:"default:false;index" json:"is_system"`                     // 是否为系统试卷
 
 	// 关联关系
 	Shares     []ExamShare `gorm:"foreignKey:ExamID" json:"-"`     // 该试卷的分享记录（作为被分享试卷）

internal/services/daily_exam_service.go

@@ -0,0 +1,201 @@
+package services
+
+import (
+	"ankao/internal/database"
+	"ankao/internal/models"
+	"encoding/json"
+	"fmt"
+	"log"
+	"math/rand"
+	"time"
+
+	"gorm.io/gorm"
+)
+
+type DailyExamService struct {
+	db *gorm.DB
+}
+
+func NewDailyExamService() *DailyExamService {
+	return &DailyExamService{
+		db: database.GetDB(),
+	}
+}
+
+// GenerateDailyExam 生成每日一练试卷
+func (s *DailyExamService) GenerateDailyExam() error {
+	// 1. 获取分布式锁（使用日期作为锁ID）
+	today := time.Now().Format("20060102")
+	lockID := hashString(today) // 使用日期哈希作为锁ID
+
+	var locked bool
+	if err := s.db.Raw("SELECT pg_try_advisory_lock(?)", lockID).Scan(&locked).Error; err != nil {
+		return fmt.Errorf("获取锁失败: %w", err)
+	}
+
+	if !locked {
+		log.Println("其他实例正在生成每日一练，跳过")
+		return nil
+	}
+	defer s.db.Exec("SELECT pg_advisory_unlock(?)", lockID)
+
+	// 2. 检查今天是否已生成
+	todayStart := time.Now().Truncate(24 * time.Hour)
+	todayEnd := todayStart.Add(24 * time.Hour)
+
+	var count int64
+	s.db.Model(&models.Exam{}).
+		Where("is_system = ? AND created_at >= ? AND created_at < ?",
+			true, todayStart, todayEnd).
+		Count(&count)
+
+	if count > 0 {
+		log.Println("今日每日一练已生成，跳过")
+		return nil
+	}
+
+	// 3. 生成试卷标题
+	now := time.Now()
+	title := fmt.Sprintf("%d年%02d月%02d日的每日一练",
+		now.Year(), now.Month(), now.Day())
+
+	// 4. 随机选择题目（使用与创建试卷相同的逻辑）
+	questionIDs, totalScore, err := s.selectQuestions()
+	if err != nil {
+		return fmt.Errorf("选择题目失败: %w", err)
+	}
+
+	questionIDsJSON, _ := json.Marshal(questionIDs)
+
+	// 5. 创建试卷（使用第一个用户作为创建者，但标记为系统试卷）
+	// 获取第一个用户ID
+	var firstUser models.User
+	if err := s.db.Order("id ASC").First(&firstUser).Error; err != nil {
+		return fmt.Errorf("查询用户失败: %w", err)
+	}
+
+	exam := models.Exam{
+		UserID:      firstUser.ID, // 使用第一个用户作为创建者
+		Title:       title,
+		TotalScore:  int(totalScore),
+		Duration:    60,
+		PassScore:   80,
+		QuestionIDs: questionIDsJSON,
+		Status:      "active",
+		IsSystem:    true, // 标记为系统试卷
+	}
+
+	if err := s.db.Create(&exam).Error; err != nil {
+		return fmt.Errorf("创建试卷失败: %w", err)
+	}
+
+	log.Printf("成功创建每日一练试卷: ID=%d, Title=%s", exam.ID, exam.Title)
+
+	// 6. 分享给所有用户
+	if err := s.shareToAllUsers(exam.ID, firstUser.ID); err != nil {
+		log.Printf("分享试卷失败: %v", err)
+		// 不返回错误，因为试卷已创建成功
+	}
+
+	return nil
+}
+
+// selectQuestions 选择题目（复用现有逻辑）
+func (s *DailyExamService) selectQuestions() ([]int64, float64, error) {
