package dk.thoerup.circuitbreaker.invocations;

/* a annotation based invocation if it infeasible or you just don't like to implement yet another interface 
 * 
 *	class MyInvocation {
 *		@CircuitBreakerMethod
 *		public void doSomething() {}
 *	}
 *	
 *	..... snip......
 *
 *	MyInvocation my = new MyInvocation(); 
 *	AnnotatedInvocation invok = new AnnotatedInvocation(my);
 *  Object out = CircuitBreakerManager.getManager().getCircuitBreaker("mycb").invoke(invok);
 * 
 */


import java.lang.annotation.Annotation;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

import dk.thoerup.circuitbreaker.CircuitInvocation;

public class AnnotatedInvocation<T> implements CircuitInvocation<T> {
	
	public static class CBAnnotationException extends Exception {
		public CBAnnotationException() {
			super("No method found annotated with @CircuitBreakerMethod");
		}
		private static final long serialVersionUID = 1L;
		
	}
	
	private Object obj;
	
	public AnnotatedInvocation(Object obj) {
		this.obj = obj;
	}

	@SuppressWarnings("unchecked")
	public T proceed() throws Exception {
		
		Method methods[] = obj.getClass().getMethods();
		for(Method current : methods) {
			Annotation anno = current.getAnnotation(CircuitBreakerMethod.class);

			
			if (anno != null ) {
				try {
					return (T) current.invoke(obj, (Object[])null); //invoke the first method annotated
				} catch (InvocationTargetException e) {
					throw (Exception) e.getCause(); //unwrap any exception from InvocationTargetException
				}
			}
			
		}
		
		throw new CBAnnotationException(); //if no method was found
	}
}