1 files changed, 77 insertions, 0 deletions
diff --git a/app/services/ci/process_pipeline_service.rb b/app/services/ci/process_pipeline_service.rb
new file mode 100644
index 00000000000..f049ed628db
--- /dev/null
+++ b/app/services/ci/process_pipeline_service.rb
@@ -0,0 +1,77 @@
+module Ci
+  class ProcessPipelineService < BaseService
+    attr_reader :pipeline
+
+    def execute(pipeline)
+      @pipeline = pipeline
+
+      # This method will ensure that our pipeline does have all builds for all stages created
+      if created_builds.empty?
+        create_builds!
+      end
+
+      new_builds =
+        stage_indexes_of_created_builds.map do |index|
+          process_stage(index)
+        end
+
+      # Return a flag if a when builds got enqueued
+      new_builds.flatten.any?
+    end
+
+    private
+
+    def create_builds!
+      Ci::CreatePipelineBuildsService.new(project, current_user).execute(pipeline)
+    end
+
+    def process_stage(index)
+      current_status = status_for_prior_stages(index)
+
+      created_builds_in_stage(index).select do |build|
+        process_build(build, current_status)
+      end
+    end
+
+    def process_build(build, current_status)
+      return false unless HasStatus::COMPLETED_STATUSES.include?(current_status)
+
+      if valid_statuses_for_when(build.when).include?(current_status)
+        build.enqueue
+        true
+      else
+        build.skip
+        false
+      end
+    end
+
+    def valid_statuses_for_when(value)
+      case value
+      when 'on_success'
+        %w[success]
+      when 'on_failure'
+        %w[failed]
+      when 'always'
+        %w[success failed]
+      else
+        []
+      end
+    end
+
+    def status_for_prior_stages(index)
+      pipeline.builds.where('stage_idx < ?', index).latest.status || 'success'
+    end
+
+    def stage_indexes_of_created_builds
+      created_builds.order(:stage_idx).pluck('distinct stage_idx')
+    end
+
+    def created_builds_in_stage(index)
+      created_builds.where(stage_idx: index)
+    end
+
+    def created_builds
+      pipeline.builds.created
+    end
+  end
+end