read state is now published

app/assets/javascripts/discourse/models/topic_tracking_state.js

@@ -17,7 +17,7 @@ Discourse.TopicTrackingState = Discourse.Model.extend({
         tracker.removeTopic(data.topic_id);
       }
 
-      if (data.message_type === "new_topic" || data.message_type === "unread") {
+      if (data.message_type === "new_topic" || data.message_type === "unread" || data.message_type == "read") {
         tracker.states["t" + data.topic_id] = data.payload;
         tracker.notify(data);
       }

app/models/topic_tracking_state.rb

@@ -57,7 +57,21 @@ class TopicTrackingState
     end
   end
 
-  def self.publish_read(topic_id, highest_post_number, user_id)
+  def self.publish_read(topic_id, last_read_post_number, user_id)
+
+      highest_post_number = Topic.where(id: topic_id).pluck(:highest_post_number).first
+
+      message = {
+        topic_id: topic_id,
+        message_type: "read",
+        payload: {
+          last_read_post_number: last_read_post_number,
+          highest_post_number: highest_post_number,
+          topic_id: topic_id
+        }
+      }
+
+      MessageBus.publish("/unread/#{user_id}", message.as_json, user_ids: [user_id])
   end
 
   def self.treat_as_new_topic_clause

app/models/topic_user.rb

@@ -156,7 +156,7 @@ class TopicUser < ActiveRecord::Base
                                        tu.topic_id = :topic_id AND
                                        tu.user_id = :user_id
                                   RETURNING
-                                    topic_users.notification_level, tu.notification_level old_level
+                                    topic_users.notification_level, tu.notification_level old_level, tu.last_read_post_number
                                 ",
                                 args).values
 
@@ -164,12 +164,20 @@ class TopicUser < ActiveRecord::Base
         before = rows[0][1].to_i
         after = rows[0][0].to_i
 
+        before_last_read = rows[0][2].to_i
+
+        if before_last_read < post_number
+          TopicTrackingState.publish_read(topic_id, post_number, user.id)
+        end
+
         if before != after
           MessageBus.publish("/topic/#{topic_id}", {notification_level_change: after}, user_ids: [user.id])
         end
       end
 
       if rows.length == 0
+        TopicTrackingState.publish_read(topic_id, post_number, user.id)
+
         args[:tracking] = notification_levels[:tracking]
         args[:regular] = notification_levels[:regular]
         args[:site_setting] = SiteSetting.auto_track_topics_after