1 files changed, 76 insertions, 0 deletions
diff --git a/app/graphql/resolvers/design_management/versions_resolver.rb b/app/graphql/resolvers/design_management/versions_resolver.rb
new file mode 100644
index 00000000000..a62258dad5c
--- /dev/null
+++ b/app/graphql/resolvers/design_management/versions_resolver.rb
@@ -0,0 +1,76 @@
+# frozen_string_literal: true
+
+module Resolvers
+  module DesignManagement
+    class VersionsResolver < BaseResolver
+      type Types::DesignManagement::VersionType.connection_type, null: false
+
+      alias_method :design_or_collection, :object
+
+      argument :earlier_or_equal_to_sha, GraphQL::STRING_TYPE,
+               as: :sha,
+               required: false,
+               description: 'The SHA256 of the most recent acceptable version'
+
+      argument :earlier_or_equal_to_id, GraphQL::ID_TYPE,
+               as: :id,
+               required: false,
+               description: 'The Global ID of the most recent acceptable version'
+
+      # This resolver has a custom singular resolver
+      def self.single
+        ::Resolvers::DesignManagement::VersionInCollectionResolver
+      end
+
+      def resolve(parent: nil, id: nil, sha: nil)
+        version = cutoff(parent, id, sha)
+
+        raise ::Gitlab::Graphql::Errors::ResourceNotAvailable, 'cutoff not found' unless version.present?
+
+        if version == :unconstrained
+          find
+        else
+          find(earlier_or_equal_to: version)
+        end
+      end
+
+      private
+
+      # Find the most recent version that the client will accept
+      def cutoff(parent, id, sha)
+        if sha.present? || id.present?
+          specific_version(id, sha)
+        elsif at_version = at_version_arg(parent)
+          by_id(at_version)
+        else
+          :unconstrained
+        end
+      end
+
+      def specific_version(id, sha)
+        gid = GitlabSchema.parse_gid(id, expected_type: ::DesignManagement::Version) if id
+        find(sha: sha, version_id: gid&.model_id).first
+      end
+
+      def find(**params)
+        ::DesignManagement::VersionsFinder
+          .new(design_or_collection, current_user, params)
+          .execute
+      end
+
+      def by_id(id)
+        GitlabSchema.object_from_id(id, expected_type: ::DesignManagement::Version).sync
+      end
+
+      # Find an `at_version` argument passed to a parent node.
+      #
+      # If one is found, then a design collection further up the AST
+      # has been filtered to reflect designs at that version, and so
+      # for consistency we should only present versions up to the given
+      # version here.
+      def at_version_arg(parent)
+        ::Gitlab::Graphql::FindArgumentInParent.find(parent, :at_version, limit_depth: 4)
+      end
+    end
+  end
+end