[PM-11525] Tax calculation shown to customers potentially incorrect

src/Api/Billing/Controllers/BillingController.cs

@@ -0,0 +1,52 @@
+using Bit.Api.Billing.Models.Requests;
+using Bit.Api.Billing.Models.Responses;
+using Bit.Core.Services;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+
+namespace Bit.Api.Billing.Controllers;
+
+[Route("billing")]
+[Authorize("Application")]
+public class BillingController(
+    IStripeAdapter stripeAdapter) : Controller
+{
+    [HttpPost]
+    [Route("calculate-tax")]
+    [AllowAnonymous]
+    public async Task<IResult> CalculateTaxAsync([FromBody] CalculateTaxRequestModel requestBody)
+    {
+        var options = new Stripe.Tax.CalculationCreateOptions
+        {
+            Currency = "usd",
+            CustomerDetails = new()
+            {
+                Address = new()
+                {
+                    PostalCode = requestBody.BillingAddressPostalCode,
+                    Country = requestBody.BillingAddressCountry
+                },
+                AddressSource = "billing"
+            },
+            LineItems = new()
+            {
+                new()
+                {
+                    Amount = Convert.ToInt64(requestBody.Amount * 100),
+                    Reference = "Subscription",
+                },
+            }
+        };
+        var taxCalculation = await stripeAdapter.CalculateTaxAsync(options);
+        var response = new CalculateTaxResponseModel
+        {
+            SalesTaxRate = taxCalculation.TaxBreakdown.Any()
+                ? decimal.Parse(taxCalculation.TaxBreakdown.Single().TaxRateDetails.PercentageDecimal) / 100
+                : 0,
+            SalesTaxAmount = Convert.ToDecimal(taxCalculation.TaxAmountExclusive) / 100,
+            TaxableAmount = Convert.ToDecimal(requestBody.Amount),
+            TotalAmount = Convert.ToDecimal(taxCalculation.AmountTotal) / 100,
+        };
+        return TypedResults.Ok(response);
+    }
+}

src/Api/Billing/Models/Requests/CalculateTaxRequestModel.cs

@@ -0,0 +1,10 @@
+namespace Bit.Api.Billing.Models.Requests;
+
+public class CalculateTaxRequestModel
+{
+    public decimal Amount { get; set; }
+
+    public string BillingAddressPostalCode { get; set; }
+
+    public string BillingAddressCountry { get; set; }
+}

src/Api/Billing/Models/Responses/CalculateTaxResponseModel.cs

@@ -0,0 +1,12 @@
+namespace Bit.Api.Billing.Models.Responses;
+
+public class CalculateTaxResponseModel
+{
+    public decimal SalesTaxAmount { get; set; }
+
+    public decimal SalesTaxRate { get; set; }
+
+    public decimal TaxableAmount { get; set; }
+
+    public decimal TotalAmount { get; set; }
+}

src/Core/Services/IStripeAdapter.cs

@@ -5,6 +5,7 @@ namespace Bit.Core.Services;
 
 public interface IStripeAdapter
 {
+    Task<Stripe.Tax.Calculation> CalculateTaxAsync(Stripe.Tax.CalculationCreateOptions options);
     Task<Stripe.Customer> CustomerCreateAsync(Stripe.CustomerCreateOptions customerCreateOptions);
     Task<Stripe.Customer> CustomerGetAsync(string id, Stripe.CustomerGetOptions options = null);
     Task<Stripe.Customer> CustomerUpdateAsync(string id, Stripe.CustomerUpdateOptions options = null);

src/Core/Services/Implementations/StripeAdapter.cs

@@ -5,6 +5,7 @@ namespace Bit.Core.Services;
 
 public class StripeAdapter : IStripeAdapter
 {
+    private readonly Stripe.Tax.CalculationService _taxCalculationService;
     private readonly Stripe.CustomerService _customerService;
     private readonly Stripe.SubscriptionService _subscriptionService;
     private readonly Stripe.InvoiceService _invoiceService;
@@ -21,6 +22,7 @@ public class StripeAdapter : IStripeAdapter
 
     public StripeAdapter()
     {
+        _taxCalculationService = new Stripe.Tax.CalculationService();
         _customerService = new Stripe.CustomerService();
         _subscriptionService = new Stripe.SubscriptionService();
         _invoiceService = new Stripe.InvoiceService();
@@ -36,6 +38,11 @@ public class StripeAdapter : IStripeAdapter
         _testClockService = new Stripe.TestHelpers.TestClockService();
     }
 
+    public Task<Stripe.Tax.Calculation> CalculateTaxAsync(Stripe.Tax.CalculationCreateOptions options)
+    {
+        return _taxCalculationService.CreateAsync(options);
+    }
+
     public Task<Stripe.Customer> CustomerCreateAsync(Stripe.CustomerCreateOptions options)
     {
         return _customerService.CreateAsync(options);