feat: Add short algebraic notation for moves

src/Game/Game.php

@@ -63,7 +63,7 @@ class Game {
         }
     }
 
-    private function getOccupied(array $pieces): FieldBitMap {
+    public function getOccupied(array $pieces): FieldBitMap {
         $occupiedMap = FieldBitMap::empty();
         foreach ($pieces as $piece) {
             $occupiedMap->add($piece->getPosition());
@@ -76,7 +76,7 @@ class Game {
         return $this->getOccupied($this->pieces);
     }
 
-    private function getCaptureable(array $pieces, bool $forPawn): FieldBitMap {
+    public function getCaptureable(array $pieces, bool $forPawn): FieldBitMap {
         $captureableMap = FieldBitMap::empty();
         foreach ($pieces as $piece) {
             $captureableMap = $captureableMap->union($piece->getCaptureableMap($forPawn));

src/Game/Move.php

@@ -37,20 +37,126 @@ class Move {
             );
     }
 
-    public function getLong(): string {
+    private function getCheckMarker(?Game $game = null): string {
-        if ($this->castleWith) {
+        if (!$game) {
-            if (abs($this->piece->getPosition()->file - $this->castleWith->getPosition()->file) > 3) {
+            return "";
-                return "O-O-O";
-            } else {
-                return "O-O";
-            }
         } else {
-            return $this->piece . " " .
+            $game = $game->apply($this);
-                $this->piece->getType()->getShort() . ($this->captures ? "x" : "") . $this->target .
+            $state = $game->getGameState();
-                ($this->promoteTo ? $this->promoteTo->getShort() : "");
+
+            if ($state == GameState::CHECK) {
+                return "+";
+            } else if ($state == GameState::CHECKMATE) {
+                return "++";
+            } else {
+                return "";
+            }
         }
     }
 
+    private function isCastles(): bool {
+        return !!$this->castleWith;
+    }
+
+    private function isLongCastles(): bool {
+        return abs($this->piece->getPosition()->file - $this->castleWith->getPosition()->file) > 3;
+    }
+
+    private function getCastlesMarker(): string {
+        if ($this->isLongCastles()) {
+            return "O-O-O";
+        } else {
+            return "O-O";
+        }
+    }
+
+    private function getCapturesMarker(): string {
+        return $this->captures ? "x" : "";
+    }
+
+    private function getPromotionMarker(): string {
+        return $this->promoteTo ? $this->promoteTo->getShort() : "";
+    }
+
+    private function getMinimalSourcePositionMarker(Game $game): string {
+        $pieceClass = get_class($this->piece);
+        $piecePosition = $this->piece->getPosition();
+
+        $needsFile = false;
+        $needsRank = false;
+        $needsAny = false;
+
+        foreach ($game->getLegalMoves() as $move) {
+            if (!is_a($move->piece, $pieceClass)) {
+                continue;
+            }
+            if (!$this->target->equals($move->target)) {
+                continue;
+            }
+            if ($this->piece->equals($move->piece)) {
+                continue;
+            }
+
+            $otherPosition = $move->piece->getPosition();
+
+            $wouldNeedRank = $piecePosition->file == $otherPosition->file;
+            $wouldNeedFile = $piecePosition->rank == $otherPosition->rank;
+
+            if ($wouldNeedRank) {
+                $needsRank = true;
+                $needsAny = false;
+            }
+            if ($wouldNeedFile) {
+                $needsFile = true;
+                $needsAny = false;
+            }
+            if (!$needsRank && !$needsFile) {
+                $needsAny = true;
+            }
+        }
+
+        $result = "";
+        if ($needsFile || $needsAny) {
+            $result .= $piecePosition->getFileString();
+        }
+        if ($needsRank) {
+            $result .= $piecePosition->getRankString();
+        }
+
+        return $result;
+    }
+
+    public function getLong(?Game $game = null): string {
+        if ($this->isCastles()) {
+            $result = $this->getCastlesMarker();
+        } else {
+            $result = $this->piece;
+            $result .= $this->getCapturesMarker();
+            $result .= $this->target;
+            $result .= $this->getPromotionMarker();
+        }
+
+        $result .= $this->getCheckMarker($game);
+
+        return $result;
+    }
+
+    public function getShort(Game $game): string {
+        if ($this->isCastles()) {
+            $result = $this->getCastlesMarker();
+        } else {
+            $result = $this->piece->getType()->getShort();
+            $result .= $this->getMinimalSourcePositionMarker($game);
+            $result .= $this->getCapturesMarker();
+            $result .= $this->target;
+            $result .= $this->getPromotionMarker();
+        }
+
+        $result .= $this->getCheckMarker($game);
+
+        return $result;
+    }
+
     public function __toString(): string {
         return $this->getLong();
     }

src/Game/Position.php

@@ -21,8 +21,16 @@ class Position {
         return ($this->rank % 2) ^ ($this->file % 2) ? Side::WHITE : Side::BLACK;
     }
 
