Apply changes from team members in own editor

app/channels/application_cable/connection.rb

@@ -2,10 +2,12 @@
 
 module ApplicationCable
   class Connection < ActionCable::Connection::Base
-    identified_by :current_user
+    identified_by :current_user, :current_contributor
 
     def connect
+      # The order is important here, because a valid user is required to find a valid contributor.
       self.current_user = find_verified_user
+      self.current_contributor = find_verified_contributor
     end
 
     def disconnect
@@ -24,5 +26,14 @@ module ApplicationCable
       current_user = ExternalUser.find_by(id: session[:external_user_id]) || InternalUser.find_by(id: session[:user_id])
       current_user || reject_unauthorized_connection
     end
+
+    def find_verified_contributor
+      # Finding the current_contributor is similar to the code used in application_controller.rb#current_contributor
+      if session[:pg_id]
+        current_user.programming_groups.find(session[:pg_id])
+      else
+        current_user
+      end
+    end
   end
 end

app/channels/synchronized_editor_channel.rb

@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+class SynchronizedEditorChannel < ApplicationCable::Channel
+  def subscribed
+    stream_from specific_channel
+  end
+
+  def unsubscribed
+    # Any cleanup needed when channel is unsubscribed
+    stop_all_streams
+  end
+
+  def specific_channel
+    reject unless ProgrammingGroupPolicy.new(current_user, programming_group).stream_sync_editor?
+    "synchronized_editor_channel_group_#{programming_group.id}"
+  end
+
+  def programming_group
+    current_contributor if current_contributor.programming_group?
+  end
+
+  def send_changes(message)
+    ActionCable.server.broadcast(specific_channel, message['delta_with_user_id'])
+  end
+end