/**
    * This file Copyright (c) 2003-2015 Magnolia International
    * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
    *
    *
    * This file is dual-licensed under both the Magnolia
    * Network Agreement and the GNU General Public License.
    * You may elect to use one or the other of these licenses.
    *
   * This file is distributed in the hope that it will be
   * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
   * implied warranty of MERCHANTABILITY or FITNESS FOR A
   * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
   * Redistribution, except as permitted by whichever of the GPL
   * or MNA you select, is prohibited.
   *
   * 1. For the GPL license (GPL), you can redistribute and/or
   * modify this file under the terms of the GNU General
   * Public License, Version 3, as published by the Free Software
   * Foundation.  You should have received a copy of the GNU
   * General Public License, Version 3 along with this program;
   * if not, write to the Free Software Foundation, Inc., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * 2. For the Magnolia Network Agreement (MNA), this file
   * and the accompanying materials are made available under the
   * terms of the MNA which accompanies this distribution, and
   * is available at http://www.magnolia-cms.com/mna.html
   *
   * Any modifications to this file must keep this entire header
   * intact.
   *
   */
  package info.magnolia.cms.util;
  
  import info.magnolia.cms.core.SystemProperty;
  import info.magnolia.init.MagnoliaInitPaths;
  import info.magnolia.objectfactory.Components;
  
  import java.io.File;
  import java.io.FilenameFilter;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.UnsupportedEncodingException;
  import java.net.URL;
  import java.net.URLClassLoader;
  import java.net.URLDecoder;
  import java.util.Collection;
  import java.util.Enumeration;
  import java.util.HashSet;
  import java.util.Set;
  import java.util.jar.JarEntry;
  import java.util.jar.JarFile;
  import java.util.regex.Pattern;
  
  import org.apache.commons.beanutils.BeanUtils;
  import org.apache.commons.io.FileUtils;
  import org.apache.commons.io.filefilter.TrueFileFilter;
  import org.apache.commons.lang.ArrayUtils;
  import org.apache.commons.lang.StringUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Util to find resources in the classpath (WEB-INF/lib and WEB-INF/classes).
   */
  public class ClasspathResourcesUtil {
      private static final Logger log = LoggerFactory.getLogger(ClasspathResourcesUtil.class);
  
      /**
       * Filter for filtering the resources.
       */
      public static interface Filter {
          public boolean accept(String name);
      }
  
      /**
       * A filter using a regex pattern.
       */
      public static class PatternFilter implements Filter {
          private final Pattern pattern;
  
          public PatternFilter(String pattern) {
              this.pattern = Pattern.compile(pattern);
          }
  
          @Override
          public boolean accept(String name) {
              return pattern.matcher(name).matches();
          }
      }
  
      private static boolean isCache() {
          final String devMode = SystemProperty.getProperty("magnolia.develop");
          return !"true".equalsIgnoreCase(devMode);
      }
  
      /**
       * Return a collection containing the resource names which match the regular expression.
      * 
      * @return string array of found resources TODO : (lazy) cache ?
      */
     public static String[] findResources(String regex) {
         return findResources(new PatternFilter(regex));
     }
 
     /**
      * Return a collection containing the resource names which passed the filter.
      * 
      * @return string array of found resources TODO : (lazy) cache ?
      */
     public static String[] findResources(Filter filter) {
         final Set<String> resources = new HashSet<String>();
         final ClassLoader cl = getCurrentClassLoader();
 
