[PM-31359] Show new price to premium users who have yet to be migrated (#6963)

* test: add tests for legacy pricing pivot in GetBitwardenSubscriptionQuery

* feat(billing): preview next charge at new price for users on legacy Premium pricing

* chore: apply dotnet format

src/Core/Billing/Subscriptions/Queries/GetBitwardenSubscriptionQuery.cs

@@ -14,6 +14,7 @@ namespace Bit.Core.Billing.Subscriptions.Queries;
 
 using static StripeConstants;
 using static Utilities;
+using PremiumPlan = Bit.Core.Billing.Pricing.Premium.Plan;
 
 public interface IGetBitwardenSubscriptionQuery
 {
@@ -107,11 +108,28 @@ public class GetBitwardenSubscriptionQuery(
 
         var (cartLevelDiscount, productLevelDiscounts) = GetStripeDiscounts(subscription);
 
+        var availablePlan = plans.First(plan => plan.Available);
+        var onCurrentPricing = passwordManagerSeatsItem.Price.Id == availablePlan.Seat.StripePriceId;
+
+        decimal seatCost;
+        decimal estimatedTax;
+
+        if (onCurrentPricing)
+        {
+            seatCost = GetCost(passwordManagerSeatsItem);
+            estimatedTax = await EstimatePremiumTaxAsync(subscription);
+        }
+        else
+        {
+            seatCost = availablePlan.Seat.Price;
+            estimatedTax = await EstimatePremiumTaxAsync(subscription, plans, availablePlan);
+        }
+
         var passwordManagerSeats = new CartItem
         {
             TranslationKey = "premiumMembership",
             Quantity = passwordManagerSeatsItem.Quantity,
-            Cost = GetCost(passwordManagerSeatsItem),
+            Cost = seatCost,
             Discount = productLevelDiscounts.FirstOrDefault(discount => discount.AppliesTo(passwordManagerSeatsItem))
         };
 
@@ -125,8 +143,6 @@ public class GetBitwardenSubscriptionQuery(
             }
             : null;
 
-        var estimatedTax = await EstimateTaxAsync(subscription);
-
         return new Cart
         {
             PasswordManager = new PasswordManagerCartItems
@@ -142,15 +158,45 @@ public class GetBitwardenSubscriptionQuery(
 
     #region Utilities
 
-    private async Task<decimal> EstimateTaxAsync(Subscription subscription)
+    private async Task<decimal> EstimatePremiumTaxAsync(
+        Subscription subscription,
+        List<PremiumPlan>? plans = null,
+        PremiumPlan? availablePlan = null)
     {
         try
         {
-            var invoice = await stripeAdapter.CreateInvoicePreviewAsync(new InvoiceCreatePreviewOptions
+            var options = new InvoiceCreatePreviewOptions
             {
-                Customer = subscription.Customer.Id,
-                Subscription = subscription.Id
-            });
+                Customer = subscription.Customer.Id
+            };
+
+            if (plans != null && availablePlan != null)
+            {
+                options.AutomaticTax = new InvoiceAutomaticTaxOptions
+                {
+                    Enabled = subscription.AutomaticTax?.Enabled ?? false
+                };
+
+                options.SubscriptionDetails = new InvoiceSubscriptionDetailsOptions
+                {
+                    Items = subscription.Items.Select(item =>
+                    {
+                        var isSeatItem = plans.Any(plan => plan.Seat.StripePriceId == item.Price.Id);
+
+                        return new InvoiceSubscriptionDetailsItemOptions
+                        {
+                            Price = isSeatItem ? availablePlan.Seat.StripePriceId : item.Price.Id,
+                            Quantity = item.Quantity
+                        };
+                    }).ToList()
+                };
+            }
+            else
+            {
+                options.Subscription = subscription.Id;
+            }
+
+            var invoice = await stripeAdapter.CreateInvoicePreviewAsync(options);
 
             return GetCost(invoice.TotalTaxes);
         }

test/Core.Test/Billing/Subscriptions/Queries/GetBitwardenSubscriptionQueryTests.cs

@@ -461,6 +461,77 @@ public class GetBitwardenSubscriptionQueryTests
         Assert.Equal(PlanCadenceType.Annually, result.Cart.Cadence);
     }
 
