/**
 * Helios, OpenSource Monitoring
 * Brought to you by the Helios Development Group
 *
 * Copyright 2012, Helios Development Group and individual contributors
 * as indicated by the @author tags. See the copyright.txt file in the
 * distribution for a full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org. 
 *
 */
package org.helios.apmrouter.instrumentation;

import javassist.ClassPool;
import javassist.CtClass;
import org.helios.apmrouter.util.SimpleLogger;

import java.lang.instrument.ClassFileTransformer;
import java.lang.instrument.IllegalClassFormatException;
import java.lang.reflect.Modifier;
import java.security.ProtectionDomain;

/**
 * <p>Title: SocketStreamClassTransformer</p>
 * <p>Description: Modifies accessors on socket input and output streams</p> 
 * <p>Company: Helios Development Group LLC</p>
 * @author Whitehead (nwhitehead AT heliosdev DOT org)
 * <p><code>org.helios.apmrouter.instrumentation.SocketStreamClassTransformer</code></p>
 */

public class SocketStreamClassTransformer implements ClassFileTransformer {
	public static final String SOS = "java/net/SocketOutputStream"; 
	/**
	 * {@inheritDoc}
	 * @see java.lang.instrument.ClassFileTransformer#transform(java.lang.ClassLoader, java.lang.String, java.lang.Class, java.security.ProtectionDomain, byte[])
	 */
	@Override
	public byte[] transform(ClassLoader loader, String className,
			Class<?> classBeingRedefined, ProtectionDomain protectionDomain,
			byte[] classfileBuffer) throws IllegalClassFormatException {
		ClassPool tClassPool = null;
		try {
			if(SOS.equals(className)) {
				tClassPool = new ClassPool();
				tClassPool.appendSystemPath();
				CtClass clazz = tClassPool.get("java.net.SocketOutputStream");
				clazz.setModifiers(clazz.getModifiers() | Modifier.PUBLIC);
				
				byte[] byteCode = clazz.toBytecode();
				SimpleLogger.info("\n\tGenerated Byte Code for [" , clazz.getName(), "]\n");
				return byteCode;
			}
		} catch (Throwable ex) {
			SimpleLogger.warn("Failed to  instrument [", className, "]", ex);
			return classfileBuffer;
		}
		return classfileBuffer;
	}
	
	/**
	 * Converts a class name to the binary name used by the class file transformer, or returns the passed name if it is already a binary name
	 * @param name The class name to convert
	 * @return the binary name
	 */
	protected String convertToBinaryName(String name) {
		int index = name.indexOf('.');
		if(index!=-1) {
			return name.replace('.', '/');
		}
		return name;
	}
	
	/**
	 * Converts a class name from the binary name used by the class file transformer to the standard dot notated form, or returns the passed name if it is already a binary name
	 * @param name The class name to convert
	 * @return the standard dot notated class name
	 */
	protected String convertFromBinaryName(String name) {
		int index = name.indexOf('/');
		if(index!=-1) {
			return name.replace('/', '.');
		}
		return name;
	}
	

}