step3/api/QuestionsApi/Services/StripeAccessGateway.cs

using QuestionsApi.Models;
using Stripe;
using Stripe.Checkout;

namespace QuestionsApi.Services;

public interface IStripeAccessGateway
{
    Task<StripeCheckoutResult> CreateCheckoutAsync(AccessPurchase purchase, AccessProduct product, CancellationToken cancellationToken);
}

public sealed class StripeAccessGateway(IConfiguration configuration) : IStripeAccessGateway
{
    public async Task<StripeCheckoutResult> CreateCheckoutAsync(
        AccessPurchase purchase, AccessProduct product, CancellationToken cancellationToken)
    {
        var secretKey = configuration["Stripe:SecretKey"];
        if (string.IsNullOrWhiteSpace(secretKey)) throw new InvalidOperationException("Stripe secret key is not configured.");
        var successUrl = configuration["Stripe:AccessSuccessUrl"]
            ?? "https://doctor.ranaze.com/donation-complete.html?session_id={CHECKOUT_SESSION_ID}";
        var cancelUrl = configuration["Stripe:AccessCancelUrl"]
            ?? "https://doctor.ranaze.com/donation-canceled.html";
        var metadata = new Dictionary<string, string>
        {
            ["access_purchase_id"] = purchase.Id ?? "",
            ["access_sku"] = product.Sku,
            ["user_id"] = purchase.UserId
        };
        var service = new SessionService(new StripeClient(secretKey));
        var session = await service.CreateAsync(new SessionCreateOptions
        {
            Mode = "payment",
            SuccessUrl = successUrl,
            CancelUrl = cancelUrl,
            ClientReferenceId = purchase.Id,
            CustomerCreation = "always",
            BillingAddressCollection = "auto",
            AutomaticTax = new SessionAutomaticTaxOptions { Enabled = true },
            Metadata = metadata,
            PaymentIntentData = new SessionPaymentIntentDataOptions { Metadata = metadata },
            LineItems =
            [
                new SessionLineItemOptions
                {
                    Quantity = 1,
                    PriceData = new SessionLineItemPriceDataOptions
                    {
                        Currency = product.Currency,
                        UnitAmount = product.AmountCents,
                        ProductData = new SessionLineItemPriceDataProductDataOptions
                        {
                            Name = product.Name,
                            Description = "A manually activated RanaZe access entitlement."
                        }
                    }
                }
            ]
        }, null, cancellationToken);
        if (string.IsNullOrWhiteSpace(session.Id) || string.IsNullOrWhiteSpace(session.Url))
            throw new InvalidOperationException("Stripe did not return a checkout URL.");
        return new StripeCheckoutResult(session.Id, session.Url);
    }
}