+	questionTypes := []struct {
+		Type  string
+		Count int
+		Score float64
+	}{
+		{Type: "fill-in-blank", Count: 20, Score: 2.0},      // 40分
+		{Type: "true-false", Count: 10, Score: 1.0},         // 10分
+		{Type: "multiple-choice", Count: 10, Score: 1.0},    // 10分
+		{Type: "multiple-selection", Count: 10, Score: 2.0}, // 20分
+		{Type: "short-answer", Count: 1, Score: 10.0},       // 10分
+		{Type: "ordinary-essay", Count: 1, Score: 10.0},     // 10分（普通涉密人员论述题）
+		{Type: "management-essay", Count: 1, Score: 10.0},   // 10分（保密管理人员论述题）
+	}
+
+	var allQuestionIDs []int64
+	var totalScore float64
+
+	for _, qt := range questionTypes {
+		var questions []models.PracticeQuestion
+		if err := s.db.Where("type = ?", qt.Type).Find(&questions).Error; err != nil {
+			return nil, 0, err
+		}
+
+		// 检查题目数量是否足够
+		if len(questions) < qt.Count {
+			return nil, 0, fmt.Errorf("题型 %s 题目数量不足，需要 %d 道，实际 %d 道",
+				qt.Type, qt.Count, len(questions))
+		}
+
+		// 随机抽取 (Fisher-Yates 洗牌算法)
+		rand.Seed(time.Now().UnixNano())
+		for i := len(questions) - 1; i > 0; i-- {
+			j := rand.Intn(i + 1)
+			questions[i], questions[j] = questions[j], questions[i]
+		}
+		selectedQuestions := questions[:qt.Count]
+
+		for _, q := range selectedQuestions {
+			allQuestionIDs = append(allQuestionIDs, q.ID)
+		}
+
+		totalScore += float64(qt.Count) * qt.Score
+	}
+
+	// 随机打乱题目ID顺序
+	rand.Seed(time.Now().UnixNano())
+	for i := len(allQuestionIDs) - 1; i > 0; i-- {
+		j := rand.Intn(i + 1)
+		allQuestionIDs[i], allQuestionIDs[j] = allQuestionIDs[j], allQuestionIDs[i]
+	}
+
+	return allQuestionIDs, totalScore, nil
+}
+
+// shareToAllUsers 分享给所有用户
+func (s *DailyExamService) shareToAllUsers(examID uint, sharedByID uint) error {
+	// 查询所有用户（排除创建者）
+	var users []models.User
+	if err := s.db.Where("id != ?", sharedByID).Find(&users).Error; err != nil {
+		return err
+	}
+
+	// 批量创建分享记录
+	now := time.Now()
+	shares := make([]models.ExamShare, 0, len(users))
+	for _, user := range users {
+		shares = append(shares, models.ExamShare{
+			ExamID:     examID,
+			SharedByID: int64(sharedByID),
+			SharedToID: int64(user.ID),
+			SharedAt:   now,
+		})
+	}
+
+	if len(shares) > 0 {
+		// 批量插入
+		if err := s.db.Create(&shares).Error; err != nil {
+			return err
+		}
+		log.Printf("成功分享给 %d 个用户", len(shares))
+	}
+
+	return nil
+}
+
+// hashString 计算字符串哈希值（用于生成锁ID）
+func hashString(s string) int64 {
+	var hash int64
+	for _, c := range s {
+		hash = hash*31 + int64(c)
+	}
+	// 确保返回正数
+	if hash < 0 {
+		hash = -hash
+	}
+	return hash
+}

