1 files changed, 57 insertions, 0 deletions
diff --git a/app/graphql/resolvers/design_management/design_resolver.rb b/app/graphql/resolvers/design_management/design_resolver.rb
new file mode 100644
index 00000000000..05bdbbbe407
--- /dev/null
+++ b/app/graphql/resolvers/design_management/design_resolver.rb
@@ -0,0 +1,57 @@
+# frozen_string_literal: true
+
+module Resolvers
+  module DesignManagement
+    class DesignResolver < BaseResolver
+      argument :id, GraphQL::ID_TYPE,
+               required: false,
+               description: 'Find a design by its ID'
+
+      argument :filename, GraphQL::STRING_TYPE,
+               required: false,
+               description: 'Find a design by its filename'
+
+      def resolve(filename: nil, id: nil)
+        params = parse_args(filename, id)
+
+        build_finder(params).execute.first
+      end
+
+      def self.single
+        self
+      end
+
+      private
+
+      def issue
+        object.issue
+      end
+
+      def build_finder(params)
+        ::DesignManagement::DesignsFinder.new(issue, current_user, params)
+      end
+
+      def error(msg)
+        raise ::Gitlab::Graphql::Errors::ArgumentError, msg
+      end
+
+      def parse_args(filename, id)
+        provided = [filename, id].map(&:present?)
+
+        if provided.none?
+          error('one of id or filename must be passed')
+        elsif provided.all?
+          error('only one of id or filename may be passed')
+        elsif filename.present?
+          { filenames: [filename] }
+        else
+          { ids: [parse_gid(id)] }
+        end
+      end
+
+      def parse_gid(gid)
+        GitlabSchema.parse_gid(gid, expected_type: ::DesignManagement::Design).model_id
+      end
+    end
+  end
+end