1 files changed, 47 insertions, 0 deletions
diff --git a/lib/gitlab/global_id/deprecations.rb b/lib/gitlab/global_id/deprecations.rb
new file mode 100644
index 00000000000..ac4a44e0e10
--- /dev/null
+++ b/lib/gitlab/global_id/deprecations.rb
@@ -0,0 +1,47 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module GlobalId
+    module Deprecations
+      Deprecation = Struct.new(:old_model_name, :new_model_name, :milestone, keyword_init: true)
+
+      # Contains the deprecations in place.
+      # Example:
+      #
+      #   DEPRECATIONS = [
+      #     Deprecation.new(old_model_name: 'PrometheusService', new_model_name: 'Integrations::Prometheus', milestone: '14.0')
+      #   ].freeze
+      DEPRECATIONS = [
+        # This works around an accidentally released argument named as `"EEIterationID"` in 7000489db.
+        Deprecation.new(old_model_name: 'EEIteration', new_model_name: 'Iteration', milestone: '13.3')
+      ].freeze
+
+      # Maps of the DEPRECATIONS Hash for quick access.
+      OLD_NAME_MAP = DEPRECATIONS.index_by(&:old_model_name).freeze
+      NEW_NAME_MAP = DEPRECATIONS.index_by(&:new_model_name).freeze
+      OLD_GRAPHQL_NAME_MAP = DEPRECATIONS.index_by do |d|
+        Types::GlobalIDType.model_name_to_graphql_name(d.old_model_name)
+      end.freeze
+
+      def self.deprecated?(old_model_name)
+        OLD_NAME_MAP.key?(old_model_name)
+      end
+
+      def self.deprecation_for(old_model_name)
+        OLD_NAME_MAP[old_model_name]
+      end
+
+      def self.deprecation_by(new_model_name)
+        NEW_NAME_MAP[new_model_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 self.apply_to_graphql_name(graphql_name)
+        return graphql_name unless deprecation = OLD_GRAPHQL_NAME_MAP[graphql_name]
+
+        Types::GlobalIDType.model_name_to_graphql_name(deprecation.new_model_name)
+      end
+    end
+  end
+end