isInsufficientMaterial method

Implementation

bool isInsufficientMaterial() {
  List<ChessPiece> remainingPieces = [];

  for (int row = 0; row < 8; row++) {
    for (int col = 0; col < 8; col++) {
      ChessPiece? piece = getPiece(Position(row: row, col: col));
      if (piece != null) {
        remainingPieces.add(piece);
      }
    }
  }

  // Only kings left
  if (remainingPieces.length == 2) {
    return remainingPieces.every((p) => p.type == PieceType.king);
  }

  // King and bishop or knight vs king
  if (remainingPieces.length == 3) {
    bool hasOneMinor =
        remainingPieces
            .where(
              (p) => p.type == PieceType.bishop || p.type == PieceType.knight,
            )
            .length ==
        1;
    return hasOneMinor;
  }

  // King and bishop vs king and bishop (same color bishops)
  if (remainingPieces.length == 4) {
    List<ChessPiece> bishops =
        remainingPieces.where((p) => p.type == PieceType.bishop).toList();

    if (bishops.length == 2) {
      // Get their positions to compare bishop square colors
      List<Position> positions = [];

      for (int row = 0; row < 8; row++) {
        for (int col = 0; col < 8; col++) {
          ChessPiece? piece = getPiece(Position(row: row, col: col));
          if (piece != null && piece.type == PieceType.bishop) {
            positions.add(Position(row: row, col: col));
          }
        }
      }

      if (positions.length == 2) {
        bool sameColorSquares =
            (positions[0].row + positions[0].col) % 2 ==
            (positions[1].row + positions[1].col) % 2;
        return sameColorSquares;
      }
    }
  }

  return false;
}