1 files changed, 193 insertions, 3 deletions

diff --git a/src/ch/epfl/maze/physical/GhostPredator.java b/src/ch/epfl/maze/physical/GhostPredator.java
index 34b8c4f..44bb1f6 100644
--- a/src/ch/epfl/maze/physical/GhostPredator.java
+++ b/src/ch/epfl/maze/physical/GhostPredator.java
@@ -1,7 +1,11 @@
 package ch.epfl.maze.physical;
 
+import ch.epfl.maze.util.Direction;
 import ch.epfl.maze.util.Vector2D;
 
+import java.util.ArrayList;
+import java.util.List;
+
 /**
  * Predator ghost that have two different modes and a home position in the labyrinth.
  *
@@ -9,9 +13,45 @@ import ch.epfl.maze.util.Vector2D;
  */
 abstract public class GhostPredator extends Predator {
 
-    /* constants relative to the Pac-Man game */
-    public static final int SCATTER_DURATION = 14;
-    public static final int CHASE_DURATION = 40;
+    public enum Mode {
+        CHASE(40),
+        SCATTER(14);
+
+        public static final Mode DEFAULT = CHASE;
+        public final int duration;
+
+        /**
+         * Constructs a new Mode with the given duration.
+         *
+         * @param duration The duration in cycles
+         */
+        Mode(int duration) {
+            this.duration = duration;
+        }
+
+        /**
+         * Returns the next Mode.
+         *
+         * @return The next Mode
+         */
+        public Mode getNext() {
+            switch (this) {
+                case CHASE:
+                    return SCATTER;
+                case SCATTER:
+                    return CHASE;
+                default:
+                    return DEFAULT;
+            }
+        }
+    }
+
+    private static Prey commonPrey;
+
+    private final Vector2D homePosition;
+
+    private Mode mode;
+    private int modeCycle;
 
     /**
      * Constructs a predator with a specified position.
@@ -20,6 +60,156 @@ abstract public class GhostPredator extends Predator {
      */
     public GhostPredator(Vector2D position) {
         super(position);
+
+        this.homePosition = position;
+
+        this.mode = Mode.DEFAULT;
+        this.modeCycle = 0;
     }
 
+    /**
+     * Selects a new random Prey to chase in the Daedalus.
+     *
+     * @param daedalus The Daedalus
+     * @return The Chosen One
+     */
+    private static Prey selectRandomPrey(Daedalus daedalus) {
+        if (daedalus.getPreys().isEmpty()) return null;
+
+        int randomPreyIndex = GhostPredator.RANDOM_SOURCE.nextInt(daedalus.getPreys().size());
+        return daedalus.getPreys().get(randomPreyIndex);
+    }
+
+    /**
+     * Returns the commonly targeted Prey.
+     *
+     * @param daedalus The Daedalus
+     * @return The common Prey
+     */
+    private static Prey getPrey(Daedalus daedalus) {
+        if (GhostPredator.commonPrey == null || !daedalus.hasPrey(GhostPredator.commonPrey))
+            GhostPredator.commonPrey = GhostPredator.selectRandomPrey(daedalus);
+
+        return GhostPredator.commonPrey;
+    }
+
+    /**
+     * Returns the commonly targeted Prey's position.
+     *
+     * @param daedalus The Daedalus
+     * @return The position of the Prey
+     */
+    protected final Vector2D getPreyPosition(Daedalus daedalus) {
+        Prey prey = GhostPredator.getPrey(daedalus);
+
+        if (prey == null) return this.homePosition;
+        return prey.getPosition();
+    }
+
+    /**
+     * Returns the commonly targeted Prey's Direction.
+     *
+     * @param daedalus The Daedalus
+     * @return The Direction the Prey is facing
+     */
+    protected final Direction getPreyDirection(Daedalus daedalus) {
+        Prey prey = GhostPredator.getPrey(daedalus);
+
+        if (prey == null) return Direction.NONE;
+        return prey.getCurrentDirection();
+    }
+
+    /**
+     * Calculates the Euclidean distance from the adjacent position at the given Direction to the target position.
+     *
+     * @param dir The adjacent Direction
+     * @param targetPosition The targeted position
+     * @return The Euclidean distance between the two positions
+     */
+    private double calcDistanceFromAdjacentDirectionTo(Direction dir, Vector2D targetPosition) {
+        return this
+                .getPosition()
+                .addDirectionTo(dir)
+                .sub(targetPosition)
+                .dist();
+    }
+
+    /**
+     * Selects the best Direction in the given choices by minimizing the Euclidean distance to the targeted position.
+     *
+     * @param targetPosition The targeted position
+     * @param choices An array of Direction choices
+     * @return An array of optimal Direction choices
+     */
+    private Direction[] selectBestPaths(Vector2D targetPosition, Direction[] choices) {
+        List<Direction> bestPaths = new ArrayList<>();
+        double minDist = Double.MAX_VALUE;
+
+        for (Direction dir : choices) {
+            double dist = this.calcDistanceFromAdjacentDirectionTo(dir, targetPosition);
+
+            if (dist < minDist) {
+                minDist = dist;
+                bestPaths.clear();
+            }
+
+            if (dist <= minDist)
+                bestPaths.add(dir);
+        }
+
+        return bestPaths.toArray(new Direction[bestPaths.size()]);
+    }
+
+    /**
+     * Rotates to the next Mode.
+     */
+    protected void rotateMode() {
+        this.mode = this.mode.getNext();
+        this.modeCycle = 0;
+    }
+
+    /**
+     * Increments the cycle counter and rotates to the next Mode if the Mode's duration has been reached.
+     */
+    private void countCycle() {
+        this.modeCycle += 1;
+
+        if (this.modeCycle >= this.mode.duration)
+            this.rotateMode();
+    }
+
+    @Override
+    public Direction move(Direction[] choices, Daedalus daedalus) {
+        this.countCycle();
+
+        Direction[] smartChoices = choices.length > 1 ? this.excludeOrigin(choices) : choices;
+        Direction[] bestPaths = this.selectBestPaths(this.getTargetPosition(daedalus), smartChoices);
+        return this.move(bestPaths);
+    }
+
+    /**
+     * Returns the position to target according to the current Mode.
+     *
+     * @param daedalus The Daedalus
+     * @return The position to target
+     */
+    protected Vector2D getTargetPosition(Daedalus daedalus) {
+        switch (this.mode) {
+            case CHASE:
+                return this.getPreyTargetPosition(daedalus);
+            case SCATTER:
+                return this.homePosition;
+            default:
+                return this.homePosition;
+        }
+    }
+
+    /**
+     * Returns the Prey's projected targeted position.
+     *
+     * @param daedalus The Daedalus
+     * @return The projected position
+     */
+    protected abstract Vector2D getPreyTargetPosition(Daedalus daedalus);
+
 }