private bool TryMove(int dx, int dy)
{
//preconditions
if (dx * dy != 0)
{
throw new InvalidOperationException("Only horizontal or vertical movement allowed.");
}
if (dx < -1 || dx > 1)
{
throw new ArgumentException(nameof(dx));
}
if (dy < -1 || dy > 1)
{
throw new ArgumentException(nameof(dy));
}
var x = PlayerX + dx;
var y = PlayerY + dy;
if (x < 0 || x >= Width || y < 0 || y >= Height)
{
return(false);
}
//Wall
if (Walls.Any(wall => wall.Item1 == x && wall.Item2 == y))
{
return(false);
}
var step = new Step();
//Crate
var crate = Crates.FirstOrDefault(c => c.X == x && c.Y == y);
if (crate != null)
{
var x0 = x + dx;
var y0 = y + dy;
if (Walls.Any(wall => wall.Item1 == x0 && wall.Item2 == y0) || Crates.Any(c => c.X == x0 && c.Y == y0))
{
return(false);
}
step.Crate = crate;
step.OldCrateX = crate.X;
step.OldCrateY = crate.Y;
crate.X += dx;
crate.Y += dy;
}
step.OldPlayerX = PlayerX;
step.OldPlayerY = PlayerY;
_steps.Push(step);
PlayerX += dx;
PlayerY += dy;
return(true);
}