discounts

src/chain-of-responsability/discounts-calculator/Calculator.ts

@@ -1,20 +1,19 @@
 import Budget from "./Budget";
+import DiscountMoreThanTwoItems from "./discounts/DiscountMoreThanTwoItems";
+import DiscountHigherThan500 from "./discounts/DiscountHigherThan500";
+import NoDiscount from "./discounts/NoDiscount";
 
 export default class Calculator {
   constructor(private budged: Budget) {}
 
   calculate(): number {
-    const total: number = this.budged.getTotal();
-    let discount = 0;
-    // discount more than 2 items
-    if (this.budged.getItems().length > 2) {
-      discount += total * 0.1;
-    }
+    const moreThantwo = new DiscountMoreThanTwoItems();
+    const higherThan500 = new DiscountHigherThan500();
+    const nodiscount = new NoDiscount();
 
-    if (total > 500) {
-      discount += total * 0.07;
-    }
+    moreThantwo.setNext(higherThan500);
+    higherThan500.setNext(nodiscount);
 
-    return total - discount;
+    return this.budged.getTotal() - moreThantwo.calculate(this.budged);
   }
 }

src/chain-of-responsability/discounts-calculator/discounts/Discount.ts

@@ -0,0 +1,6 @@
+import Budget from "../Budget";
+
+export default interface Discount {
+  calculate(budget: Budget): number;
+  setNext(discount: Discount): void;
+}

src/chain-of-responsability/discounts-calculator/discounts/DiscountHigherThan500.ts

@@ -0,0 +1,17 @@
+import Discount from "./Discount";
+import Budget from "../Budget";
+
+export default class DiscountHigherThan500 implements Discount {
+  private next!: Discount;
+  calculate(budget: Budget): number {
+    if (budget.getTotal() > 500) {
+      console.log("Disconto aplicado foi DiscountHigherThan500");
+      return budget.getTotal() * 0.15;
+    } else {
+      return this.next.calculate(budget);
+    }
+  }
+  setNext(next: Discount): void {
+    this.next = next;
+  }
+}

src/chain-of-responsability/discounts-calculator/discounts/DiscountMoreThanTwoItems.ts

@@ -0,0 +1,17 @@
+import Discount from "./Discount";
+import Budget from "../Budget";
+
+export default class DiscountMoreThanTwoItems implements Discount {
+  private next!: Discount;
+  calculate(budget: Budget): number {
+    if (budget.getItems().length > 2) {
+      console.log("Disconto aplicado foi DiscountMoreThanTwoItems");
+      return budget.getTotal() * 0.1;
+    } else {
+      return this.next.calculate(budget);
+    }
+  }
+  setNext(next: Discount): void {
+    this.next = next;
+  }
+}

src/chain-of-responsability/discounts-calculator/discounts/NoDiscount.ts

@@ -0,0 +1,12 @@
+import Discount from "./Discount";
+import Budget from "../Budget";
+
+export default class NoDiscount implements Discount {
+  calculate(budget: Budget): number {
+    console.log("Disconto aplicado foi NoDiscount");
+    return 0;
+  }
+  setNext(next: Discount): void {
+    throw new Error("No DIscount should be the last one implemented" + next);
+  }
+}