# Add or remove subscription intervals

### Adding or removing intervals

Subscription intervals can be added or removed via an event subscriber that listens to the `DeliveryIntervalCollectorEvent`

```php
// <plugin root>/src/Subscriber/DeliveryIntervalSubscriber.php

namespace B2bSellersExample\Subscriber;

use Shopware\Core\Framework\DataAbstractionLayer\Event\EntityLoadedEvent;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use B2bProductSubscription\Components\ProductSubscription\Events\DeliveryIntervalCollectorEvent;
use Symfony\Contracts\Translation\TranslatorInterface;

class DeliveryIntervalSubscriber implements EventSubscriberInterface
{
    public function __construct(
       private readonly TranslatorInterface $translator
    )
    {}
    
    public static function getSubscribedEvents(): array
    {
        return [
            DeliveryIntervalCollectorEvent::class=> 'onChangeDeliveryIntervals'
        ];
    }

    public function onChangeDeliveryIntervals(DeliveryIntervalCollectorEvent $event)
    {
        $collection = $event->getCollection();
        
        // removing the weekly interval option
        $collection->remove('weekly');

        // Adding your custom interval
        $key = 'custom';
        
        $collection->set($key, new DeliveryIntervalStruct(
            $key,
            $this->translator->trans('b2bProductSubscription.interval.' . $key),
            'b2bProductSubscription.interval.' . $key
        ));
    }
}
```

### Providing a processor for custom intervals

If you add a new subscription interval, a corresponding processor for calculating the next delivery/order date must also be available.

The processor must implement the `IntervalProcessorInterface` and must be registered as a service via the `b2b_product_subscription.interval.processor` tag.

```php
// <plugin root>/src/ProductSubscription/DeliveryInterval/Processor/CustomIntervalProcessor .php

namespace B2bSellersExample\ProductSubscription\DeliveryInterval\Processor;

class CustomIntervalProcessor implements IntervalProcessorInterface
{
    public const DELIVERY_KEY = 'custom';

    public function isSupported(string $key)
    {
        return self::DELIVERY_KEY === $key;
    }

    public function process(\DateTimeInterface $lastOrderDate, ?\DateTimeInterface $result)
    {
        $dateTime = new \DateTime($lastOrderDate->format('Y-m-d'));

        // Calculate your next delivery/order date
        // Example: $dateTime->add(new \DateInterval('P5M'));

        return $dateTime;
    }
}
```

```xml
<!-- <plugin root>/src/Resources/config/services.xml -->

<?xml version="1.0" ?>
<container xmlns="http://symfony.com/schema/dic/services"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">
    <services>
           <service id="B2bSellersExample\ProductSubscription\DeliveryInterval\Processor\CustomIntervalProcessor">
            <tag name="b2b_product_subscription.interval.processor"/>
        </service>
    </services>
</container>
```


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