OrderStatus and CardTypes as Enumerations

Author: eiximenis

src/Services/Ordering/Ordering.Domain/AggregatesModel/BuyerAggregate/CardType.cs

@@ -1,26 +1,24 @@
-using Microsoft.eShopOnContainers.Services.Ordering.Domain.Seedwork;
+using Microsoft.eShopOnContainers.Services.Ordering.Domain.SeedWork;
 using System;
 using System.Collections.Generic;
 using System.Linq;
 
 namespace Microsoft.eShopOnContainers.Services.Ordering.Domain.AggregatesModel.BuyerAggregate
 {
-    
+
     public class CardType
-        : Entity
+        : Enumeration
     {
         public static CardType Amex = new CardType(1, "Amex");
         public static CardType Visa = new CardType(2, "Visa");
         public static CardType MasterCard = new CardType(3, "MasterCard");
 
-        public string Name { get; private set; }
-
         protected CardType() { }
 
         public CardType(int id, string name)
+            : base(id, name)
         {
-            Id = id;
-            Name = name;
+
         }
 
         public static IEnumerable<CardType> List()

src/Services/Ordering/Ordering.Domain/AggregatesModel/OrderAggregate/OrderStatus.cs

@@ -1,15 +1,14 @@
 namespace Microsoft.eShopOnContainers.Services.Ordering.Domain.AggregatesModel.OrderAggregate
 {
     using Seedwork;
+    using SeedWork;
     using System;
     using System.Collections.Generic;
     using System.Linq;
 
     public class OrderStatus
-        :Entity
+        : Enumeration
     {
-        public string Name { get; private set; }
-
         public static OrderStatus InProcess = new OrderStatus(1, nameof(InProcess).ToLowerInvariant());
         public static OrderStatus Shipped = new OrderStatus(2, nameof(Shipped).ToLowerInvariant());
         public static OrderStatus Canceled = new OrderStatus(3, nameof(Canceled).ToLowerInvariant());
@@ -19,9 +18,8 @@ protected OrderStatus()
         }
 
         public OrderStatus(int id, string name)
+            : base(id, name)
         {
-            Id = id;
-            Name = name;
         }
 
         public static IEnumerable<OrderStatus> List()

src/Services/Ordering/Ordering.Domain/SeedWork/Enumeration.cs

@@ -0,0 +1,103 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+
+namespace Microsoft.eShopOnContainers.Services.Ordering.Domain.SeedWork
+{
+    public abstract class Enumeration : IComparable
+    {
+        public string Name { get; private set; }
+
+        public int Id { get; private set; }
+
+        protected Enumeration()
+        {
+        }
+
+        protected Enumeration(int id, string name)
+        {
+            Id = id;
+            Name = name;
+        }
+
+        public override string ToString()
+        {
+            return Name;
+        }
+
+        public static IEnumerable<T> GetAll<T>() where T : Enumeration, new()
+        {
+            var type = typeof(T);
+            var fields = type.GetTypeInfo().GetFields(BindingFlags.Public | BindingFlags.Static | BindingFlags.DeclaredOnly);
+
+            foreach (var info in fields)
+            {
+                var instance = new T();
+                var locatedValue = info.GetValue(instance) as T;
+
+                if (locatedValue != null)
+                {
+                    yield return locatedValue;
+                }
+            }
+        }
+
+        public override bool Equals(object obj)
+        {
+            var otherValue = obj as Enumeration;
+
+            if (otherValue == null)
+            {
+                return false;
+            }
+
+            var typeMatches = GetType().Equals(obj.GetType());
+            var valueMatches = Id.Equals(otherValue.Id);
+
+            return typeMatches && valueMatches;
+        }
+
+        public override int GetHashCode()
+        {
+            return Id.GetHashCode();
+        }
+
+        public static int AbsoluteDifference(Enumeration firstValue, Enumeration secondValue)
+        {
+            var absoluteDifference = Math.Abs(firstValue.Id - secondValue.Id);
+            return absoluteDifference;
+        }
+
+        public static T FromValue<T>(int value) where T : Enumeration, new()
+        {
+            var matchingItem = parse<T, int>(value, "value", item => item.Id == value);
+            return matchingItem;
+        }
+
+        public static T FromDisplayName<T>(string displayName) where T : Enumeration, new()
+        {
+            var matchingItem = parse<T, string>(displayName, "display name", item => item.Name == displayName);
+            return matchingItem;
+        }
+
+        private static T parse<T, K>(K value, string description, Func<T, bool> predicate) where T : Enumeration, new()
+        {
+            var matchingItem = GetAll<T>().FirstOrDefault(predicate);
+
+            if (matchingItem == null)
+            {
+                var message = string.Format("'{0}' is not a valid {1} in {2}", value, description, typeof(T));
+
+                throw new InvalidOperationException(message);
+            }
+
+            return matchingItem;
+        }
+
+        public int CompareTo(object other)
+        {
+            return Id.CompareTo(((Enumeration)other).Id);
+        }
+    }
+}