package org.openslx.taskmanager.util;

import java.io.File;
import java.io.IOException;
import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLClassLoader;

public class ClassLoaderHack
{
	@SuppressWarnings( "rawtypes" )
	private static final Class[] parameters = new Class[] { URL.class };

	public static void addFile( String s ) throws IOException
	{
		File f = new File( s );
		addFile( f );
	}

	public static void addFile( File f ) throws IOException
	{
		addURL( f.toURI().toURL() );
	}

	public static void addURL( URL u ) throws IOException
	{
		URLClassLoader sysloader = (URLClassLoader)ClassLoader.getSystemClassLoader();
		Class<URLClassLoader> sysclass = URLClassLoader.class;

		try {
			Method method = sysclass.getDeclaredMethod( "addURL", parameters );
			method.setAccessible( true );
			method.invoke( sysloader, new Object[] { u } );
			System.out.println( "Loaded " + u.toString() );
		} catch ( Throwable t ) {
			t.printStackTrace();
			throw new IOException( "Error, could not add URL to system classloader" );
		}

	}

	/**
	 * Get Class meta-object for given class in package. Only return class if it's somehow
	 * extending from given baseClass.
	 * 
	 * @param packageName package to search in
	 * @param className name of class to look for
	 * @param baseClass class the class in question has to be extended from
	 * @return class meta object, or null if not found
	 */
	@SuppressWarnings( "unchecked" )
	public static <T> Class<? extends T> getClass( String packageName, String className, Class<T> baseClass )
	{
		final Class<?> clazz;
		try {
			clazz = Class.forName( packageName + '.' + className );
		} catch ( ClassNotFoundException e ) {
			return null;
		}
		if ( clazz == null || ( baseClass != null && !baseClass.isAssignableFrom( clazz ) ) ) {
			return null;
		}
		return (Class<? extends T>)clazz;
	}

}