From efaf2e947af135101337db14c73e299cfdbfc34b Mon Sep 17 00:00:00 2001
From: Kamron Batman <3953314+kamronbatman@users.noreply.github.com>
Date: Tue, 22 Nov 2022 19:53:20 -0800
Subject: [PATCH] feat: Adds weighted values (#1265)

---
 Projects/Server/Random/WeightedValue.cs | 34 +++++++++
 Projects/Server/Utilities/Utility.cs    | 96 +++++++++++++++++++++++++
 2 files changed, 130 insertions(+)
 create mode 100644 Projects/Server/Random/WeightedValue.cs

diff --git a/Projects/Server/Random/WeightedValue.cs b/Projects/Server/Random/WeightedValue.cs
new file mode 100644
index 000000000..5295d5095
--- /dev/null
+++ b/Projects/Server/Random/WeightedValue.cs
@@ -0,0 +1,34 @@
+/*************************************************************************
+ * ModernUO                                                              *
+ * Copyright 2019-2022 - ModernUO Development Team                       *
+ * Email: hi@modernuo.com                                                *
+ * File: WeightedValue.cs                                                *
+ *                                                                       *
+ * This program is free software: you can redistribute it and/or modify  *
+ * it under the terms of the GNU General Public License as published by  *
+ * the Free Software Foundation, either version 3 of the License, or     *
+ * (at your option) any later version.                                   *
+ *                                                                       *
+ * You should have received a copy of the GNU General Public License     *
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>. *
+ *************************************************************************/
+
+using System;
+
+namespace Server.Random;
+
+public struct WeightedValue<T>
+{
+    public T Value { get; }
+    public int Weight { get; }
+
+    public WeightedValue(int weight, T value)
+    {
+        Value = value;
+        Weight = weight;
+    }
+
+    public bool IsValid => Weight > 0;
+
+    public static implicit operator WeightedValue<T>(ValueTuple<int, T> pair) => new(pair.Item1, pair.Item2);
+}
diff --git a/Projects/Server/Utilities/Utility.cs b/Projects/Server/Utilities/Utility.cs
index 92eb76035..9effa3b73 100644
--- a/Projects/Server/Utilities/Utility.cs
+++ b/Projects/Server/Utilities/Utility.cs
@@ -1042,6 +1042,102 @@ public static class Utility
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public static T RandomElement<T>(this IList<T> list) => list.RandomElement(default);
 
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static WeightedValue<T> RandomWeightedElement<T>(this IList<WeightedValue<T>> weightedValues)
+    {
+        var totalWeight = 0;
+        for (var i = 0; i < weightedValues.Count; i++)
+        {
+            totalWeight += weightedValues[i].Weight;
+        }
+
+        return RandomWeightedElement(weightedValues, totalWeight);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static WeightedValue<T> RandomWeightedElement<T>(this ReadOnlySpan<WeightedValue<T>> weightedValues, int totalWeight)
+    {
+        var random = Random(totalWeight);
+
+        for (var i = 0; i < weightedValues.Length; i++)
+        {
+            var weightedValue = weightedValues[i];
+            random -= weightedValue.Weight;
+
+            if (random <= 0)
+            {
+                return weightedValue;
+            }
+        }
+
+        return default;
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static WeightedValue<T> RandomWeightedElement<T>(this ReadOnlySpan<WeightedValue<T>> weightedValues)
+    {
+        var totalWeight = 0;
+        for (var i = 0; i < weightedValues.Length; i++)
+        {
+            totalWeight += weightedValues[i].Weight;
+        }
+
+        return RandomWeightedElement(weightedValues, totalWeight);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static WeightedValue<T> RandomWeightedElement<T>(this IList<WeightedValue<T>> weightedValues, int totalWeight)
+    {
+        var random = Random(totalWeight);
+
+        for (var i = 0; i < weightedValues.Count; i++)
+        {
+            var weightedValue = weightedValues[i];
+            random -= weightedValue.Weight;
+
+            if (random <= 0)
+            {
+                return weightedValue;
+            }
+        }
+
+        return default;
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static WeightedValue<T> RandomWeightedElement<T>(this PooledRefList<WeightedValue<T>> weightedValues)
+    {
+        var totalWeight = 0;
+        for (var i = 0; i < weightedValues.Count; i++)
+        {
+            totalWeight += weightedValues[i].Weight;
+        }
+
+        return RandomWeightedElement(weightedValues, totalWeight);
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static WeightedValue<T> RandomWeightedElement<T>(
+        this PooledRefList<WeightedValue<T>> weightedValues,
+        int totalWeight
+    )
+    {
+        var random = Random(totalWeight);
+
+        for (var i = 0; i < weightedValues.Count; i++)
+        {
+            var weightedValue = weightedValues[i];
+            random -= weightedValue.Weight;
+
+            if (random <= 0)
+            {
+                return weightedValue;
+            }
+        }
+
+        return default;
+    }
+
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public static T TakeRandomElement<T>(this IList<T> list)
     {