Walker.cs

using System.Collections.Generic;
using System.Drawing;
using System.Linq;

namespace Dungeon
{
	public class Walker
	{
		private static readonly Dictionary<MoveDirection, Size> directionToOffset = new Dictionary<MoveDirection, Size>
		{
			{MoveDirection.Up, new Size(0, -1)},
			{MoveDirection.Down, new Size(0, 1)},
			{MoveDirection.Left, new Size(-1, 0)},
			{MoveDirection.Right, new Size(1, 0)}
		};

		private static readonly Dictionary<Size, MoveDirection> offsetToDirection = new Dictionary<Size, MoveDirection>
		{
			{new Size(0, -1), MoveDirection.Up},
			{new Size(0, 1), MoveDirection.Down},
			{new Size(-1, 0), MoveDirection.Left},
			{new Size(1, 0), MoveDirection.Right}
		};

		public static readonly IReadOnlyList<Size> PossibleDirections = offsetToDirection.Keys.ToList();


		public Point Position { get; }
		public Point? PointOfCollision { get; }

		public Walker(Point position)
		{
			Position = position;
			PointOfCollision = null;
		}

		private Walker(Point position, Point pointOfCollision)
		{
			Position = position;
			PointOfCollision = pointOfCollision;
		}

		public Walker WalkInDirection(Map map, MoveDirection direction)
		{
			var newPoint = Position + directionToOffset[direction];
			if (!map.InBounds(newPoint))
				return new Walker(Position, Position);
			return map.Dungeon[newPoint.X, newPoint.Y] == MapCell.Wall ? new Walker(newPoint, newPoint) : new Walker(newPoint);
		}

		public static MoveDirection ConvertOffsetToDirection(Size offset)
		{
			return offsetToDirection[offset];
		}
	}
}