/**
 * Copyright (c) 2015, Lucee Assosication Switzerland. All rights reserved.
 *
 * This library 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 library 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 library.  If not, see <http://www.gnu.org/licenses/>.
 * 
 */
package lucee.commons.lang;

import java.io.IOException;
import java.lang.instrument.ClassDefinition;
import java.lang.instrument.UnmodifiableClassException;

import lucee.aprint;
import lucee.commons.io.SystemUtil;
import lucee.runtime.config.Config;
import lucee.runtime.instrumentation.InstrumentationFactory;

/**
 * ClassLoader that loads classes in memory that are not stored somewhere physically
 */
public final class MemoryClassLoader extends ExtendableClassLoader {
	
	private Config config;
	private ClassLoader pcl;
	private long size;
	
	
	/**
	 * Constructor of the class
	 * @param directory
	 * @param parent
	 * @throws IOException
	 */
	public MemoryClassLoader(Config config,ClassLoader parent) throws IOException {
		super(parent);
		this.pcl=parent;
		this.config=config;
	}

	@Override
	public Class<?> loadClass(String name) throws ClassNotFoundException {
		return loadClass(name, false);
	}

	@Override
	protected synchronized Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
		// First, check if the class has already been loaded
		Class<?> c = findLoadedClass(name);
		if (c == null) {
			try {
				c =pcl.loadClass(name);//if(name.indexOf("sub")!=-1)print.ds(name);
			} 
			catch(Throwable t) {
				ExceptionUtil.rethrowIfNecessary(t);
				c = findClass(name);
			}
		}
		if (resolve) {
			resolveClass(c);
		}
		return c;
   }

	@Override
	protected Class<?> findClass(String name) throws ClassNotFoundException {
		throw new ClassNotFoundException("class "+name+" is invalid or doesn't exist");
	}
	

	@Override
	public synchronized Class<?> loadClass(String name, byte[] barr) throws UnmodifiableClassException {
		Class<?> clazz=null;
		try {
			clazz = loadClass(name);
		} catch (ClassNotFoundException cnf) {}
		
		// if class already exists
		if(clazz!=null) {
			try {
				InstrumentationFactory.getInstrumentation(config).redefineClasses(new ClassDefinition(clazz,barr));
			} 
			catch (ClassNotFoundException e) {
				// the documentation clearly sais that this exception only exists for backward compatibility and never happen
			}
			aprint.e("redefined:memory:"+clazz.getName());
			return clazz;
		}
		// class not exists yet
		return _loadClass(name, barr);
	}
	
	private synchronized Class<?> _loadClass(String name, byte[] barr) {
		size+=barr.length;
		// class not exists yet
		try {
			return defineClass(name,barr,0,barr.length);
		} 
		catch(Throwable t) {
			ExceptionUtil.rethrowIfNecessary(t);
			SystemUtil.sleep(1);
			try {
				return defineClass(name,barr,0,barr.length);
			} 
			catch (Throwable t2) {
				ExceptionUtil.rethrowIfNecessary(t2);
				SystemUtil.sleep(1);
				return defineClass(name,barr,0,barr.length);
			}
		}
	}
	
	public long getSize(){
		return size;
	}
}