// CSE 142, Marty Stepp
//
// A Snake moves in a lengthening horizontal "slither" pattern:
// E, S, WW, S, EEE, S, WWWW, S, EEEEE, S, ...
//
// We did this example in lecture to practice figuring out what state
// is needed to implement a particular complex movement pattern.

public class Snake extends Critter {
	private boolean west;   // am I going west right now?
	private int moves;      // how many moves have I made in current direction?
	private int layer;      // which E/W pass am I on?
	
	public Snake() {
		west = false;       // initially going east, not west
		moves = 0;
		layer = 1;          // will walk a total of 1 move east, at first
	}

	// Implements the slithering pattern of movement.
	// E, S, WW, S, EEE, S, WWWW, S, EEEEE, S, ...
	public Direction getMove() {
		if (moves < layer) {
			// I still need to go sideways more
			moves++;
			if (west) {
				return Direction.WEST;
			} else {
				return Direction.EAST;
			}
		} else {
			// I am done walking sideways;
			// go down, reset moves, and increase slither walk length
			west = !west;
			moves = 1;
			layer++;
			return Direction.SOUTH;
		}
	}
	
	public String toString() {
		return "S";
	}
}