/*
    * ====================================================================
    * 
    * The Apache Software License, Version 1.1
    *
    * Copyright (c) 2003 Nick Lothian. All rights reserved.
    *
    * Redistribution and use in source and binary forms, with or without
    * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer. 
   *
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   *
   * 3. The end-user documentation included with the redistribution, if
   *    any, must include the following acknowlegement:  
   *       "This product includes software developed by the 
   *        developers of Classifier4J (http://classifier4j.sf.net/)."
   *    Alternately, this acknowlegement may appear in the software itself,
   *    if and wherever such third-party acknowlegements normally appear.
   *
   * 4. The name "Classifier4J" must not be used to endorse or promote 
   *    products derived from this software without prior written 
   *    permission. For written permission, please contact   
   *    http://sourceforge.net/users/nicklothian/.
   *
   * 5. Products derived from this software may not be called 
   *    "Classifier4J", nor may "Classifier4J" appear in their names 
   *    without prior written permission. For written permission, please 
   *    contact http://sourceforge.net/users/nicklothian/.
   *
   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   * ====================================================================
   */
  
  package net.sf.classifier4J.util;
  
  import java.io.*;
  import java.net.*;
  import java.util.*;
  
  /***
   * <p>A class to locate resources, retrieve their contents, and determine their
   * last modified time. To find the resource the class searches the CLASSPATH
   * first, then Resource.class.getResource("/" + name). If the Resource finds
   * a "file:" URL, the file path will be treated as a file. Otherwise, the
   * path is treated as a URL and has limited last modified info.</p>
   * 
   * <p>Heavily based on the example from http://www.onjava.com/pub/a/onjava/excerpt/jebp_3/index1.html?page=3#ex3-4</p>
   * 
   */
  public class Resource implements Serializable {
  
      private String name;
      private File file;
      private URL url;
  
      public Resource(String name) throws IOException {
          this.name = name;
          SecurityException exception = null;
  
          try {
              // Search using the CLASSPATH. If found, "file" is set and the call
              // returns true.  A SecurityException might bubble up.
              if (tryClasspath(name)) {
                  return;
              }
          } catch (SecurityException e) {
              exception = e; // Save for later.
          }
  
          try {
              // Search using the classloader getResource(  ). If found as a file,
              // "file" is set; if found as a URL, "url" is set.
              if (tryLoader(name)) {
                  return;
              }
          } catch (SecurityException e) {
              exception = e; // Save for later.
          }
  
          // If you get here, something went wrong. Report the exception.
          String msg = "";
         if (exception != null) {
             msg = ": " + exception;
         }
 
         throw new IOException("Resource '" + name + "' could not be found in " + "the CLASSPATH (" + System.getProperty("java.class.path") + "), nor could it be located by the classloader responsible for the " + "web application (WEB-INF/classes)" + msg);
     }
 
     /***
      * Returns the resource name, as passed to the constructor
      */
     public String getName() {
         return name;
     }
 
     /***
      * Returns an input stream to read the resource contents
      */
     public InputStream getInputStream() throws IOException {
         if (file != null) {
             return new BufferedInputStream(new FileInputStream(file));
         } else if (url != null) {
             return new BufferedInputStream(url.openStream());
         }
         return null;
     }
 
     /***
      * Returns when the resource was last modified. If the resource 
      * was found using a URL, this method will work only if the URL 
      * connection supports last modified information. If there's no 
      * support, Long.MAX_VALUE is returned. Perhaps this should return 
      * -1, but you should return MAX_VALUE on the assumption that if
      * you can't determine the time, it's maximally new.
      */
     public long lastModified() {
         if (file != null) {
             return file.lastModified();
         } else if (url != null) {
             try {
                 return url.openConnection().getLastModified(); // Hail Mary
             } catch (IOException e) {
                 return Long.MAX_VALUE;
             }
         }
         return 0; // can't happen
     }
 
     /***
      * Returns the directory containing the resource, or null if the 
      * resource isn't directly available on the filesystem. 
      * This value can be used to locate the configuration file on disk,
      * or to write files in the same directory.
      */
     public String getDirectory() {
         if (file != null) {
             return file.getParent();
         } else if (url != null) {
             return null;
         }
         return null;
     }
 
     // Returns true if found
     private boolean tryClasspath(String filename) {
         String classpath = System.getProperty("java.class.path");
         String[] paths = split(classpath, File.pathSeparator);
         file = searchDirectories(paths, filename);
         return (file != null);
     }
 
     private static File searchDirectories(String[] paths, String filename) {
         SecurityException exception = null;
         for (int i = 0; i < paths.length; i++) {
             try {
                 File file = new File(paths[i], filename);
                 if (file.exists() && !file.isDirectory()) {
                     return file;
                 }
             } catch (SecurityException e) {
                 // Security exceptions can usually be ignored, but if all attempts
                 // to find the file fail, report the (last) security exception.
                 exception = e;
             }
         }
         // Couldn't find any match
         if (exception != null) {
             throw exception;
         } else {
             return null;
         }
     }
 
     // Splits a String into pieces according to a delimiter.
     // Uses JDK 1.1 classes for backward compatibility.
     // JDK 1.4 actually has a split(  ) method now.
     private static String[] split(String str, String delim) {
         // Use a Vector to hold the split strings.
         Vector v = new Vector();
 
         // Use a StringTokenizer to do the splitting.
         StringTokenizer tokenizer = new StringTokenizer(str, delim);
         while (tokenizer.hasMoreTokens()) {
             v.addElement(tokenizer.nextToken());
         }
 
         String[] ret = new String[v.size()];
         v.copyInto(ret);
         return ret;
     }
 
     // Returns true if found
     private boolean tryLoader(String name) {
         name = "/" + name;
         URL res = Resource.class.getResource(name);
         if (res == null) {
             return false;
         } else {
             // Try converting from a URL to a File.
             File resFile = urlToFile(res);
             if (resFile != null) {
                 file = resFile;
             } else {
                 url = res;
             }
             return true;
         }
 
     }
 
     private static File urlToFile(URL res) {
         String externalForm = res.toExternalForm();
         if (externalForm.startsWith("file:")) {
             return new File(externalForm.substring(5));
         }
         return null;
     }
 
     public String toString() {
         return "[Resource: File: " + file + " URL: " + url + "]";
     }
 }