/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
    * with the License.  You may obtain a copy of the License at
    *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  package org.apache.myfaces.view.facelets.util;
  
  import java.io.File;
  import java.io.IOException;
  import java.io.InputStream;
  import java.net.JarURLConnection;
  import java.net.URL;
  import java.net.URLConnection;
  import java.net.URLDecoder;
  import java.util.Arrays;
  import java.util.Enumeration;
  import java.util.HashSet;
  import java.util.LinkedHashSet;
  import java.util.Set;
  import java.util.jar.JarEntry;
  import java.util.jar.JarFile;
  import java.util.zip.ZipEntry;
  import java.util.zip.ZipInputStream;
  
  import org.apache.myfaces.shared.util.ClassUtils;
  import java.nio.ByteBuffer;
  import java.nio.charset.Charset;
  import java.security.AccessController;
  import java.security.PrivilegedAction;
  /**
   * @author Jacob Hookom
   * @author Roland Huss
   * @author Ales Justin (ales.justin@jboss.org)
   * @version $Id$
   */
  public final class Classpath
  {
      private static final Charset UTF8 = Charset.forName("UTF-8");
      private static final Set<String> EXCLUDED_PREFIX_SET = new HashSet<String>(Arrays.asList("rar:", "sar:"));
      private static final Set<String> EXCLUDED_SUFFIX_SET = new HashSet<String>(Arrays.asList(".rar", ".sar"));
  
      private Classpath()
      {
      }
  
      public static URL[] search(String prefix, String suffix) throws IOException
      {
          return search(ClassUtils.getContextClassLoader(), prefix, suffix);
      }
  
      public static URL[] search(ClassLoader loader, String prefix, String suffix) throws IOException
      {
          Set<URL> all = new LinkedHashSet<URL>();
  
          _searchResource(all, loader, prefix, prefix, suffix);
          _searchResource(all, loader, prefix + "MANIFEST.MF", prefix, suffix);
  
          URL[] urlArray = (URL[]) all.toArray(new URL[all.size()]);
  
          return urlArray;
      }
  
      private static void _searchResource(Set<URL> result, ClassLoader loader, String resource, String prefix,
                                          String suffix) throws IOException
      {
          for (Enumeration<URL> urls = loader.getResources(resource); urls.hasMoreElements();)
          {
              URL url = urls.nextElement();
              URLConnection conn = url.openConnection();
              conn.setUseCaches(false);
              conn.setDefaultUseCaches(false);
  
              JarFile jar = null;
              try 
              {
                  if (conn instanceof JarURLConnection)
                  {
                          jar = ((JarURLConnection) conn).getJarFile();
                  }
                  else
                  {
                      jar = _getAlternativeJarFile(url);
                  }
      
                  if (jar != null)
                  {
                     _searchJar(loader, result, jar, prefix, suffix);
                 }
                 else
                 {
                     if (!_searchDir(result, new File(URLDecoder.decode(url.getFile(), "UTF-8")), suffix))
                     {
                         _searchFromURL(result, prefix, suffix, url);
                     }
                 }    
             }
             catch (Throwable e)
             {
                 // This can happen if the classloader provided us a URL that it thinks exists
                 // but really doesn't.  In particular, if a JAR contains META-INF/MANIFEST.MF
                 // but not META-INF/, some classloaders may incorrectly report that META-INF/
                 // exists and we'll end up here.  Just ignore this case.
                 
                 continue;
             }
             finally 
             {
                 if (jar != null) 
                 {
                     jar.close();
                 }
             }
         }
     }
 
     private static boolean _searchDir(Set<URL> result, File dir, String suffix) throws IOException
     {
         boolean dirExists = false;
         if (System.getSecurityManager() != null)
         {
             final File finalDir = dir;
             dirExists = (Boolean) AccessController.doPrivileged(new PrivilegedAction()
             {
                 public Object run() 
                 {
                     return finalDir.exists();
                 }
             });
         }  
         else
         {
             dirExists = dir.exists();
         }
         if (dirExists && dir.isDirectory())
         {
             File[] dirFiles = dir.listFiles();
             if (dirFiles != null) 
             {
                 for (File file : dirFiles)
                 {
                     String path = file.getAbsolutePath();
                     if (file.isDirectory())
                     {
                         _searchDir(result, file, suffix);
                     }
                     else if (path.endsWith(suffix))
                     {
                         result.add(file.toURI().toURL());
                     }
                 }
                 return true;
             }
         }
 
         return false;
     }
 
     /**
      * Search from URL. Fall back on prefix tokens if not able to read from original url param.
      * 
      * @param result
      *            the result urls
      * @param prefix
      *            the current prefix
      * @param suffix
      *            the suffix to match
      * @param url
      *            the current url to start search
      * @throws IOException
      *             for any error
      */
     private static void _searchFromURL(Set<URL> result, String prefix, String suffix, URL url) throws IOException
     {
         boolean done = false;
 
         InputStream is = _getInputStream(url);
         if (is != null)
         {
             try
             {
                 ZipInputStream zis;
                 if (is instanceof ZipInputStream)
                 {
                     zis = (ZipInputStream) is;
                 }
                 else
                 {
                     zis = new ZipInputStream(is);
                 }
 
                 try
                 {
                     ZipEntry entry = zis.getNextEntry();
                     // initial entry should not be null
                     // if we assume this is some inner jar
                     done = entry != null;
 
                     while (entry != null)
                     {
                         String entryName = entry.getName();
                         if (entryName.endsWith(suffix))
                         {
                             result.add(new URL(url.toExternalForm() + entryName));
                         }
 
