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NitroxModel/DataStructures/CircularBuffer.cs

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+using System;
+using System.Collections;
+using System.Collections.Generic;
+
+namespace NitroxModel.DataStructures;
+
+/// <summary>
+///     Given a fixed size, fills to capacity and then overwrites earliest item.
+/// </summary>
+public class CircularBuffer<T> : IList<T>
+{
+    private readonly List<T> data;
+    private readonly int maxSize;
+
+    /// <summary>
+    ///     Returns the index last changed. If <see cref="CircularBuffer{T}" /> is empty, returns -1.
+    /// </summary>
+    public int LastChangedIndex { get; protected set; } = -1;
+
+    /// <summary>
+    ///     Gets the item at the index, wrapping around the buffer if out-of-range.
+    /// </summary>
+    public T this[int index]
+    {
+        // Proper modulus operator which C# doesn't have. % = remainder operator and doesn't work in reverse for negative numbers.
+        get => data[Math.Abs((index % data.Count + data.Count) % data.Count)];
+        set => throw new NotSupportedException();
+    }
+
+    public int Count => data.Count;
+    public bool IsReadOnly => false;
+
+    public CircularBuffer(int maxSize, int initialCapacity = 0)
+    {
+        if (maxSize < 0) throw new ArgumentOutOfRangeException(nameof(maxSize), "Max size must be larger than -1");
+
+        this.maxSize = maxSize;
+        data = new List<T>(Math.Max(0, Math.Min(initialCapacity, maxSize)));
+    }
+
+    public int IndexOf(T item)
+    {
+        return data.IndexOf(item);
+    }
+
+    public void Insert(int index, T item)
+    {
+        throw new NotImplementedException();
+    }
+
+    public void RemoveAt(int index)
+    {
+        data.RemoveAt(index);
+    }
+
+    public bool Remove(T item)
+    {
+        return data.Remove(item);
+    }
+
+    public void Add(T item)
+    {
+        if (maxSize == 0) return;
+        if (data.Count < maxSize)
+        {
+            data.Add(item);
+            LastChangedIndex++;
+            return;
+        }
+
+        LastChangedIndex = (LastChangedIndex + 1) % maxSize;
+        data[LastChangedIndex] = item;
+    }
+
+    public void AddRange(IEnumerable<T> items)
+    {
+        foreach (T item in items) Add(item);
+    }
+
+    public void AddRange(params T[] items)
+    {
+        foreach (T item in items) Add(item);
+    }
+
+    public void Clear()
+    {
+        data.Clear();
+        LastChangedIndex = -1;
+    }
+
+    public bool Contains(T item)
+    {
+        return data.Contains(item);
+    }
+
+    public void CopyTo(T[] array, int arrayIndex)
+    {
+        data.CopyTo(array, arrayIndex);
+    }
+
+    public IEnumerator<T> GetEnumerator()
+    {
+        return data.GetEnumerator();
+    }
+
+    IEnumerator IEnumerable.GetEnumerator()
+    {
+        return GetEnumerator();
+    }
+}