One PaymentGateway interface for Stripe, PayPal and Razorpay

<?php

namespace App\Billing\Contracts;

use App\Billing\Data\WebhookEvent;
use Illuminate\Http\Request;

/** One payment provider. Amounts are integer minor units (cents). */
interface PaymentGateway
{
    public function name(): string;

    /** Create a hosted payment page and return the URL to send the customer to. */
    public function checkout(string $reference, int $amount, string $currency, string $returnUrl): string;

    /** Verify the signature and normalise the provider payload. Must throw on a bad signature. */
    public function parseWebhook(Request $request): WebhookEvent;

    /** Refund everything when $amount is null. */
    public function refund(string $providerRef, ?int $amount = null): void;
}

<?php

namespace App\Billing;

use App\Billing\Contracts\PaymentGateway;
use App\Billing\Drivers\FakeGateway;
use App\Billing\Drivers\PaypalGateway;
use App\Billing\Drivers\RazorpayGateway;
use App\Billing\Drivers\StripeGateway;
use Illuminate\Support\Manager;

/**
 * @method PaymentGateway driver(?string $driver = null)
 */
class PaymentManager extends Manager
{
    public function getDefaultDriver(): string
    {
        return (string) $this->config->get('billing.default', 'fake');
    }

    /** Provider settings live in config/billing.php under gateways.<name>. */
    private function settings(string $name): array
    {
        return (array) $this->config->get("billing.gateways.{$name}", []);
    }

    protected function createStripeDriver(): PaymentGateway
    {
        return new StripeGateway($this->settings('stripe'));
    }

    protected function createPaypalDriver(): PaymentGateway
    {
        return new PaypalGateway($this->settings('paypal'));
    }

    protected function createRazorpayDriver(): PaymentGateway
    {
        return new RazorpayGateway($this->settings('razorpay'));
    }

    protected function createFakeDriver(): PaymentGateway
    {
        return new FakeGateway;
    }
}