Add Pricing Strategies for Subscriptions (Strategy Pattern)

giddev · Apr 20, 2021 · c5e3b90 · c5e3b90
1 parent 78e3ec5
commit c5e3b90
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Showing 13 changed files with 160 additions and 25 deletions.
diff --git a/...es/Payments/Application/PriceListItems/GetPriceListItems/GetPriceListItemsQueryHandler.cs b/...es/Payments/Application/PriceListItems/GetPriceListItems/GetPriceListItemsQueryHandler.cs
@@ -17,7 +17,7 @@ public GetPriceListItemsQueryHandler(ISqlConnectionFactory sqlConnectionFactory)
 
         public async Task<List<PriceListItemDto>> Handle(GetPriceListItemsQuery request, CancellationToken cancellationToken)
         {
-            return await PriceListProvider.GetPriceListItems(_sqlConnectionFactory.GetOpenConnection());
+            return await PriceListFactory.GetPriceListItems(_sqlConnectionFactory.GetOpenConnection());
         }
     }
 }
diff --git a/...ation/PriceListItems/PriceListProvider.cs → ...cation/PriceListItems/PriceListFactory.cs b/...ation/PriceListItems/PriceListProvider.cs → ...cation/PriceListItems/PriceListFactory.cs
@@ -3,27 +3,34 @@
 using System.Linq;
 using System.Threading.Tasks;
 using CompanyName.MyMeetings.Modules.Payments.Domain.PriceListItems;
+using CompanyName.MyMeetings.Modules.Payments.Domain.PriceListItems.PricingStrategies;
 using CompanyName.MyMeetings.Modules.Payments.Domain.SeedWork;
 using CompanyName.MyMeetings.Modules.Payments.Domain.Subscriptions;
 using Dapper;
 
 namespace CompanyName.MyMeetings.Modules.Payments.Application.PriceListItems
 {
-    public static class PriceListProvider
+    public static class PriceListFactory
     {
-        public static async Task<PriceList> GetPriceList(IDbConnection connection)
+        public static async Task<PriceList> CreatePriceList(IDbConnection connection)
         {
             var priceListItemList = await GetPriceListItems(connection);
 
-            return PriceList.CreateFromItems(
-                priceListItemList
-                    .Select(x =>
-                        new PriceListItemData(
-                            x.CountryCode,
-                            SubscriptionPeriod.Of(x.SubscriptionPeriodCode),
-                            MoneyValue.Of(x.MoneyValue, x.MoneyCurrency),
-                            PriceListItemCategory.Of(x.CategoryCode)))
-                    .ToList());
+            var priceListItems = priceListItemList
+                .Select(x =>
+                    new PriceListItemData(
+                        x.CountryCode,
+                        SubscriptionPeriod.Of(x.SubscriptionPeriodCode),
+                        MoneyValue.Of(x.MoneyValue, x.MoneyCurrency),
+                        PriceListItemCategory.Of(x.CategoryCode)))
+                .ToList();
+
+            // This is place for selecting pricing strategy based on provided data and the system state.
+            IPricingStrategy pricingStrategy = new DirectValueFromPriceListPricingStrategy(priceListItems);
+
+            return PriceList.Create(
+                priceListItems,
+                pricingStrategy);
         }
 
         public static async Task<List<PriceListItemDto>> GetPriceListItems(IDbConnection connection)

diff --git a/...dules/Payments/Application/Subscriptions/BuySubscription/BuySubscriptionCommandHandler.cs b/...dules/Payments/Application/Subscriptions/BuySubscription/BuySubscriptionCommandHandler.cs
@@ -31,7 +31,7 @@ internal BuySubscriptionCommandHandler(
 
         public async Task<Guid> Handle(BuySubscriptionCommand command, CancellationToken cancellationToken)
         {
-            var priceList = await PriceListProvider.GetPriceList(_sqlConnectionFactory.GetOpenConnection());
+            var priceList = await PriceListFactory.CreatePriceList(_sqlConnectionFactory.GetOpenConnection());
 
