//
   //  ========================================================================
   //  Copyright (c) 1995-2012 Mort Bay Consulting Pty. Ltd.
   //  ------------------------------------------------------------------------
   //  All rights reserved. This program and the accompanying materials
   //  are made available under the terms of the Eclipse Public License v1.0
   //  and Apache License v2.0 which accompanies this distribution.
   //
   //      The Eclipse Public License is available at
  //      http://www.eclipse.org/legal/epl-v10.html
  //
  //      The Apache License v2.0 is available at
  //      http://www.opensource.org/licenses/apache2.0.php
  //
  //  You may elect to redistribute this code under either of these licenses.
  //  ========================================================================
  //
  
  package org.eclipse.jetty.util;
  
  import java.io.File;
  import java.net.URL;
  import java.net.URLClassLoader;
  import java.util.Locale;
  import java.util.MissingResourceException;
  import java.util.ResourceBundle;
  
  import org.eclipse.jetty.util.resource.Resource;
  
  /* ------------------------------------------------------------ */
  /** ClassLoader Helper.
   * This helper class allows classes to be loaded either from the
   * Thread's ContextClassLoader, the classloader of the derived class
   * or the system ClassLoader.
   *
   * <B>Usage:</B><PRE>
   * public class MyClass {
   *     void myMethod() {
   *          ...
   *          Class c=Loader.loadClass(this.getClass(),classname);
   *          ...
   *     }
   * </PRE>          
   * 
   */
  public class Loader
  {
      /* ------------------------------------------------------------ */
      public static URL getResource(Class<?> loadClass,String name, boolean checkParents)
          throws ClassNotFoundException
      {
          URL url =null;
          ClassLoader loader=Thread.currentThread().getContextClassLoader();
          while (url==null && loader!=null )
          {
              url=loader.getResource(name); 
              loader=(url==null&&checkParents)?loader.getParent():null;
          }      
          
          loader=loadClass==null?null:loadClass.getClassLoader();
          while (url==null && loader!=null )
          {
              url=loader.getResource(name); 
              loader=(url==null&&checkParents)?loader.getParent():null;
          }       
  
          if (url==null)
          {
              url=ClassLoader.getSystemResource(name);
          }   
  
          return url;
      }
  
      /* ------------------------------------------------------------ */
      @SuppressWarnings("rawtypes")
      public static Class loadClass(Class loadClass,String name)
          throws ClassNotFoundException
      {
          return loadClass(loadClass,name,false);
      }
      
      /* ------------------------------------------------------------ */
      /** Load a class.
       * 
       * @param loadClass
       * @param name
       * @param checkParents If true, try loading directly from parent classloaders.
       * @return Class
       * @throws ClassNotFoundException
       */
      @SuppressWarnings("rawtypes")
      public static Class loadClass(Class loadClass,String name,boolean checkParents)
          throws ClassNotFoundException
      {
          ClassNotFoundException ex=null;
          Class<?> c =null;
          ClassLoader loader=Thread.currentThread().getContextClassLoader();
          while (c==null && loader!=null )
         {
             try { c=loader.loadClass(name); }
             catch (ClassNotFoundException e) {if(ex==null)ex=e;}
             loader=(c==null&&checkParents)?loader.getParent():null;
         }      
         
         loader=loadClass==null?null:loadClass.getClassLoader();
         while (c==null && loader!=null )
         {
             try { c=loader.loadClass(name); }
             catch (ClassNotFoundException e) {if(ex==null)ex=e;}
             loader=(c==null&&checkParents)?loader.getParent():null;
         }       
 
         if (c==null)
         {
             try { c=Class.forName(name); }
             catch (ClassNotFoundException e) {if(ex==null)ex=e;}
         }   
 
         if (c!=null)
             return c;
         throw ex;
     }
     
     
     
     /* ------------------------------------------------------------ */
     public static ResourceBundle getResourceBundle(Class<?> loadClass,String name,boolean checkParents, Locale locale)
         throws MissingResourceException
     {
         MissingResourceException ex=null;
         ResourceBundle bundle =null;
         ClassLoader loader=Thread.currentThread().getContextClassLoader();
         while (bundle==null && loader!=null )
         {
             try { bundle=ResourceBundle.getBundle(name, locale, loader); }
             catch (MissingResourceException e) {if(ex==null)ex=e;}
             loader=(bundle==null&&checkParents)?loader.getParent():null;
         }      
         
         loader=loadClass==null?null:loadClass.getClassLoader();
         while (bundle==null && loader!=null )
         {
             try { bundle=ResourceBundle.getBundle(name, locale, loader); }
             catch (MissingResourceException e) {if(ex==null)ex=e;}
             loader=(bundle==null&&checkParents)?loader.getParent():null;
         }       
 
         if (bundle==null)
         {
             try { bundle=ResourceBundle.getBundle(name, locale); }
             catch (MissingResourceException e) {if(ex==null)ex=e;}
         }   
 
         if (bundle!=null)
             return bundle;
         throw ex;
     }
     
     
     /* ------------------------------------------------------------ */
     /**
      * Generate the classpath (as a string) of all classloaders
      * above the given classloader.
      * 
      * This is primarily used for jasper.
      * @return the system class path
      */
     public static String getClassPath(ClassLoader loader) throws Exception
     {
         StringBuilder classpath=new StringBuilder();
         while (loader != null && (loader instanceof URLClassLoader))
         {
             URL[] urls = ((URLClassLoader)loader).getURLs();
             if (urls != null)
             {     
                 for (int i=0;i<urls.length;i++)
                 {
                     Resource resource = Resource.newResource(urls[i]);
                     File file=resource.getFile();
                     if (file!=null && file.exists())
                     {
                         if (classpath.length()>0)
                             classpath.append(File.pathSeparatorChar);
                         classpath.append(file.getAbsolutePath());
                     }
                 }
             }
             loader = loader.getParent();
         }
         return classpath.toString();
     }
 }