/*
 * Copyright 2012-2014 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.boot.loader.tools;

import java.io.File;
import java.lang.management.ManagementFactory;
import java.lang.reflect.Method;
import java.util.List;

/**
 * Utility class to attach an instrumentation agent to the running JVM.
 *
 * @author Dave Syer
 */
public abstract class AgentAttacher {

	private static final String VIRTUAL_MACHINE_CLASS_NAME = "com.sun.tools.attach.VirtualMachine";

	public static void attach(File agent) {
		try {
			String name = ManagementFactory.getRuntimeMXBean().getName();
			String pid = name.substring(0, name.indexOf('@'));
			ClassLoader classLoader = JvmUtils.getToolsClassLoader();
			Class<?> vmClass = classLoader.loadClass(VIRTUAL_MACHINE_CLASS_NAME);
			Method attachMethod = vmClass.getDeclaredMethod("attach", String.class);
			Object vm = attachMethod.invoke(null, pid);
			Method loadAgentMethod = vmClass.getDeclaredMethod("loadAgent", String.class);
			loadAgentMethod.invoke(vm, agent.getAbsolutePath());
			vmClass.getDeclaredMethod("detach").invoke(vm);
		}
		catch (Exception ex) {
			throw new RuntimeException("Unable to attach agent to the JVM", ex);
		}
	}

	public static List<String> commandLineArguments() {
		return ManagementFactory.getRuntimeMXBean().getInputArguments();
	}

	public static boolean hasNoVerify() {
		return commandLineArguments().contains("-Xverify:none");
	}

}