             var subscription = SubscriptionPayment.Buy(
                 _payerContext.PayerId,

diff --git a/.../Application/Subscriptions/BuySubscriptionRenewal/BuySubscriptionRenewalCommandHandler.cs b/.../Application/Subscriptions/BuySubscriptionRenewal/BuySubscriptionRenewalCommandHandler.cs
@@ -36,7 +36,7 @@ internal BuySubscriptionRenewalCommandHandler(
 
         public async Task<Guid> Handle(BuySubscriptionRenewalCommand command, CancellationToken cancellationToken)
         {
-            var priceList = await PriceListProvider.GetPriceList(_sqlConnectionFactory.GetOpenConnection());
+            var priceList = await PriceListFactory.CreatePriceList(_sqlConnectionFactory.GetOpenConnection());
 
             var subscriptionId = new SubscriptionId(command.SubscriptionId);
 

diff --git a/src/Modules/Payments/Domain/PriceListItems/PriceList.cs b/src/Modules/Payments/Domain/PriceListItems/PriceList.cs
@@ -1,6 +1,6 @@
 using System.Collections.Generic;
-using System.Linq;
 using CompanyName.MyMeetings.BuildingBlocks.Domain;
+using CompanyName.MyMeetings.Modules.Payments.Domain.PriceListItems.PricingStrategies;
 using CompanyName.MyMeetings.Modules.Payments.Domain.SeedWork;
 using CompanyName.MyMeetings.Modules.Payments.Domain.SubscriptionPayments.Rules;
 using CompanyName.MyMeetings.Modules.Payments.Domain.Subscriptions;
@@ -11,14 +11,21 @@ public class PriceList : ValueObject
     {
         private readonly List<PriceListItemData> _items;
 
-        private PriceList(List<PriceListItemData> items)
+        private readonly IPricingStrategy _pricingStrategy;
+
+        private PriceList(
+            List<PriceListItemData> items,
+            IPricingStrategy pricingStrategy)
         {
             _items = items;
+            _pricingStrategy = pricingStrategy;
         }
 
-        public static PriceList CreateFromItems(List<PriceListItemData> items)
+        public static PriceList Create(
+            List<PriceListItemData> items,
+            IPricingStrategy pricingStrategy)
         {
-            return new PriceList(items);
+            return new PriceList(items, pricingStrategy);
         }
 
         public MoneyValue GetPrice(
@@ -28,11 +35,7 @@ public MoneyValue GetPrice(
         {
             CheckRule(new PriceForSubscriptionMustBeDefinedRule(countryCode, subscriptionPeriod, _items, category));
 
