From 62f23b0d9d6c1d53a5cd0de3619b67fbdadc2fd0 Mon Sep 17 00:00:00 2001
From: kraktus <kraktus@users.noreply.github.com>
Date: Tue, 26 Nov 2024 19:32:25 +0100
Subject: [PATCH] Add `plyToTurn` util function

It's defined in three different places in lila.
---
 src/util.test.ts | 10 +++++++++-
 src/util.ts      |  2 ++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/util.test.ts b/src/util.test.ts
index b1bc79aa..b0beb8f3 100644
--- a/src/util.test.ts
+++ b/src/util.test.ts
@@ -1,5 +1,5 @@
 import { expect, test } from '@jest/globals';
-import { makeUci, parseUci } from './util.js';
+import { makeUci, parseUci, plyToTurn } from './util.js';
 
 test('parse uci', () => {
   expect(parseUci('a1a2')).toEqual({ from: 0, to: 8 });
@@ -12,3 +12,11 @@ test('make uci', () => {
   expect(makeUci({ from: 2, to: 3 })).toBe('c1d1');
   expect(makeUci({ from: 0, to: 0, promotion: 'pawn' })).toBe('a1a1p');
 });
+
+test('plyToTurn', () => {
+  expect(plyToTurn(1)).toBe(1);
+  expect(plyToTurn(2)).toBe(1);
+  expect(plyToTurn(3)).toBe(2);
+  expect(plyToTurn(4)).toBe(2);
+  expect(plyToTurn(5)).toBe(3);
+});
diff --git a/src/util.ts b/src/util.ts
index 1b68ba02..b054bc26 100644
--- a/src/util.ts
+++ b/src/util.ts
@@ -39,6 +39,8 @@ export const roleToChar = (role: Role): string => {
   }
 };
 
+export const plyToTurn = (ply: number): number => Math.floor((ply - 1) / 2) + 1;
+
 export function charToRole(ch: 'p' | 'n' | 'b' | 'r' | 'q' | 'k' | 'P' | 'N' | 'B' | 'R' | 'Q' | 'K'): Role;
 export function charToRole(ch: string): Role | undefined;
 export function charToRole(ch: string): Role | undefined {