Simplify Mastermind (C#) folder structure

60_Mastermind/csharp/CodeFactory.cs

@@ -0,0 +1,92 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace Game
+{
+    /// <summary>
+    /// Provides methods for generating codes with a given number of positions
+    /// and colors.
+    /// </summary>
+    public class CodeFactory
+    {
+        /// <summary>
+        /// Gets the number of colors in codes generated by this factory.
+        /// </summary>
+        public int Colors { get; }
+
+        /// <summary>
+        /// Gets the number of positions in codes generated by this factory.
+        /// </summary>
+        public int Positions { get; }
+
+        /// <summary>
+        /// Gets the number of distinct codes that this factory can
+        /// generate.
+        /// </summary>
+        public int Possibilities { get; }
+
+        /// <summary>
+        /// Initializes a new instance of the CodeFactory class.
+        /// </summary>
+        /// <param name="positions">
+        /// The number of positions.
+        /// </param>
+        /// <param name="colors">
+        /// The number of colors.
+        /// </param>
+        public CodeFactory(int positions, int colors)
+        {
+            if (positions < 1)
+                throw new ArgumentException("A code must contain at least one position");
+
+            if (colors < 1)
+                throw new ArgumentException("A code must contain at least one color");
+
+            if (colors > Game.Colors.List.Length)
+                throw new ArgumentException($"A code can contain no more than {Game.Colors.List.Length} colors");
+
+            Positions     = positions;
+            Colors        = colors;
+            Possibilities = (int)Math.Pow(colors, positions);
+        }
+
+        /// <summary>
+        /// Creates a specified code.
+        /// </summary>
+        /// <param name="number">
+        /// The number of the code to create from 0 to Possibilities - 1.
+        /// </param>
+        public Code Create(int number) =>
+            EnumerateCodes().Skip(number).First();
+
+        /// <summary>
+        /// Creates a random code using the provided random number generator.
+        /// </summary>
+        /// <param name="random">
+        /// The random number generator.
+        /// </param>
+        public Code Create(Random random) =>
+            Create(random.Next(Possibilities));
+
+        /// <summary>
+        /// Generates a collection of codes containing every code that this
+        /// factory can create exactly once.
+        /// </summary>
+        public IEnumerable<Code> EnumerateCodes()
+        {
+            var current = new int[Positions];
+            var position = default(int);
+
+            do
+            {
+                yield return new Code(current);
+
+                position = 0;
+                while (position < Positions && ++current[position] == Colors)
+                    current[position++] = 0;
+            }
+            while (position < Positions);
+        }
+    }
+}