Implement guards.

README.md

@@ -57,6 +57,16 @@ default:
       to:   canceled
 ```
 
+Transitions can be further restricted by [guards](https://github.com/bojanz/commerce_workflow/blob/8.x-1.x/src/WorkflowGuard/WorkflowGuardInterface.php), which are implemented as tagged services:
+```yaml
+  mymodule.fulfillment_guard:
+    class: Drupal\mymodule\WorkflowGuard\FulfillmentGuard
+    tags:
+      - { name: commerce_workflow.workflow_guard, group: order }
+```
+The group argument allows the guard factory to only instantiate the guards relevant
+to a specific workflow group.
+
 The current state is stored in a [StateItem](https://github.com/bojanz/commerce_workflow/blob/8.x-1.x/src/Plugin/Field/FieldType/StateItem.php) field.
 A field setting specifies the used workflow, or a value callback that allows
 the workflow to be resolved at runtime (checkout workflow based on the used plugin, etc.

commerce_workflow.services.yml

 services:
+  commerce_workflow.workflow_guard_factory:
+    class: Drupal\commerce_workflow\WorkflowGuard\WorkflowGuardFactory
+    arguments: ['@service_container']
+
   plugin.manager.workflow:
     class: Drupal\commerce_workflow\WorkflowManager
     arguments: ['@module_handler', '@cache.discovery', '@plugin.manager.workflow_group']

src/CommerceWorkflowServiceProvider.php

+<?php
+
+/**
+ * @file
+ * Contains \Drupal\commerce_workflow\CommerceWorkflowServiceProvider.
+ */
+
+namespace Drupal\commerce_workflow;
+
+use Drupal\Core\DependencyInjection\ServiceProviderInterface;
+use Drupal\Core\DependencyInjection\ContainerBuilder;
+use Drupal\commerce_workflow\DependencyInjection\Compiler\WorkflowGuardsPass;
+
+/**
+ * Registers the workflow guard compiler pass.
+ */
+class CommerceWorkflowServiceProvider implements ServiceProviderInterface  {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function register(ContainerBuilder $container) {
+    $container->addCompilerPass(new WorkflowGuardsPass());
+  }
+
+}

src/DependencyInjection/Compiler/WorkflowGuardsPass.php

+<?php
+
+/**
+ * @file
+ * Contains \Drupal\commerce_workflow\DependencyInjection\Compiler\WorkflowGuardsPass.
+ */
+
+namespace Drupal\commerce_workflow\DependencyInjection\Compiler;
+
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
+
+/**
+ * Adds the context provider service IDs to the context manager.
+ */
+class WorkflowGuardsPass implements CompilerPassInterface {
+
+  /**
+   * {@inheritdoc}
+   *
+   * Passes the grouped service IDs of workflow guards to the guard factory.
+   */
+  public function process(ContainerBuilder $container) {
+    $guards = [];
+    foreach ($container->findTaggedServiceIds('commerce_workflow.workflow_guard') as $id => $attributes) {
+      if (empty($attributes[0]['group'])) {
+        continue;
+      }
+
+      $guards[$attributes[0]['group']][] = $id;
+    }
+
+    $definition = $container->getDefinition('commerce_workflow.workflow_guard_factory');
+    $definition->addArgument($guards);
+  }
+
+}

src/Plugin/Workflow/Workflow.php

@@ -7,13 +7,23 @@
 
 namespace Drupal\commerce_workflow\Plugin\Workflow;
 
+use Drupal\commerce_workflow\WorkflowGuard\WorkflowGuardFactoryInterface;
 use Drupal\Core\Entity\EntityInterface;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
 use Drupal\Core\Plugin\PluginBase;
+use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
  * Defines the class for workflows.
  */
-class Workflow extends PluginBase implements WorkflowInterface {
+class Workflow extends PluginBase implements WorkflowInterface, ContainerFactoryPluginInterface {
+
+  /**
+   * The workflow guard factory.
+   *
+   * @var \Drupal\commerce_workflow\WorkflowGuard\WorkflowGuardFactoryInterface
+   */
+  protected $guardFactory;
 
   /**
    * The initialized states.
@@ -30,11 +40,21 @@ class Workflow extends PluginBase implements WorkflowInterface {
   protected $transitions = [];
 
   /**
-   * {@inheritdoc}
+   * Constructs a new Workflow object.
+   *
+   * @param array $configuration
+   *   The plugin configuration.
+   * @param string $plugin_id
+   *   The workflow plugin_id.
+   * @param mixed $plugin_definition
+   *   The workflow plugin implementation definition.
+   * @param \Drupal\commerce_workflow\WorkflowGuard\WorkflowGuardFactoryInterface $guard_factory
+   *   The workflow guard factory.
