feat(post): implement share recording functionality

- Added RecordShare method in PostHandler to handle sharing posts and increment share count.
- Introduced IncrementShares method in PostRepository to update shares_count for published posts.
- Updated PostService to include RecordShare, ensuring cache invalidation for post details and lists.
- Integrated new share route in the router for handling share requests.

internal/handler/post_handler.go

@@ -6,6 +6,7 @@ import (
 	"strconv"
 
 	"github.com/gin-gonic/gin"
+	"gorm.io/gorm"
 
 	"carrot_bbs/internal/dto"
 	"carrot_bbs/internal/model"
@@ -145,6 +146,41 @@ func (h *PostHandler) RecordView(c *gin.Context) {
 	response.Success(c, gin.H{"success": true})
 }
 
+// RecordShare 记录帖子分享（shares_count +1，仅已发布）
+// 支持可选 JSON：{"channel":"wechat"|"qq"|"copy_link"|"system"|...}，用于后续统计
+func (h *PostHandler) RecordShare(c *gin.Context) {
+	id := c.Param("id")
+	_ = c.GetString("user_id") // 预留：登录用户维度统计
+
+	type shareBody struct {
+		Channel string `json:"channel"`
+	}
+	var body shareBody
+	if c.Request.ContentLength > 0 {
+		if err := c.ShouldBindJSON(&body); err != nil {
+			response.BadRequest(c, "invalid json body")
+			return
+		}
+	}
+
+	sharesCount, err := h.postService.RecordShare(c.Request.Context(), id, c.GetString("user_id"))
+	if err != nil {
+		if errors.Is(err, gorm.ErrRecordNotFound) {
+			response.NotFound(c, "post not found")
+			return
+		}
+		fmt.Printf("[ERROR] RecordShare post %s: %v\n", id, err)
+		response.InternalServerError(c, "failed to record share")
+		return
+	}
+
+	data := gin.H{"success": true, "shares_count": sharesCount}
+	if body.Channel != "" {
+		data["channel"] = body.Channel
+	}
+	response.Success(c, data)
+}
+
 // List 获取帖子列表（支持游标分页和偏移分页）
 func (h *PostHandler) List(c *gin.Context) {
 	// 检查是否使用游标分页

internal/repository/post_repo.go

@@ -413,6 +413,32 @@ func (r *PostRepository) IncrementViews(postID string) error {
 		}).Error
 }
 
+// IncrementShares 已发布帖子分享次数 +1，返回新的 shares_count；非已发布或不存在返回 gorm.ErrRecordNotFound
+func (r *PostRepository) IncrementShares(postID string) (int, error) {
+	var newCount int
+	err := r.db.Transaction(func(tx *gorm.DB) error {
+		res := tx.Model(&model.Post{}).
+			Where("id = ? AND status = ?", postID, model.PostStatusPublished).
+			Updates(map[string]interface{}{
+				"shares_count": gorm.Expr("shares_count + 1"),
+				"updated_at":   gorm.Expr("updated_at"),
+			})
+		if res.Error != nil {
+			return res.Error
+		}
+		if res.RowsAffected == 0 {
+			return gorm.ErrRecordNotFound
+		}
+		var p model.Post
+		if err := tx.Select("shares_count").Where("id = ?", postID).First(&p).Error; err != nil {
+			return err
+		}
+		newCount = p.SharesCount
+		return nil
+	})
+	return newCount, err
+}
+
 // Search 搜索帖子
 func (r *PostRepository) Search(keyword string, page, pageSize int) ([]*model.Post, int64, error) {
 	var posts []*model.Post

internal/router/router.go

@@ -220,6 +220,8 @@ func (r *Router) setupRoutes() {
 
 			// 浏览量记录（可选认证，允许游客浏览）
 			posts.POST("/:id/view", middleware.OptionalAuth(r.jwtService), r.postHandler.RecordView)
+			// 分享计数（可选认证；仅已发布帖子生效）
+			posts.POST("/:id/share", middleware.OptionalAuth(r.jwtService), r.postHandler.RecordShare)
 
 			// 点赞
 			posts.POST("/:id/like", authMiddleware, r.postHandler.Like)

internal/service/post_service.go

@@ -64,6 +64,8 @@ type PostService interface {
 
 	// 其他
 	IncrementViews(ctx context.Context, postID, userID string) error
+	// RecordShare 记录分享（仅已发布帖子计数 +1），返回最新 shares_count
+	RecordShare(ctx context.Context, postID, userID string) (sharesCount int, err error)
 
 	// 日志服务设置
 	SetLogService(logService *LogService)
@@ -492,6 +494,19 @@ func (s *postServiceImpl) IncrementViews(ctx context.Context, postID, userID str
 	return nil
 }
 
+// RecordShare 记录分享：仅已发布帖子增加 shares_count，并失效帖子详情与列表缓存
+func (s *postServiceImpl) RecordShare(ctx context.Context, postID, userID string) (int, error) {
+	n, err := s.postRepo.IncrementShares(postID)
+	if err != nil {
+		return 0, err
+	}
+	if s.cache != nil {
+		cache.InvalidatePostDetail(s.cache, postID)
+		cache.InvalidatePostList(s.cache)
+	}
+	return n, nil
+}
+
 // GetFavorites 获取收藏列表
 func (s *postServiceImpl) GetFavorites(ctx context.Context, userID string, page, pageSize int) ([]*model.Post, int64, error) {
 	return s.postRepo.GetFavorites(userID, page, pageSize)