1 files changed, 51 insertions, 0 deletions

diff --git a/src/ch/epfl/maze/physical/stragegies/reducer/CostReducer.java b/src/ch/epfl/maze/physical/stragegies/reducer/CostReducer.java
new file mode 100644
index 0000000..bfa5191
--- /dev/null
+++ b/src/ch/epfl/maze/physical/stragegies/reducer/CostReducer.java
@@ -0,0 +1,51 @@
+package ch.epfl.maze.physical.stragegies.reducer;
+
+import ch.epfl.maze.physical.Daedalus;
+import ch.epfl.maze.util.Direction;
+
+import java.util.EnumSet;
+import java.util.Set;
+
+/**
+ * A filter keeping only the cheapest choices.
+ *
+ * @author Pacien TRAN-GIRARD
+ */
+public interface CostReducer extends ChoiceReducer {
+
+    /**
+     * Returns the cost of a choice.
+     *
+     * @param choice   The Direction choice
+     * @param daedalus The Daedalus
+     * @return The cost of the given choice
+     */
+    int getChoiceCost(Direction choice, Daedalus daedalus);
+
+    @Override
+    default Set<Direction> reduce(Set<Direction> choices) {
+        return this.reduce(choices, null);
+    }
+
+    @Override
+    default Set<Direction> reduce(Set<Direction> choices, Daedalus daedalus) {
+        Set<Direction> cheaperChoices = EnumSet.noneOf(Direction.class);
+        int minimalCost = Integer.MAX_VALUE;
+
+        for (Direction choice : choices) {
+            int choiceCost = this.getChoiceCost(choice, daedalus);
+
+            if (choiceCost < minimalCost) {
+                cheaperChoices.clear();
+                minimalCost = choiceCost;
+            }
+
+            if (choiceCost <= minimalCost) {
+                cheaperChoices.add(choice);
+            }
+        }
+
+        return cheaperChoices;
+    }
+
+}