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package ch.epfl.maze.physical;
import ch.epfl.maze.util.Direction;
import ch.epfl.maze.util.Vector2D;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Random;
import java.util.stream.Collectors;
/**
* A probabilistic animal that use a random component in its decision making process.
*
* @author Pacien TRAN-GIRARD
*/
abstract public class ProbabilisticAnimal extends Animal {
private final Random randomSource;
protected Direction currentDirection;
/**
* Constructs a probabilistic animal with a starting position
*
* @param position Starting position of the probabilistic animal in the labyrinth
*/
public ProbabilisticAnimal(Vector2D position) {
super(position); // no pun intended
this.randomSource = new Random();
this.currentDirection = Direction.NONE;
}
/**
* Excludes the given direction from possible choices.
*
* @param choices An array of choices
* @param toExclude The Direction to exclude
* @return An array of smart choices
*/
protected Direction[] excludeDirection(Direction[] choices, Direction toExclude) {
return (new ArrayList<>(Arrays.asList(choices)))
.stream()
.filter(dir -> dir != toExclude)
.collect(Collectors.toList())
.toArray(new Direction[0]);
}
/**
* Excludes the origin direction from possible choices.
*
* @param choices An array of choices
* @return An array of smart choices
*/
protected Direction[] excludeOrigin(Direction[] choices) {
return this.excludeDirection(choices, this.currentDirection.reverse());
}
/**
* Returns a random Direction from the given choices.
*
* @param choices An array of Direction
* @return A random Direction taken from the given choices
*/
protected Direction getRandomDirection(Direction[] choices) {
return choices[randomSource.nextInt(choices.length)];
}
/**
* Moves according to an improved version of a <i>random walk</i> : the
* probabilistic animal does not directly retrace its steps if not forced.
*/
@Override
public Direction move(Direction[] choices) {
if (choices.length == 0) return Direction.NONE;
Direction[] smartChoices = choices.length > 1 ? this.excludeOrigin(choices) : choices;
this.currentDirection = this.getRandomDirection(smartChoices);
return this.currentDirection;
}
}
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