package springbook.learningtest.jdk.proxy;

import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertThat;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;

import org.junit.Test;


public class DynamicProxyTest {
	@Test
	public void simpleProxy() {
		Hello hello = new HelloTarget();
		assertThat(hello.sayHello("Toby"), is("Hello Toby"));
		assertThat(hello.sayHi("Toby"), is("Hi Toby"));
		assertThat(hello.sayThankYou("Toby"), is("Thank You Toby"));
		
		Hello proxiedHello = (Hello)Proxy.newProxyInstance(
				getClass().getClassLoader(), 
				new Class[] { Hello.class},
				new UppercaseHandler(new HelloTarget()));
		
//		Hello proxiedHello = new HelloUppercase(new HelloTarget());
		assertThat(proxiedHello.sayHello("Toby"), is("HELLO TOBY"));
		assertThat(proxiedHello.sayHi("Toby"), is("HI TOBY"));
		assertThat(proxiedHello.sayThankYou("Toby"), is("THANK YOU TOBY"));
	}
	
	static class HelloUppercase implements Hello {
		Hello hello;
		
		public HelloUppercase(Hello hello) {
			this.hello = hello;
		}

		public String sayHello(String name) {
			return hello.sayHello(name).toUpperCase();
		}

		public String sayHi(String name) {
			return hello.sayHi(name).toUpperCase();
		}

		public String sayThankYou(String name) {
			return hello.sayThankYou(name).toUpperCase();
		}
		
	}
	
	static class UppercaseHandler implements InvocationHandler {
		Object target;

		private UppercaseHandler(Object target) {
			this.target = target;
		}

		public Object invoke(Object proxy, Method method, Object[] args)
				throws Throwable {
			Object ret = method.invoke(target, args);
			if (ret instanceof String && method.getName().startsWith("say")) {
				return ((String)ret).toUpperCase();
			}
			else {
				return ret;
			}
		}
	}
	
	static interface Hello {
		String sayHello(String name);
		String sayHi(String name);
		String sayThankYou(String name);
	}
	
	static class HelloTarget implements Hello {
		public String sayHello(String name) {
			return "Hello " + name;
		}

		public String sayHi(String name) {
			return "Hi " + name;
		}

		public String sayThankYou(String name) {
			return "Thank You " + name;
		}
	}
}