From 4268762a0c8570c017ff75d164a571a4c41a8ee5 Mon Sep 17 00:00:00 2001
From: cosmonaut <evan@moonside.games>
Date: Thu, 6 Apr 2023 14:54:20 -0700
Subject: [PATCH] fix EntitiesInRandomOrder

---
 src/Filter.cs        |  2 +-
 src/FilterStorage.cs | 29 +++++++++++++++++++++++++++--
 2 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/src/Filter.cs b/src/Filter.cs
index d08e1ca..f841c39 100644
--- a/src/Filter.cs
+++ b/src/Filter.cs
@@ -15,7 +15,7 @@ namespace MoonTools.ECS
 		}
 
 		public ReverseSpanEnumerator<Entity> Entities => FilterStorage.FilterEntities(Signature);
-		public LinearCongruentialEnumerator EntitiesInRandomOrder => FilterStorage.FilterEntitiesRandom(Signature);
+		public RandomEntityEnumerator EntitiesInRandomOrder => FilterStorage.FilterEntitiesRandom(Signature);
 		public Entity RandomEntity => FilterStorage.FilterRandomEntity(Signature);
 
 		public int Count => FilterStorage.FilterCount(Signature);
diff --git a/src/FilterStorage.cs b/src/FilterStorage.cs
index 91b3a0c..804ed93 100644
--- a/src/FilterStorage.cs
+++ b/src/FilterStorage.cs
@@ -54,9 +54,12 @@ namespace MoonTools.ECS
 			return filterSignatureToEntityIDs[filterSignature].GetEnumerator();
 		}
 
-		public LinearCongruentialEnumerator FilterEntitiesRandom(FilterSignature filterSignature)
+		public RandomEntityEnumerator FilterEntitiesRandom(FilterSignature filterSignature)
 		{
-			return RandomGenerator.LinearCongruentialGenerator(FilterCount(filterSignature));
+			return new RandomEntityEnumerator(
+				this,
+				filterSignature,
+				RandomGenerator.LinearCongruentialGenerator(FilterCount(filterSignature)));
 		}
 
 		public Entity FilterNthEntity(FilterSignature filterSignature, int index)
@@ -178,4 +181,26 @@ namespace MoonTools.ECS
 			removeCallbacks.Add(filterSignature, callback);
 		}
 	}
+
+	public ref struct RandomEntityEnumerator
+	{
+		public RandomEntityEnumerator GetEnumerator() => this;
+
+		private FilterStorage FilterStorage;
+		private FilterSignature FilterSignature;
+		private LinearCongruentialEnumerator LinearCongruentialEnumerator;
+
+		internal RandomEntityEnumerator(
+			FilterStorage filterStorage,
+			FilterSignature filterSignature,
+			LinearCongruentialEnumerator linearCongruentialEnumerator)
+		{
+			FilterStorage = filterStorage;
+			FilterSignature = filterSignature;
+			LinearCongruentialEnumerator = linearCongruentialEnumerator;
+		}
+
+		public bool MoveNext() => LinearCongruentialEnumerator.MoveNext();
+		public Entity Current => FilterStorage.FilterNthEntity(FilterSignature, LinearCongruentialEnumerator.Current);
+	}
 }