MM-62745: [Shared Channels] Fix duplicate mentioning - local user with the same username as someone on the remote server - Part2 (#32101) (#33414)

Automatic Merge

server/platform/services/sharedchannel/service.go

@@ -380,3 +380,8 @@ func (scs *Service) OnReceiveSyncMessageForTesting(msg model.RemoteClusterMsg, r
 func (scs *Service) HandleChannelNotSharedErrorForTesting(msg *model.SyncMsg, rc *model.RemoteCluster) {
 	scs.handleChannelNotSharedError(msg, rc)
 }
+
+// TransformMentionsOnReceiveForTesting allows testing the full mention transformation flow
+func (scs *Service) TransformMentionsOnReceiveForTesting(ctx request.CTX, post *model.Post, targetChannel *model.Channel, rc *model.RemoteCluster, mentionTransforms map[string]string) {
+	scs.transformMentionsOnReceive(ctx, post, targetChannel, rc, mentionTransforms)
+}

server/platform/services/sharedchannel/sync_recv.go

@@ -197,7 +197,7 @@ func (scs *Service) processSyncMessage(c request.CTX, syncMsg *model.SyncMsg, rc
 		}
 
 		// add/update post
-		rpost, err := scs.upsertSyncPost(post, targetChannel, rc)
+		rpost, err := scs.upsertSyncPost(post, targetChannel, rc, syncMsg.MentionTransforms)
 		if err != nil {
 			syncResp.PostErrors = append(syncResp.PostErrors, post.Id)
 			scs.server.Log().Log(mlog.LvlSharedChannelServiceError, "Error upserting sync post",
@@ -454,7 +454,7 @@ func (scs *Service) updateSyncUser(rctx request.CTX, patch *model.UserPatch, use
 	return nil, fmt.Errorf("error updating sync user %s: %w", user.Id, err)
 }
 
-func (scs *Service) upsertSyncPost(post *model.Post, targetChannel *model.Channel, rc *model.RemoteCluster) (*model.Post, error) {
+func (scs *Service) upsertSyncPost(post *model.Post, targetChannel *model.Channel, rc *model.RemoteCluster, mentionTransforms map[string]string) (*model.Post, error) {
 	var appErr *model.AppError
 
 	post.RemoteId = model.NewPointer(rc.RemoteId)
@@ -483,11 +483,14 @@ func (scs *Service) upsertSyncPost(post *model.Post, targetChannel *model.Channe
 			return nil, fmt.Errorf("post sync failed: %w", ErrRemoteIDMismatch)
 		}
 
+		scs.transformMentionsOnReceive(rctx, post, targetChannel, rc, mentionTransforms)
+
 		rpost, appErr = scs.app.CreatePost(rctx, post, targetChannel, model.CreatePostFlags{TriggerWebhooks: true, SetOnline: true})
 		if appErr == nil {
 			scs.server.Log().Log(mlog.LvlSharedChannelServiceDebug, "Created sync post",
 				mlog.String("post_id", post.Id),
-				mlog.String("channel_id", post.ChannelId))
+				mlog.String("channel_id", post.ChannelId),
+			)
 		}
 	} else if post.DeleteAt > 0 {
 		// delete post
@@ -499,6 +502,7 @@ func (scs *Service) upsertSyncPost(post *model.Post, targetChannel *model.Channe
 			)
 		}
 	} else if post.EditAt > rpost.EditAt || post.Message != rpost.Message || post.UpdateAt > rpost.UpdateAt || post.Metadata != nil {
+		scs.transformMentionsOnReceive(rctx, post, targetChannel, rc, mentionTransforms)
 		var priority *model.PostPriority
 		var acknowledgements []*model.PostAcknowledgement
 
@@ -741,3 +745,44 @@ func (scs *Service) upsertSyncAcknowledgement(acknowledgement *model.PostAcknowl
 	}
 	return savedAcknowledgement, retErr
 }
+
+// transformMentionsOnReceive transforms mentions in received posts using explicit mentionTransforms.
+func (scs *Service) transformMentionsOnReceive(rctx request.CTX, post *model.Post, targetChannel *model.Channel, rc *model.RemoteCluster, mentionTransforms map[string]string) {
+	if post.Message == "" || len(mentionTransforms) == 0 {
+		return
+	}
+
+	// Process mentions directly using mentionTransforms - no need to re-parse with regex
+	for mention, userID := range mentionTransforms {
+		oldMention := "@" + mention
+		var newMention string
+
+		// Get the user to determine transformation type
+		if user, err := scs.server.GetStore().User().Get(context.Background(), userID); err == nil && user != nil {
+			// User exists in receiver's database
+			if strings.Contains(mention, ":") {
+				// Colon mention (e.g., "@admin:remote1") - always use the user's actual username
+				newMention = "@" + user.Username
+			} else {
+				// Simple mention (e.g., "@admin")
+				if user.GetRemoteID() == "" {
+					// This is a local user, keep as-is
+					newMention = "@" + mention
+				} else {
+					// This is a remote user that was synced, use their synced username
+					newMention = "@" + user.Username
+				}
+			}
+		} else {
+			// User doesn't exist in receiver's database
+			if strings.Contains(mention, ":") {
+				// Colon mention for unknown user - keep as-is
+				newMention = oldMention
+			} else {
+				// Simple mention for unknown user - add cluster suffix to indicate it's from remote
+				newMention = "@" + mention + ":" + rc.Name
+			}
+		}
+		post.Message = strings.ReplaceAll(post.Message, oldMention, newMention)
+	}
+}

server/platform/services/sharedchannel/sync_send_remote.go

@@ -32,13 +32,14 @@ type syncData struct {
 	rc   *model.RemoteCluster
 	scr  *model.SharedChannelRemote
 
