Jignesh Patel Refactor Challenge

RefactorThis.Domain.Tests/InvoicePaymentProcessorTests.cs

@@ -1,20 +1,28 @@
 using System;
 using System.Collections.Generic;
 using NUnit.Framework;
+using RefactorThis.Domain.PaymentProcessor;
+using RefactorThis.Domain.PaymentProcessor.Validators;
 using RefactorThis.Persistence;
 
 namespace RefactorThis.Domain.Tests
 {
 	[TestFixture]
 	public class InvoicePaymentProcessorTests
-	{
+    {
+        private readonly IPaymentProcessorValidator _paymentProcessorValidator;
+        public InvoicePaymentProcessorTests()
+        {
+            _paymentProcessorValidator = new PaymentProcessorValidator(new PaymentValidatorAbstractFactory());
+        }
+
 		[Test]
 		public void ProcessPayment_Should_ThrowException_When_NoInoiceFoundForPaymentReference( )
 		{
 			var repo = new InvoiceRepository( );
 
 			Invoice invoice = null;
-			var paymentProcessor = new InvoicePaymentProcessor( repo );
+			var paymentProcessor = new InvoicePaymentProcessor( repo, _paymentProcessorValidator);
 
 			var payment = new Payment( );
 			var failureMessage = "";
@@ -45,7 +53,7 @@ public void ProcessPayment_Should_ReturnFailureMessage_When_NoPaymentNeeded( )
 
 			repo.Add( invoice );
 
-			var paymentProcessor = new InvoicePaymentProcessor( repo );
+			var paymentProcessor = new InvoicePaymentProcessor(repo, _paymentProcessorValidator);
 
 			var payment = new Payment( );
 
@@ -73,7 +81,7 @@ public void ProcessPayment_Should_ReturnFailureMessage_When_InvoiceAlreadyFullyP
 			};
 			repo.Add( invoice );
 
-			var paymentProcessor = new InvoicePaymentProcessor( repo );
+			var paymentProcessor = new InvoicePaymentProcessor(repo, _paymentProcessorValidator);
 
 			var payment = new Payment( );
 
@@ -100,7 +108,7 @@ public void ProcessPayment_Should_ReturnFailureMessage_When_PartialPaymentExists
 			};
 			repo.Add( invoice );
 
-			var paymentProcessor = new InvoicePaymentProcessor( repo );
+			var paymentProcessor = new InvoicePaymentProcessor(repo, _paymentProcessorValidator);
 
 			var payment = new Payment( )
 			{
@@ -124,7 +132,7 @@ public void ProcessPayment_Should_ReturnFailureMessage_When_NoPartialPaymentExis
 			};
 			repo.Add( invoice );
 
-			var paymentProcessor = new InvoicePaymentProcessor( repo );
+			var paymentProcessor = new InvoicePaymentProcessor(repo, _paymentProcessorValidator);
 
 			var payment = new Payment( )
 			{
@@ -154,7 +162,7 @@ public void ProcessPayment_Should_ReturnFullyPaidMessage_When_PartialPaymentExis
 			};
 			repo.Add( invoice );
 
-			var paymentProcessor = new InvoicePaymentProcessor( repo );
+			var paymentProcessor = new InvoicePaymentProcessor(repo, _paymentProcessorValidator);
 
 			var payment = new Payment( )
 			{
@@ -178,7 +186,7 @@ public void ProcessPayment_Should_ReturnFullyPaidMessage_When_NoPartialPaymentEx
 			};
 			repo.Add( invoice );
 
-			var paymentProcessor = new InvoicePaymentProcessor( repo );
+			var paymentProcessor = new InvoicePaymentProcessor(repo, _paymentProcessorValidator);
 
 			var payment = new Payment( )
 			{
@@ -208,7 +216,7 @@ public void ProcessPayment_Should_ReturnPartiallyPaidMessage_When_PartialPayment
 			};
 			repo.Add( invoice );
 
-			var paymentProcessor = new InvoicePaymentProcessor( repo );
+			var paymentProcessor = new InvoicePaymentProcessor(repo, _paymentProcessorValidator);
 
 			var payment = new Payment( )
 			{
@@ -232,7 +240,7 @@ public void ProcessPayment_Should_ReturnPartiallyPaidMessage_When_NoPartialPayme
 			};
 			repo.Add( invoice );
 
-			var paymentProcessor = new InvoicePaymentProcessor( repo );
+			var paymentProcessor = new InvoicePaymentProcessor(repo, _paymentProcessorValidator);
 
 			var payment = new Payment( )
 			{

RefactorThis.Domain/Common/ValidationModel/ValidationStatus.cs

@@ -0,0 +1,14 @@
+namespace RefactorThis.Domain.Common.ValidationModel
+{
+    public class ValidationStatus
+    {
+        public bool Success { get;}
+        public string Message { get;}
+
+        public ValidationStatus(bool success, string message)
+        {
+            Success = success;
+            Message = message;
+        }
+    }
+}

