basic model

app/src/main/java/chess/model/Direction.java

@@ -0,0 +1,46 @@
+package chess.model;
+
+public enum Direction {
+
+	Unset(65),
+	Front(8), Back(-8), Left(-1), Right(1),
+	FrontLeft(7), FrontRight(9), BackLeft(-9), BackRight(-7);
+
+	private final int indexOffset;
+
+	Direction(int indexOffset) {
+		this.indexOffset = indexOffset;
+	}
+
+	public int getIndexOffset() {
+		return indexOffset;
+	}
+
+	public static Direction findDirection(Move move) {
+		assert move.isValid() : "Move is invalid!";
+		int diffX = move.getFinish().getX() - move.getStart().getX();
+		int diffY = move.getFinish().getY() - move.getStart().getY();
+
+		if (diffX == 0 && diffY < 0)
+			return Direction.Back;
+		if (diffX == 0 && diffY > 0)
+			return Direction.Front;
+
+		if (diffX < 0 && diffY == 0)
+			return Direction.Left;
+		if (diffX > 0 && diffY == 0)
+			return Direction.Right;
+
+		if (diffX < 0 && -diffX == diffY)
+			return Direction.FrontLeft;
+		if (diffX > 0 && diffX == diffY)
+			return Direction.FrontRight;
+
+		if (diffY < 0 && diffX == diffY)
+			return Direction.BackLeft;
+		if (diffY > 0 && diffX == -diffY)
+			return Direction.BackRight;
+
+		return Direction.Unset;
+	}
+}