// Helene Martin, CSE 142
// Snake critters move in a lengthening horizontal "slither" pattern:
// E, S, WW, S, EEE, S, WWWW, S, EEEEE, S, ...

public class Snake extends Critter {
   private int horizontalSize;   // size of current horizontal move
   private int currentSteps;     // steps taken in current direction   
   
   public Snake() {
      horizontalSize = 1;
   }
   
   // Development strategy: 
   // - we started by writing out several moves a Snake would make
   // - we identified properties of the pattern we wanted to create
   // - we chose the state we would use to create the movement
   // - we wrote the method
   
   // Scratch work:
   // E S W W S E E E S W W W W S E E E E E
   //             ^
   // 1 1 2 2 2 3 3 3 3 4         5
   // E   W     E       W         E
   // 0 1 0 1 2 0 1 2 3 0 1 2 3 4 5
   // always starts at E
   // number of E or W movement increments after each S
   //    - E and W alternate
   //    - always go E an odd number of times, W an even number of times
   // always go S just once
   public Direction getMove() {
      if (horizontalSize == currentSteps) {
         currentSteps = 0;
         horizontalSize++;
         return Direction.SOUTH;
      } else { // we haven't reached S in the pattern (currentSteps < horizontalSize)
         currentSteps++;
         if (horizontalSize % 2 == 1) {
            return Direction.EAST;
         } else {
            return Direction.WEST;
         }
      }
   }

   public String toString() {
      return "S";
   }
}