Mailchimp subscriber service in Laravel example

AppServiceProvider.php

<?php

namespace App\Providers;

use App\Contracts\SubscriberService;
use App\Services\Mailchimp\MailchimpSubscriberService;
use MailchimpMarketing\ApiClient;

class AppServiceProvider extends ServiceProvider
{
    public function register(): void
    {
        $this->app->singleton(ApiClient::class, function (): ApiClient {
            $client = new ApiClient();
            
            return $client->setConfig([
                'apiKey' => $this->app->make('config')->get('services.mailchimp.api_key'),
                'server' => $this->app->make('config')->get('services.mailchimp.server_prefix'),
            ]);
        });
        
        $this->app->singleton(SubscriberService::class, MailchimpSubscriberService::class);
    }
}

MailchimpSubscriberService.php

<?php

namespace App\Services\Mailchimp;

use App\Contracts\SubscriberService;

class MailchimpSubscriberService implements SubscriberService
{
    protected ApiClient $client;
    
    public function __construct(ApiClient $client)
    {
        $this->client = $client;
    }
    
    public function subscribe(string $listId, string $email): bool
    {
        $hash = md5(strtolower($email));

        $this->client->lists->setListMember($listId, $hash, [
            'email_address' => $email,
            'status_if_new' => 'pending',
        ]);

        return true;
    }
}

SubscriberService.php

<?php

namespace App\Contracts;

interface SubscriberService
{
    public function subscribe(string $listId, string $email): bool;
}