Pattern Strategy With Visitor Embeded in Enum on Domain Object

StrategyVisitor.java

package core.chapadaguides;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.Getter;
import lombok.ToString;

import java.math.BigDecimal;
import java.util.List;

public class StrategyMain {

    interface Strategy {
        Result execute(Payment payment);

        default Result calculateResult(Payment payment, double feeAmountPercentage1) {
            BigDecimal amount = payment.getAmount();
            BigDecimal amountFee = amount.multiply(BigDecimal.valueOf(feeAmountPercentage1));
            BigDecimal netAmount = amount.subtract(amountFee);
            return Result.of(amount, netAmount, amountFee);
        }

    }

    @Getter
    @AllArgsConstructor
    enum StrategyType {
        CREDIT_CARD(new CreditCardStrategy()),
        DEBIT_CARD(new DebitCardStrategy()),
        PIX(new PixStrategy());

        final Strategy strategy;
    }

    static class CreditCardStrategy implements Strategy {

        final double feeAmountPercentage = 0.10; // 10%

        @Override
        public Result execute(Payment payment) {
            return calculateResult(payment, feeAmountPercentage);
        }
    }

    static class DebitCardStrategy implements Strategy {

        final double feeAmountPercentage = 0.05; // 5%

        @Override
        public Result execute(Payment payment) {
            return calculateResult(payment, feeAmountPercentage);
        }
    }

    static class PixStrategy implements Strategy {

        final double feeAmountPercentage = 0.01; // 1%

        @Override
        public Result execute(Payment payment) {
            return calculateResult(payment, feeAmountPercentage);
        }

    }


    @Data
    @AllArgsConstructor
    static class Payment {

        private StrategyType type;
        private String name;
        private BigDecimal amount;

        public Result calculateAmount() {
            return type.getStrategy().execute(this);
        }

    }

    @ToString
    @Data
    @AllArgsConstructor(staticName = "of")
    static class Result {
        final BigDecimal amount;
        final BigDecimal netAmount;
        final BigDecimal amountFee;
    }

    private static void process() {
        List<Payment> paymentList = List.of(
                new Payment(StrategyType.CREDIT_CARD, "Boll", BigDecimal.valueOf(1_000)),
                new Payment(StrategyType.DEBIT_CARD, "Phone", BigDecimal.valueOf(300)),
                new Payment(StrategyType.PIX, "Car", BigDecimal.valueOf(1_000_000))
        );
        for (Payment payment : paymentList) {
            Result result = payment.calculateAmount();
            System.out.println(payment.getName() + " | " + payment.getType() + " : " + result);
        }

        // ------> Output <-------
        // ------------------------------------------------------------------------------------
        // Boll | CREDIT_CARD : StrategyMain.Result(amount=1000, netAmount=900.0, amountFee=100.0)
        // Phone | DEBIT_CARD : StrategyMain.Result(amount=300, netAmount=285.00, amountFee=15.00)
        // Car | PIX : StrategyMain.Result(amount=1000000, netAmount=990000.00, amountFee=10000.00)
    }

    public static void main(String[] args) {
        process();
    }

}

The idea was simplify the Strategy and so the mutability became from the Domain Object (DO)