         // if the classloader is an URLClassloader we have a better method for discovering resources
         // whis will also fetch files from jars outside WEB-INF/lib, useful during development
         if (cl instanceof URLClassLoader) {
             final URLClassLoader urlClassLoader = (URLClassLoader) cl;
             final URL[] urls = urlClassLoader.getURLs();
             if (log.isDebugEnabled()) {
                 log.debug("Loading resources from: " + ArrayUtils.toString(urls));
             }
             if (urls.length == 1 && urls[0].getPath().endsWith("WEB-INF/classes/")) {
                 // working around MAGNOLIA-2577
                 log.warn("Looks like we're in a JBoss 5 expanded war directory, will attempt to load resources from the file system instead; see MAGNOLIA-2577.");
             } else {
                 collectFromURLs(resources, urls, filter);
                 return resources.toArray(new String[resources.size()]);
             }
         }
 
         try {
             // be friendly to WAS developers too...
             // in development mode under RAD 7.5 here we have an instance of com.ibm.ws.classloader.WsClassLoader
             // and jars are NOT deployed to WEB-INF/lib by default, so they can't be found without this explicit check
             //
             // but since we don't want to depend on WAS stuff we just check if the cl exposes a "classPath" property
             String classpath = BeanUtils.getProperty(cl, "classPath");
 
             if (StringUtils.isNotEmpty(classpath)) {
                 collectFromClasspathString(resources, classpath, filter);
                 return resources.toArray(new String[resources.size()]);
             }
         } catch (Throwable e) {
             // no, it's not a classloader we can handle in a special way
         }
 
         // no way, we have to assume a standard war structure and look in the WEB-INF/lib and WEB-INF/classes dirs
         // read the jars in the lib dir
         collectFromFileSystem(filter, resources);
         return resources.toArray(new String[resources.size()]);
     }
 
     protected static void collectFromURLs(Collection<String> resources, URL[] urls, Filter filter) {
         // tomcat classloader is org.apache.catalina.loader.WebappClassLoader
         for (int j = 0; j < urls.length; j++) {
             final File tofile = sanitizeToFile(urls[j]);
             if (tofile != null) {
                 collectFiles(resources, tofile, filter);
             }
         }
     }
 
     protected static void collectFromClasspathString(Collection<String> resources, String classpath, Filter filter) {
         String[] paths = classpath.split(File.pathSeparator);
         for (int j = 0; j < paths.length; j++) {
             final File tofile = new File(paths[j]);
             // there can be several missing (optional?) paths here...
             if (tofile.exists()) {
                 collectFiles(resources, tofile, filter);
             }
         }
     }
 
     protected static void collectFromFileSystem(Filter filter, Collection<String> resources) {
         // We need to have access to the MAGNOLIA_APP_ROOTDIR. Unfortunately, this is not yet initialised.
         String rootDire = Components.getComponent(MagnoliaInitPaths.class).getRootPath();
         String libString = new File(new File(rootDire), "WEB-INF/lib").getAbsolutePath();
 
         File dir = new File(libString);
         if (dir.exists()) {
             File[] files = dir.listFiles(new FilenameFilter() {
                 @Override
                 public boolean accept(File file, String name) {
                     return name.endsWith(".jar");
                 }
             });
 
             for (int i = 0; i < files.length; i++) {
                 collectFiles(resources, files[i], filter);
             }
         }
 
         // read files in WEB-INF/classes
         String classString = new File(new File(rootDire), "WEB-INF/classes").getAbsolutePath();
         File classFileDir = new File(classString);
 
         if (classFileDir.exists()) {
             collectFiles(resources, classFileDir, filter);
         }
     }
 
     public static File sanitizeToFile(URL url) {
         if (!"file".equals(url.getProtocol()) && !StringUtils.startsWith(url.toString(), "jar:file:")) { // only file:/ and jar:file/ are supported
             log.warn("Cannot load resources '{}' from '{}' protocol. Only 'file' and 'jar-file' protocols are supported.", url, url.getProtocol());
             return null;
         }
         try {
             String fileUrl = url.getFile();
             // needed because somehow the URLClassLoader has encoded URLs, and getFile does not decode them.
             fileUrl = URLDecoder.decode(fileUrl, "UTF-8");
             // needed for Resin - for some reason, its URLs are formed as jar:file:/absolutepath/foo/bar.jar instead of
             // using the :///abs.. notation
             fileUrl = StringUtils.removeStart(fileUrl, "file:");
             fileUrl = StringUtils.removeEnd(fileUrl, "!/");
             return new File(fileUrl);
         } catch (UnsupportedEncodingException e) {
             throw new RuntimeException(e);
         }
     }
 
