// reflection/NullRobot.java
// (c)2021 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://OnJava8.com for more book information.
// Using a dynamic proxy to create an Optional

import onjava.*;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.Collections;
import java.util.List;
import java.util.stream.Stream;

class NullRobotProxyHandler
        implements InvocationHandler {
    private String nullName;
    private Robot proxied = new NRobot();

    NullRobotProxyHandler(Class<? extends Robot> type) {
        nullName = type.getSimpleName() + " NullRobot";
    }

    @Override
    public Object
    invoke(Object proxy, Method method, Object[] args)
            throws Throwable {
        return method.invoke(proxied, args);
    }

    private class NRobot implements Null, Robot {
        @Override
        public String name() {
            return nullName;
        }

        @Override
        public String model() {
            return nullName;
        }

        @Override
        public List<Operation> operations() {
            return Collections.emptyList();
        }
    }
}

public class NullRobot {
    public static Robot
    newNullRobot(Class<? extends Robot> type) {
        return (Robot) Proxy.newProxyInstance(
                NullRobot.class.getClassLoader(),
                new Class[]{Null.class, Robot.class},
                new NullRobotProxyHandler(type));
    }

    public static void main(String[] args) {
        Stream.of(
                new SnowRobot("SnowBee"),
                newNullRobot(SnowRobot.class)
        ).forEach(Robot::test);
    }
}
/* Output:
Robot name: SnowBee
Robot model: SnowBot Series 11
SnowBee can shovel snow
SnowBee shoveling snow
SnowBee can chip ice
SnowBee chipping ice
SnowBee can clear the roof
SnowBee clearing roof
[Null Robot]
Robot name: SnowRobot NullRobot
Robot model: SnowRobot NullRobot
*/