1 files changed, 43 insertions, 0 deletions
diff --git a/app/services/packages/rubygems/dependency_resolver_service.rb b/app/services/packages/rubygems/dependency_resolver_service.rb
new file mode 100644
index 00000000000..c44b26e2b92
--- /dev/null
+++ b/app/services/packages/rubygems/dependency_resolver_service.rb
@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+module Packages
+  module Rubygems
+    class DependencyResolverService < BaseService
+      include Gitlab::Utils::StrongMemoize
+
+      DEFAULT_PLATFORM = 'ruby'
+
+      def execute
+        return ServiceResponse.error(message: "forbidden", http_status: :forbidden) unless Ability.allowed?(current_user, :read_package, project)
+        return ServiceResponse.error(message: "#{gem_name} not found", http_status: :not_found) if packages.empty?
+
+        payload = packages.map do |package|
+          dependencies = package.dependency_links.map do |link|
+            [link.dependency.name, link.dependency.version_pattern]
+          end
+
+          {
+            name: gem_name,
+            number: package.version,
+            platform: DEFAULT_PLATFORM,
+            dependencies: dependencies
+          }
+        end
+
+        ServiceResponse.success(payload: payload)
+      end
+
+      private
+
+      def packages
+        strong_memoize(:packages) do
+          project.packages.with_name(gem_name)
+        end
+      end
+
+      def gem_name
+        params[:gem_name]
+      end
+    end
+  end
+end