Workflow default status and computing positions

app/services/project_admin/workflows/statuses/batch_update.rb

@@ -40,7 +40,7 @@ module ProjectAdmin
           @task_statuses = Array(attributes).map { |e| TaskStatus.new(e) }
         end
 
-        def call(workflow)
+        def perform(workflow)
           @workflow = workflow
 
           @workflow.assign_attributes(task_statuses_attributes: task_statuses.map(&:to_model_attributes))

app/services/project_admin/workflows/statuses/update_transitions.rb

@@ -12,20 +12,50 @@ module ProjectAdmin
           attribute :next_status_ids
         end
 
-        attr_accessor :task_statuses
+        attr_accessor :workflow, :task_statuses
+
+        attribute :default_status_id, :integer
 
         def self.from_model(workflow)
-          new(task_statuses_attributes: workflow.task_statuses
-            .includes(:next_statuses)
-            .map { |ts| { id: ts.id, next_status_ids: ts.next_status_ids } })
+          new(
+            workflow:,
+            task_statuses_attributes: workflow.task_statuses
+              .includes(:next_statuses)
+              .map { |ts| { id: ts.id, next_status_ids: ts.next_status_ids } },
+            default_status_id: workflow.default_status_id
+          )
         end
 
         def task_statuses_attributes=(attributes)
           @task_statuses = Array(attributes).map { |e| TaskStatus.new(e) }
         end
 
-        def call(workflow)
-          workflow.update(task_statuses_attributes: task_statuses.map(&:attributes))
+        def perform(workflow)
+          @workflow = workflow
+          workflow.assign_attributes(default_status_id:, task_statuses_attributes: task_statuses.map(&:attributes))
+          save workflow
+        end
+
+        after_success do
+          if @workflow.default_status.nil?
+            @workflow.task_statuses.update!(position: 0)
+            return
+          end
+
+          @workflow.transaction do
+            @workflow.default_status.update!(position: 0)
+            seen_status_ids = Set[@workflow.default_status.id]
+            statuses_to_process = [@workflow.default_status]
+
+            until statuses_to_process.empty?
+              status = statuses_to_process.pop
+
+              next_statuses = status.next_statuses.where.not(id: seen_status_ids)
+              next_statuses.update(position: status.position + 1)
+              statuses_to_process.concat(next_statuses.to_a)
+              seen_status_ids.merge(next_statuses.map(&:id))
+            end
+          end
         end
       end
     end