private bool CanDragContinuosly(INavigator navigator, int keeperStartPos, int boxStartPos, int keeperEndPos, int boxEndPos, Queue <Tuple <INavigator, int, int, int, int> > scope, HashSet <INavigator> drags)
{
if (!drags.Add(navigator))
{
return(false);
}
var touchPoints = new List <SokobanPathItem>();
navigator.ForeachNeighborsRecursively(keeperStartPos, (currentPos, key, neighbor, cellType) =>
{
if (neighbor == boxStartPos)
{
var targetKeeperPos = navigator.GetPosition(navigator.GetOppositeKey(key), currentPos);
if (navigator.CanHoldKeeper(targetKeeperPos))
{
touchPoints.Add(new SokobanPathItem()
{
Position = currentPos,
Key = key,
StepsToTarget = 1
});
}
}
return(navigator.CanHoldKeeper(neighbor));
});
if (touchPoints.Count == 0)
{
// keeper doesn`t even touch the box
return(false);
}
foreach (var touchPoint in touchPoints)
{
var keeperPos = touchPoint.Position;
var keeperTarget = navigator.GetPosition(navigator.GetOppositeKey(touchPoint.Key), keeperPos);
var boxPos = navigator.GetPosition(touchPoint.Key, keeperPos);
if (keeperTarget == keeperEndPos && keeperPos == boxEndPos)
{
return(true);
}
else
{
var newNavigator = (Navigator)Drag(keeperPos, keeperTarget.Value, boxPos.Value);
scope.Enqueue(new Tuple <INavigator, int, int, int, int>(newNavigator, keeperTarget.Value, keeperPos, keeperEndPos, boxEndPos));
}
}
return(false);
}