Improved product purchasable check, related to: #18

modules/EasyAbp.EShop.Orders/src/EasyAbp.EShop.Orders.Domain/Orders/Order.cs

 using System;
+using System.Collections.Generic;
 using EasyAbp.EShop.Stores.Stores;
 using JetBrains.Annotations;
 using Volo.Abp.Domain.Entities.Auditing;
@@ -40,5 +41,7 @@ namespace EasyAbp.EShop.Orders.Orders
         
         [CanBeNull]
         public virtual string StaffRemark { get; protected set; }
+        
+        public virtual List<OrderLine> OrderLines { get; protected set; }
     }
 }
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modules/EasyAbp.EShop.Products/src/EasyAbp.EShop.Products.Application.Contracts/EasyAbp/EShop/Products/Products/IProductAppService.cs

 using System;
+using System.Collections.Generic;
 using System.Threading.Tasks;
 using EasyAbp.EShop.Products.Products.Dtos;
-using Volo.Abp.Application.Dtos;
 using Volo.Abp.Application.Services;
 
 namespace EasyAbp.EShop.Products.Products
@@ -24,6 +24,7 @@ namespace EasyAbp.EShop.Products.Products
 
         Task<ProductDto> DeleteSkuAsync(Guid productId, Guid productSkuId, Guid storeId);
 
-        Task<GetProductPurchasableStatusResult> GetPurchasableStatusAsync(Guid productId, Guid productSkuId, Guid storeId);
+        Task<CheckProductPurchasableResult> CheckPurchasableAsync(Guid productId, Guid productSkuId, Guid storeId,
+            Dictionary<string, object> extraProperties);
     }
 }
\ No newline at end of file

modules/EasyAbp.EShop.Products/src/EasyAbp.EShop.Products.Application/EasyAbp/EShop/Products/Products/ProductAppService.cs

@@ -24,20 +24,20 @@ namespace EasyAbp.EShop.Products.Products
         protected override string GetPolicyName { get; set; } = null;
         protected override string GetListPolicyName { get; set; } = null;
 
-        private readonly IProductPurchasableStatusProvider _productPurchasableStatusProvider;
+        private readonly IProductManager _productManager;
         private readonly IAttributeOptionIdsSerializer _attributeOptionIdsSerializer;
         private readonly IProductStoreRepository _productStoreRepository;
         private readonly IProductCategoryRepository _productCategoryRepository;
         private readonly IProductRepository _repository;
 
         public ProductAppService(
-            IProductPurchasableStatusProvider productPurchasableStatusProvider,
+            IProductManager productManager,
             IAttributeOptionIdsSerializer attributeOptionIdsSerializer,
             IProductStoreRepository productStoreRepository,
             IProductCategoryRepository productCategoryRepository,
             IProductRepository repository) : base(repository)
         {
-            _productPurchasableStatusProvider = productPurchasableStatusProvider;
+            _productManager = productManager;
             _attributeOptionIdsSerializer = attributeOptionIdsSerializer;
             _productStoreRepository = productStoreRepository;
             _productCategoryRepository = productCategoryRepository;
@@ -354,13 +354,14 @@ namespace EasyAbp.EShop.Products.Products
             return ObjectMapper.Map<Product, ProductDto>(product);
         }
 
-        public async Task<GetProductPurchasableStatusResult> GetPurchasableStatusAsync(Guid productId, Guid productSkuId, Guid storeId)
+        public async Task<CheckProductPurchasableResult> CheckPurchasableAsync(Guid productId, Guid productSkuId,
+            Guid storeId, Dictionary<string, object> extraProperties)
         {
             var product = await _repository.GetAsync(productId);
 
             var productSku = product.ProductSkus.Single(sku => sku.Id == productSkuId);
 
-            return await _productPurchasableStatusProvider.GetPurchasableStatusAsync(product, productSku, storeId);
+            return await _productManager.GetPurchasableStatusAsync(product, productSku, storeId, extraProperties);
         }
 
         protected virtual async Task UpdateProductCategoriesAsync(Guid productId, IEnumerable<Guid> categoryIds)

modules/EasyAbp.EShop.Products/src/EasyAbp.EShop.Products.Domain.Shared/EasyAbp/EShop/Products/Products/CheckProductPurchasableResult.cs

+namespace EasyAbp.EShop.Products.Products
+{
+    public class CheckProductPurchasableResult
+    {
+        public bool IsPurchasable { get; set; }
+        
+        public string Reason { get; set; }
+
+        public CheckProductPurchasableResult(
+            bool isPurchasable,
+            string reason = null)
+        {
+            IsPurchasable = isPurchasable;
+            Reason = reason;
+        }
+    }
+}
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modules/EasyAbp.EShop.Products/src/EasyAbp.EShop.Products.Domain.Shared/EasyAbp/EShop/Products/Products/GetProductPurchasableStatusResult.cs

