1 files changed, 29 insertions, 0 deletions
diff --git a/app/graphql/batch_loaders/merge_request_diff_summary_batch_loader.rb b/app/graphql/batch_loaders/merge_request_diff_summary_batch_loader.rb
new file mode 100644
index 00000000000..9b8737a6703
--- /dev/null
+++ b/app/graphql/batch_loaders/merge_request_diff_summary_batch_loader.rb
@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+
+module BatchLoaders
+  class MergeRequestDiffSummaryBatchLoader
+    NIL_STATS = { additions: 0, deletions: 0, file_count: 0 }.freeze
+
+    def self.load_for(merge_request)
+      BatchLoader::GraphQL.for(merge_request).batch(key: :diff_stats_summary) do |merge_requests, loader, args|
+        Preloaders::MergeRequestDiffPreloader.new(merge_requests).preload_all
+
+        merge_requests.each do |merge_request|
+          metrics = merge_request.metrics
+
+          summary = if metrics && metrics.added_lines && metrics.removed_lines
+                      { additions: metrics.added_lines, deletions: metrics.removed_lines, file_count: merge_request.merge_request_diff&.files_count || 0 }
+                    elsif merge_request.diff_stats.blank?
+                      NIL_STATS
+                    else
+                      merge_request.diff_stats.each_with_object(NIL_STATS.dup) do |status, summary|
+                        summary.merge!(additions: status.additions, deletions: status.deletions, file_count: 1) { |_, x, y| x + y }
+                      end
+                    end
+
+          loader.call(merge_request, summary)
+        end
+      end
+    end
+  end
+end