-            var priceListItem = _items.Single(x =>
-                x.CountryCode == countryCode && x.SubscriptionPeriod == subscriptionPeriod &&
-                x.Category == category);
-
-            return priceListItem.Value;
+            return _pricingStrategy.GetPrice(countryCode, subscriptionPeriod, category);
         }
     }
 }
diff --git a/...yments/Domain/PriceListItems/PricingStrategies/DirectValueFromPriceListPricingStrategy.cs b/...yments/Domain/PriceListItems/PricingStrategies/DirectValueFromPriceListPricingStrategy.cs
@@ -0,0 +1,29 @@
+using System.Collections.Generic;
+using System.Linq;
+using CompanyName.MyMeetings.Modules.Payments.Domain.SeedWork;
+using CompanyName.MyMeetings.Modules.Payments.Domain.Subscriptions;
+
+namespace CompanyName.MyMeetings.Modules.Payments.Domain.PriceListItems.PricingStrategies
+{
+    public class DirectValueFromPriceListPricingStrategy : IPricingStrategy
+    {
+        private readonly List<PriceListItemData> _items;
+
+        public DirectValueFromPriceListPricingStrategy(List<PriceListItemData> items)
+        {
+            _items = items;
+        }
+
+        public MoneyValue GetPrice(
+            string countryCode,
+            SubscriptionPeriod subscriptionPeriod,
+            PriceListItemCategory category)
+        {
+            var priceListItem = _items.Single(x =>
+                x.CountryCode == countryCode && x.SubscriptionPeriod == subscriptionPeriod &&
+                x.Category == category);
+
+            return priceListItem.Value;
+        }
+    }
+}
diff --git a/src/Modules/Payments/Domain/PriceListItems/PricingStrategies/DirectValuePricingStrategy.cs b/src/Modules/Payments/Domain/PriceListItems/PricingStrategies/DirectValuePricingStrategy.cs
@@ -0,0 +1,20 @@
+using CompanyName.MyMeetings.Modules.Payments.Domain.SeedWork;
+using CompanyName.MyMeetings.Modules.Payments.Domain.Subscriptions;
+
+namespace CompanyName.MyMeetings.Modules.Payments.Domain.PriceListItems.PricingStrategies
+{
+    public class DirectValuePricingStrategy : IPricingStrategy
+    {
+        private readonly MoneyValue _directValue;
+
+        public DirectValuePricingStrategy(MoneyValue directValue)
+        {
+            _directValue = directValue;
+        }
+
+        public MoneyValue GetPrice(string countryCode, SubscriptionPeriod subscriptionPeriod, PriceListItemCategory category)
+        {
+            return _directValue;
+        }
+    }
+}
diff --git a/...ts/Domain/PriceListItems/PricingStrategies/DiscountedValueFromPriceListPricingStrategy.cs b/...ts/Domain/PriceListItems/PricingStrategies/DiscountedValueFromPriceListPricingStrategy.cs
@@ -0,0 +1,31 @@
+using System.Collections.Generic;
+using System.Linq;
+using CompanyName.MyMeetings.Modules.Payments.Domain.SeedWork;
+using CompanyName.MyMeetings.Modules.Payments.Domain.Subscriptions;
+
+namespace CompanyName.MyMeetings.Modules.Payments.Domain.PriceListItems.PricingStrategies
+{
+    public class DiscountedValueFromPriceListPricingStrategy : IPricingStrategy
+    {
+        private readonly List<PriceListItemData> _items;
+
+        private readonly MoneyValue _discountValue;
+
+        public DiscountedValueFromPriceListPricingStrategy(
+            List<PriceListItemData> items,
+            MoneyValue discountValue)
+        {
+            _items = items;
+            _discountValue = discountValue;
+        }
+
+        public MoneyValue GetPrice(string countryCode, SubscriptionPeriod subscriptionPeriod, PriceListItemCategory category)
+        {
+            var priceListItem = _items.Single(x =>
+                x.CountryCode == countryCode && x.SubscriptionPeriod == subscriptionPeriod &&
+                x.Category == category);
+
+            return priceListItem.Value - _discountValue;
+        }
+    }
+}
diff --git a/src/Modules/Payments/Domain/PriceListItems/PricingStrategies/IPricingStrategy.cs b/src/Modules/Payments/Domain/PriceListItems/PricingStrategies/IPricingStrategy.cs
@@ -0,0 +1,13 @@
+using CompanyName.MyMeetings.Modules.Payments.Domain.SeedWork;
+using CompanyName.MyMeetings.Modules.Payments.Domain.Subscriptions;
+
+namespace CompanyName.MyMeetings.Modules.Payments.Domain.PriceListItems.PricingStrategies
+{
+    public interface IPricingStrategy
+    {
+        MoneyValue GetPrice(
+            string countryCode,
+            SubscriptionPeriod subscriptionPeriod,
+            PriceListItemCategory category);
+    }
+}
diff --git a/src/Modules/Payments/Domain/SeedWork/MoneyValue.cs b/src/Modules/Payments/Domain/SeedWork/MoneyValue.cs
@@ -37,5 +37,12 @@ public static MoneyValue Of(decimal value, string currency)
         public static bool operator >=(MoneyValue left, decimal right) => left.Value >= right;
 
