public bool LayoutNextPiece(RotatedPiece rotatedPiece)
{
int firstEmptyX;
int firstEmptyY;
var foundAnEmptySquare = FindFirstEmptySquare(out firstEmptyX, out firstEmptyY);
if (!foundAnEmptySquare)
{
throw new InvalidOperationException("The puzzle is already solved!");
}
return(PlacePieceAt(rotatedPiece, firstEmptyX, firstEmptyY));
}
public bool PlacePieceAt(RotatedPiece rotatedPiece, int x, int y)
{
if (x < 0 || x >= BoardSize)
{
throw new ArgumentOutOfRangeException("x");
}
if (y < 0 || y >= BoardSize)
{
throw new ArgumentOutOfRangeException("y");
}
if (x + rotatedPiece.Width > BoardSize)
{
return(false);
}
if (y + rotatedPiece.Height > BoardSize)
{
return(false);
}
// Check for any overlap with existing pieces before setting any squares.
for (var pieceX = 0; pieceX < rotatedPiece.Width; pieceX++)
{
for (var pieceY = 0; pieceY < rotatedPiece.Height; pieceY++)
{
var square = rotatedPiece.SquareAt(pieceX, pieceY);
if (square != null)
{
if (_pieces[x + pieceX, y + pieceY] != null)
{
return(false);
}
}
}
}
if (ColourOfSquareZeroZero.HasValue)
{
var colourOfSquareZeroZero = ColourOfSquareZeroZero.Value;
// Check that each square of the piece to be placed has
// the appropriate colour for its intended board position.
for (var pieceX = 0; pieceX < rotatedPiece.Width; pieceX++)
{
for (var pieceY = 0; pieceY < rotatedPiece.Height; pieceY++)
{
var square = rotatedPiece.SquareAt(pieceX, pieceY);
if (square != null)
{
var boardX = x + pieceX;
var boardY = y + pieceY;
var expectedColour = colourOfSquareZeroZero.RelativeColour(boardX, boardY);
if (square.Colour != expectedColour)
{
return(false);
}
}
}
}
}
Square firstSquare = null;
// It's now OK to go ahead and set the squares for the new piece.
for (var pieceX = 0; pieceX < rotatedPiece.Width; pieceX++)
{
for (var pieceY = 0; pieceY < rotatedPiece.Height; pieceY++)
{
var square = rotatedPiece.SquareAt(pieceX, pieceY);
if (square != null)
{
// Remember the first square in case we haven't set _colourOfSquareZeroZero yet.
if (firstSquare == null)
{
firstSquare = square;
}
_pieces[x + pieceX, y + pieceY] = new PieceHolder {
RotatedPiece = rotatedPiece, Square = square
};
}
}
}
if (!ColourOfSquareZeroZero.HasValue && firstSquare != null)
{
var boardX = x + firstSquare.X;
var boardY = y + firstSquare.Y;
ColourOfSquareZeroZero = firstSquare.Colour.RelativeColour(boardX, boardY);
}
return(true);
}
