Add support for payment lines (#370)

* #368 Add models for payment lines

* #368 Add integration test for payment with order line

src/Mollie.Api/Models/Payment/PaymentLine.cs

@@ -0,0 +1,66 @@
+namespace Mollie.Api.Models.Payment;
+
+public record PaymentLine {
+    /// <summary>
+    /// The type of product purchased. For example, a physical or a digital product.
+    /// Use the Mollie.Api.Models.Order.Request.OrderLineDetailsType class for a full list of known values.
+    /// </summary>
+    public required string Type { get; init; }
+
+    /// <summary>
+    /// A description of the line item. For example LEGO 4440 Forest Police Station.
+    /// </summary>
+    public required string Description { get; init; }
+
+    /// <summary>
+    /// The number of items.
+    /// </summary>
+    public required int Quantity { get; init; }
+
+    /// <summary>
+    /// The unit for the quantity. For example pcs, kg, or cm.
+    /// </summary>
+    public string? QuantityUnit { get; init; }
+
+    /// <summary>
+    /// The price of a single item including VAT. The unit price can be zero in case of free items.
+    /// </summary>
+    public required Amount UnitPrice { get; init; }
+
+    /// <summary>
+    /// Any line-specific discounts, as a positive amount. Not relevant if the line itself is already a discount type.
+    /// </summary>
+    public Amount? DiscountAmount { get; set; }
+
+    /// <summary>
+    /// The total amount of the line, including VAT and discounts.
+    /// </summary>
+    public required Amount TotalAmount { get; init; }
+
+    /// <summary>
+    /// The VAT rate applied to the line, for example 21.00 for 21%. The vatRate should be passed as a string and not
+    /// as a float, to ensure the correct number of decimals are passed.
+    /// </summary>
+    public string? VatRate { get; set; } // TODO: make it decimal?
+
+    /// <summary>
+    /// The amount of value-added tax on the line. The totalAmount field includes VAT, so the vatAmount can be
+    /// calculated with the formula totalAmount × (vatRate / (100 + vatRate)).
+    /// </summary>
+    public Amount? VatAmount { get; set; }
+
+    /// <summary>
+    /// The SKU, EAN, ISBN or UPC of the product sold.
+    /// </summary>
+    public string? Sku { get; set; }
+
+    /// <summary>
+    /// A link pointing to an image of the product sold.
+    /// </summary>
+    public string? ImageUrl { get; set; }
+
+    /// <summary>
+    /// A link pointing to the product page in your web shop of the product sold.
+    /// </summary>
+    public string? ProductUrl { get; set; }
+}

src/Mollie.Api/Models/Payment/Request/PaymentRequest.cs

@@ -41,6 +41,12 @@ public record PaymentRequest
         /// </summary>
         public string? WebhookUrl { get; set; }
 
+        /// <summary>
+        /// Optionally provide the order lines for the payment. Each line contains details such as a description of the item ordered and its price.
+        /// All lines must have the same currency as the payment.
+        /// </summary>
+        public List<PaymentLine>? Lines { get; set; }
+
         /// <summary>
         /// Allows you to preset the language to be used in the payment screens shown to the consumer. Setting a locale is highly
         /// recommended and will greatly improve your conversion rate. When this parameter is omitted, the browser language will

src/Mollie.Api/Models/Payment/Response/PaymentResponse.cs

@@ -127,6 +127,12 @@ public record PaymentResponse
         /// </summary>
         public required string WebhookUrl { get; set; }
 
+        /// <summary>
+        /// Optionally provide the order lines for the payment. Each line contains details such as a description of the item ordered and its price.
+        /// All lines must have the same currency as the payment.
+        /// </summary>
+        public List<PaymentLine>? Lines { get; set; }
+
         /// <summary>
         /// An optional routing configuration that you provided, which enables you to route a successful payment, or part of the payment, to one or more connected accounts.
         /// Additionally, you can schedule (parts of) the payment to become available on the connected account on a future date.

tests/Mollie.Tests.Integration/Api/PaymentTests.cs

@@ -17,6 +17,7 @@
 using Mollie.Api.Models.Customer.Response;
 using Mollie.Api.Models.List.Response;
 using Mollie.Api.Models.Mandate.Response;
+using Mollie.Api.Models.Order.Request;
 using Mollie.Api.Models.Payment.Request.PaymentSpecificParameters;
 using Mollie.Api.Models.Payment.Response.PaymentSpecificParameters;
 using Mollie.Api.Models.Terminal.Response;
@@ -360,6 +361,38 @@ public async Task CanCreatePaymentWithCustomMetaDataClass() {
         metadataResponse.Description.Should().Be(metadataRequest.Description);
     }
 
+    [DefaultRetryFact]
+    public async Task CanCreatePaymentWithLines() {
+        // Arrange
+        PaymentRequest paymentRequest = new PaymentRequest() {
+            Amount = new Amount(Currency.EUR, 90m),
+            Description = "Description",
+            RedirectUrl = DefaultRedirectUrl,
+            Lines = new List<PaymentLine>() {
+                new() {
+                    Type = OrderLineDetailsType.Digital,
+                    Description = "Star wars lego",
+                    Quantity = 1,
+                    QuantityUnit = "pcs",
+                    UnitPrice = new Amount(Currency.EUR, 100m),
+                    TotalAmount = new Amount(Currency.EUR, 90m),
+                    DiscountAmount = new Amount(Currency.EUR, 10m),
+                    ProductUrl = "http://www.lego.com/starwars",
+                    ImageUrl = "http://www.lego.com/starwars.jpg",
+                    Sku = "my-sku",
+                    VatAmount = new Amount(Currency.EUR, 15.62m),
+                    VatRate = "21.00"
+                }
+            }
+        };
+
+        // Act
+        PaymentResponse result = await _paymentClient.CreatePaymentAsync(paymentRequest);
+
+        // Assert
+        result.Lines.Should().BeEquivalentTo(paymentRequest.Lines);
+    }
+
     [DefaultRetryFact]
     public async Task CanCreatePaymentWithMandate() {
         // When: We create a payment with a mandate id