feat: live task and comment updates via action cable

app/channels/application_cable/connection.rb

@@ -9,11 +9,28 @@ def connect
     protected
 
     def find_verified_user
-      if verified_user = env['warden'].user
+      if verified_user = env['warden'].user || user_from_token
         verified_user
       else
         reject_unauthorized_connection
       end
     end
+
+    def user_from_token
+      username = request.params[:username]
+      auth_token = request.params[:authToken] || request.params[:auth_token] || request.params[:Auth_Token]
+      return if username.blank? || auth_token.blank?
+
+      user = User.eager_load(:role, :auth_tokens).find_by(username: username)
+      token = user&.token_for_text?(auth_token, :general)
+      return if token.blank?
+
+      if token.auth_token_expiry > Time.zone.now
+        user
+      else
+        token.destroy!
+        nil
+      end
+    end
   end
 end

app/channels/task_channel.rb

@@ -0,0 +1,13 @@
+class TaskChannel < ApplicationCable::Channel
+  include AuthorisationHelpers
+
+  def subscribed
+    project = Project.find_by(id: params[:project_id])
+    task_definition = project&.unit&.task_definitions&.find_by(id: params[:task_definition_id])
+
+    return reject unless project && task_definition && authorise?(current_user, project, :get)
+    return reject unless project.has_task_for_task_definition?(task_definition)
+
+    stream_for project.task_for_task_definition(task_definition)
+  end
+end

app/models/comments/task_comment.rb

@@ -34,9 +34,15 @@ class TaskComment < ApplicationRecord
     mark_as_read(self.user)
   end
 
+  after_commit :broadcast_comment_created, on: :create
+
   # Delete action - before dependent association
   before_destroy :delete_associated_files
 
+  def broadcast_comment_created
+    TaskChannel.broadcast_to(task, event: 'comment_created')
+  end
+
   def valid_reply_to?
     if reply_to_id.present?
       originalTaskComment = TaskComment.find(reply_to_id)

app/models/task.rb

@@ -147,6 +147,7 @@ def specific_permission_hash(role, perm_hash, _other)
   delegate :update_task_stats, to: :project
 
   after_update :update_task_stats, if: :saved_change_to_task_status_id? # TODO: consider moving to async task
+  after_commit :broadcast_status_change, on: :update, if: :saved_change_to_task_status_id?
 
   validates :task_definition_id, uniqueness: { scope: :project,
                                                message: 'must be unique within the project' }
@@ -897,6 +898,10 @@ def add_status_comment(current_user, status)
     comment
   end
 
+  def broadcast_status_change
+    TaskChannel.broadcast_to(self, event: 'status_changed')
+  end
+
   def add_discussed_comment(current_user)
     comment = 'Discussed in class'
 

config/cable.yml

@@ -0,0 +1,10 @@
+development:
+  adapter: async
+
+test:
+  adapter: test
+
+production:
+  adapter: redis
+  url: <%= ENV.fetch("DF_REDIS_CABLE_URL", ENV.fetch("DF_REDIS_SIDEKIQ_URL", "redis://localhost:6379/1")) %>
+  channel_prefix: doubtfire_production

config/routes.rb

@@ -7,6 +7,7 @@
   get 'api/units/:id/all_resources', to: 'lecture_resource_downloads#index'
 
   mount ApiRoot => '/'
+  mount ActionCable.server => '/cable'
   mount GrapeSwaggerRails::Engine => '/api/docs'
   mount Sidekiq::Web => "/sidekiq" # mount Sidekiq::Web in your Rails app