feat(comments): 支持编辑与管理可见历史，采纳展示改用楼层号

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/service/comment.go

@@ -16,6 +16,8 @@ var (
 	ErrCommentDeleteMeta  = errors.New("请填写删除理由")
 	ErrCommentInvalidType = errors.New("无效的删除类型")
 	ErrCommentNotDeleted  = errors.New("评论未被删除")
+	ErrCommentNotChanged  = errors.New("评论内容未变更")
+	ErrCommentDeleted     = errors.New("已删除的评论不可编辑")
 )
 
 // CommentService 评论服务
@@ -32,6 +34,7 @@ type CommentNode struct {
 	model.Comment
 	Deleted       bool               `json:"deleted,omitempty"`        // 软删占位
 	StaffDeleted  bool               `json:"staff_deleted,omitempty"`  // DeletedBy≠评论者
+	Edited        bool               `json:"edited,omitempty"`         // 相对创建已编辑
 	DeletedByUser *CommentActorBrief `json:"deleted_by_user,omitempty"` // 管理删执行者（公开）
 	Replies       []CommentNode      `json:"replies,omitempty"`
 }
@@ -177,8 +180,9 @@ func (s *CommentService) loadCommentActorsByIDs(ids []uint) map[uint]CommentActo
 
 // toCommentNode 软删占位：清空公开正文；版主保留原文；自删理由仅版主可见。
 func toCommentNode(c model.Comment, replies []CommentNode, revealAudit bool, deleters map[uint]CommentActorBrief) CommentNode {
+	edited := c.UpdatedAt.Sub(c.CreatedAt) > time.Minute
 	if !c.DeletedAt.Valid {
-		return CommentNode{Comment: c, Replies: replies}
+		return CommentNode{Comment: c, Edited: edited, Replies: replies}
 	}
 	staff := c.DeletedBy != 0 && c.DeletedBy != c.UserID
 	if !revealAudit {
@@ -201,11 +205,50 @@ func toCommentNode(c model.Comment, replies []CommentNode, revealAudit bool, del
 		Comment:       c,
 		Deleted:       true,
 		StaffDeleted:  staff,
+		Edited:        edited,
 		DeletedByUser: deleter,
 		Replies:       replies,
 	}
 }
 
+// FloorNumber 本帖主评楼层号（含软删占位，按 created_at/id 升序）；子评取其所属主楼。无则 0。
+func FloorNumber(db *gorm.DB, postID, commentID uint) int {
+	if db == nil || postID == 0 || commentID == 0 {
+		return 0
+	}
+	var c model.Comment
+	if err := db.Unscoped().Select("id", "post_id", "parent_id", "root_id", "created_at").
+		Where("id = ? AND post_id = ?", commentID, postID).First(&c).Error; err != nil {
+		return 0
+	}
+	floorID := c.ID
+	floorCreated := c.CreatedAt
+	if c.ParentID != nil {
+		rootID := c.ID
+		if c.RootID != nil {
+			rootID = *c.RootID
+		}
+		var root model.Comment
+		if err := db.Unscoped().Select("id", "created_at").
+			Where("id = ? AND post_id = ? AND parent_id IS NULL", rootID, postID).First(&root).Error; err != nil {
+			return 0
+		}
+		floorID = root.ID
+		floorCreated = root.CreatedAt
+	}
+	var ahead int64
+	db.Unscoped().Model(&model.Comment{}).
+		Where("post_id = ? AND parent_id IS NULL AND (created_at < ? OR (created_at = ? AND id < ?))",
+			postID, floorCreated, floorCreated, floorID).
+		Count(&ahead)
+	return int(ahead) + 1
+}
+
+// (s *CommentService) FloorNumber 见包级 FloorNumber
+func (s *CommentService) FloorNumber(postID, commentID uint) int {
+	return FloorNumber(s.db, postID, commentID)
+}
+
 // applyCommentListVisibility 评论流可见性：published，或 pending 且（作者 / 该板可审）；
 // 软删行：已发布的对所有人占位；待审软删仅作者/可审者可见占位。
 func applyCommentListVisibility(db *gorm.DB, boardID, viewerID uint, actor *Actor) *gorm.DB {
@@ -501,12 +544,141 @@ func (s *CommentService) Purge(actor *Actor, commentID, userID uint) error {
 		Where("id IN ? AND status = ? AND deleted_at IS NULL", ids, model.ContentStatusPublished).
 		Count(&livePublished)
 
