private static AsciiMapSolution FindPath(AsciiMapBoard mapBoard)
{
var letters = new StringBuilder();
var characterPath = new StringBuilder();
var currentDirection = MoveDirection.None;
while (true)
{
var currentElement = mapBoard.CurrentElement;
characterPath.Append(currentElement);
if (currentElement == Constants.EndingPositionMark)
{
break;
}
if (char.IsLetter(currentElement) && !mapBoard.CurrentPositionVisited)
{
letters.Append(currentElement);
}
currentDirection = NextMoveDirection(currentDirection, mapBoard, characterPath);
if (currentDirection == MoveDirection.None)
{
throw new InvalidMapPathException(characterPath.ToString());
}
mapBoard.Move(currentDirection);
}
return(new AsciiMapSolution(letters.ToString(), characterPath.ToString()));
}
private static MoveDirection DetermineDirection(MoveDirection first, MoveDirection second, AsciiMapBoard mapBoard, StringBuilder characterPath)
{
var canGoFirst = first != MoveDirection.None && mapBoard.CanMove(first);
var canGoSecond = second != MoveDirection.None && mapBoard.CanMove(second);
var isFirstDirectionElement = InDirection(first, mapBoard.PeekElement(first));
var isSecondDirectionElement = InDirection(second, mapBoard.PeekElement(second));
//both directions shouldn't be valid
if (canGoFirst && isFirstDirectionElement && canGoSecond && isSecondDirectionElement)
{
throw new InvalidMapPathException(characterPath.ToString());
}
else if (canGoFirst && isFirstDirectionElement)
{
return(first);
}
else if (canGoSecond && isSecondDirectionElement)
{
return(second);
}
//there is no direction element in any direction, in that case one direction should be empty
else if (canGoFirst && canGoSecond)
{
throw new InvalidMapPathException(characterPath.ToString());
}
else if (canGoFirst)
{
return(first);
}
else if (canGoSecond)
{
return(second);
}
//we are not able to move in any of the offered directions
else
{
return(MoveDirection.None);
}
}
private static MoveDirection NextMoveDirection(MoveDirection currentDirection, AsciiMapBoard mapBoard, StringBuilder characterPath)
{
var direction = currentDirection;
if (currentDirection == MoveDirection.None)
{
direction = DetermineDirection(MoveDirection.Up, MoveDirection.Right, mapBoard, characterPath);
direction = DetermineDirection(direction, MoveDirection.Down, mapBoard, characterPath);
direction = DetermineDirection(direction, MoveDirection.Left, mapBoard, characterPath);
}
else if (!mapBoard.CanMove(currentDirection))
{
if (currentDirection == MoveDirection.Up || currentDirection == MoveDirection.Down)
{
direction = DetermineDirection(MoveDirection.Left, MoveDirection.Right, mapBoard, characterPath);
}
else if (currentDirection == MoveDirection.Left || currentDirection == MoveDirection.Right)
{
direction = DetermineDirection(MoveDirection.Up, MoveDirection.Down, mapBoard, characterPath);
}
}
return(direction);
}
