public IEnumerable<LayoutInstance> Scan(PuzzleBoard board)
{
var result = new List<LayoutInstance>();
if (board.Dimensions.Y < 1)
return result;
int numFreeBlocks = 2 * board.Dimensions.X;
foreach (LayoutDescription desc in layouts)
{
int layoutWidth = desc.Bottom.Length;
int layoutHeight = string.IsNullOrEmpty(desc.Top) ? 1 : 2;
if (layoutWidth > board.Dimensions.X)
continue;
for (int y = ((layoutHeight == 1) ? 0 : 1); y >= layoutHeight - 1; y--)
{
for (int x = 0; x <= board.Dimensions.X - layoutWidth; x += 2)
{
if (MatchLayout(board, desc, x, board.Dimensions.Y - 1 - y))
{
var instance = new LayoutInstance(desc, new Point(x, board.Dimensions.Y - 1 - y));
result.Add(instance);
ClearLayout(board, desc, x, board.Dimensions.Y - 1 - y);
x += layoutWidth;
numFreeBlocks -= layoutWidth * layoutHeight;
if (numFreeBlocks <= 0)
return result;
}
}
}
}
return result;
}
protected bool MatchLayout(PuzzleBoard board, LayoutDescription desc, int startX, int startY)
{
int layoutWidth = desc.Bottom.Length;
int layoutHeight = (string.IsNullOrEmpty(desc.Top) ? 1 : 2);
string pattern = desc.Top + desc.Bottom;
int i = 0;
for (int y = startY; y < startY + layoutHeight; y++)
for (int x = startX; x < startX + layoutWidth; x++)
{
if (board.Blocks[x, y] != CharToBlock(pattern[i++]))
return false;
}
return true;
}
private void ClearLayout(PuzzleBoard board, LayoutDescription desc, int startX, int startY)
{
int layoutWidth = desc.Bottom.Length;
int layoutHeight = (string.IsNullOrEmpty(desc.Top) ? 1 : 2);
for (int y = startY; y < startY + layoutHeight; y++)
for (int x = startX; x < startX + layoutWidth; x++)
{
board.Blocks[x, y] = BlockType.Empty;
}
}