/**
* Transform a game to standard Forsyth Edwards Notation
* http://en.wikipedia.org/wiki/Forsyth%E2%80%93Edwards_Notation
*/
public static function export(Game $game, $positionOnly = false)
{
static $reverseClasses = array('Pawn' => 'p', 'Rook' => 'r', 'Knight' => 'n', 'Bishop' => 'b', 'Queen' => 'q', 'King' => 'k');
$board = $game->getBoard();
$emptySquare = 0;
$forsyth = '';
for ($y = 8; $y > 0; $y--) {
for ($x = 1; $x < 9; $x++) {
if ($piece = $board->getPieceByPosNoCheck($x, $y)) {
if ($emptySquare) {
$forsyth .= $emptySquare;
$emptySquare = 0;
}
$notation = $reverseClasses[$piece->getClass()];
if ('white' === $piece->getColor()) {
$notation = strtoupper($notation);
}
$forsyth .= $notation;
} else {
++$emptySquare;
}
}
if ($emptySquare) {
$forsyth .= $emptySquare;
$emptySquare = 0;
}
$forsyth .= '/';
}
$forsyth = trim($forsyth, '/');
if ($positionOnly) {
return $forsyth;
}
// b ou w to indicate turn
$forsyth .= ' ';
$forsyth .= substr($game->getTurnColor(), 0, 1);
// possibles castles
$forsyth .= ' ';
$hasCastle = false;
$analyser = new Analyser($board);
foreach ($game->getPlayers() as $player) {
if ($analyser->canCastleKingSide($player)) {
$hasCastle = true;
$forsyth .= $player->isWhite() ? 'K' : 'k';
}
if ($analyser->canCastleQueenSide($player)) {
$hasCastle = true;
$forsyth .= $player->isWhite() ? 'Q' : 'q';
}
}
if (!$hasCastle) {
$forsyth .= '-';
}
// en passant
$enPassant = '-';
foreach (PieceFilter::filterClass(PieceFilter::filterAlive($game->getPieces()), 'Pawn') as $piece) {
if ($piece->getFirstMove() === $game->getTurns() - 1) {
$color = $piece->getPlayer()->getColor();
$y = $piece->getY();
if ($color === 'white' && 4 === $y || $color === 'black' && 5 === $y) {
$enPassant = Board::posToKey($piece->getX(), 'white' === $color ? $y - 1 : $y + 1);
break;
}
}
}
$forsyth .= ' ' . $enPassant;
// Halfmove clock: This is the number of halfmoves since the last pawn advance or capture.
// This is used to determine if a draw can be claimed under the fifty-move rule.
$forsyth .= ' ' . $game->getHalfmoveClock();
// Fullmove number: The number of the full move. It starts at 1, and is incremented after Black's move.
$forsyth .= ' ' . $game->getFullMoveNumber();
return $forsyth;
}