         public static bool operator <=(MoneyValue left, decimal right) => left.Value <= right;
+
+        public static MoneyValue operator -(MoneyValue left, MoneyValue right)
+        {
+            CheckRule(new MoneyMustHaveTheSameCurrencyRule(left, right));
+
+            return Of(left.Value - right.Value, left.Currency);
+        }
     }
 }
diff --git a/src/Modules/Payments/Domain/SeedWork/Rules/MoneyMustHaveTheSameCurrencyRule.cs b/src/Modules/Payments/Domain/SeedWork/Rules/MoneyMustHaveTheSameCurrencyRule.cs
@@ -0,0 +1,21 @@
+using CompanyName.MyMeetings.BuildingBlocks.Domain;
+
+namespace CompanyName.MyMeetings.Modules.Payments.Domain.SeedWork.Rules
+{
+    public class MoneyMustHaveTheSameCurrencyRule : IBusinessRule
+    {
+        private readonly MoneyValue _left;
+
+        private readonly MoneyValue _right;
+
+        public MoneyMustHaveTheSameCurrencyRule(MoneyValue left, MoneyValue right)
+        {
+            _left = left;
+            _right = right;
+        }
+
+        public bool IsBroken() => _left.Currency != _right.Currency;
+
+        public string Message => "Currency of money must be the same.";
+    }
+}
diff --git a/src/Modules/Payments/Tests/UnitTests/SubscriptionPayments/SubscriptionPaymentTestsBase.cs b/src/Modules/Payments/Tests/UnitTests/SubscriptionPayments/SubscriptionPaymentTestsBase.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using CompanyName.MyMeetings.Modules.Payments.Domain.Payers;
 using CompanyName.MyMeetings.Modules.Payments.Domain.PriceListItems;
+using CompanyName.MyMeetings.Modules.Payments.Domain.PriceListItems.PricingStrategies;
 using CompanyName.MyMeetings.Modules.Payments.Domain.SeedWork;
 using CompanyName.MyMeetings.Modules.Payments.Domain.Subscriptions;
 using CompanyName.MyMeetings.Modules.Payments.Domain.UnitTests.SeedWork;
@@ -48,7 +49,8 @@ private PriceList CreatePriceList()
                 MoneyValue.Of(60, "PLN"),
                 PriceListItemCategory.New);
 
-            var priceList = PriceList.CreateFromItems(new List<PriceListItemData> { priceListItem });
+            var priceListItems = new List<PriceListItemData> { priceListItem };
+            var priceList = PriceList.Create(priceListItems, new DirectValueFromPriceListPricingStrategy(priceListItems));
 
             return priceList;
         }

diff --git a/...yments/Tests/UnitTests/SubscriptionRenewalPayments/SubscriptionRenewalPaymentTestsBase.cs b/...yments/Tests/UnitTests/SubscriptionRenewalPayments/SubscriptionRenewalPaymentTestsBase.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using CompanyName.MyMeetings.Modules.Payments.Domain.Payers;
 using CompanyName.MyMeetings.Modules.Payments.Domain.PriceListItems;
+using CompanyName.MyMeetings.Modules.Payments.Domain.PriceListItems.PricingStrategies;
 using CompanyName.MyMeetings.Modules.Payments.Domain.SeedWork;
 using CompanyName.MyMeetings.Modules.Payments.Domain.Subscriptions;
 using CompanyName.MyMeetings.Modules.Payments.Domain.UnitTests.SeedWork;
@@ -48,7 +49,8 @@ private PriceList CreatePriceList()
                 MoneyValue.Of(60, "PLN"),
                 PriceListItemCategory.Renewal);
 
-            var priceList = PriceList.CreateFromItems(new List<PriceListItemData> { priceListItem });
+            var priceListItems = new List<PriceListItemData> { priceListItem };
+            var priceList = PriceList.Create(priceListItems, new DirectValueFromPriceListPricingStrategy(priceListItems));
 
             return priceList;
         }