1 files changed, 46 insertions, 0 deletions
diff --git a/lib/gitlab/config/entry/validators/nested_array_helpers.rb b/lib/gitlab/config/entry/validators/nested_array_helpers.rb
new file mode 100644
index 00000000000..9f5d17d74b0
--- /dev/null
+++ b/lib/gitlab/config/entry/validators/nested_array_helpers.rb
@@ -0,0 +1,46 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Config
+    module Entry
+      module Validators
+        # Include this module to validate deeply nested array of values
+        #
+        # class MyNestedValidator < ActiveModel::EachValidator
+        #   include NestedArrayHelpers
+        #
+        #   def validate_each(record, attribute, value)
+        #     max_depth = options.fetch(:max_depth, 1)
+        #
+        #     unless validate_nested_array(value, max_depth) { |v| v.is_a?(Integer) }
+        #       record.errors.add(attribute, "is invalid")
+        #     end
+        #   end
+        # end
+        #
+        module NestedArrayHelpers
+          def validate_nested_array(value, max_depth = 1, &validator_proc)
+            return false unless value.is_a?(Array)
+
+            validate_nested_array_recursively(value, max_depth, &validator_proc)
+          end
+
+          private
+
+          # rubocop: disable Performance/RedundantBlockCall
+          # Disables Rubocop rule for easier readability reasons.
+          def validate_nested_array_recursively(value, nesting_level, &validator_proc)
+            return true if validator_proc.call(value)
+            return false if nesting_level <= 0
+            return false unless value.is_a?(Array)
+
+            value.all? do |element|
+              validate_nested_array_recursively(element, nesting_level - 1, &validator_proc)
+            end
+          end
+          # rubocop: enable Performance/RedundantBlockCall
+        end
+      end
+    end
+  end
+end