1 files changed, 63 insertions, 0 deletions
diff --git a/app/services/auto_merge/base_service.rb b/app/services/auto_merge/base_service.rb
new file mode 100644
index 00000000000..d726085b89a
--- /dev/null
+++ b/app/services/auto_merge/base_service.rb
@@ -0,0 +1,63 @@
+# frozen_string_literal: true
+
+module AutoMerge
+  class BaseService < ::BaseService
+    include Gitlab::Utils::StrongMemoize
+
+    def execute(merge_request)
+      merge_request.merge_params.merge!(params)
+      merge_request.auto_merge_enabled = true
+      merge_request.merge_user = current_user
+      merge_request.auto_merge_strategy = strategy
+
+      return :failed unless merge_request.save
+
+      yield if block_given?
+
+      # Notify the event that auto merge is enabled or merge param is updated
+      AutoMergeProcessWorker.perform_async(merge_request.id)
+
+      strategy.to_sym
+    end
+
+    def update(merge_request)
+      merge_request.merge_params.merge!(params)
+
+      return :failed unless merge_request.save
+
+      strategy.to_sym
+    end
+
+    def cancel(merge_request)
+      if cancel_auto_merge(merge_request)
+        yield if block_given?
+
+        success
+      else
+        error("Can't cancel the automatic merge", 406)
+      end
+    end
+
+    private
+
+    def strategy
+      strong_memoize(:strategy) do
+        self.class.name.demodulize.remove('Service').underscore
+      end
+    end
+
+    def cancel_auto_merge(merge_request)
+      merge_request.auto_merge_enabled = false
+      merge_request.merge_user = nil
+
+      merge_request.merge_params&.except!(
+        'should_remove_source_branch',
+        'commit_message',
+        'squash_commit_message',
+        'auto_merge_strategy'
+      )
+
+      merge_request.save
+    end
+  end
+end