1 files changed, 132 insertions, 0 deletions
diff --git a/lib/gitlab/analytics/cycle_analytics/records_fetcher.rb b/lib/gitlab/analytics/cycle_analytics/records_fetcher.rb
new file mode 100644
index 00000000000..90d03142b2a
--- /dev/null
+++ b/lib/gitlab/analytics/cycle_analytics/records_fetcher.rb
@@ -0,0 +1,132 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Analytics
+    module CycleAnalytics
+      class RecordsFetcher
+        include Gitlab::Utils::StrongMemoize
+        include StageQueryHelpers
+        include Gitlab::CycleAnalytics::MetricsTables
+
+        MAX_RECORDS = 20
+
+        MAPPINGS = {
+          Issue => {
+            finder_class: IssuesFinder,
+            serializer_class: AnalyticsIssueSerializer,
+            includes_for_query: { project: [:namespace], author: [] },
+            columns_for_select: %I[title iid id created_at author_id project_id]
+          },
+          MergeRequest => {
+            finder_class: MergeRequestsFinder,
+            serializer_class: AnalyticsMergeRequestSerializer,
+            includes_for_query: { target_project: [:namespace], author: [] },
+            columns_for_select: %I[title iid id created_at author_id state target_project_id]
+          }
+        }.freeze
+
+        delegate :subject_class, to: :stage
+
+        def initialize(stage:, query:, params: {})
+          @stage = stage
+          @query = query
+          @params = params
+        end
+
+        def serialized_records
+          strong_memoize(:serialized_records) do
+            # special case (legacy): 'Test' and 'Staging' stages should show Ci::Build records
+            if default_test_stage? || default_staging_stage?
+              AnalyticsBuildSerializer.new.represent(ci_build_records.map { |e| e['build'] })
+            else
+              records.map do |record|
+                project = record.project
+                attributes = record.attributes.merge({
+                  project_path: project.path,
+                  namespace_path: project.namespace.path,
+                  author: record.author
+                })
+                serializer.represent(attributes)
+              end
+            end
+          end
+        end
+
+        private
+
+        attr_reader :stage, :query, :params
+
+        def finder_query
+          MAPPINGS
+            .fetch(subject_class)
+            .fetch(:finder_class)
+            .new(params.fetch(:current_user), finder_params.fetch(stage.parent.class))
+            .execute
+        end
+
+        def columns
+          MAPPINGS.fetch(subject_class).fetch(:columns_for_select).map do |column_name|
+            subject_class.arel_table[column_name]
+          end
+        end
+
+        # EE will override this to include Group rules
+        def finder_params
+          {
+            Project => { project_id: stage.parent_id }
+          }
+        end
+
+        def default_test_stage?
+          stage.matches_with_stage_params?(Gitlab::Analytics::CycleAnalytics::DefaultStages.params_for_test_stage)
+        end
+
+        def default_staging_stage?
+          stage.matches_with_stage_params?(Gitlab::Analytics::CycleAnalytics::DefaultStages.params_for_staging_stage)
+        end
+
+        def serializer
+          MAPPINGS.fetch(subject_class).fetch(:serializer_class).new
+        end
+
+        # Loading Ci::Build records instead of MergeRequest records
+        # rubocop: disable CodeReuse/ActiveRecord
+        def ci_build_records
+          ci_build_join = mr_metrics_table
+            .join(build_table)
+            .on(mr_metrics_table[:pipeline_id].eq(build_table[:commit_id]))
+            .join_sources
+
+          q = ordered_and_limited_query
+            .joins(ci_build_join)
+            .select(build_table[:id], round_duration_to_seconds.as('total_time'))
+
+          results = execute_query(q).to_a
+
+          Gitlab::CycleAnalytics::Updater.update!(results, from: 'id', to: 'build', klass: ::Ci::Build.includes({ project: [:namespace], user: [], pipeline: [] }))
+        end
+
+        def ordered_and_limited_query
+          query
+            .reorder(stage.end_event.timestamp_projection.desc)
+            .limit(MAX_RECORDS)
+        end
+
+        def records
+          results = finder_query
+            .merge(ordered_and_limited_query)
+            .select(*columns, round_duration_to_seconds.as('total_time'))
+
+          # using preloader instead of includes to avoid AR generating a large column list
+          ActiveRecord::Associations::Preloader.new.preload(
+            results,
+            MAPPINGS.fetch(subject_class).fetch(:includes_for_query)
+          )
+
+          results
+        end
+        # rubocop: enable CodeReuse/ActiveRecord
+      end
+    end
+  end
+end