+    public function getFileString(): string {
+        return ["a", "b", "c", "d", "e", "f", "g", "h"][$this->file];
+    }
+
+    public function getRankString(): string {
+        return strval($this->rank + 1);
+    }
+
     public function __toString(): string {
-        return ["a", "b", "c", "d", "e", "f", "g", "h"][$this->file] . ($this->rank + 1);
+        return $this->getFileString() . $this->getRankString();
     }
 
     public function equals(Position $position): bool {

tests/Game/MoveTest.php

@@ -0,0 +1,102 @@
+<?php
+declare(strict_types=1);
+
+namespace Game;
+
+use PHPUnit\Framework\TestCase;
+
+final class MoveTest extends TestCase {
+
+    public function testShort_noSourceCollision() {
+        $game = new Game([
+            new King(new Position(0,0), Side::WHITE),
+            new King(new Position(7, 7), Side::BLACK),
+            new Pawn(new Position(3, 3), Side::BLACK, true),
+            new Knight(new Position(2, 1), Side::WHITE),
+        ], Side::WHITE);
+
+        $subject = new Move(
+            new Knight(new Position(2, 1), Side::WHITE),
+            new Position(3, 3),
+            new Pawn(new Position(3, 3), Side::BLACK),
+        );
+
+        $this->assertEquals("Nxd4", $subject->getShort($game));
+    }
+
+    public function testShort_simpleCollisionAndCheck() {
+        $game = new Game([
+            new King(new Position(0,0), Side::WHITE),
+            new King(new Position(2, 5), Side::BLACK),
+            new Pawn(new Position(3, 3), Side::BLACK, true),
+            new Knight(new Position(2, 1), Side::WHITE),
+            new Knight(new Position(4, 5), Side::WHITE),
+        ], Side::WHITE);
+
+        $subject = new Move(
+            new Knight(new Position(2, 1), Side::WHITE),
+            new Position(3, 3),
+            new Pawn(new Position(3, 3), Side::BLACK),
+        );
+
+        $this->assertEquals("Ncxd4+", $subject->getShort($game));
+    }
+
+    public function testShort_fileCollision() {
+        $game = new Game([
+            new King(new Position(0,0), Side::WHITE),
+            new King(new Position(7, 7), Side::BLACK),
+            new Pawn(new Position(3, 3), Side::BLACK, true),
+            new Knight(new Position(2, 1), Side::WHITE),
+            new Knight(new Position(2, 5), Side::WHITE),
+        ], Side::WHITE);
+
+        $subject = new Move(
+            new Knight(new Position(2, 1), Side::WHITE),
+            new Position(3, 3),
+            new Pawn(new Position(3, 3), Side::BLACK),
+        );
+
+        $this->assertEquals("N2xd4", $subject->getShort($game));
+    }
+
+    public function testShort_rankCollision() {
+        $game = new Game([
+            new King(new Position(0,0), Side::WHITE),
+            new King(new Position(0, 0), Side::BLACK),
+            new Pawn(new Position(3, 3), Side::BLACK, true),
+            new Knight(new Position(2, 1), Side::WHITE),
+            new Knight(new Position(4, 1), Side::WHITE),
+        ], Side::WHITE);
+
+        $subject = new Move(
+            new Knight(new Position(2, 1), Side::WHITE),
+            new Position(3, 3),
+            new Pawn(new Position(3, 3), Side::BLACK),
+        );
+
+        $this->assertEquals("Ncxd4", $subject->getShort($game));
+    }
+
+    public function testShort_fullCollisionAndCheckmate() {
+        $game = new Game([
+            new King(new Position(0,0), Side::WHITE),
+            new King(new Position(4, 5), Side::BLACK),
+            new Pawn(new Position(3, 3), Side::BLACK, true),
+            new Knight(new Position(2, 1), Side::WHITE),
+            new Knight(new Position(2, 5), Side::WHITE),
+            new Knight(new Position(4, 1), Side::WHITE),
+            new Queen(new Position(6, 6), Side::WHITE),
+            new Rook(new Position(3, 7), Side::WHITE),
+        ], Side::WHITE);
+
+        $subject = new Move(
+            new Knight(new Position(2, 1), Side::WHITE),
+            new Position(3, 3),
+            new Pawn(new Position(3, 3), Side::BLACK),
+        );
+
+        $this->assertEquals("Nc2xd4++", $subject->getShort($game));
+    }
+
+}