-	users            map[string]*model.User
-	profileImages    map[string]*model.User
-	posts            []*model.Post
-	reactions        []*model.Reaction
-	acknowledgements []*model.PostAcknowledgement
-	statuses         []*model.Status
-	attachments      []attachment
+	users             map[string]*model.User
+	profileImages     map[string]*model.User
+	posts             []*model.Post
+	reactions         []*model.Reaction
+	acknowledgements  []*model.PostAcknowledgement
+	statuses          []*model.Status
+	attachments       []attachment
+	mentionTransforms map[string]string
 
 	resultRepeat                bool
 	resultNextCursor            model.GetPostsSinceForSyncCursor
@@ -47,11 +48,12 @@ type syncData struct {
 
 func newSyncData(task syncTask, rc *model.RemoteCluster, scr *model.SharedChannelRemote) *syncData {
 	return &syncData{
-		task:          task,
-		rc:            rc,
-		scr:           scr,
-		users:         make(map[string]*model.User),
-		profileImages: make(map[string]*model.User),
+		task:              task,
+		rc:                rc,
+		scr:               scr,
+		users:             make(map[string]*model.User),
+		profileImages:     make(map[string]*model.User),
+		mentionTransforms: make(map[string]string),
 		resultNextCursor: model.GetPostsSinceForSyncCursor{
 			LastPostUpdateAt: scr.LastPostUpdateAt, LastPostUpdateID: scr.LastPostUpdateID,
 			LastPostCreateAt: scr.LastPostCreateAt, LastPostCreateID: scr.LastPostCreateID,
@@ -444,9 +446,6 @@ func (scs *Service) fetchPostUsersForSync(sd *syncData) error {
 	}
 
 	for _, post := range sd.posts {
-		// add author
-		userIDs[post.UserId] = p2mm{}
-
 		// get mentions and users for each mention
 		mentionMap := scs.app.MentionsToTeamMembers(request.EmptyContext(scs.server.Log()), post.Message, sc.TeamId)
 
@@ -458,10 +457,19 @@ func (scs *Service) fetchPostUsersForSync(sd *syncData) error {
 			}
 
 			// Skip remote users unless mention contains a colon (@username:remote)
-			if user.RemoteId != nil && !strings.Contains(mention, ":") {
+			if user.IsRemote() && !strings.Contains(mention, ":") {
 				continue
 			}
+		}
 
+		// add author with post and mentionMap so transformations can be applied
+		userIDs[post.UserId] = p2mm{
+			post:       post,
+			mentionMap: mentionMap,
+		}
+
+		// Add all mentioned users
+		for _, userID := range mentionMap {
 			userIDs[userID] = p2mm{
 				post:       post,
 				mentionMap: mentionMap,
@@ -470,7 +478,6 @@ func (scs *Service) fetchPostUsersForSync(sd *syncData) error {
 	}
 
 	merr := merror.New()
-
 	for userID, v := range userIDs {
 		user, err := scs.server.GetStore().User().Get(context.Background(), userID)
 		if err != nil {
@@ -480,7 +487,7 @@ func (scs *Service) fetchPostUsersForSync(sd *syncData) error {
 
 		sync, syncImage, err2 := scs.shouldUserSync(user, sd.task.channelID, sd.rc)
 		if err2 != nil {
-			merr.Append(fmt.Errorf("could not check should sync user %s: %w", userID, err))
+			merr.Append(fmt.Errorf("could not check should sync user %s: %w", userID, err2))
 			continue
 		}
 
@@ -492,9 +499,15 @@ func (scs *Service) fetchPostUsersForSync(sd *syncData) error {
 			sd.profileImages[user.Id] = user
 		}
 
-		// Transform @username:remote to @username when sending to a user's home cluster
-		if v.post != nil && user.RemoteId != nil && *user.RemoteId == sd.rc.RemoteId {
-			fixMention(v.post, v.mentionMap, user)
+		// Collect mention transforms for all mentioned users
+		if v.mentionMap != nil {
+			for mention, mentionUserID := range v.mentionMap {
+				if mentionUserID == userID {
+					// Always add the mention transform - let receiver decide how to display
+					// The sender should NOT modify the message, only provide the mapping
+					sd.mentionTransforms[mention] = userID
+				}
+			}
 		}
 	}
 	return merr.ErrorOrNil()
@@ -690,6 +703,7 @@ func (scs *Service) sendPostSyncData(sd *syncData) error {
 
 	msg := model.NewSyncMsg(sd.task.channelID)
 	msg.Posts = sd.posts
+	msg.MentionTransforms = sd.mentionTransforms
 
 	return scs.sendSyncMsgToRemote(msg, sd.rc, func(syncResp model.SyncResponse, errResp error) {
 		if len(syncResp.PostErrors) != 0 {