Add Minimal API and Service layer for eCommerce

Sample/ECommerce/CartsMinimalApi/Carts.Api/Carts.Api.csproj

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+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+    <PropertyGroup>
+        <TargetFramework>net6.0</TargetFramework>
+        <Nullable>enable</Nullable>
+        <ImplicitUsings>enable</ImplicitUsings>
+    </PropertyGroup>
+
+    <ItemGroup>
+      <PackageReference Include="Carter" Version="6.0.0" />
+    </ItemGroup>
+
+    <ItemGroup>
+      <ProjectReference Include="..\Carts\Carts.csproj" />
+    </ItemGroup>
+
+</Project>

Sample/ECommerce/CartsMinimalApi/Carts.Api/Program.cs

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+using Carter;
+
+var builder = WebApplication.CreateBuilder(args);
+builder.Services.AddCarter();
+
+var app = builder.Build();
+app.MapCarter();
+
+app.Run();

Sample/ECommerce/CartsMinimalApi/Carts.Api/ShoppingCartModule.cs

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+using Carter;
+using Carter.Request;
+using Carts.ShoppingCarts;
+using Carts.ShoppingCarts.AddingProduct;
+using Carts.ShoppingCarts.CancellingCart;
+using Carts.ShoppingCarts.ConfirmingCart;
+using Carts.ShoppingCarts.OpeningCart;
+using Carts.ShoppingCarts.RemovingProduct;
+
+public class ShoppingCartModule: ICarterModule
+{
+    public void AddRoutes(IEndpointRouteBuilder app)
+    {
+        app.MapPost("/shoppingcart", OpenCart);
+        app.MapPost("/shoppingcart/{cartId:guid}/products", AddProduct);
+        app.MapDelete("/shoppingcart/{cartId:guid}/products/{productId:guid}", RemoveProduct);
+        app.MapPut("/shoppingcart/{cartId:guid}/confirmation", ConfirmCart);
+        app.MapDelete("/shoppingcart/{cartId:guid}", CancelCart);
+    }
+
+    private IResult CancelCart(HttpContext context, Guid cartId, ICancelCartService cancelCartService)
+    {
+        cancelCartService.CancelCart(cartId);
+        return Results.StatusCode(204);
+    }
+
+    private IResult ConfirmCart(HttpContext context, Guid cartId, IConfirmCartService confirmCartService)
+    {
+        confirmCartService.Confirm(cartId);
+        return Results.StatusCode(204);
+    }
+
+    private IResult RemoveProduct(HttpContext context, Guid cartId, Guid productId,
+        IRemoveProductService removeProductService)
+    {
+        removeProductService.RemoveProduct(cartId, productId, context.Request.Query.As<int?>("quantity"),
+            context.Request.Query.As<decimal?>("unitPrice"));
+        return Results.StatusCode(204);
+    }
+
+    private IResult AddProduct(HttpContext context, Guid cartId, AddProductRequest model,
+        IAddProductService addProductService)
+    {
+        addProductService.AddProduct(cartId, model.ProductId, model.Quantity);
+        return Results.StatusCode(204);
+    }
+
+    private IResult OpenCart(HttpContext context, OpenShoppingCartRequest model, IOpenCartService openCartService)
+    {
+        var cartId = openCartService.OpenCart(model.ClientId);
+        return Results.Created($"/shoppingcart/{cartId}", null);
+    }
+}

Sample/ECommerce/CartsMinimalApi/Carts.Api/ShoppingCartsRequests.cs

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+namespace Carts.ShoppingCarts;
+
+public record OpenShoppingCartRequest(
+    Guid ClientId
+);
+
+public record AddProductRequest(
+    Guid ProductId,
+    int Quantity
+);
+
+public record PricedProductItemRequest(
+    Guid? ProductId,
+    int? Quantity,
+    decimal? UnitPrice
+);
+
+public record RemoveProductRequest(
+    PricedProductItemRequest? ProductItem
+);
+
+public record ConfirmShoppingCartRequest;
+
+public record GetCartAtVersionRequest(
+    Guid? CartId,
+    long? Version
+);

Sample/ECommerce/CartsMinimalApi/Carts.Api/appsettings.Development.json

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+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  }
+}

Sample/ECommerce/CartsMinimalApi/Carts.Api/appsettings.json

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+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  },
+  "AllowedHosts": "*"
+}

