The UserSubscription Manager will handle creation and persistence of `UserSubscription` entities.

It can be connected to Doctrine, or you're free to use your own logic.

## Create your UserSubscription manager

Then, create a class that implements `BenTools\WebPushBundle\Model\Subscription\UserSubscriptionManagerInterface` with your own logic.

Example with Doctrine:
```php
# src/Services/UserSubscriptionManager.php

namespace App\Services;

use App\Entity\UserSubscription;
use BenTools\WebPushBundle\Model\Subscription\UserSubscriptionInterface;
use BenTools\WebPushBundle\Model\Subscription\UserSubscriptionManagerInterface;
use Doctrine\Persistence\ManagerRegistry;
use Symfony\Component\Security\Core\User\UserInterface;

class UserSubscriptionManager implements UserSubscriptionManagerInterface
{
    /**
     * @var ManagerRegistry
     */
    private $doctrine;

    /**
     * UserSubscriptionManager constructor.
     * @param ManagerRegistry $doctrine
     */
    public function __construct(ManagerRegistry $doctrine)
    {
        $this->doctrine = $doctrine;
    }

    /**
     * @inheritDoc
     */
    public function factory(UserInterface $user, string $subscriptionHash, array $subscription, array $options = []): UserSubscriptionInterface
    {
        // $options is an arbitrary array that can be provided through the front-end code.
        // You can use it to store meta-data about the subscription: the user agent, the referring domain, ...
        return new UserSubscription($user, $subscriptionHash, $subscription);
    }
    
    /**
     * @inheritDoc
     */
    public function hash(string $endpoint, UserInterface $user): string {
        return md5($endpoint); // Encode it as you like    
    }

    /**
     * @inheritDoc
     */
    public function getUserSubscription(UserInterface $user, string $subscriptionHash): ?UserSubscriptionInterface
    {
        return $this->doctrine->getManager()->getRepository(UserSubscription::class)->findOneBy([
            'user' => $user,
            'subscriptionHash' => $subscriptionHash,
        ]);
    }

    /**
     * @inheritDoc
     */
    public function findByUser(UserInterface $user): iterable
    {
        return $this->doctrine->getManager()->getRepository(UserSubscription::class)->findBy([
            'user' => $user,
        ]);
    }

    /**
     * @inheritDoc
     */
    public function findByHash(string $subscriptionHash): iterable
    {
        return $this->doctrine->getManager()->getRepository(UserSubscription::class)->findBy([
            'subscriptionHash' => $subscriptionHash,
        ]);
    }

    /**
     * @inheritDoc
     */
    public function save(UserSubscriptionInterface $userSubscription): void
    {
        $this->doctrine->getManager()->persist($userSubscription);
        $this->doctrine->getManager()->flush();
    }

    /**
     * @inheritDoc
     */
    public function delete(UserSubscriptionInterface $userSubscription): void
    {
        $this->doctrine->getManager()->remove($userSubscription);
        $this->doctrine->getManager()->flush();
    }

}
```

Now, register your `UserSubscriptionManager` in your `services.yaml`:

```yaml
# app/config/services.yml (SF3)
# config/services.yaml (SF4) 

services:
    App\Services\UserSubscriptionManager:
        class: App\Services\UserSubscriptionManager
        arguments:
            - '@doctrine'
        tags:
            - { name: bentools_webpush.subscription_manager, user_class: 'App\Entity\User' }
```

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Next: [Configuration](03%20-%20Configuration.md)