main.go

@@ -4,11 +4,13 @@ import (
 	"ankao/internal/database"
 	"ankao/internal/handlers"
 	"ankao/internal/middleware"
+	"ankao/internal/services"
 	"log"
 	"net/http"
 	"time"
 
 	"github.com/gin-gonic/gin"
+	"github.com/robfig/cron/v3"
 )
 
 func main() {
@@ -81,6 +83,7 @@ func main() {
 			auth.GET("/exam-records/:record_id/answers", handlers.GetExamUserAnswers) // 获取用户答案
 			auth.GET("/users/shareable", handlers.GetShareableUsers)                  // 获取可分享的用户列表
 			auth.POST("/exams/:id/share", handlers.ShareExam)                         // 分享试卷
+			auth.GET("/daily-exam/ranking", handlers.GetDailyExamRanking)             // 获取每日一练排行榜
 		}
 
 		// 题库管理API（需要管理员权限）
@@ -114,6 +117,9 @@ func main() {
 		MaxHeaderBytes: 1 << 20,          // 最大请求头：1MB
 	}
 
+	// 启动定时任务
+	startCronJobs()
+
 	log.Printf("服务器启动在端口 %s，超时配置：读/写 5分钟", port)
 
 	// 启动服务器
@@ -121,3 +127,38 @@ func main() {
 		panic("服务器启动失败: " + err.Error())
 	}
 }
+
+// startCronJobs 启动定时任务
+func startCronJobs() {
+	// 创建定时任务调度器（使用中国时区 UTC+8）
+	c := cron.New(cron.WithLocation(time.FixedZone("CST", 8*3600)))
+
+	// 每天凌晨1点执行
+	_, err := c.AddFunc("0 1 * * *", func() {
+		log.Println("开始生成每日一练...")
+		service := services.NewDailyExamService()
+		if err := service.GenerateDailyExam(); err != nil {
+			log.Printf("生成每日一练失败: %v", err)
+		} else {
+			log.Println("每日一练生成成功")
+		}
+	})
+
+	if err != nil {
+		log.Printf("添加定时任务失败: %v", err)
+		return
+	}
+
+	// 启动调度器
+	c.Start()
+	log.Println("定时任务已启动：每天凌晨1点生成每日一练")
+
+	// 可选：应用启动时立即生成一次（用于测试）
+	// go func() {
+	// 	log.Println("应用启动，立即生成一次每日一练...")
+	// 	service := services.NewDailyExamService()
+	// 	if err := service.GenerateDailyExam(); err != nil {
+	// 		log.Printf("生成每日一练失败: %v", err)
+	// 	}
+	// }()
+}

web/src/api/exam.ts

@@ -94,3 +94,24 @@ export const getExam = (examId: number, showAnswer?: boolean) => {
 export const submitExam = (examId: number, data: SubmitExamRequest) => {
   return request.post<ApiResponse<SubmitExamResponse>>(`/exam/${examId}/submit`, data)
 }
+
+// 获取每日一练排行榜
+export const getDailyExamRanking = () => {
+  return request<{
+    success: boolean
+    data: {
+      exam_id: number
+      exam_title: string
+      rankings: Array<{
+        user_id: number
+        username: string
+        nickname: string
+        avatar: string
+        score: number
+        time_spent: number
+        rank: number
+      }>
+      total: number
+    }
+  }>('/daily-exam/ranking')
+}

web/src/pages/ExamManagement.tsx

@@ -31,7 +31,8 @@ import {
   ArrowLeftOutlined,
   ShareAltOutlined,
   UserOutlined,
-  TeamOutlined
+  TeamOutlined,
+  CrownOutlined
 } from '@ant-design/icons'
 import * as examApi from '../api/exam'
 import styles from './ExamManagement.module.less'
@@ -50,6 +51,7 @@ interface ExamListItem {
   participant_count: number  // 共享试卷的参与人数
   created_at: string
   is_shared?: boolean
+  is_system?: boolean  // 是否为系统试卷
   shared_by?: {
     id: number
     username: string
@@ -299,10 +301,19 @@ const ExamManagement: React.FC = () => {
                       <div className={styles.coverInfo}>
                         <h3
                           className={styles.examTitle}
-                          style={{ marginBottom: exam.is_shared && exam.shared_by ? '12px' : '0' }}
+                          style={{ marginBottom: (exam.is_system || (exam.is_shared && exam.shared_by)) ? '12px' : '0' }}
                         >
                           {exam.title}
                         </h3>
+                        {exam.is_system && (
+                          <Tag
+                            icon={<CrownOutlined />}
+                            color="orange"
+                            className={styles.shareTag}
+                          >
+                            系统
+                          </Tag>
+                        )}
                         {exam.is_shared && exam.shared_by && (
                           <Tag
                             icon={<ShareAltOutlined />}
@@ -324,8 +335,8 @@ const ExamManagement: React.FC = () => {
                     >
                       {exam.has_in_progress_exam ? '继续' : '考试'}
                     </Button>,
-                    // 只有自己创建的试卷才能分享
+                    // 只有非系统且自己创建的试卷才能分享
-                    !exam.is_shared && (
+                    !exam.is_system && !exam.is_shared && (
                       <Button
                         type="text"
                         icon={<ShareAltOutlined />}
@@ -359,8 +370,8 @@ const ExamManagement: React.FC = () => {
                     >
                       打印
                     </Button>,
-                    // 只有自己创建的试卷才能删除
+                    // 只有非系统且自己创建的试卷才能删除
-                    !exam.is_shared && (
+                    !exam.is_system && !exam.is_shared && (
                       <Button
                         type="text"
                         danger