1 files changed, 57 insertions, 0 deletions
diff --git a/lib/gitlab/ci/config/edge_stages_injector.rb b/lib/gitlab/ci/config/edge_stages_injector.rb
new file mode 100644
index 00000000000..64ff9f951e4
--- /dev/null
+++ b/lib/gitlab/ci/config/edge_stages_injector.rb
@@ -0,0 +1,57 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Ci
+    class Config
+      class EdgeStagesInjector
+        PRE_PIPELINE = '.pre'
+        POST_PIPELINE = '.post'
+        EDGES = [PRE_PIPELINE, POST_PIPELINE].freeze
+
+        def self.wrap_stages(stages)
+          stages = stages.to_a - EDGES
+          stages.unshift PRE_PIPELINE
+          stages.push POST_PIPELINE
+
+          stages
+        end
+
+        def initialize(config)
+          @config = config.to_h.deep_dup
+        end
+
+        def to_hash
+          if config.key?(:stages)
+            process(:stages)
+          elsif config.key?(:types)
+            process(:types)
+          else
+            config
+          end
+        end
+
+        private
+
+        attr_reader :config
+
+        delegate :wrap_stages, to: :class
+
+        def process(keyword)
+          stages = extract_stages(keyword)
+          return config if stages.empty?
+
+          stages = wrap_stages(stages)
+          config[keyword] = stages
+          config
+        end
+
+        def extract_stages(keyword)
+          stages = config[keyword]
+          return [] unless stages.is_a?(Array)
+
+          stages
+        end
+      end
+    end
+  end
+end