package fcm;

import java.lang.reflect.Method;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;

public class MethodReferenceTest {

  public static class TargetClass {
    
    public String getFoo() {
      return foo;
    }
    
    public void setFoo(String foo) {
      this.foo = foo;
    }
    
    private String foo;
  }
  
  public static class OriginClass {
    
    public void setBar(String bar) {
      this.bar = bar;
    }
    
    public String getBar() {
      return this.bar;
    }
    
    private String bar;
    
  }

  public static void mapProperty(Object from, Method fromMethod, Object to, Method toMethod) throws IllegalAccessException, InvocationTargetException {
    toMethod.invoke(to, fromMethod.invoke(from));
  }
  
  public static void mapField(Object from, Field fromField, Object to, Field toField) {
    toField.setAccessible(true);
    fromField.setAccessible(true);
    try {
      toField.set(to, fromField.get(from));
    } catch (IllegalAccessException e) {
      throw new RuntimeException("Impossible! We set everything accessible: " + e);
    }
  }
  
  public static void main(String[] args) throws IllegalAccessException, InvocationTargetException {
    OriginClass origin = new OriginClass();
    origin.setBar("origin mapped as property");
    TargetClass target = new TargetClass();

    mapProperty(origin, OriginClass#getBar(), target, TargetClass#setFoo(String));    
    System.out.println(target.getFoo());
    
    origin.setBar("origin mapped as field");
    mapField(origin, OriginClass#bar, target, TargetClass#foo);
    System.out.println(target.getFoo());
  }
  
  public static void theOldWay() throws
      NoSuchMethodException, IllegalAccessException, InvocationTargetException
  {
    OriginClass origin = new OriginClass();
    origin.setBar("bar on origin");    
    TargetClass target = new TargetClass();
    
    // We now want to copy the "bar" property of OriginClass to the "foo" property of the TargetClass
    Method fromMethod = OriginClass.class.getMethod("getFoo");
    Method toMethod = TargetClass.class.getMethod("setFoo", String.class);
    toMethod.invoke(target, fromMethod.invoke(origin));
    
    System.out.println(target.getFoo());
  }
  
  public static void theNewWay() throws
      IllegalAccessException, InvocationTargetException
  {
    OriginClass origin = new OriginClass();
    origin.setBar("bar on origin");    
    TargetClass target = new TargetClass();
    
    // We now want to copy the "bar" property of OriginClass to the "foo" property of the TargetClass
    // The compiler catches this error: Method fromMethod = OriginClass#getFoo();
    Method fromMethod = OriginClass#getBar();
    Method toMethod = TargetClass#setFoo(String);
    toMethod.invoke(target, fromMethod.invoke(origin));
    
    System.out.println(target.getFoo());
  }
  
  public static void withLibrarySupport() {
    OriginClass origin = new OriginClass();
    origin.setBar("bar on origin");    
    TargetClass target = new TargetClass();

    mapField(origin, OriginClass#bar, target, TargetClass#foo);

    System.out.println(target.getFoo());
  }

  
}