[ECP-9801] Improve partial payments response handling

[candemiralp]

Description

Tested scenarios

Fixes

[gemini-code-assist]

Summary of Changes

Hello @candemiralp, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly improves the robustness and error handling for partial payments, particularly those involving gift cards, within the Adyen payment module. It ensures that payment flows are correctly terminated upon refusal of a gift card payment and introduces explicit cancellation of Adyen Checkout API orders when a transaction fails. These changes lead to a more reliable and predictable payment experience for multi-payment scenarios.

Highlights

• Enhanced Partial Payment Handling: Introduced a new GiftcardPaymentException and refined the payment processing flow to immediately halt further payment instrument authorization if a gift card payment is refused. This ensures that subsequent payment attempts are not made on an already failed partial payment order.
• Adyen Checkout API Order Management: Implemented mechanisms to store and retrieve Adyen Checkout API order data (pspReference and orderData) in temporary storage and payment additional information. This data is now used to explicitly cancel the Checkout API order if the overall payment transaction is refused or cancelled, improving consistency and preventing orphaned orders.
• Refactored Dependency Injection: Updated several classes to leverage PHP 8.1+ readonly properties in their constructors, streamlining dependency injection and improving code readability and immutability.
• Improved Error Messaging: Added a specific error message (authError_giftcard_refused) for when gift card payments are refused, providing clearer feedback to users and administrators.

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[gemini-code-assist]

Code Review

This pull request improves the handling of partial payments, particularly with gift cards, by introducing a more robust cancellation flow. When a partial payment fails, the entire Adyen order is now cancelled to prevent inconsistent states. The changes include introducing a GiftcardPaymentException, refactoring to use the Adyen Orders API for cancellations, and cleaning up related code.

My review focuses on ensuring the new logic is sound and identifying potential issues. I've found a couple of areas for improvement in Helper/OrdersApi.php: one is a potential runtime error due to operating on a null value, and the other is an incorrect docblock. Overall, the changes are a significant improvement to the payment flow.

[gemini-code-assist]

The checkoutApiOrder property is initialized as null. Attempting to set an array key on a null value will result in a warning in some PHP versions and a fatal error in PHP 8. It's safer to assign the entire array at once to avoid this issue.

        $this->checkoutApiOrder = ['pspReference' => $pspReference, 'orderData' => $orderData];

[gemini-code-assist]

The docblock return type CreateOrderResponse|null does not match the function's return type ?array. Please update the docblock for consistency.

     * @return array|null