Refactor: Refine Tier abstraction with enum

Author: mikybars

exercises/tiered_pricing/solutions/mperezi/src/main/java/tv/codely/checkout/TieredPricing.java

@@ -2,17 +2,25 @@
 
 public class TieredPricing {
 
-  private static final double FIRST_TIER_UNIT_PRICE = 299.0;
-  private static final double SECOND_TIER_UNIT_PRICE = 239.0;
-  public static final double THIRD_TIER_UNIT_PRICE = 219.0;
+  private enum Tier {
+    FIRST(299.0),
+    SECOND(239.0),
+    THIRD(219.0);
+
+    final double unitPrice;
+
+    Tier(double unitPrice) {
+      this.unitPrice = unitPrice;
+    }
+  }
 
   public double totalPrice(int subscriptions) {
     if (subscriptions < 3) {
-      return subscriptions * FIRST_TIER_UNIT_PRICE;
+      return subscriptions * Tier.FIRST.unitPrice;
     }
     if (subscriptions < 11) {
-      return subscriptions * SECOND_TIER_UNIT_PRICE;
+      return subscriptions * Tier.SECOND.unitPrice;
     }
-    return subscriptions * THIRD_TIER_UNIT_PRICE;
+    return subscriptions * Tier.THIRD.unitPrice;
   }
 }