1 files changed, 48 insertions, 0 deletions
diff --git a/lib/gitlab/graphql/deprecations_base.rb b/lib/gitlab/graphql/deprecations_base.rb
new file mode 100644
index 00000000000..2ee14620907
--- /dev/null
+++ b/lib/gitlab/graphql/deprecations_base.rb
@@ -0,0 +1,48 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Graphql
+    # include DeprecationsBase at the end of the target module
+    module DeprecationsBase
+      NameDeprecation = Struct.new(:old_name, :new_name, :milestone, keyword_init: true)
+
+      def self.included(klass)
+        klass.extend(ClassMethods)
+
+        klass.const_set('OLD_GRAPHQL_NAME_MAP', klass::DEPRECATIONS.index_by do |d|
+          klass.map_graphql_name(d.old_name)
+        end.freeze)
+        klass.const_set('OLD_NAME_MAP', klass::DEPRECATIONS.index_by(&:old_name).freeze)
+        klass.const_set('NEW_NAME_MAP', klass::DEPRECATIONS.index_by(&:new_name).freeze)
+      end
+
+      module ClassMethods
+        def deprecated?(old_name)
+          self::OLD_NAME_MAP.key?(old_name)
+        end
+
+        def deprecation_for(old_name)
+          self::OLD_NAME_MAP[old_name]
+        end
+
+        def deprecation_by(new_name)
+          self::NEW_NAME_MAP[new_name]
+        end
+
+        # Returns the new `graphql_name` (Type#graphql_name) of a deprecated GID,
+        # or the `graphql_name` argument given if no deprecation applies.
+        def apply_to_graphql_name(graphql_name)
+          return graphql_name unless deprecation = self::OLD_GRAPHQL_NAME_MAP[graphql_name]
+
+          self.map_graphql_name(deprecation.new_name)
+        end
+
+        private
+
+        def map_graphql_name(name)
+          raise NotImplementedError, "Implement `#{__method__}` in #{self.name}"
+        end
+      end
+    end
+  end
+end