From 1d9f6f5736577f38753d1c65e5e6333ce850397a Mon Sep 17 00:00:00 2001
From: overflowerror <mail@overflowerror.com>
Date: Sun, 7 Jan 2024 16:40:54 +0100
Subject: [PATCH] feat: Add fifty-move-rule

---
 src/Game/Game.php       |  24 +++++++++
 tests/Game/GameTest.php | 112 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 136 insertions(+)

diff --git a/src/Game/Game.php b/src/Game/Game.php
index 0bcecc0..150ffd8 100644
--- a/src/Game/Game.php
+++ b/src/Game/Game.php
@@ -13,6 +13,9 @@ class Game {
 
     private ?array $moveCache = null;
 
+    private int $movesSinceLastCapture = 0;
+    private int $movesSinceLastPawnMove = 0;
+
     public function __construct(array $pieces, Side $current) {
         $this->pieces = $pieces;
         $this->current = $current;
@@ -281,6 +284,9 @@ class Game {
     public function applyInPlace(Move $move): void {
         $this->tick();
 
+        $this->movesSinceLastPawnMove++;
+        $this->movesSinceLastCapture++;
+
         if ($move->castleWith) {
             $king = $this->findPiece($move->piece);
             $rook = $this->findPiece($move->castleWith);
@@ -294,7 +300,12 @@ class Game {
         } else {
             if ($move->captures) {
                 $this->removePiece($move->captures);
+                $this->movesSinceLastCapture = 0;
             }
+            if ($move->piece instanceof Pawn) {
+                $this->movesSinceLastPawnMove = 0;
+            }
+
             if ($move->promoteTo) {
                 $this->removePiece($move->piece);
 
@@ -352,6 +363,15 @@ class Game {
             }
     }
 
+    public function _testFiftyMoveRule(int $movesSinceLastCapture, int $movesSinceLastPawnMove) {
+        $this->movesSinceLastPawnMove = $movesSinceLastPawnMove;
+        $this->movesSinceLastCapture = $movesSinceLastCapture;
+    }
+
+    private function isFiftyMoveRule(): bool {
+        return $this->movesSinceLastCapture >= 50 && $this->movesSinceLastPawnMove >= 50;
+    }
+
     public function getGameState(bool $onlyIsLegal = false): GameState {
         $allOccupied = $this->getAllOccupied();
 
@@ -371,6 +391,10 @@ class Game {
             return GameState::DEAD_POSITION;
         }
 
+        if ($this->isFiftyMoveRule()) {
+            return GameState::FIFTY_MOVE_RULE;
+        }
+
         $legalMoves = $this->getLegalMoves();
 
         if ($this->isCheck($allOccupied)) {
diff --git a/tests/Game/GameTest.php b/tests/Game/GameTest.php
index 9193eea..ff1241d 100644
--- a/tests/Game/GameTest.php
+++ b/tests/Game/GameTest.php
@@ -351,6 +351,118 @@ final class GameTest extends TestCase {
         $this->assertEquals(GameState::DEFAULT, $subject->getGameState());
     }
 
+    public function testGameState_fiftyMoveRule() {
+        $subject = new Game(
+            [
+                new King(new Position(2, 7), Side::WHITE, true),
+                new King(new Position(0, 0), Side::BLACK, true),
+                new Rook(new Position(1, 0), Side::BLACK),
+            ],
+            Side::BLACK
+        );
+        $subject->_testFiftyMoveRule(49, 49);
+        $this->assertEquals(GameState::DEFAULT, $subject->getGameState());
+
+        $subject->applyInPlace(new Move(
+            new Rook(new Position(1, 0), Side::BLACK),
+            new Position(3, 0)
+        ));
+
+        echo $subject->visualize();
+
+        $this->assertEquals(GameState::FIFTY_MOVE_RULE, $subject->getGameState());
+    }
+
+    public function testGameState_fiftyMoveRule_notLongEnoughSincePawnMove() {
+        $subject = new Game(
+            [
+                new King(new Position(2, 7), Side::WHITE, true),
+                new King(new Position(0, 0), Side::BLACK, true),
+                new Rook(new Position(1, 0), Side::BLACK),
+            ],
+            Side::BLACK
+        );
+        $subject->_testFiftyMoveRule(49, 48);
+        $this->assertEquals(GameState::DEFAULT, $subject->getGameState());
+
+        $subject->applyInPlace(new Move(
+            new Rook(new Position(1, 0), Side::BLACK),
+            new Position(3, 0)
+        ));
+
+        echo $subject->visualize();
+
+        $this->assertEquals(GameState::DEFAULT, $subject->getGameState());
+    }
+
+    public function testGameState_fiftyMoveRule_notLongEnoughSinceCapture() {
+        $subject = new Game(
+            [
+                new King(new Position(2, 7), Side::WHITE, true),
+                new King(new Position(0, 0), Side::BLACK, true),
+                new Rook(new Position(1, 0), Side::BLACK),
+            ],
+            Side::BLACK
+        );
+        $subject->_testFiftyMoveRule(48, 49);
+        $this->assertEquals(GameState::DEFAULT, $subject->getGameState());
+
+        $subject->applyInPlace(new Move(
+            new Rook(new Position(1, 0), Side::BLACK),
+            new Position(3, 0)
+        ));
+
+        echo $subject->visualize();
+
+        $this->assertEquals(GameState::DEFAULT, $subject->getGameState());
+    }
+
+    public function testGameState_fiftyMoveRule_capture() {
+        $subject = new Game(
+            [
+                new King(new Position(2, 7), Side::WHITE, true),
+                new King(new Position(0, 0), Side::BLACK, true),
+                new Rook(new Position(1, 0), Side::BLACK),
+                new Bishop(new Position(3, 0), Side::WHITE),
+            ],
+            Side::BLACK
+        );
+        $subject->_testFiftyMoveRule(49, 49);
+        $this->assertEquals(GameState::DEFAULT, $subject->getGameState());
+
+        $subject->applyInPlace(new Move(
+            new Rook(new Position(1, 0), Side::BLACK),
+            new Position(3, 0),
+            new Bishop(new Position(3, 0), Side::WHITE)
+        ));
+
+        echo $subject->visualize();
+
+        $this->assertEquals(GameState::DEFAULT, $subject->getGameState());
+    }
+
+    public function testGameState_fiftyMoveRule_pawnMove() {
+        $subject = new Game(
+            [
+                new King(new Position(2, 7), Side::WHITE, true),
+                new King(new Position(0, 0), Side::BLACK, true),
+                new Pawn(new Position(6, 5), Side::BLACK, true)
+            ],
+            Side::BLACK
+        );
+        $subject->_testFiftyMoveRule(49, 49);
+        $this->assertEquals(GameState::DEFAULT, $subject->getGameState());
+
+        $subject->applyInPlace(new Move(
+            new Pawn(new Position(6, 5), Side::BLACK),
+            new Position(6, 4),
+        ));
+
+        echo $subject->visualize();
+
+        $this->assertEquals(GameState::DEFAULT, $subject->getGameState());
+    }
+
     public function testLegalMoves_pawnPinnedBecauseOfCheckKingRestrictedByQueenAndPawn() {
         $subject = new Game(
             [