private void SolveBackEdge(Block block)
{
var nonBackSide = GetSideToRotate(block, Side.Back);
var nonWhiteColour = (block.Back == Colour.White ? block.GetColour(nonBackSide) : block.Back) ?? throw
new ArgumentException("Edge blocks must have a white and a non-white side.");
if (block.Back == nonWhiteColour)
{
ReOrientateBackEdge(nonBackSide);
block = _cube.GetBlock(block);
}
while (!BackEdgeIsOnCorrectSide(block, nonWhiteColour))
{
_cube.RotateClockwise(Side.Back);
block = _cube.GetBlock(block);
}
var layer = block.GetLayer(nonWhiteColour) ?? throw new Exception();
_cube.RotateClockwise(layer);
_cube.RotateClockwise(layer);
}