1 files changed, 65 insertions, 0 deletions
diff --git a/lib/gitlab/cycle_analytics/base_event_fetcher.rb b/lib/gitlab/cycle_analytics/base_event_fetcher.rb
new file mode 100644
index 00000000000..0d8791d396b
--- /dev/null
+++ b/lib/gitlab/cycle_analytics/base_event_fetcher.rb
@@ -0,0 +1,65 @@
+module Gitlab
+  module CycleAnalytics
+    class BaseEventFetcher
+      include BaseQuery
+
+      attr_reader :projections, :query, :stage, :order
+
+      def initialize(project:, stage:, options:)
+        @project = project
+        @stage = stage
+        @options = options
+      end
+
+      def fetch
+        update_author!
+
+        event_result.map do |event|
+          serialize(event) if has_permission?(event['id'])
+        end.compact
+      end
+
+      def order
+        @order || default_order
+      end
+
+      private
+
+      def update_author!
+        return unless event_result.any? && event_result.first['author_id']
+
+        Updater.update!(event_result, from: 'author_id', to: 'author', klass: User)
+      end
+
+      def event_result
+        @event_result ||= ActiveRecord::Base.connection.exec_query(events_query.to_sql).to_a
+      end
+
+      def events_query
+        diff_fn = subtract_datetimes_diff(base_query, @options[:start_time_attrs], @options[:end_time_attrs])
+
+        base_query.project(extract_diff_epoch(diff_fn).as('total_time'), *projections).order(order.desc)
+      end
+
+      def default_order
+        [@options[:start_time_attrs]].flatten.first
+      end
+
+      def serialize(_event)
+        raise NotImplementedError.new("Expected #{self.name} to implement serialize(event)")
+      end
+
+      def has_permission?(id)
+        allowed_ids.nil? || allowed_ids.include?(id.to_i)
+      end
+
+      def allowed_ids
+        nil
+      end
+
+      def event_result_ids
+        event_result.map { |event| event['id'] }
+      end
+    end
+  end
+end