/*
 * JasperReports - Free Java Reporting Library.
 * Copyright (C) 2001 - 2009 Jaspersoft Corporation. All rights reserved.
 * http://www.jaspersoft.com
 *
 * Unless you have purchased a commercial license agreement from Jaspersoft,
 * the following license terms apply:
 *
 * This program is part of JasperReports.
 *
 * JasperReports 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 3 of the License, or
 * (at your option) any later version.
 *
 * JasperReports 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 JasperReports. If not, see <http://www.gnu.org/licenses/>.
 */
package net.sf.jasperreports.engine.util;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.security.ProtectionDomain;


/**
 * @author Teodor Danciu (teodord@users.sourceforge.net)
 * @version $Id: JRClassLoader.java 3633 2010-03-26 17:19:43Z teodord $
 */
public class JRClassLoader extends ClassLoader
{

	private static ProtectionDomainFactory protectionDomainFactory = null;
	
	protected static synchronized ProtectionDomainFactory getProtectionDomainFactory()
	{
		if (protectionDomainFactory == null)
		{
			protectionDomainFactory = new SingleProtectionDomainFactory(JRClassLoader.class.getProtectionDomain());
		}

		return protectionDomainFactory;
	}
	
	/**
	 * Sets the protection to be used for classes loaded via
	 * the {@link #loadClassFromBytes(String, byte[]) loadClassFromBytes} method.
	 *
	 * By default, the protection domain of this class is used for the loaded classes. 
	 * 
	 * @param protectionDomain the protection domain to be used
	 * @see #loadClassFromBytes(String, byte[])
	 */
	public static void setProtectionDomain(ProtectionDomain protectionDomain)
	{
		SingleProtectionDomainFactory factory = new SingleProtectionDomainFactory(protectionDomain);
		setProtectionDomainFactory(factory);
	}
	
	/**
	 * Sets a protection domain factory to be used for creating protection domains
	 * for the classes loaded by instances of this class.
	 * <p>
	 * For every instance of this class,
	 * {@link ProtectionDomainFactory#getProtectionDomain(ClassLoader) getProtectionDomain} is called
	 * and the resulting protection domain is used when loading classes through the newly created
	 * classloader.
	 * 
	 * @param protectionDomainFactory the protection domain factory.
	 * @see ProtectionDomainFactory#getProtectionDomain(ClassLoader)
	 */
	public static void setProtectionDomainFactory(ProtectionDomainFactory protectionDomainFactory)
	{
		JRClassLoader.protectionDomainFactory = protectionDomainFactory;
	}
	
	private ProtectionDomain protectionDomain;
	
	/**
	 *
	 */
	protected JRClassLoader()
	{
		super();
	}

	/**
	 *
	 */
	protected JRClassLoader(ClassLoader parent)
	{
		super(parent);
	}


	/**
	 *
	 */
	public static Class loadClassForName(String className) throws ClassNotFoundException
	{
		Class clazz = null;

		String classRealName = className;
		ClassNotFoundException initialEx = null;

		try
		{
			clazz = loadClassForRealName(classRealName);
		}
		catch (ClassNotFoundException e)
		{
			initialEx = e;
		}
		
		int lastDotIndex = 0;
		while (clazz == null && (lastDotIndex = classRealName.lastIndexOf('.')) > 0)
		{
			classRealName = 
				classRealName.substring(0, lastDotIndex) + "$" + classRealName.substring(lastDotIndex + 1);
			try
			{
				clazz = loadClassForRealName(classRealName);
			}
			catch (ClassNotFoundException e)
			{
			}
		}
		
		if (clazz == null)
		{
			throw initialEx;
		}
		
		return clazz;
	}


	/**
	 *
	 */
	public static Class loadClassForRealName(String className) throws ClassNotFoundException
	{
		Class clazz = null;

		ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
		if (classLoader != null)
		{
			try
			{
				clazz = Class.forName(className, true, classLoader);
			}
			catch (ClassNotFoundException e)
			{
				//if (log.isWarnEnabled())
				//	log.warn("Failure using Thread.currentThread().getContextClassLoader() in JRClassLoader class. Using JRClassLoader.class.getClassLoader() instead.");
			}
		}

		if (clazz == null)
		{
			classLoader = JRClassLoader.class.getClassLoader();
			if (classLoader == null)
			{
				clazz = Class.forName(className);
			}
			else
			{
				clazz = Class.forName(className, true, classLoader);
			}
		}

		return clazz;
	}


	/**
	 *
	 */
	public static Class loadClassFromFile(String className, File file) throws IOException
	{
		Class clazz = null;

		ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
		if (classLoader != null)
		{
			try
			{
				clazz = 
					(new JRClassLoader(classLoader))
						.loadClass(className, file);
			}
			catch(NoClassDefFoundError e)
			{
				//if (log.isWarnEnabled())
				//	log.warn("Failure using Thread.currentThread().getContextClassLoader() in JRClassLoader class. Using JRClassLoader.class.getClassLoader() instead.");
			}
		}
	
		if (clazz == null)
		{
			classLoader = JRClassLoader.class.getClassLoader();
			if (classLoader == null)
			{
				clazz = 
					(new JRClassLoader())
						.loadClass(className, file);
			}
			else
			{
				clazz = 
					(new JRClassLoader(classLoader))
						.loadClass(className, file);
			}
		}
		
		return clazz;
	}


	/**
	 *
	 */
	public static Class loadClassFromBytes(String className, byte[] bytecodes)
	{
		Class clazz = null;

		ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
		if (classLoader != null)
		{
			try
			{
				clazz = 
					(new JRClassLoader(classLoader))
						.loadClass(className, bytecodes);
			}
			catch(NoClassDefFoundError e)
			{
				//if (log.isWarnEnabled())
				//	log.warn("Failure using Thread.currentThread().getContextClassLoader() in JRClassLoader class. Using JRClassLoader.class.getClassLoader() instead.");
			}
		}
	
		if (clazz == null)
		{
			classLoader = JRClassLoader.class.getClassLoader();
			if (classLoader == null)
			{
				clazz = 
					(new JRClassLoader())
						.loadClass(className, bytecodes);
			}
			else
			{
				clazz = 
					(new JRClassLoader(classLoader))
						.loadClass(className, bytecodes);
			}
		}

		return clazz;
	}


	/**
	 *
	 */
	protected Class loadClass(String className, File file) throws IOException
	{
		FileInputStream fis = null;
		ByteArrayOutputStream baos = null;

		byte[] bytecodes = new byte[10000];
		int ln = 0;

		try
		{
			fis = new FileInputStream(file);
			baos = new ByteArrayOutputStream();

			while ( (ln = fis.read(bytecodes)) > 0 )
			{
				baos.write(bytecodes, 0, ln);
			}

			baos.flush();
		}
		finally
		{
			if (baos != null)
			{
				try
				{
					baos.close();
				}
				catch(IOException e)
				{
				}
			}

			if (fis != null)
			{
				try
				{
					fis.close();
				}
				catch(IOException e)
				{
				}
			}
		}

		return loadClass(className, baos.toByteArray());
	}

	protected synchronized ProtectionDomain getProtectionDomain()
	{
		if (protectionDomain == null)
		{
			protectionDomain = getProtectionDomainFactory().getProtectionDomain(this);
		}
		return protectionDomain;
	}
	
	/**
	 *
	 */
	protected Class loadClass(String className, byte[] bytecodes)
	{
		Class clazz = null;

		clazz = 
			defineClass(
				className, 
				bytecodes, 
				0, 
				bytecodes.length,
				getProtectionDomain()
				);

		return clazz;
	}


	/**
	 *
	 */
	public static String getClassRealName(String className)
	{
		if (className == null)
		{
			return null;
		}
		
		int arrayDimension = 0;
		int classNameEnd = className.length();
		int index = 0;
		int pos = 0;
		while (index < classNameEnd && (pos = className.indexOf('[', index)) >= 0)
		{
			if (index == 0)
			{
				classNameEnd = pos;
			}
			index = pos;
			arrayDimension++;
		}

		if (arrayDimension > 0)
		{
			StringBuffer sbuffer = new StringBuffer();
			
			for(int i = 0; i < arrayDimension; i++)
			{
				sbuffer.append('[');
			}
			
			sbuffer.append('L');
			sbuffer.append(className.substring(0, classNameEnd));
			sbuffer.append(';');

			return sbuffer.toString();
		}
		
		return className;
	}


}