                         entry = zis.getNextEntry();
                     }
                 }
                 finally
                 {
                     zis.close();
                 }
             }
             catch (Exception ignore)
             {
             }
         }
 
         if (!done && prefix.length() > 0)
         {
             // we add '/' at the end since join adds it as well
             String urlString = url.toExternalForm() + "/";
 
             String[] split = prefix.split("/");
 
             prefix = _join(split, true);
 
             String end = _join(split, false);
             urlString = urlString.substring(0, urlString.lastIndexOf(end));
             if (isExcludedPrefix(urlString))
             {
                 // excluded URL found, ignore it
                 return;
             }
             url = new URL(urlString);
 
             _searchFromURL(result, prefix, suffix, url);
         }
     }
 
     /**
      * Join tokens, exlude last if param equals true.
      * 
      * @param tokens
      *            the tokens
      * @param excludeLast
      *            do we exclude last token
      * @return joined tokens
      */
     private static String _join(String[] tokens, boolean excludeLast)
     {
         StringBuilder join = new StringBuilder();
         int length = tokens.length - (excludeLast ? 1 : 0);
         for (int i = 0; i < length; i++)
         {
             join.append(tokens[i]).append("/");
         }
 
         return join.toString();
     }
 
     /**
      * Open input stream from url. Ignore any errors.
      * 
      * @param url
      *            the url to open
      * @return input stream or null if not possible
      */
     private static InputStream _getInputStream(URL url)
     {
         try
         {
             return url.openStream();
         }
         catch (Throwable t)
         {
             return null;
         }
     }
 
     /**
      * For URLs to JARs that do not use JarURLConnection - allowed by the servlet spec - attempt to produce a JarFile
      * object all the same. Known servlet engines that function like this include Weblogic and OC4J. This is not a full
      * solution, since an unpacked WAR or EAR will not have JAR "files" as such.
      */
     private static JarFile _getAlternativeJarFile(URL url) throws IOException
     {
         String urlFile = url.getFile();
 
         // Find suffix prefixed by "!/" on Weblogic
         int wlIndex = urlFile.indexOf("!/");
         // Find suffix prefixed by '!' on OC4J
         int oc4jIndex = urlFile.indexOf('!');
         // Take the first found suffix
         int separatorIndex = wlIndex == -1 && oc4jIndex == -1 ? -1 : wlIndex < oc4jIndex ? wlIndex : oc4jIndex;
 
         if (separatorIndex != -1)
         {
             String jarFileUrl = urlFile.substring(0, separatorIndex);
             // And trim off any "file:" prefix.
             if (jarFileUrl.startsWith("file:"))
             {
                 jarFileUrl = jarFileUrl.substring("file:".length());
             }
             // make sure this is a valid file system path by removing escaping of white-space characters, etc. 
             jarFileUrl = decodeFilesystemUrl(jarFileUrl);
             if (isExcludedPrefix(jarFileUrl) || isExcludedSuffix(jarFileUrl))
             {
                 // excluded URL found, ignore it
                 return null;
             }
             return new JarFile(jarFileUrl);
         }
 
         return null;
     }
 
     private static boolean isExcludedPrefix(String url)
     {
         return EXCLUDED_PREFIX_SET.contains(url.substring(0, 4));
     }
 
     private static boolean isExcludedSuffix(String url)
     {
         int length = url.length();
         return EXCLUDED_SUFFIX_SET.contains(url.substring(length - 4, length));
     }
 
     private static void _searchJar(ClassLoader loader, Set<URL> result, JarFile file, String prefix, String suffix)
             throws IOException
     {
         Enumeration<JarEntry> e = file.entries();
         while (e.hasMoreElements())
         {
             try
             {
                 String name = e.nextElement().getName();
                 if (name.startsWith(prefix) && name.endsWith(suffix))
                 {
                     Enumeration<URL> e2 = loader.getResources(name);
                     while (e2.hasMoreElements())
                     {
                         result.add(e2.nextElement());
                     }
                 }
             }
             catch (Throwable t)
             {
                 // shallow
             }
         }
     }
 
     private static String decodeFilesystemUrl(String url)
     {
         //borrowed from commons-io FileUtils.
         String decoded = url;
         if (url != null && url.indexOf('%') >= 0)
         {
             int n = url.length();
             StringBuffer buffer = new StringBuffer();
             ByteBuffer bytes = ByteBuffer.allocate(n);
             for (int i = 0; i < n; )
             {
                 if (url.charAt(i) == '%')
                 {
                     try
                     {
                         do
                         {
                             byte octet = (byte) Integer.parseInt(url.substring(i + 1, i + 3), 16);
                             bytes.put(octet);
                             i += 3;
                         } while (i < n && url.charAt(i) == '%');
                         continue;
                     }
                     catch (RuntimeException e)
                     {
                         // malformed percent-encoded octet, fall through and
                         // append characters literally
                     }
                     finally
                     {
                         if (bytes.position() > 0)
                         {
                             bytes.flip();
                             buffer.append(UTF8.decode(bytes).toString());
                             bytes.clear();
                         }
                     }
                 }
                 buffer.append(url.charAt(i++));
             }
             decoded = buffer.toString();
         }
         return decoded;
     }
 
 }