a simplified example of how I typically structure Azure Functions for payment processing and webhook integration, using C# (.NET 8+). This pattern is representative of how I’ve integrated Worldpay and similar payment gateways:

AzureFunctions_PaymentProcessing.cs

// Azure Function for Processing Payment (HTTP Trigger)
[Function("ProcessPayment")]
public async Task<IActionResult> ProcessPayment(
    [HttpTrigger(AuthorizationLevel.Function, "post")] HttpRequestData req,
    FunctionContext executionContext)
{
    var logger = executionContext.GetLogger("ProcessPayment");
    var requestBody = await new StreamReader(req.Body).ReadToEndAsync();
    var paymentRequest = JsonSerializer.Deserialize<PaymentRequest>(requestBody);

    // Call to external Worldpay API (pseudo-code)
    var response = await _worldpayClient.ChargeAsync(paymentRequest);

    if (response.Success)
    {
        logger.LogInformation("Payment successful for {0}", paymentRequest.MerchantId);
        return new OkObjectResult(new { Status = "Success", TransactionId = response.Id });
    }
    else
    {
        logger.LogError("Payment failed: {0}", response.ErrorMessage);
        return new BadRequestObjectResult(new { Status = "Error", Message = response.ErrorMessage });
    }
}

// Azure Function for Handling Worldpay Webhook (HTTP Trigger)
[Function("WorldpayWebhook")]
public async Task<IActionResult> WorldpayWebhook(
    [HttpTrigger(AuthorizationLevel.Function, "post")] HttpRequestData req,
    FunctionContext executionContext)
{
    var logger = executionContext.GetLogger("WorldpayWebhook");
    var payload = await new StreamReader(req.Body).ReadToEndAsync();
    var eventData = JsonSerializer.Deserialize<WorldpayWebhookEvent>(payload);

    // Handle settlement, chargeback, payout, etc.
    await _paymentService.HandleWebhookAsync(eventData);

    logger.LogInformation("Webhook received: {0}", eventData.EventType);
    return new OkResult();
}