RefactorThis.Domain/PaymentProcessor/InvoicePaymentProcessor.cs

@@ -0,0 +1,39 @@
+using RefactorThis.Domain.PaymentProcessor.Validators;
+using RefactorThis.Persistence;
+
+namespace RefactorThis.Domain.PaymentProcessor
+{
+	public class InvoicePaymentProcessor
+	{
+		private readonly InvoiceRepository _invoiceRepository;
+        private readonly IPaymentProcessorValidator _paymentProcessorValidator;
+
+		public InvoicePaymentProcessor( InvoiceRepository invoiceRepository, IPaymentProcessorValidator paymentProcessorValidator )
+		{
+			_invoiceRepository = invoiceRepository;
+            _paymentProcessorValidator = paymentProcessorValidator;
+        }
+
+		public string ProcessPayment( Payment payment )
+		{
+			var inv = _invoiceRepository.GetInvoice( payment.Reference );
+
+            var validationStatus = _paymentProcessorValidator.Validate(inv, payment);
+
+            if (validationStatus.Success)
+            {
+                AddPayment(payment, inv);
+            }
+
+            inv.Save();
+
+			return validationStatus.Message;
+		}
+
+        private static void AddPayment(Payment payment, Invoice inv)
+        {
+            inv.AmountPaid += payment.Amount;
+            inv.Payments.Add(payment);
+        }
+    }
+}

RefactorThis.Domain/PaymentProcessor/Validators/AdditionalPaymentValidator.cs

@@ -0,0 +1,41 @@
+using System.Linq;
+using RefactorThis.Domain.Common.ValidationModel;
+using RefactorThis.Persistence;
+
+namespace RefactorThis.Domain.PaymentProcessor.Validators
+{
+    public class AdditionalPaymentValidator : IPaymentValidator
+    {
+        public ValidationStatus Validate(Invoice invoice, Payment payment)
+        {
+            if (InvoiceIsPaid(invoice))
+            {
+                return new ValidationStatus(false, "invoice was already fully paid");
+            }
+
+            if (PaymentGreaterThanAmountRemaining(payment, invoice))
+            {
+                return new ValidationStatus(false, "the payment is greater than the partial amount remaining");
+            }
+
+            return IsFinalPayment(payment, invoice) ?
+                new ValidationStatus(true, "final partial payment received, invoice is now fully paid") :
+                new ValidationStatus(true, "another partial payment received, still not fully paid");
+        }
+
+        private static bool InvoiceIsPaid(Invoice invoice)
+        {
+            return invoice.Payments.Sum(x => x.Amount) != 0 && invoice.Amount == invoice.Payments.Sum(x => x.Amount);
+        }
+
+        private static bool PaymentGreaterThanAmountRemaining(Payment payment, Invoice invoice)
+        {
+            return invoice.Payments.Sum(x => x.Amount) != 0 && payment.Amount > (invoice.Amount - invoice.AmountPaid);
+        }
+
+        private static bool IsFinalPayment(Payment payment, Invoice invoice)
+        {
+            return (invoice.Amount - invoice.AmountPaid) == payment.Amount;
+        }
+    }
+}

RefactorThis.Domain/PaymentProcessor/Validators/FirstPaymentValidator.cs

@@ -0,0 +1,30 @@
+using RefactorThis.Domain.Common.ValidationModel;
+using RefactorThis.Persistence;
+
+namespace RefactorThis.Domain.PaymentProcessor.Validators
+{
+    public class FirstPaymentValidator : IPaymentValidator
+    {
+        public ValidationStatus Validate(Invoice invoice, Payment payment)
+        {
+            if (PaymentGreaterThanAmount(invoice, payment))
+            {
+                return new ValidationStatus(false, "the payment is greater than the invoice amount");
+            }
+
+            return PaymentEqualsAmount(invoice, payment) ?
+                new ValidationStatus(true, "invoice is now fully paid") :
+                new ValidationStatus(true, "invoice is now partially paid");
+        }
+
+        private static bool PaymentEqualsAmount(Invoice invoice, Payment payment)
+        {
+            return invoice.Amount == payment.Amount;
+        }
+
+        private static bool PaymentGreaterThanAmount(Invoice invoice, Payment payment)
+        {
+            return payment.Amount > invoice.Amount;
+        }
+    }
+}

RefactorThis.Domain/PaymentProcessor/Validators/IPaymentProcessorValidator.cs

@@ -0,0 +1,10 @@
+using RefactorThis.Domain.Common.ValidationModel;
+using RefactorThis.Persistence;
+
+namespace RefactorThis.Domain.PaymentProcessor.Validators
+{
+    public interface IPaymentProcessorValidator
+    {
+        ValidationStatus Validate(Invoice invoice, Payment payment);
+    }
+}

RefactorThis.Domain/PaymentProcessor/Validators/IPaymentValidator.cs

@@ -0,0 +1,10 @@
+using RefactorThis.Domain.Common.ValidationModel;
+using RefactorThis.Persistence;
+
+namespace RefactorThis.Domain.PaymentProcessor.Validators
+{
+    public interface IPaymentValidator
+    {
+        ValidationStatus Validate(Invoice invoice, Payment payment);
+    }
+}

RefactorThis.Domain/PaymentProcessor/Validators/IPaymentValidatorAbstractFactory.cs

@@ -0,0 +1,8 @@
+namespace RefactorThis.Domain.PaymentProcessor.Validators
+{
+    public interface IPaymentValidatorAbstractFactory
+    {
+        IPaymentValidator GetFirstPaymentValidator();
+        IPaymentValidator GetAdditionalPaymentValidator();
+    }
+}