Improve assignee handling and task assignment logic

- Added `hasAssigneeChanged` method for detecting assignee change
- Updated `onTaskAssigned` logic to trigger only on assignee change

src/Bundle/ChillTaskBundle/Controller/SingleTaskController.php

@@ -13,7 +13,6 @@ namespace Chill\TaskBundle\Controller;
 
 use Chill\MainBundle\Entity\User;
 use Chill\MainBundle\Pagination\PaginatorFactory;
-use Chill\MainBundle\Security\Resolver\CenterResolverDispatcherInterface;
 use Chill\MainBundle\Serializer\Model\Collection;
 use Chill\MainBundle\Serializer\Model\Counter;
 use Chill\MainBundle\Templating\Listing\FilterOrderHelper;
@@ -49,7 +48,6 @@ use Symfony\Contracts\Translation\TranslatorInterface;
 final class SingleTaskController extends AbstractController
 {
     public function __construct(
-        private readonly CenterResolverDispatcherInterface $centerResolverDispatcher,
         private readonly PaginatorFactory $paginatorFactory,
         private readonly SingleTaskAclAwareRepositoryInterface $singleTaskAclAwareRepository,
         private readonly TranslatorInterface $translator,
@@ -170,6 +168,9 @@ final class SingleTaskController extends AbstractController
             ->setForm($this->setCreateForm($task, TaskVoter::UPDATE));
         $this->eventDispatcher->dispatch($event, UIEvent::EDIT_FORM);
 
+        //        To keep track of specific assignee change
+        $initialAssignee = $task->getAssignee();
+
         $form = $event->getForm();
 
         $form->handleRequest($request);
@@ -179,6 +180,13 @@ final class SingleTaskController extends AbstractController
                 $em = $this->managerRegistry->getManager();
                 $em->persist($task);
 
+                if (null !== $task->getAssignee()) {
+                    $this->eventDispatcher->dispatch(
+                        new AssignTaskEvent($task, $initialAssignee),
+                        AssignTaskEvent::PERSIST
+                    );
+                }
+
                 $em->flush();
 
                 $this->addFlash('success', $this->translator
@@ -528,7 +536,7 @@ final class SingleTaskController extends AbstractController
 
                 if (null !== $task->getAssignee()) {
                     $this->eventDispatcher->dispatch(
-                        new AssignTaskEvent($task, $user),
+                        new AssignTaskEvent($task),
                         AssignTaskEvent::PERSIST
                     );
                 }

src/Bundle/ChillTaskBundle/Event/AssignTaskEvent.php

@@ -20,7 +20,7 @@ class AssignTaskEvent extends Event
     final public const PERSIST = 'chill_task.assign_task';
     public function __construct(
         private readonly SingleTask $task,
-        private readonly User $assignedUser,
+        private readonly User $initialAssignee,
     ) {}
 
     public function getTask(): SingleTask
@@ -28,8 +28,13 @@ class AssignTaskEvent extends Event
         return $this->task;
     }
 
-    public function getAssignedUser(): User
+    public function getInitialAssignee(): User
     {
-        return $this->assignedUser;
+        return $this->initialAssignee;
+    }
+
+    public function hasAssigneeChanged(): bool
+    {
+        return $this->initialAssignee !== $this->task->getAssignee();
     }
 }

src/Bundle/ChillTaskBundle/Event/TaskAssignEventSubscriber.php

@@ -33,13 +33,16 @@ readonly class TaskAssignEventSubscriber implements EventSubscriberInterface
 
     /**
      * Send a notification when a user is assigned to a task.
-     *
-     * The notification will be sent to the newly assigned user
+     * Only triggers when the assignee actually changes.
      */
     public function onTaskAssigned(AssignTaskEvent $event): void
     {
+        if (!$event->hasAssigneeChanged()) {
+            return;
+        }
+
         $task = $event->getTask();
-        $assignedUser = $event->getAssignedUser();
+        $assignedUser = $task->getAssignee();
 
         $title = $task->getTitle();