SECURE BY DESIGN DAY 04

import static org.apache.commons.lang3.Validate.*;

// 1. Immutable Value Object พร้อม Fail-Fast Invariant
public final class CreditScore {
    private static final int MIN_INVOICE_SCORE = 500;
    private final int score;

    public CreditScore(int computedScore) {
        isTrue(computedScore >= 0, "Credit score cannot be negative");
        this.score = computedScore;
    }
    public boolean isAcceptedForInvoicePayment() {
        return score > MIN_INVOICE_SCORE;
    }
}

// 2. Immutable Entity ปลอดภัยข้าม Threads โดยไม่ต้องใช้ synchronized
public final class Customer {
    private final CustomerId id;
    private final CreditScore creditScore;

    public Customer(CustomerId id, CreditScore creditScore) {
        this.id = notNull(id, "CustomerId required");
        this.creditScore = notNull(creditScore, "CreditScore required");
    }
    public CustomerId id() { return id; }
    public CreditScore creditScore() { return creditScore; }

    public boolean isAcceptedForInvoicePayment() {
        return creditScore.isAcceptedForInvoicePayment();
    }
}