-namespace EasyAbp.EShop.Products.Products
-{
-    public class GetProductPurchasableStatusResult
-    {
-        public ProductPurchasableStatus PurchasableStatus { get; set; }
-        
-        public string Reason { get; set; }
-    }
-}
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modules/EasyAbp.EShop.Products/src/EasyAbp.EShop.Products.Domain.Shared/EasyAbp/EShop/Products/Products/ProductPurchasableStatus.cs

-namespace EasyAbp.EShop.Products.Products
-{
-    public enum ProductPurchasableStatus
-    {
-        CanBePurchased = 1,
-        CanNotBePurchased = 2
-    }
-}
\ No newline at end of file

modules/EasyAbp.EShop.Products/src/EasyAbp.EShop.Products.Domain/EasyAbp/EShop/Products/Products/BasicProductPurchasableCheckHandler.cs

+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using Volo.Abp.DependencyInjection;
+
+namespace EasyAbp.EShop.Products.Products
+{
+    public class BasicProductPurchasableCheckHandler : IProductPurchasableCheckHandler, ITransientDependency
+    {
+        private readonly IProductInventoryProvider _productInventoryProvider;
+
+        public BasicProductPurchasableCheckHandler(
+            IProductInventoryProvider productInventoryProvider)
+        {
+            _productInventoryProvider = productInventoryProvider;
+        }
+        
+        public async Task<CheckProductPurchasableResult> CheckAsync(Product product, ProductSku productSku, Guid storeId,
+            Dictionary<string, object> extraProperties)
+        {
+            if (!await IsProductPublishedAsync(product))
+            {
+                return new CheckProductPurchasableResult(false, "Unpublished project");
+            }
+            
+            if (!await IsInventorySufficientAsync(product, productSku, storeId, extraProperties))
+            {
+                return new CheckProductPurchasableResult(false, "Insufficient inventory");
+            }
+
+            return new CheckProductPurchasableResult(true);
+        }
+
+        protected virtual Task<bool> IsProductPublishedAsync(Product product)
+        {
+            return Task.FromResult(product.IsPublished);
+        }
+
+        protected virtual async Task<bool> IsInventorySufficientAsync(Product product, ProductSku productSku, Guid storeId, Dictionary<string, object> extraProperties)
+        {
+            if (!extraProperties.TryGetValue("Quantity", out var quantity))
+            {
+                throw new ProductPurchasableCheckHandlerMissingPropertyException(
+                    nameof(BasicProductPurchasableCheckHandler), "Quantity");
+            }
+
+            return await _productInventoryProvider.IsInventorySufficientAsync(product, productSku, storeId,
+                Convert.ToInt32(quantity));
+        }
+    }
+}
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modules/EasyAbp.EShop.Products/src/EasyAbp.EShop.Products.Domain/EasyAbp/EShop/Products/Products/DefaultProductInventoryProvider.cs

+using System;
+using System.Threading.Tasks;
+using Volo.Abp.DependencyInjection;
+
+namespace EasyAbp.EShop.Products.Products
+{
+    [Dependency(TryRegister = true)]
+    public class DefaultProductInventoryProvider : IProductInventoryProvider, ITransientDependency
+    {
+        public virtual async Task<bool> IsInventorySufficientAsync(Product product, ProductSku productSku, Guid storeId, int quantity)
+        {
+            var inventory = await GetInventoryAsync(product, productSku, storeId);
+            
+            return product.InventoryStrategy == InventoryStrategy.NoNeed || inventory - quantity >= 0;
+        }
+
+        public virtual Task<int> GetInventoryAsync(Product product, ProductSku productSku, Guid storeId)
+        {
+            return Task.FromResult(productSku.Inventory);
+        }
+    }
+}
\ No newline at end of file

modules/EasyAbp.EShop.Products/src/EasyAbp.EShop.Products.Domain/EasyAbp/EShop/Products/Products/IProductInventoryProvider.cs

+using System;
+using System.Threading.Tasks;
+
+namespace EasyAbp.EShop.Products.Products
+{
+    public interface IProductInventoryProvider
+    {
+        Task<bool> IsInventorySufficientAsync(Product product, ProductSku productSku, Guid storeId, int quantity);
+        
+        Task<int> GetInventoryAsync(Product product, ProductSku productSku, Guid storeId);
+    }
+}
\ No newline at end of file

modules/EasyAbp.EShop.Products/src/EasyAbp.EShop.Products.Domain/EasyAbp/EShop/Products/Products/IProductPurchasableStatusProvider.cs → modules/EasyAbp.EShop.Products/src/EasyAbp.EShop.Products.Domain/EasyAbp/EShop/Products/Products/IProductManager.cs

 using System;
+using System.Collections.Generic;
 using System.Threading.Tasks;
+using Volo.Abp.Domain.Services;
 
 namespace EasyAbp.EShop.Products.Products
 {
-    public interface IProductPurchasableStatusProvider
+    public interface IProductManager : IDomainService
     {
-        Task CheckPurchasableAsync(Product product, ProductSku productSku, Guid storeId);
+        Task CheckPurchasableAsync(Product product, ProductSku productSku, Guid storeId,
+            Dictionary<string, object> extraProperties);
 