    */
-  public function __construct(array $configuration, $plugin_id, $plugin_definition) {
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, WorkflowGuardFactoryInterface $guard_factory) {
     parent::__construct($configuration, $plugin_id, $plugin_definition);
 
+    $this->guardFactory = $guard_factory;
     // Populate value objects for states and transitions.
     foreach ($plugin_definition['states'] as $id => $state_definition) {
       $this->states[$id] = new WorkflowState($id, $state_definition['label']);
@@ -50,6 +70,18 @@ class Workflow extends PluginBase implements WorkflowInterface {
     }
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $container->get('commerce_workflow.workflow_guard_factory')
+    );
+  }
+
   /**
    * {@inheritdoc}
    */
@@ -135,7 +167,12 @@ class Workflow extends PluginBase implements WorkflowInterface {
    *   TRUE if the transition is allowed, FALSE otherwise.
    */
   protected function isTransitionAllowed(WorkflowTransition $transition, EntityInterface $entity) {
-    // @todo
+    foreach ($this->guardFactory->get($this->getGroup()) as $guard) {
+      if ($guard->allowed($transition, $this, $entity) === FALSE) {
+        return FALSE;
+      }
+    }
+
     return TRUE;
   }
 

src/WorkflowGuard/WorkflowGuardFactory.php

+<?php
+
+/**
+ * @file
+ * Contains \Drupal\commerce_workflow\WorkflowGuard\WorkflowGuardFactory.
+ */
+
+namespace Drupal\commerce_workflow\WorkflowGuard;
+
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+class WorkflowGuardFactory {
+
+  /**
+   * The service container.
+   *
+   * @var \Symfony\Component\DependencyInjection\ContainerInterface
+   */
+  protected $container;
+
+  /**
+   * The guard service ids, grouped by workflow group id.
+   *
+   * @var string[]
+   */
+  protected $guardServiceIds;
+
+  /**
+   * Constructs a new WorkflowGuardFactory object.
+   *
+   * @param \Symfony\Component\DependencyInjection\ContainerInterface $container
+   *   The service container.
+   * @param string[] $guard_service_ids
+   *   The guard service ids, grouped by workflow group id
+   */
+  public function __construct(ContainerInterface $container, array $guard_service_ids) {
+    $this->container = $container;
+    $this->guardServiceIds = $guard_service_ids;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function get($group_id) {
+    if (!isset($this->guardServiceIds[$group_id])) {
+      return [];
+    }
+
+    $guards = [];
+    foreach ($this->guardServiceIds[$group_id] as $service_id) {
+      $guards[] = $this->container->get($service_id);
+    }
+
+    return $guards;
+  }
+
+}

src/WorkflowGuard/WorkflowGuardFactoryInterface.php

+<?php
+
+/**
+ * @file
+ * Contains \Drupal\commerce_workflow\WorkflowGuard\WorkflowGuardFactoryInterface.
+ */
+
+namespace Drupal\commerce_workflow\WorkflowGuard;
+
+/**
+ * Defines the interface for workflow guard factories.
+ */
+interface WorkflowGuardFactoryInterface {
+
+ /**
+   * Gets the instantiated workflow guards for the given group id.
+   *
+   * @param string $group_id
+   *   The group id.
+   *
+   * @return \Drupal\commerce_workflow\WorkflowGuard\WorkflowGuardInterface[]
+   */
+  public function get($group_id);
+
+}

src/WorkflowGuard/WorkflowGuardInterface.php

+<?php
+
+/**
+ * @file
+ * Contains \Drupal\commerce_workflow\WorkflowGuard\WorkflowGuardInterface.
+ */
+
+namespace Drupal\commerce_workflow\WorkflowGuard;
+
+use Drupal\commerce_workflow\Plugin\Workflow\WorkflowInterface;
+use Drupal\commerce_workflow\Plugin\Workflow\WorkflowTransition;
+use Drupal\Core\Entity\EntityInterface;
+
+/**
+ * Defines the interface for workflow guards.
+ *
+ * Allows for custom logic controling the availability of specific transitions.
+ * Transitions could be restricted based on the current user's permissions, a
+ * parent entity field, etc.
+ *
+ * By default, a transition is allowed unless at least one guard returns FALSE.
+ */
+interface WorkflowGuardInterface {
+
+  /**
+   * Checks whether the given transition is allowed.
+   *
+   * @param \Drupal\commerce_workflow\Plugin\Workflow\WorkflowTransition $transition
+   *   The transition.
+   * @param \Drupal\commerce_workflow\Plugin\Workflow\WorkflowInterface $workflow
+   *   The workflow.
+   * @param \Drupal\Core\Entity\EntityInterface $entity
+   *   The parent entity.
+   *
+   * @return bool
+   *   TRUE if the transition is allowed, FALSE otherwise.
+   */
+  public function allowed(WorkflowTransition $transition, WorkflowInterface $workflow, EntityInterface $entity);
+
+}