feat: create loyal points

Signed-off-by: Otavio Santana <otaviopolianasantana@gmail.com>

chapter-04/src/main/java/expert/os/books/ddd/chapter04/Customer.java

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+package expert.os.books.ddd.chapter04;
+
+public record Customer(String name, String email) {
+
+}

chapter-04/src/main/java/expert/os/books/ddd/chapter04/CustomerCategory.java

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+package expert.os.books.ddd.chapter04;
+
+public enum CustomerCategory {
+
+ BRONZE(0, 0),
+ SILVER(1000, 5),
+ GOLD(5000, 10),
+ PLATINUM(10000, 15);
+
+ private final int pointsThreshold;
+ private final int discountPercentage;
+
+ CustomerCategory(int pointsThreshold, int discountPercentage) {
+ this.pointsThreshold = pointsThreshold;
+ this.discountPercentage = discountPercentage;
+ }
+
+ public int pointsThreshold() {
+ return pointsThreshold;
+ }
+
+ public int discountPercentage() {
+ return discountPercentage;
+ }
+
+ public static CustomerCategory getCategoryByPoints(int points) {
+ if (points >= PLATINUM.pointsThreshold) {
+ return PLATINUM;
+ } else if (points >= GOLD.pointsThreshold) {
+ return GOLD;
+ } else if (points >= SILVER.pointsThreshold) {
+ return SILVER;
+ } else {
+ return BRONZE;
+ }
+ }
+
+}

chapter-04/src/main/java/expert/os/books/ddd/chapter04/LoyaltyCard.java

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+package expert.os.books.ddd.chapter04;
+
+public class LoyaltyCard {
+
+ private final String id;
+
+ private final Customer customer;
+ private LoyaltyPoints loyaltyPoints;
+ private boolean isPremium;
+ private CustomerCategory category;
+
+ public LoyaltyCard(String id, Customer customer) {
+ this.id = id;
+ this.customer = customer;
+ this.loyaltyPoints = new LoyaltyPoints(0);
+ this.isPremium = false;
+ this.category = CustomerCategory.BRONZE;
+ }
+
+ public String getId() {
+ return id;
+ }
+
+ public Customer getCustomer() {
+ return customer;
+ }
+
+ public int getPoints() {
+ return loyaltyPoints.getPoints();
+ }
+
+ public boolean isPremium() {
+ return isPremium;
+ }
+
+ public CustomerCategory getCategory() {
+ return category;
+ }
+
+ public void addPoints(int points) {
+ loyaltyPoints.addPoints(points);
+ updateCategory();
+ if (loyaltyPoints.canUpgradeToPremium()) {
+ this.isPremium = true;
+ }
+ }
+
+ private void updateCategory() {
+ this.category = CustomerCategory.getCategoryByPoints(loyaltyPoints.getPoints());
+ }
+}

chapter-04/src/main/java/expert/os/books/ddd/chapter04/LoyaltyPoints.java

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+package expert.os.books.ddd.chapter04;
+
+public class LoyaltyPoints {
+
+ private int points;
+
+ public LoyaltyPoints(int initialPoints) {
+ this.points = initialPoints;
+ }
+
+ public int getPoints() {
+ return points;
+ }
+
+ public void addPoints(int additionalPoints) {
+ this.points += additionalPoints;
+ }
+
+ public boolean canUpgradeToPremium() {
+ return this.points >= 1000;
+ }
+}