2) Модели (SRP)

2) Модели (SRP)

import java.util.UUID;

public record Money(String currency, java.math.BigDecimal amount) {
    public Money add(Money other) {
        if (!currency.equals(other.currency)) throw new IllegalArgumentException("Currency mismatch");
        return new Money(currency, amount.add(other.amount));
    }
    public Money subtract(Money other) {
        if (!currency.equals(other.currency)) throw new IllegalArgumentException("Currency mismatch");
        return new Money(currency, amount.subtract(other.amount));
    }
}

public final class Order {
    private final String id = UUID.randomUUID().toString();
    private final String customerEmail;
    private Money total;
    private boolean paid;

    public Order(String customerEmail, Money total) {
        this.customerEmail = customerEmail;
        this.total = total;
    }
    public String id()              { return id; }
    public String customerEmail()   { return customerEmail; }
    public Money total()            { return total; }
    public boolean isPaid()         { return paid; }
    public void markPaid()          { this.paid = true; }
    public void applyDiscount(Money discounted) { this.total = discounted; }
}

public record PaymentResult(boolean success, String txId, String message) { }