Refs: #3478@2h Access correct referential in line_footnotes Ctrl

  + ApplicationController provides Pundit's UserContext's referential with `@referential` instead of `current_referential`,
    (`@referential` is computed from the URL,  while `current_referential` was aliased to different methods, **not always**
     pointing to `Referential` instances)

  + ApplicationPolicy uses the record's referential in its `referential method` iff it is an instance of `Referential` else
    it uses the abovely provided referential, locally named `@current_referential` (as it should be named in the Ctrl too)
    This assures, in combination with the Ctrl Change, that `referential` **always** returns an instance of `Referential`!

  - TODO: Review my understanding of _Referential Setup_ inside the Ctrls

3 files changed, 19 insertions, 8 deletions

diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index 42b7c2a25..8fcaa3b1b 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -19,7 +19,7 @@ class ApplicationController < ActionController::Base
   end
 
   def pundit_user
-    UserContext.new(current_user, referential: self.try(:current_referential))
+    UserContext.new(current_user, referential: @referential)
   end
 
   protected
diff --git a/app/controllers/line_footnotes_controller.rb b/app/controllers/line_footnotes_controller.rb
index c42aa785b..6a9048392 100644
--- a/app/controllers/line_footnotes_controller.rb
+++ b/app/controllers/line_footnotes_controller.rb
@@ -34,7 +34,7 @@ class LineFootnotesController < BreadcrumbController
   private
   def resource
     @referential = Referential.find params[:referential_id]
-    @line = @referential.lines.find params[:line_id]
+    @line        = @referential.lines.find params[:line_id]
   end
 
   def line_params
diff --git a/app/policies/application_policy.rb b/app/policies/application_policy.rb
index a863404ae..f2521fa44 100644
--- a/app/policies/application_policy.rb
+++ b/app/policies/application_policy.rb
@@ -1,18 +1,19 @@
 class ApplicationPolicy
-  attr_reader :user, :record
+  attr_reader :current_referential, :record, :user
 
   def initialize(user_context, record)
-    @user = user_context.user
-    @referential = user_context.context[:referential]
-    @record = record
+    @user                = user_context.user
+    @current_referential = user_context.context[:referential]
+    @record              = record
   end
 
   def archived?
-    !!referential.try(:archived_at)
+    return @is_archived if instance_variable_defined?(:@is_archived)
+    @is_archived = is_archived
   end
 
   def referential
-    @referential ||= record_referential
+    @referential ||=  current_referential || record_referential
   end
 
   def record_referential
@@ -77,4 +78,14 @@ class ApplicationPolicy
       scope
     end
   end
+
+  private
+  def is_archived
+    !!case referential
+    when Referential
+      referential.archived_at
+    else
+      current_referential.try(:archived_at)
+    end
+  end
 end