+    [Fact]
+    public async Task Run_UserOnLegacyPricing_ReturnsCostFromPricingService()
+    {
+        var user = CreateUser();
+        var subscription = CreateSubscription(SubscriptionStatus.Active, legacyPricing: true);
+        var premiumPlans = CreatePremiumPlans();
+        var availablePlan = premiumPlans.First(p => p.Available);
+
+        _stripeAdapter.GetSubscriptionAsync(user.GatewaySubscriptionId, Arg.Any<SubscriptionGetOptions>())
+            .Returns(subscription);
+        _pricingClient.ListPremiumPlans().Returns(premiumPlans);
+
+        var previewInvoice = CreateInvoicePreview(totalTax: 150);
+        _stripeAdapter.CreateInvoicePreviewAsync(Arg.Any<InvoiceCreatePreviewOptions>())
+            .Returns(previewInvoice);
+
+        var result = await _query.Run(user);
+
+        Assert.NotNull(result);
+        Assert.Equal(availablePlan.Seat.Price, result.Cart.PasswordManager.Seats.Cost);
+        Assert.Equal(1.50m, result.Cart.EstimatedTax);
+    }
+
+    [Fact]
+    public async Task Run_UserOnLegacyPricing_CallsPreviewInvoiceWithRebuiltSubscription()
+    {
+        var user = CreateUser();
+        var subscription = CreateSubscription(SubscriptionStatus.Active, legacyPricing: true);
+        var premiumPlans = CreatePremiumPlans();
+        var availablePlan = premiumPlans.First(p => p.Available);
+
+        _stripeAdapter.GetSubscriptionAsync(user.GatewaySubscriptionId, Arg.Any<SubscriptionGetOptions>())
+            .Returns(subscription);
+        _pricingClient.ListPremiumPlans().Returns(premiumPlans);
+
+        var previewInvoice = CreateInvoicePreview();
+        _stripeAdapter.CreateInvoicePreviewAsync(Arg.Any<InvoiceCreatePreviewOptions>())
+            .Returns(previewInvoice);
+
+        await _query.Run(user);
+
+        await _stripeAdapter.Received(1).CreateInvoicePreviewAsync(
+            Arg.Is<InvoiceCreatePreviewOptions>(opts =>
+                opts.Subscription == null &&
+                opts.AutomaticTax != null &&
+                opts.AutomaticTax.Enabled == true &&
+                opts.SubscriptionDetails != null &&
+                opts.SubscriptionDetails.Items.Any(i =>
+                    i.Price == availablePlan.Seat.StripePriceId &&
+                    i.Quantity == 1)));
+    }
+
+    [Fact]
+    public async Task Run_UserOnCurrentPricing_ReturnsCostFromSubscriptionItem()
+    {
+        var user = CreateUser();
+        var subscription = CreateSubscription(SubscriptionStatus.Active, legacyPricing: false);
+        var premiumPlans = CreatePremiumPlans();
+
+        _stripeAdapter.GetSubscriptionAsync(user.GatewaySubscriptionId, Arg.Any<SubscriptionGetOptions>())
+            .Returns(subscription);
+        _pricingClient.ListPremiumPlans().Returns(premiumPlans);
+        _stripeAdapter.CreateInvoicePreviewAsync(Arg.Any<InvoiceCreatePreviewOptions>())
+            .Returns(CreateInvoicePreview());
+
+        var result = await _query.Run(user);
+
+        Assert.NotNull(result);
+        Assert.Equal(19.80m, result.Cart.PasswordManager.Seats.Cost);
+    }
+
     #region Helper Methods
 
     private static User CreateUser()
@@ -477,11 +548,14 @@ public class GetBitwardenSubscriptionQueryTests
     private static Subscription CreateSubscription(
         string status,
         bool includeStorage = false,
+        bool legacyPricing = false,
         DateTime? cancelAt = null,
         DateTime? canceledAt = null,
         string collectionMethod = "charge_automatically")
     {
         var currentPeriodEnd = DateTime.UtcNow.AddMonths(1);
+        var seatPriceId = legacyPricing ? "price_legacy_premium_seat" : "price_premium_seat";
+        var seatUnitAmount = legacyPricing ? 1000 : 1980;
         var items = new List<SubscriptionItem>
         {
             new()
@@ -489,8 +563,8 @@ public class GetBitwardenSubscriptionQueryTests
                 Id = "si_premium_seat",
                 Price = new Price
                 {
-                    Id = "price_premium_seat",
-                    UnitAmountDecimal = 1000,
+                    Id = seatPriceId,
+                    UnitAmountDecimal = seatUnitAmount,
                     Product = new Product { Id = "prod_premium_seat" }
                 },
                 Quantity = 1,
@@ -521,6 +595,7 @@ public class GetBitwardenSubscriptionQueryTests
             Id = "sub_test123",
             Status = status,
             Created = DateTime.UtcNow.AddMonths(-1),
+            AutomaticTax = new SubscriptionAutomaticTax { Enabled = true },
             Customer = new Customer
             {
                 Id = "cus_test123",
@@ -548,6 +623,24 @@ public class GetBitwardenSubscriptionQueryTests
                 Seat = new Bit.Core.Billing.Pricing.Premium.Purchasable
                 {
                     StripePriceId = "price_premium_seat",
+                    Price = 19.80m,
+                    Provided = 1
+                },
+                Storage = new Bit.Core.Billing.Pricing.Premium.Purchasable
+                {
+                    StripePriceId = "price_storage",
+                    Price = 4.0m,
+                    Provided = 1
+                }
+            },
+            new()
+            {
+                Name = "Premium",
+                Available = false,
+                LegacyYear = 2024,
+                Seat = new Bit.Core.Billing.Pricing.Premium.Purchasable
+                {
+                    StripePriceId = "price_legacy_premium_seat",
                     Price = 10.0m,
                     Provided = 1
                 },