feat(graduated-tiered-pricing): [tpp] 🔵 push logic to SubscriptionsBeingPurchased

Author: santakadev

exercises/graduated_tiered_prices/solutions/codely_triangulation-with-tpp/src/SubscriptionsBeingPurchased.ts

@@ -1,3 +1,17 @@
+import { Tier } from "./Tier";
+
 export class SubscriptionsBeingPurchased {
-  constructor(public value: number) {}
+  constructor(private value: number) {}
+
+  covers(tier: Tier): boolean {
+    return this.value >= tier.to;
+  }
+
+  reaches(tier: Tier): boolean {
+    return this.value >= tier.from;
+  }
+
+  numberOfSubscriptionsInTier(tier: Tier): number {
+    return this.value - tier.from + 1;
+  }
 }

exercises/graduated_tiered_prices/solutions/codely_triangulation-with-tpp/src/Tier.ts

@@ -11,19 +11,19 @@ export class Tier {
     return this.to - this.from + 1;
   }
 
-  fullTierTotal(): number {
+  private fullTierTotal(): number {
     return this.size() * this.price;
   }
 
   totalFor(subscriptions: SubscriptionsBeingPurchased): number {
-    if (subscriptions.value >= this.to) {
+    if (subscriptions.covers(this)) {
       return this.fullTierTotal();
     }
 
-    if (subscriptions.value < this.from) {
+    if (!subscriptions.reaches(this)) {
       return 0;
     }
-
-    return (subscriptions.value - this.from + 1) * this.price;
+    1;
+    return subscriptions.numberOfSubscriptionsInTier(this) * this.price;
   }
 }