-	if err := s.db.Unscoped().Delete(&model.Comment{}, ids).Error; err != nil {
-		return err
-	}
-	if livePublished > 0 {
-		s.db.Model(&model.Post{}).Where("id = ?", comment.PostID).
-			UpdateColumn("comment_count", gorm.Expr("GREATEST(comment_count - ?, 0)", livePublished))
-	}
-	return nil
+	return s.db.Transaction(func(tx *gorm.DB) error {
+		if err := tx.Where("comment_id IN ?", ids).Delete(&model.CommentEditHistory{}).Error; err != nil {
+			return err
+		}
+		if err := tx.Unscoped().Delete(&model.Comment{}, ids).Error; err != nil {
+			return err
+		}
+		if livePublished > 0 {
+			return tx.Model(&model.Post{}).Where("id = ?", comment.PostID).
+				UpdateColumn("comment_count", gorm.Expr("GREATEST(comment_count - ?, 0)", livePublished)).Error
+		}
+		return nil
+	})
+}
+
+// Update 编辑评论（作者本人或版主；已软删不可改）；先写入旧正文快照再更新。
+func (s *CommentService) Update(actor *Actor, commentID, userID uint, content string) (*CommentNode, error) {
+	content = strings.TrimSpace(content)
+	if content == "" {
+		return nil, errors.New("评论内容不能为空")
+	}
+	var comment model.Comment
+	if err := s.db.Unscoped().First(&comment, commentID).Error; err != nil {
+		return nil, ErrCommentNotFound
+	}
+	if comment.DeletedAt.Valid {
+		return nil, ErrCommentDeleted
+	}
+	if comment.UserID != userID {
+		var post model.Post
+		if err := s.db.Select("id", "board_id").First(&post, comment.PostID).Error; err != nil {
+			return nil, ErrCommentNotFound
+		}
+		if actor == nil || !actor.CanModerateBoard(post.BoardID) {
+			return nil, ErrCommentForbidden
+		}
+	}
+	if comment.Content == content {
+		return nil, ErrCommentNotChanged
+	}
+
+	old := comment.Content
+	if err := s.db.Transaction(func(tx *gorm.DB) error {
+		hist := model.CommentEditHistory{
+			CommentID:  comment.ID,
+			EditorID:   userID,
+			OldContent: old,
+		}
+		if err := tx.Create(&hist).Error; err != nil {
+			return err
+		}
+		return tx.Model(&comment).Update("content", content).Error
+	}); err != nil {
+		return nil, err
+	}
+
+	if err := s.db.Preload("User").First(&comment, comment.ID).Error; err != nil {
+		return nil, err
+	}
+	node := toCommentNode(comment, nil, false, nil)
+	return &node, nil
+}
+
+// CommentEditHistoryItem 管理可见的评论修订记录
+type CommentEditHistoryItem struct {
+	ID         uint               `json:"id"`
+	Editor     CommentActorBrief  `json:"editor"`
+	OldContent string             `json:"old_content"`
+	CreatedAt  time.Time          `json:"created_at"`
+}
+
+// ListEditHistory 评论编辑历史（仅版主；含软删评论；按创建时间倒序分页）
+func (s *CommentService) ListEditHistory(actor *Actor, commentID uint, page, size int) ([]CommentEditHistoryItem, int64, error) {
+	if page < 1 {
+		page = 1
+	}
+	if size < 1 || size > 50 {
+		size = 10
+	}
+	var comment model.Comment
+	if err := s.db.Unscoped().Select("id", "post_id").First(&comment, commentID).Error; err != nil {
+		return nil, 0, ErrCommentNotFound
+	}
+	var post model.Post
+	if err := s.db.Unscoped().Select("id", "board_id").First(&post, comment.PostID).Error; err != nil {
+		return nil, 0, ErrCommentNotFound
+	}
+	if actor == nil || !actor.CanModerateBoard(post.BoardID) {
+		return nil, 0, ErrCommentForbidden
+	}
+
+	q := s.db.Model(&model.CommentEditHistory{}).Where("comment_id = ?", commentID)
+	var total int64
+	if err := q.Count(&total).Error; err != nil {
+		return nil, 0, err
+	}
+
+	var rows []model.CommentEditHistory
+	if err := s.db.Where("comment_id = ?", commentID).
+		Order("created_at DESC").
+		Offset((page - 1) * size).Limit(size).
+		Find(&rows).Error; err != nil {
+		return nil, 0, err
+	}
+	editorIDs := make([]uint, 0, len(rows))
+	seen := map[uint]struct{}{}
+	for _, r := range rows {
+		if _, ok := seen[r.EditorID]; ok {
+			continue
+		}
+		seen[r.EditorID] = struct{}{}
+		editorIDs = append(editorIDs, r.EditorID)
+	}
+	editors := map[uint]CommentActorBrief{}
+	if len(editorIDs) > 0 {
+		var users []model.User
+		s.db.Select("id", "username", "nickname", "avatar").Where("id IN ?", editorIDs).Find(&users)
+		for _, u := range users {
+			editors[u.ID] = CommentActorBrief{
+				ID: u.ID, Username: u.Username, Nickname: u.Nickname, Avatar: u.Avatar,
+			}
+		}
+	}
+	items := make([]CommentEditHistoryItem, 0, len(rows))
+	for _, r := range rows {
+		ed := editors[r.EditorID]
+		if ed.ID == 0 {
+			ed = CommentActorBrief{ID: r.EditorID, Username: "已注销", Nickname: "已注销"}
+		}
+		items = append(items, CommentEditHistoryItem{
+			ID:         r.ID,
+			Editor:     ed,
+			OldContent: r.OldContent,
+			CreatedAt:  r.CreatedAt,
+		})
+	}
+	return items, total, nil
 }