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package org.openjdk.jmc.agent.jfrnext.impl;

import java.lang.reflect.Method;
import java.security.ProtectionDomain;
import java.util.logging.Level;
import java.util.logging.Logger;

import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
import org.openjdk.jmc.agent.jfr.JFRTransformDescriptor;
import org.openjdk.jmc.agent.util.TypeUtils;

public class JFRNextClassVisitor extends ClassVisitor {
	private final JFRTransformDescriptor transformDescriptor;
	private final ClassLoader definingClassLoader;
	private final ProtectionDomain protectionDomain;

	public JFRNextClassVisitor(ClassWriter cv, JFRTransformDescriptor descriptor, ClassLoader definingLoader,
			ProtectionDomain protectionDomain) {
		super(Opcodes.ASM5, cv);
		this.transformDescriptor = descriptor;
		this.definingClassLoader = definingLoader;
		this.protectionDomain = protectionDomain;
	}

	@Override
	public MethodVisitor visitMethod(int access, String name, String desc, String signature, String[] exceptions) {
		MethodVisitor mv = super.visitMethod(access, name, desc, signature, exceptions);
		if (name.equals(transformDescriptor.getMethod().getName())
				&& desc.equals(transformDescriptor.getMethod().getSignature())) {
			return new JFRNextMethodAdvisor(transformDescriptor, Opcodes.ASM5, mv, access, name, desc);
		}
		return mv;
	}

	@Override
	public void visitEnd() {
		try {
			reflectiveRegister(generateEventClass());
		} catch (Exception e) {
			Logger.getLogger(JFRNextClassVisitor.class.getName()).log(Level.SEVERE,
					"Failed to generate event class for " + transformDescriptor.toString(), e); //$NON-NLS-1$
		}
		super.visitEnd();
	}

	// NOTE: multi-release jars should let us compile against jdk9 and do a direct call here
	private void reflectiveRegister(Class<?> generateEventClass) throws Exception {
		Class<?> jfr = Class.forName("jdk.jfr.FlightRecorder"); //$NON-NLS-1$
		Method registerMethod = jfr.getDeclaredMethod("register", Class.class); //$NON-NLS-1$
		registerMethod.invoke(null,  generateEventClass);		
	}

	private Class<?> generateEventClass() throws Exception {
		byte[] eventClass = JFRNextEventClassGenerator.generateEventClass(transformDescriptor);
		return TypeUtils.defineClass(transformDescriptor.getEventClassName(), eventClass, 0,
				eventClass.length, definingClassLoader, protectionDomain);
	}
}
