package com.khotyn.test;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.lang.annotation.Annotation;
import java.lang.instrument.ClassDefinition;
import java.lang.instrument.UnmodifiableClassException;

import org.objectweb.asm.AnnotationVisitor;
import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.Type;

/**
 * Test adding an annotation to a class then redefine it.
 * 
 * @author khotyn
 * 
 */
public class AnnotationAddTest {
    public static void main(String[] args) throws FileNotFoundException, IOException, ClassNotFoundException, UnmodifiableClassException, NoSuchFieldException, SecurityException,
            IllegalArgumentException, IllegalAccessException {
        ClassReader classReader = new ClassReader(new FileInputStream(new File("D:/workspace/test/target/classes/com/khotyn/test/Test.class")));
        ClassWriter classWriter = new ClassWriter(0);
        ClassVisitor annotationAdder = new ClassVisitor(Opcodes.ASM4, classWriter) {
            @Override
            public void visitEnd() {
                AnnotationVisitor av = cv.visitAnnotation(Type.getDescriptor(TestAnnotation.class), true);
                if (av != null) {
                    av.visitEnd();
                }
                super.visitEnd();
            }

        };
        classReader.accept(annotationAdder, 0);

        InstrumentationHolder.getInstrumentation().redefineClasses(new ClassDefinition(Test.class, classWriter.toByteArray()));

        Annotation[] annotations = Test.class.getAnnotations();
        if (annotations != null && annotations.length != 0) {
            System.out.println("Added annotation! " + annotations.length);
        } else {
            System.out.println("Empty annotation!");
        }
    }
}