-        Task<GetProductPurchasableStatusResult> GetPurchasableStatusAsync(Product product, ProductSku productSku,
-            Guid storeId);
+        Task<CheckProductPurchasableResult> GetPurchasableStatusAsync(Product product, ProductSku productSku,
+            Guid storeId, Dictionary<string, object> extraProperties);
     }
 }
\ No newline at end of file

modules/EasyAbp.EShop.Products/src/EasyAbp.EShop.Products.Domain/EasyAbp/EShop/Products/Products/IProductPurchasableCheckHandler.cs

+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+
+namespace EasyAbp.EShop.Products.Products
+{
+    public interface IProductPurchasableCheckHandler
+    {
+        Task<CheckProductPurchasableResult> CheckAsync(Product product, ProductSku productSku, Guid storeId,
+            Dictionary<string, object> extraProperties);
+    }
+}
\ No newline at end of file

modules/EasyAbp.EShop.Products/src/EasyAbp.EShop.Products.Domain/EasyAbp/EShop/Products/Products/ProductManager.cs

+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using Microsoft.Extensions.DependencyInjection;
+using Volo.Abp.Domain.Services;
+
+namespace EasyAbp.EShop.Products.Products
+{
+    public class ProductManager : DomainService, IProductManager
+    {
+        public async Task CheckPurchasableAsync(Product product, ProductSku productSku, Guid storeId,
+            Dictionary<string, object> extraProperties)
+        {
+            var result = await GetPurchasableStatusAsync(product, productSku, storeId, extraProperties);
+
+            if (!result.IsPurchasable)
+            {
+                throw new ProductIsNotPurchasableException(product.Id, result.Reason);
+            }
+        }
+
+        public async Task<CheckProductPurchasableResult> GetPurchasableStatusAsync(Product product,
+            ProductSku productSku, Guid storeId, Dictionary<string, object> extraProperties)
+        {
+            var handlers = ServiceProvider.GetServices<IProductPurchasableCheckHandler>();
+
+            foreach (var handler in handlers)
+            {
+                var result = await handler.CheckAsync(product, productSku, storeId, extraProperties);
+
+                if (!result.IsPurchasable)
+                {
+                    return result;
+                }
+            }
+
+            return new CheckProductPurchasableResult(true);
+        }
+    }
+}
\ No newline at end of file

modules/EasyAbp.EShop.Products/src/EasyAbp.EShop.Products.Domain/EasyAbp/EShop/Products/Products/ProductPurchasableCheckHandlerMissingPropertyException.cs

+using System;
+using Volo.Abp;
+
+namespace EasyAbp.EShop.Products.Products
+{
+    public class ProductPurchasableCheckHandlerMissingPropertyException : BusinessException
+    {
+        public ProductPurchasableCheckHandlerMissingPropertyException(string handlerName, string propertyKey) : base(
+            message: $"The {handlerName} is missing extra property: {propertyKey}")
+        {
+        }
+    }
+}
\ No newline at end of file

modules/EasyAbp.EShop.Products/src/EasyAbp.EShop.Products.Domain/EasyAbp/EShop/Products/Products/ProductPurchasableStatusProvider.cs

-using System;
-using System.Threading.Tasks;
-using Volo.Abp.DependencyInjection;
-
-namespace EasyAbp.EShop.Products.Products
-{
-    public class ProductPurchasableStatusProvider : IProductPurchasableStatusProvider, ITransientDependency
-    {
-        public async Task CheckPurchasableAsync(Product product, ProductSku productSku, Guid storeId)
-        {
-            var result = await GetPurchasableStatusAsync(product, productSku, storeId);
-            
-            if  (result.PurchasableStatus != ProductPurchasableStatus.CanBePurchased)
-            {
-                throw new ProductIsNotPurchasableException(product.Id, result.Reason);
-            }
-        }
-
-        public async Task<GetProductPurchasableStatusResult> GetPurchasableStatusAsync(Product product, ProductSku productSku, Guid storeId)
-        {
-            // Todo: Determine whether the product can be purchased.
-            return new GetProductPurchasableStatusResult
-            {
-                PurchasableStatus = ProductPurchasableStatus.CanBePurchased,
-                Reason = null
-            };
-        }
-    }
-}
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