/// <summary>
/// Determine next direction
/// </summary>
/// <param name="currentDirection"></param>
/// <param name="mapBoard"></param>
/// <param name="characterPath"></param>
/// <returns></returns>
private static MapMove FindNextMove(MapMove currentDirection, MapDirections mapBoard, StringBuilder characterPath)
{
var direction = currentDirection;
if (currentDirection == MapMove.None)
{
direction = GetDirection(MapMove.Up, MapMove.Right, mapBoard, characterPath);
direction = GetDirection(direction, MapMove.Down, mapBoard, characterPath);
direction = GetDirection(direction, MapMove.Left, mapBoard, characterPath);
}
else if (!mapBoard.IsValidMove(currentDirection))
{
// if current position is up or down go left or right and vice versa
if (currentDirection == MapMove.Up || currentDirection == MapMove.Down)
{
direction = GetDirection(MapMove.Left, MapMove.Right, mapBoard, characterPath);
}
else if (currentDirection == MapMove.Left || currentDirection == MapMove.Right)
{
direction = GetDirection(MapMove.Up, MapMove.Down, mapBoard, characterPath);
}
}
return(direction);
}
/// <summary>
/// Based on two input directions determine next move
/// </summary>
/// <param name="first"></param>
/// <param name="second"></param>
/// <param name="mapBoard"></param>
/// <param name="characterPath"></param>
/// <returns></returns>
private static MapMove GetDirection(MapMove first, MapMove second, MapDirections mapBoard, StringBuilder characterPath)
{
var takeFirst = first != MapMove.None && mapBoard.IsValidMove(first);
var takeSecond = second != MapMove.None && mapBoard.IsValidMove(second);
var firstDirectionMark = GetDirectionMove(first, mapBoard.SearchNextChar(first));
var secondDirectionMark = GetDirectionMove(second, mapBoard.SearchNextChar(second));
// first check for possible invalid moves
// only one direction is valid
if (takeFirst && firstDirectionMark && takeSecond && secondDirectionMark)
{
string exceptionMessage = "Path is invalid at character: " + characterPath.ToString();
throw new MapException(exceptionMessage);
}
// only one direction is valid
else if (takeFirst && takeSecond)
{
string exceptionMessage = "Path is invalid at character: " + characterPath.ToString();
throw new MapException(exceptionMessage);
}
// take valid move
else if (takeFirst && firstDirectionMark)
{
return(first);
}
else if (takeSecond && secondDirectionMark)
{
return(second);
}
else if (takeFirst)
{
return(first);
}
else if (takeSecond)
{
return(second);
}
else
{
return(MapMove.None);
}
}
/// <summary>
/// Iterate until end character is found and build map
/// </summary>
/// <param name="mapBoard"></param>
/// <returns></returns>
private static MapTravelResult CreateMapResult(MapDirections mapBoard)
{
var letters = new StringBuilder();
var characterPath = new StringBuilder();
var currentDirection = MapMove.None;
while (true)
{
var currentElement = mapBoard.CurrentElement;
characterPath.Append(currentElement);
if (currentElement == MapConstant.End)
{
break;
}
if (char.IsLetter(currentElement) && !mapBoard.CurrentPosition)
{
letters.Append(currentElement);
}
currentDirection = FindNextMove(currentDirection, mapBoard, characterPath);
if (currentDirection == MapMove.None)
{
string exceptionMessage = "Path is invalid at character: " + characterPath.ToString();
throw new MapException(exceptionMessage);
}
mapBoard.AdjustIndexes(currentDirection);
}
return(new MapTravelResult(letters.ToString(), characterPath.ToString()));
}