Add consisten steps map rule for workflow validation

[MAILPOET-4629]

mailpoet/lib/Automation/Engine/Validation/WorkflowRules/ConsistentStepMapRule.php

@@ -0,0 +1,24 @@
+<?php declare(strict_types = 1);
+
+namespace MailPoet\Automation\Engine\Validation\WorkflowRules;
+
+use MailPoet\Automation\Engine\Data\Workflow;
+use MailPoet\Automation\Engine\Exceptions;
+use MailPoet\Automation\Engine\Validation\WorkflowGraph\WorkflowNode;
+use MailPoet\Automation\Engine\Validation\WorkflowGraph\WorkflowNodeVisitor;
+
+class ConsistentStepMapRule implements WorkflowNodeVisitor {
+  public function initialize(Workflow $workflow): void {
+    foreach ($workflow->getSteps() as $id => $step) {
+      if ($id !== $step->getId()) {
+        throw Exceptions::workflowStructureNotValid(__('TODO', 'mailpoet'));
+      }
+    }
+  }
+
+  public function visitNode(Workflow $workflow, WorkflowNode $node): void {
+  }
+
+  public function complete(Workflow $workflow): void {
+  }
+}