Sample/ECommerce/CartsMinimalApi/Carts/Carts.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <TargetFramework>net6.0</TargetFramework>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
+    </PropertyGroup>
+
+    <ItemGroup>
+      <ProjectReference Include="..\..\..\..\Core\Core.csproj" />
+    </ItemGroup>
+
+</Project>

Sample/ECommerce/CartsMinimalApi/Carts/DataAccess/IShoppingCartRepository.cs

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+namespace Carts.DataAccess;
+
+public interface IShoppingCartRepository
+{
+    ShoppingCart GetById(Guid id);
+    void Save(ShoppingCart cart);
+}

Sample/ECommerce/CartsMinimalApi/Carts/Pricing/IProductPriceCalculator.cs

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+using Carts.ShoppingCarts.Products;
+
+namespace Carts.Pricing;
+
+public interface IProductPriceCalculator
+{
+    IReadOnlyList<PricedProductItem> Calculate(params ProductItem[] productItems);
+}

Sample/ECommerce/CartsMinimalApi/Carts/Pricing/RandomProductPriceCalculator.cs

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+using Carts.ShoppingCarts.Products;
+
+namespace Carts.Pricing;
+
+public class RandomProductPriceCalculator: IProductPriceCalculator
+{
+    public IReadOnlyList<PricedProductItem> Calculate(params ProductItem[] productItems)
+    {
+        if (productItems.Length == 0)
+            throw new ArgumentOutOfRangeException(nameof(productItems.Length));
+
+        var random = new Random();
+
+        return productItems
+            .Select(pi =>
+                PricedProductItem.Create(pi, Math.Round(new decimal(random.NextDouble() * 100), 2)))
+            .ToList();
+    }
+}

Sample/ECommerce/CartsMinimalApi/Carts/ShoppingCart.cs

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+using Carts.Pricing;
+using Carts.ShoppingCarts.Products;
+using Core.Extensions;
+
+namespace Carts;
+
+public class ShoppingCart
+{
+    public Guid Id { get; private set; }
+
+    public Guid ClientId { get; private set; }
+
+    public ShoppingCartStatus Status { get; private set; }
+
+    public IList<PricedProductItem> ProductItems { get; private set; } = default!;
+
+    public Money TotalPrice => ProductItems.Sum(pi => pi.TotalPrice);
+
+    public static ShoppingCart Open(
+        Guid cartId,
+        Guid clientId)
+    {
+        return new ShoppingCart(cartId, clientId);
+    }
+
+    public ShoppingCart() { }
+
+    private ShoppingCart(
+        Guid id,
+        Guid clientId)
+    {
+        Id = id;
+        ClientId = clientId;
+        ProductItems = new List<PricedProductItem>();
+        Status = ShoppingCartStatus.Pending;
+    }
+
+    public void AddProduct(
+        IProductPriceCalculator productPriceCalculator,
+        ProductItem productItem)
+    {
+        if (Status != ShoppingCartStatus.Pending)
+            throw new InvalidOperationException($"Adding product for the cart in '{Status}' status is not allowed.");
+
+        var pricedProductItem = productPriceCalculator.Calculate(productItem).Single();
+
+        var existingProductItem = FindProductItemMatchingWith(pricedProductItem);
+
+        if (existingProductItem is null)
+        {
+            ProductItems.Add(pricedProductItem);
+            return;
+        }
+
+        ProductItems.Replace(
+            existingProductItem,
+            existingProductItem.MergeWith(pricedProductItem)
+        );
+    }
+
+
+    public void RemoveProduct(
+        PricedProductItem productItemToBeRemoved)
+    {
+        if (Status != ShoppingCartStatus.Pending)
+            throw new InvalidOperationException($"Removing product from the cart in '{Status}' status is not allowed.");
+
+        var existingProductItem = FindProductItemMatchingWith(productItemToBeRemoved);
+
+        if (existingProductItem is null)
+            throw new InvalidOperationException(
+                $"Product with id `{productItemToBeRemoved.ProductId}` and price '{productItemToBeRemoved.UnitPrice}' was not found in cart.");
+
+        if (!existingProductItem.HasEnough(productItemToBeRemoved.Quantity))
+            throw new InvalidOperationException(
+                $"Cannot remove {productItemToBeRemoved.Quantity} items of Product with id `{productItemToBeRemoved.ProductId}` as there are only ${existingProductItem.Quantity} items in card");
+
+
+        if (existingProductItem.HasTheSameQuantity(productItemToBeRemoved))
+        {
+            ProductItems.Remove(existingProductItem);
+            return;
+        }
+
+        ProductItems.Replace(
+            existingProductItem,
+            existingProductItem.Subtract(productItemToBeRemoved)
+        );
+    }
+
+    public void Confirm()
+    {
+        if (Status != ShoppingCartStatus.Pending)
+            throw new InvalidOperationException($"Confirming cart in '{Status}' status is not allowed.");
+
+        Status = ShoppingCartStatus.Confirmed;
+    }
+
+
+    public void Cancel()
+    {
+        if (Status != ShoppingCartStatus.Pending)
+            throw new InvalidOperationException($"Canceling cart in '{Status}' status is not allowed.");
+
+
+        Status = ShoppingCartStatus.Canceled;
+    }
+
+    private PricedProductItem? FindProductItemMatchingWith(PricedProductItem productItem)
+    {
+        return ProductItems
+            .SingleOrDefault(pi => pi.MatchesProductAndPrice(productItem));
+    }
+}

