1 files changed, 63 insertions, 0 deletions
diff --git a/lib/gitlab/markdown/reference_gatherer_filter.rb b/lib/gitlab/markdown/reference_gatherer_filter.rb
new file mode 100644
index 00000000000..00f983675e6
--- /dev/null
+++ b/lib/gitlab/markdown/reference_gatherer_filter.rb
@@ -0,0 +1,63 @@
+require 'gitlab/markdown'
+require 'html/pipeline/filter'
+
+module Gitlab
+  module Markdown
+    # HTML filter that gathers all referenced records that the current user has
+    # permission to view.
+    #
+    # Expected to be run in its own post-processing pipeline.
+    #
+    class ReferenceGathererFilter < HTML::Pipeline::Filter
+      def initialize(*)
+        super
+
+        result[:references] ||= Hash.new { |hash, type| hash[type] = [] }
+      end
+
+      def call
+        doc.css('a.gfm').each do |node|
+          gather_references(node)
+        end
+
+        load_lazy_references unless context[:load_lazy_references] == false
+
+        doc
+      end
+
+      private
+
+      def gather_references(node)
+        return unless node.has_attribute?('data-reference-filter')
+
+        reference_type = node.attr('data-reference-filter')
+        reference_filter = reference_type.constantize
+
+        return if context[:reference_filter] && reference_filter != context[:reference_filter]
+
+        return unless reference_filter.user_can_reference?(current_user, node, context)
+
+        references = reference_filter.referenced_by(node)
+        return unless references
+
+        references.each do |type, values|
+          Array.wrap(values).each do |value|
+            result[:references][type] << value
+          end
+        end
+      end
+
+      # Will load all references of one type using one query.
+      def load_lazy_references
+        refs = result[:references]
+        refs.each do |type, values|
+          refs[type] = ReferenceFilter::LazyReference.load(values)
+        end
+      end
+
+      def current_user
+        context[:current_user]
+      end
+    end
+  end
+end