Automatic channel category sorting (#30866)

* Automatic channel category sorting

* Fix types

* AIed

* Fix issue where categories are updated for all users

* Move all logic to server, clean up

* PR feedback

* Fix lint

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/channels/app/channel.go

@@ -181,6 +181,8 @@ func (a *App) CreateChannelWithUser(c request.CTX, channel *model.Channel, userI
 		return nil, err
 	}
 
+	a.addChannelToDefaultCategory(c, userID, channel)
+
 	var user *model.User
 	if user, err = a.GetUser(userID); err != nil {
 		return nil, err
@@ -208,6 +210,10 @@ func (a *App) RenameChannel(c request.CTX, channel *model.Channel, newChannelNam
 		return nil, model.NewAppError("RenameChannel", "api.channel.rename_channel.cant_rename_group_messages.app_error", nil, "", http.StatusBadRequest)
 	}
 
+	// Clean up the channel name and display name
+	newChannelName = strings.TrimSpace(newChannelName)
+	newDisplayName = strings.TrimSpace(newDisplayName)
+
 	channel.Name = newChannelName
 	if newDisplayName != "" {
 		channel.DisplayName = newDisplayName
@@ -222,6 +228,8 @@ func (a *App) RenameChannel(c request.CTX, channel *model.Channel, newChannelNam
 }
 
 func (a *App) CreateChannel(c request.CTX, channel *model.Channel, addMember bool) (*model.Channel, *model.AppError) {
+	a.handleChannelCategoryName(channel)
+
 	channel.DisplayName = strings.TrimSpace(channel.DisplayName)
 	sc, nErr := a.Srv().Store().Channel().Save(c, channel, *a.Config().TeamSettings.MaxChannelsPerTeam)
 	if nErr != nil {
@@ -864,11 +872,14 @@ func (a *App) PatchChannel(c request.CTX, channel *model.Channel, patch *model.C
 	oldChannelPurpose := channel.Purpose
 
 	channel.Patch(patch)
+	a.handleChannelCategoryName(channel)
 	channel, err := a.UpdateChannel(c, channel)
 	if err != nil {
 		return nil, err
 	}
 
+	a.addChannelToDefaultCategory(c, userID, channel)
+
 	if oldChannelDisplayName != channel.DisplayName {
 		if err = a.PostUpdateChannelDisplayNameMessage(c, userID, channel, oldChannelDisplayName, channel.DisplayName); err != nil {
 			c.Logger().Warn(err.Error())
@@ -1665,6 +1676,8 @@ func (a *App) AddUserToChannel(c request.CTX, user *model.User, channel *model.C
 		return nil, err
 	}
 
+	a.addChannelToDefaultCategory(c, user.Id, channel)
+
 	// We are sending separate websocket events to the user added and to the channel
 	// This is to get around potential cluster syncing issues where other nodes may not receive the most up to date channel members
 	message := model.NewWebSocketEvent(model.WebsocketEventUserAdded, "", channel.Id, "", map[string]bool{user.Id: true}, "")
@@ -3878,3 +3891,56 @@ func (a *App) ChannelAccessControlled(c request.CTX, channelID string) (bool, *m
 
 	return true, nil
 }
+
+func (a *App) handleChannelCategoryName(channel *model.Channel) {
+	if *a.Config().ExperimentalSettings.ExperimentalChannelCategorySorting && strings.Contains(channel.DisplayName, "/") {
+		parts := strings.Split(channel.DisplayName, "/")
+		channel.DisplayName = strings.TrimSpace(strings.Join(parts[1:], "/"))
+		channel.DefaultCategoryName = strings.TrimSpace(parts[0])
+	}
+}
+
+func (a *App) addChannelToDefaultCategory(c request.CTX, userID string, channel *model.Channel) {
+	// Add channel to default category if specified
+	if channel.DefaultCategoryName != "" && *a.Config().ExperimentalSettings.ExperimentalChannelCategorySorting {
+		// Get user's categories for this team
+		categories, err := a.GetSidebarCategoriesForTeamForUser(c, userID, channel.TeamId)
+		if err != nil {
+			mlog.Error("Failed to get sidebar categories", mlog.String("user_id", userID), mlog.String("team_id", channel.TeamId), mlog.Err(err))
+			return
+		}
+		// Find or create the category
+		var targetCategory *model.SidebarCategoryWithChannels
+		for _, category := range categories.Categories {
+			if category.Type == model.SidebarCategoryCustom && strings.EqualFold(category.DisplayName, channel.DefaultCategoryName) {
+				targetCategory = category
+				break
+			}
+		}
+
+		if targetCategory == nil {
+			// Create new category if it doesn't exist
+			targetCategory = &model.SidebarCategoryWithChannels{
+				SidebarCategory: model.SidebarCategory{
+					UserId:      userID,
+					TeamId:      channel.TeamId,
+					Type:        model.SidebarCategoryCustom,
+					DisplayName: channel.DefaultCategoryName,
+					Sorting:     model.SidebarCategorySortDefault,
+				},
+				Channels: []string{channel.Id},
+			}
+			_, err = a.CreateSidebarCategory(c, userID, channel.TeamId, targetCategory)
+			if err != nil {
+				mlog.Error("Failed to create default category", mlog.String("user_id", userID), mlog.String("team_id", channel.TeamId), mlog.String("category_name", channel.DefaultCategoryName), mlog.Err(err))
+			}
+		} else {
+			// Add channel to existing category
+			targetCategory.Channels = append([]string{channel.Id}, targetCategory.Channels...)
+			_, err = a.UpdateSidebarCategories(c, userID, channel.TeamId, []*model.SidebarCategoryWithChannels{targetCategory})
+			if err != nil {
+				mlog.Error("Failed to update default category", mlog.String("user_id", userID), mlog.String("team_id", channel.TeamId), mlog.String("category_name", channel.DefaultCategoryName), mlog.Err(err))
+			}
+		}
+	}
+}