Sample/ECommerce/CartsMinimalApi/Carts/ShoppingCartStatus.cs

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+namespace Carts;
+
+public enum ShoppingCartStatus
+{
+    Pending = 1,
+    Confirmed = 2,
+    Canceled = 4
+}

Sample/ECommerce/CartsMinimalApi/Carts/ShoppingCarts/AddingProduct/AddProductService.cs

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+using Carts.DataAccess;
+using Carts.Pricing;
+using Carts.ShoppingCarts.Products;
+
+namespace Carts.ShoppingCarts.AddingProduct;
+
+public class AddProductService: IAddProductService
+{
+    private readonly IProductPriceCalculator productPriceCalculator;
+    private readonly IShoppingCartRepository shoppingCartRepository;
+
+    public AddProductService(IProductPriceCalculator productPriceCalculator,
+        IShoppingCartRepository shoppingCartRepository)
+    {
+        this.productPriceCalculator = productPriceCalculator;
+        this.shoppingCartRepository = shoppingCartRepository;
+    }
+
+    public void AddProduct(Guid cartId, Guid productId, int quantity)
+    {
+        var cart = this.shoppingCartRepository.GetById(cartId);
+        cart.AddProduct(this.productPriceCalculator, ProductItem.Create(productId, quantity));
+        this.shoppingCartRepository.Save(cart);
+    }
+}

Sample/ECommerce/CartsMinimalApi/Carts/ShoppingCarts/AddingProduct/IAddProductService.cs

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+namespace Carts.ShoppingCarts.AddingProduct;
+
+public interface IAddProductService
+{
+    void AddProduct(Guid cartId, Guid productId, int quantity);
+}

Sample/ECommerce/CartsMinimalApi/Carts/ShoppingCarts/CancellingCart/CancelCartService.cs

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+using Carts.DataAccess;
+
+namespace Carts.ShoppingCarts.CancellingCart;
+
+public class CancelCartService: ICancelCartService
+{
+    private readonly IShoppingCartRepository shoppingCartRepository;
+
+    public CancelCartService(IShoppingCartRepository shoppingCartRepository)
+    {
+        this.shoppingCartRepository = shoppingCartRepository;
+    }
+
+    public void CancelCart(Guid cartId)
+    {
+        var cart = this.shoppingCartRepository.GetById(cartId);
+        cart.Cancel();
+        this.shoppingCartRepository.Save(cart);
+    }
+}

Sample/ECommerce/CartsMinimalApi/Carts/ShoppingCarts/CancellingCart/ICancelCartService.cs

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+namespace Carts.ShoppingCarts.CancellingCart;
+
+public interface ICancelCartService
+{
+    void CancelCart(Guid cartId);
+}

Sample/ECommerce/CartsMinimalApi/Carts/ShoppingCarts/ConfirmingCart/ConfirmCartService.cs

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+using Carts.DataAccess;
+
+namespace Carts.ShoppingCarts.ConfirmingCart;
+
+public class ConfirmCartService: IConfirmCartService
+{
+    private readonly IShoppingCartRepository shoppingCartRepository;
+
+    public ConfirmCartService(IShoppingCartRepository shoppingCartRepository)
+    {
+        this.shoppingCartRepository = shoppingCartRepository;
+    }
+
+    public void Confirm(Guid cartId)
+    {
+        var cart = this.shoppingCartRepository.GetById(cartId);
+        cart.Confirm();
+        this.shoppingCartRepository.Save(cart);
+    }
+}