     /**
      * Load resources from jars or directories.
      * 
      * @param resources found resources will be added to this collection
      * @param jarOrDir a File, can be a jar or a directory
      * @param filter used to filter resources
      */
     private static void collectFiles(Collection<String> resources, File jarOrDir, Filter filter) {
 
         if (!jarOrDir.exists()) {
             log.warn("missing file: {}", jarOrDir.getAbsolutePath());
             return;
         }
 
         if (jarOrDir.isDirectory()) {
             log.debug("looking in dir {}", jarOrDir.getAbsolutePath());
 
             Collection<File> files = FileUtils.listFiles(jarOrDir, TrueFileFilter.TRUE, TrueFileFilter.TRUE);
             for (File file : files) {
                 String name = StringUtils.substringAfter(file.getPath(), jarOrDir.getPath());
 
                 // please, be kind to Windows!!!
                 name = StringUtils.replace(name, "\\", "/");
                 if (!name.startsWith("/")) {
                     name = "/" + name;
                 }
 
                 if (filter.accept(name)) {
                     resources.add(name);
                 }
             }
         }
         else if (jarOrDir.getName().endsWith(".jar")) {
             log.debug("looking in jar {}", jarOrDir.getAbsolutePath());
             JarFile jar;
             try {
                 jar = new JarFile(jarOrDir);
             } catch (IOException e) {
                 log.error("IOException opening file {}, skipping", jarOrDir.getAbsolutePath());
                 return;
             }
             for (Enumeration<JarEntry> em = jar.entries(); em.hasMoreElements();) {
                 JarEntry entry = em.nextElement();
                 if (!entry.isDirectory()) {
                     if (filter.accept("/" + entry.getName())) {
                         resources.add("/" + entry.getName());
                     }
                 }
             }
             try {
                 jar.close();
             } catch (IOException e) {
                 log.error("Failed to close jar file : " + e.getMessage());
                 log.debug("Failed to close jar file", e);
             }
         }
         else {
             log.debug("Unknown (not jar) file in classpath: {}, skipping.", jarOrDir.getName());
         }
 
     }
 
     public static InputStream getStream(String name) throws IOException {
         return getStream(name, isCache());
     }
 
     /**
      * Checks last modified and returns the new content if changed and the cache flag is not set to true.
      * 
      * @return the input stream
      */
     public static InputStream getStream(String name, boolean cache) throws IOException {
         if (cache) {
             return getCurrentClassLoader().getResourceAsStream(StringUtils.removeStart(name, "/"));
         }
 
         // TODO use the last modified attribute
         URL url = getResource(name);
         if (url != null) {
             return url.openStream();
         }
 
         log.debug("Can't find {}", name);
         return null;
     }
 
     /**
      * From http://stackoverflow.com/questions/1771679/difference-between-threads-context-class-loader-and-normal-classloader.
      * <p>
      * <em>"Each class will use its own classloader to load other classes. So if ClassA.class references ClassB.class then ClassB needs to be on the classpath of the classloader of ClassA, or its parents.
      * The thread context classloader is the current classloader for the current thread. An object can be created from a class in ClassLoaderC and then passed to a thread owned by ClassLoaderD.
      * In this case the object needs to use Thread.currentThread().getContextClassLoader() directly if it wants to load resources that are not available on its own classloader."</em>
      * 
      * @return current classloader
      */
     public static ClassLoader getCurrentClassLoader() {
         return Thread.currentThread().getContextClassLoader();
     }
 
     /**
      * Get the resource using the current class loader. The leading / is removed as the call to class.getResource()
      * would do.
      * 
      * @return the resource
      */
     public static URL getResource(String name) {
         return getCurrentClassLoader().getResource(StringUtils.removeStart(name, "/"));
     }
 
 }