Add random pick / take methods for sets (space-wizards#4821)

* Add random pick / take methods for sets

I want it don't at me.

* cleanup (mraow)

* Revert "cleanup (mraow)"

This reverts commit e279957.

* flatpak

* notes

RELEASE-NOTES.md

@@ -40,6 +40,7 @@ END TEMPLATE-->
 ### New features
 
 * `TextEdit.OnTextChanged`
+* Add Pick and PickAndTake versions for System.Random for ICollections.
 
 ### Bugfixes
 

Robust.Shared/Random/IRobustRandom.cs

@@ -1,9 +1,11 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Numerics;
 using System.Runtime.CompilerServices;
 using Robust.Shared.Collections;
 using Robust.Shared.Maths;
+using Robust.Shared.Toolshed.Commands.Generic;
 
 namespace Robust.Shared.Random;
 

Robust.Shared/Random/RandomExtensions.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using Robust.Shared.Collections;
 using Robust.Shared.Maths;
 using Robust.Shared.Utility;
@@ -47,7 +48,7 @@ public static T Pick<T>(this IRobustRandom random, IReadOnlyCollection<T> collec
                 }
             }
 
-            throw new InvalidOperationException("This should be unreachable!");
+            throw new UnreachableException("This should be unreachable!");
         }
 
         public static T PickAndTake<T>(this IRobustRandom random, IList<T> list)
@@ -58,6 +59,36 @@ public static T PickAndTake<T>(this IRobustRandom random, IList<T> list)
             return element;
         }
 
+        /// <summary>
+        /// Picks a random element from a set and returns it.
+        /// This is O(n) as it has to iterate the collection until the target index.
+        /// </summary>
+        public static T Pick<T>(this System.Random random, ICollection<T> collection)
+        {
+            var index = random.Next(collection.Count);
+            var i = 0;
+            foreach (var t in collection)
+            {
+                if (i++ == index)
+                {
+                    return t;
+                }
+            }
+
+            throw new UnreachableException("This should be unreachable!");
+        }
+
+        /// <summary>
+        /// Picks a random from a collection then removes it and returns it.
+        /// This is O(n) as it has to iterate the collection until the target index.
+        /// </summary>
+        public static T PickAndTake<T>(this System.Random random, ICollection<T> set)
+        {
+            var tile = Pick(random, set);
+            set.Remove(tile);
+            return tile;
+        }
+
         /// <summary>
         ///     Generate a random number from a normal (gaussian) distribution.
         /// </summary>