About of payment gateway development

[BeycanDeveloper]

We developed an integration for our CryptoPay plugin. It works fine in Visual Forms, but unfortunately it does not redirect in the Legacy system. Can you help with this issue?

Here is repo, you can check it.

https://github.com/BeycanPress/givewp-cryptopay-gateway

[glaubersilva]

Hi @BeycanDeveloper

Hope you doing well.

We need better documentation for it, but for now, if you take a look at this class you'll see that we provide in the $gatewayData var some default redirect URLs that work for both: option-based (legacy) and visual builder forms.

To use it in your integration, all you need to do is replace this line:

'givewp-success-url' => urlencode(give_get_success_page_uri())

By this one:

'givewp-success-url' => $gatewayData['successUrl'],

Let me know if it works for you!

[BeycanDeveloper]

In fact, when it succeeds, there is no problem with routing. The "createPayment" method returns the link to the payment page created by our plugin with the "RedirectOffsite" class. However, Legacy Form tries to open it on the same page instead of redirecting to this page.

    public function createPayment(Donation $donation, $gatewayData): RedirectOffsite
    {
        return Processor::createPayment(Type::LITE, $donation, $this->generateSecureGatewayRouteUrl(
            'handleCreatePaymentRedirect',
            $donation->id,
            [
                'givewp-donation-id' => $donation->id,
                'givewp-payment-token' => 'cp_payment_token',
                'givewp-transaction-id' => 'cp_transaction_id',
                'givewp-success-url' => urlencode(give_get_success_page_uri()),
            ]
        ));
    }

https://github.com/BeycanPress/givewp-cryptopay-gateway/blob/c3e12baba1eabbc38810729a58a2ff26d0545e76/app/Gateways/GatewayPro.php#L84

https://github.com/BeycanPress/givewp-cryptopay-gateway/blob/c3e12baba1eabbc38810729a58a2ff26d0545e76/app/Gateways/Processor.php#L91

[glaubersilva]

Hi @BeycanDeveloper

Not sure if I understand what you said. So I would like to confirm a few things:

1. Are you having the same problem even using the $gatewayData['successUrl'] value?
2. For legacy forms, is the createPayment() method not redirecting to the external payment page?

If the reply to the last question is yes, let me know what happens when you replace your createPayment() method with this one:

public function createPayment(Donation $donation, $gatewayData): RedirectOffsite
{
     return new RedirectOffsite('https://givewp.com/');        
}

[BeycanDeveloper]

Yes second one and already i am using RedirectOffsite class.

[glaubersilva]

@BeycanDeveloper I know you are already using the RedirectOffsite class, but I was trying to check what happens when you replace the link generated by the Helpers::createSPP() method with any other link.

In my tests, when I replace the return value of the createPayment() method with the https://givewp.com/ URL, the redirect works as expected.

I just noticed that the Helpers::createSPP() method is returning this: return home_url("/?cp_spp={$token}");

So, seems it's using the home_url() function from the WP core and it should explain why the redirect to the external page isn't working.

[BeycanDeveloper]

So with this logic, it expects an external link. If it's the same site, it tries to open it inside. So how do we prevent this? Because our plugin works completely within WordPress.

[glaubersilva]

@BeycanDeveloper Sorry for the late reply here.

Yes, you are right. The RedirectOffsite wasn't designed to be used with internal URLs from the WordPress website.

If your gateway doesn't provide an external page, ideally, loading the gateway fields on the donation form is the most indicated.

However, there is a workaround to allow you to simulate an off-site gateway using an on-site link, so I'll provide a few samples for these two approaches.

Approach 1 - Loading the gateway fields on the donation form.

For this approach, you should handle the transaction creation inside the createPayment() method and return another GatewayCommand different from the RedirectOffsite.

A few options would be:

return new PaymentProcessing($transactionId);
return new PaymentComplete($transactionId);

Also, to use this approach on Legacy Forms is necessary to implement the getLegacyFormFieldMarkup() method in the gateway class, here is a sample: https://github.com/impress-org/givewp/blob/develop/src/PaymentGateways/Gateways/Stripe/CreditCardGateway.php#L105-L108

Here is the CreditCardForm trait used in the sample above:
https://github.com/impress-org/givewp/blob/develop/src/PaymentGateways/Gateways/Stripe/Traits/CreditCardForm.php

The final result is something like this:

For the new Visual Form Builder Forms, you need to implement the gateway frontend logic in a separate JS/tsx file, here is a sample: https://github.com/impress-org/givewp/blob/develop/src/PaymentGateways/Gateways/Stripe/StripePaymentElementGateway/stripePaymentElementGateway.tsx

Then, you need to enqueue this script in the gateway class through the enqueueScript() method. You also can pass any value from the backend to the frontend file through the formSettings() method.

Here is a sample using both methods: https://github.com/impress-org/givewp/blob/develop/src/PaymentGateways/Gateways/Stripe/StripePaymentElementGateway/StripePaymentElementGateway.php#L54-L89

The final result is something like this:

Approach 2 - Simulating a redirect off-site gateway.

Let's suppose that you are redirecting the users to the following URL:

return new RedirectOffsite(add_query_arg('off-site-gateway-simulation', true, home_url())); //https://your-site-home-url.com/?off-site-gateway-simulation=true

So, to simulate an off-site gateway, you need to use the WordPress init hook to intercept the original redirect and replace it with something like this:

add_action('init', function () {
    if ( ! isset($_GET['off-site-gateway-simulation'])) {
        return;
    }

    if (isLegacyFormReferrer()) {
        echo '<script>window.top.location.href ="' . home_url($_SERVER['REQUEST_URI']) . '";</script>';
        exit();
    }

    echo 'Off-site Gateway Simulation - You should load your "off-site" gateway here...';

    exit();
});

function isLegacyFormReferrer(): bool
{
    //V2 referrer: https://example.com/give/v2-tests?giveDonationFormInIframe=1
    //V3 referrer: https://example.com/?givewp-route=donation-form-view&form-id=1350
    return strpos($_SERVER['HTTP_REFERER'], 'giveDonationFormInIframe') !== false;
}