From f465bdecae30073371dede3e18f5501aa2bd5295 Mon Sep 17 00:00:00 2001
From: DualFroz <me@dualfroz.com>
Date: Tue, 25 Aug 2026 19:15:00 +0200
Subject: [PATCH] feat(rules): add draw detection

---
 Draw.scala | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)
 create mode 100644 Draw.scala

diff --git a/Draw.scala b/Draw.scala
new file mode 100644
index 0000000..e0c1704
--- /dev/null
+++ b/Draw.scala
@@ -0,0 +1,24 @@
+package gambit
+
+object Draw:
+  def isFiftyMove(pos: Position): Boolean = pos.halfmove >= 100
+
+  def isInsufficientMaterial(pos: Position): Boolean =
+    var minors = 0
+    var sq = 0
+    while sq < 128 do
+      if Square.onBoard(sq) then
+        Piece.typeOf(pos.board(sq)) match
+          case Piece.Pawn | Piece.Rook | Piece.Queen => return false
+          case Piece.Knight | Piece.Bishop           => minors += 1
+          case _                                      => ()
+      sq += 1
+    minors <= 1
+
+  def isThreefold(history: collection.Seq[Long], current: Long): Boolean =
+    var count = 0
+    var i = 0
+    while i < history.length do
+      if history(i) == current then count += 1
+      i += 1
+    count >= 3