Extract private methods in api/v1/instances/domain_blocks (mastodon#2…

…7844)

app/controllers/api/v1/instances/domain_blocks_controller.rb

@@ -13,7 +13,7 @@ def index
       cache_if_unauthenticated!
     end
 
-    render json: @domain_blocks, each_serializer: REST::DomainBlockSerializer, with_comment: (Setting.show_domain_blocks_rationale == 'all' || (Setting.show_domain_blocks_rationale == 'users' && user_signed_in?))
+    render json: @domain_blocks, each_serializer: REST::DomainBlockSerializer, with_comment: show_rationale_in_response?
   end
 
   private
@@ -25,4 +25,16 @@ def require_enabled_api!
   def set_domain_blocks
     @domain_blocks = DomainBlock.with_user_facing_limitations.by_severity
   end
+
+  def show_rationale_in_response?
+    always_show_rationale? || show_rationale_for_user?
+  end
+
+  def always_show_rationale?
+    Setting.show_domain_blocks_rationale == 'all'
+  end
+
+  def show_rationale_for_user?
+    Setting.show_domain_blocks_rationale == 'users' && user_signed_in?
+  end
 end