2 files changed, 78 insertions, 54 deletions

diff --git a/src/ch/epfl/maze/physical/zoo/Panda.java b/src/ch/epfl/maze/physical/zoo/Panda.java
index f4c2035..2f46b6d 100644
--- a/src/ch/epfl/maze/physical/zoo/Panda.java
+++ b/src/ch/epfl/maze/physical/zoo/Panda.java
@@ -1,7 +1,8 @@
 package ch.epfl.maze.physical.zoo;
 
 import ch.epfl.maze.physical.Animal;
-import ch.epfl.maze.physical.ProbabilisticAnimal;
+import ch.epfl.maze.physical.stragegies.picker.RandomPicker;
+import ch.epfl.maze.physical.stragegies.reducer.BackwardReducer;
 import ch.epfl.maze.util.Direction;
 import ch.epfl.maze.util.Trail;
 import ch.epfl.maze.util.Vector2D;
@@ -16,7 +17,7 @@ import java.util.stream.Collectors;
  * @author EPFL
  * @author Pacien TRAN-GIRARD
  */
-public class Panda extends ProbabilisticAnimal {
+public class Panda extends Animal implements BackwardReducer, RandomPicker {
 
     private final Trail trail;
 
@@ -27,20 +28,65 @@ public class Panda extends ProbabilisticAnimal {
      */
     public Panda(Vector2D position) {
         super(position);
+
         this.trail = new Trail();
     }
 
     /**
+     * Reduces the set of Direction choice using <i>Trémeaux's Algorithm</i> and,
+     * if possible, avoiding going backward.
+     *
+     * @param choices A set of possible choices
+     * @return A subset of choices
+     */
+    @Override
+    public Set<Direction> reduce(Set<Direction> choices) {
+        Set<Direction> bestChoices = this.selectBestDirections(choices);
+        return bestChoices.size() > 1 ? BackwardReducer.super.reduce(bestChoices) : bestChoices;
+    }
+
+    /**
+     * Moves according to <i>Trémeaux's Algorithm</i>: when the panda
+     * moves, it will mark the ground at most two times (with two different
+     * colors). It will prefer taking the least marked paths. Special cases
+     * have to be handled, especially when the panda is at an intersection.
+     */
+    @Override
+    public Direction move(Set<Direction> choices) {
+        Direction choice = this.pick(this.reduce(choices));
+
+        if (this.shouldMarkCurrentPosition(choices, choice))
+            this.markCurrentPosition(choices);
+
+        return choice;
+    }
+
+    @Override
+    public Animal copy() {
+        return new Panda(this.getPosition());
+    }
+
+    /**
      * Checks if the current position is an intersection given the possible choices.
      *
      * @param choices A set of possible Directions
-     * @return T(the current position is an intersection)
+     * @return T(The set of choices corresponds to an intersection)
      */
-    private boolean isIntersection(Set<Direction> choices) {
+    private boolean onIntersection(Set<Direction> choices) {
         return choices.size() > 2;
     }
 
     /**
+     * Checks if the current position is a dead end.
+     *
+     * @param choices A set of possible Directions
+     * @return T(The set of choices and their Marking corresponds to a dead end)
+     */
+    private boolean inDeadEnd(Set<Direction> choices) {
+        return choices.size() == 1 && this.allChoicesLeadingTo(choices, Trail.Marking.AVOID_MARKING);
+    }
+
+    /**
      * Get the Marking at the adjacent position given the Direction.
      *
      * @param dir The Direction from the current position
@@ -52,6 +98,32 @@ public class Panda extends ProbabilisticAnimal {
     }
 
