From 07ddb5537471632806e23cbd8c56f60908b30b98 Mon Sep 17 00:00:00 2001
From: grandsilence <mixtape774@gmail.com>
Date: Tue, 4 Dec 2018 16:19:29 +0300
Subject: [PATCH] Added Randomizer and extension for all collections
 "NextRandom".

---
 Leaf.Core/Extensions/CollectionExtensions.cs | 21 ++++++++++++++++++++
 Leaf.Core/Randomizer.cs                      | 13 ++++++++++++
 2 files changed, 34 insertions(+)
 create mode 100644 Leaf.Core/Extensions/CollectionExtensions.cs
 create mode 100644 Leaf.Core/Randomizer.cs

diff --git a/Leaf.Core/Extensions/CollectionExtensions.cs b/Leaf.Core/Extensions/CollectionExtensions.cs
new file mode 100644
index 0000000..ccd1447
--- /dev/null
+++ b/Leaf.Core/Extensions/CollectionExtensions.cs
@@ -0,0 +1,21 @@
+using System.Collections.Generic;
+
+namespace Leaf.Core.Extensions
+{
+    public static class CollectionExtensions
+    {
+        /// <summary>
+        /// Получить следующий случайный элемент.
+        /// </summary>
+        /// <typeparam name="T">Тип элементов в коллекции</typeparam>
+        /// <param name="list">Список с элементами</param>
+        /// <returns>Вернет случайный элемент из коллекции.</returns>
+        public static T NextRandom<T>(this IReadOnlyList<T> list)
+        {
+            if (list.Equals(default(IReadOnlyList<T>)) || list.Count == 0)
+                return default(T);
+
+            return list[Randomizer.Instance.Next(0, list.Count)];
+        }
+    }
+}
\ No newline at end of file
diff --git a/Leaf.Core/Randomizer.cs b/Leaf.Core/Randomizer.cs
new file mode 100644
index 0000000..549429b
--- /dev/null
+++ b/Leaf.Core/Randomizer.cs
@@ -0,0 +1,13 @@
+using System;
+
+namespace Leaf.Core
+{
+    /// <summary>
+    /// Singleton for Random class.
+    /// </summary>
+    public static class Randomizer
+    {
+        [ThreadStatic] private static Random _rand;
+        public static Random Instance => _rand ?? (_rand = new Random());
+    }
+}
\ No newline at end of file