     /**
+     * Determines if the current position should be marked according to the rules of the <i>Trémeaux's Algorithm</i>,
+     * avoiding intersections over-marking.
+     *
+     * @param choices A set of possible Directions
+     * @param choice  The selected Direction
+     * @return T(the current position should be marked)
+     */
+    private boolean shouldMarkCurrentPosition(Set<Direction> choices, Direction choice) {
+        return !(this.onIntersection(choices)
+                && this.trail.getMarking(this.getPosition()) == Trail.Marking.AVOID_MARKING
+                && this.getMarkingAtDirection(choice) == Trail.Marking.NO_MARKING);
+    }
+
+    /**
+     * Marks the current position according to the rules of the <i>Trémeaux's Algorithm</i>.
+     *
+     * @param choices A set of possible Direction to take
+     */
+    private void markCurrentPosition(Set<Direction> choices) {
+        if (this.inDeadEnd(choices))
+            this.trail.markPosition(this.getPosition(), Trail.Marking.NO_GO_MARKING);
+        else
+            this.trail.markPosition(this.getPosition());
+    }
+
+    /**
      * Checks if all Direction choices are leading to the given Marking.
      *
      * @param choices A set of possible Directions
@@ -86,7 +158,7 @@ public class Panda extends ProbabilisticAnimal {
      */
     private Set<Direction> selectBestDirections(Set<Direction> choices) {
         // special case
-        if (this.isIntersection(choices) && this.allChoicesLeadingTo(choices, Trail.Marking.AVOID_MARKING))
+        if (this.onIntersection(choices) && this.allChoicesLeadingTo(choices, Trail.Marking.AVOID_MARKING))
             return EnumSet.of(this.getDirection().reverse());
 
         // general case
@@ -99,52 +171,4 @@ public class Panda extends ProbabilisticAnimal {
         return EnumSet.noneOf(Direction.class);
     }
 
-    /**
-     * Determines if the current position should be marked according to the rules of the <i>Trémeaux's Algorithm</i>,
-     * avoiding intersections over-marking.
-     *
-     * @param choices A set of possible Directions
-     * @param choice  The selected Direction
-     * @return T(the current position should be marked)
-     */
-    private boolean shouldMarkCurrentPosition(Set<Direction> choices, Direction choice) {
-        return !(this.isIntersection(choices)
-                && this.trail.getMarking(this.getPosition()) == Trail.Marking.AVOID_MARKING
-                && this.getMarkingAtDirection(choice) == Trail.Marking.NO_MARKING);
-    }
-
-    /**
-     * Marks the current position according to the rules of the <i>Trémeaux's Algorithm</i>.
-     *
-     * @param choices A set of possible Direction to take
-     */
-    private void markCurrentPosition(Set<Direction> choices) {
-        if (choices.size() == 1 && this.allChoicesLeadingTo(choices, Trail.Marking.AVOID_MARKING)) // dead end
-            this.trail.markPosition(this.getPosition(), Trail.Marking.NO_GO_MARKING);
-        else
-            this.trail.markPosition(this.getPosition());
-    }
-
-    /**
-     * Moves according to <i>Trémeaux's Algorithm</i>: when the panda
-     * moves, it will mark the ground at most two times (with two different
-     * colors). It will prefer taking the least marked paths. Special cases
-     * have to be handled, especially when the panda is at an intersection.
-     */
-    @Override
-    public Direction move(Set<Direction> choices) {
-        Set<Direction> smartChoices = this.selectBestDirections(choices);
-        Direction choice = super.move(smartChoices);
-
-        if (this.shouldMarkCurrentPosition(choices, choice))
-            this.markCurrentPosition(choices);
-
-        return choice;
-    }
-
-    @Override
-    public Animal copy() {
-        return new Panda(this.getPosition());
-    }
-
 }
diff --git a/src/ch/epfl/maze/util/Trail.java b/src/ch/epfl/maze/util/Trail.java
index ed806c5..33e0975 100644
--- a/src/ch/epfl/maze/util/Trail.java
+++ b/src/ch/epfl/maze/util/Trail.java
@@ -54,7 +54,7 @@ public class Trail {
      */
     public Marking getMarking(Vector2D position) {
         Marking marking = this.trail.get(position);
-        return marking != null ? marking : Marking.DEFAULT;
+        return marking != null ? marking : Marking.NO_MARKING;
     }
 
     /**