package com.atlassian.plugin.url;
   
   import java.io.IOException;
   import java.io.InputStream;
   import java.net.JarURLConnection;
   import java.net.MalformedURLException;
   import java.net.URL;
   import java.net.URLDecoder;
   import java.util.ArrayList;
  import java.util.List;
  import java.util.StringTokenizer;
  import java.util.jar.JarEntry;
  import java.util.jar.JarFile;
  import java.util.jar.JarInputStream;
  
  class InnerJarURLConnection extends JarURLConnection {
      private URL baseResource;
      private String[] segments;
      private InputStream in;
  
      public InnerJarURLConnection(URL url) throws IOException {
          super(url = normaliseURL(url));
  
          String baseText = url.getPath();
  
          int bangLoc = baseText.indexOf("!");
  
          String baseResourceText = baseText.substring(0, bangLoc);
  
          String extraText;
  
          if (bangLoc <= (baseText.length() - 2)
                  &&
                  baseText.charAt(bangLoc + 1) == '/') {
              if (bangLoc + 2 == baseText.length()) {
                  extraText = "";
              } else {
                  extraText = baseText.substring(bangLoc + 1);
              }
          } else {
              throw new MalformedURLException("No !/ in url: " + url.toExternalForm());
          }
  
  
          List<String> segments = new ArrayList<>();
  
          StringTokenizer tokens = new StringTokenizer(extraText, "!");
  
          while (tokens.hasMoreTokens()) {
              segments.add(tokens.nextToken());
          }
  
          this.segments = segments.toArray(new String[0]);
          this.baseResource = new URL(baseResourceText);
      }
  
      protected static URL normaliseURL(URL url) throws MalformedURLException {
          String text = normalizeUrlPath(url.toString());
  
          if (!text.startsWith("jar:")) {
              text = "jar:" + text;
          }
  
          if (text.indexOf('!') < 0) {
              text = text + "!/";
          }
  
          return new URL(text);
      }
  
      /**
       * Retrieve the nesting path segments.
       *
       * @return The segments.
       */
      protected String[] getSegments() {
          return this.segments;
      }
  
      /**
       * Retrieve the base resource <code>URL</code>.
       *
       * @return The base resource url.
       */
      protected URL getBaseResource() {
          return this.baseResource;
      }
  
      /**
       * @see java.net.URLConnection
       */
      public void connect() throws IOException {
          if (this.segments.length == 0) {
              setupBaseResourceInputStream();
          } else {
              setupPathedInputStream();
          }
      }
  
     /**
      * Setup the <code>InputStream</code> purely from the base resource.
      *
      * @throws java.io.IOException If an I/O error occurs.
      */
     protected void setupBaseResourceInputStream() throws IOException {
         this.in = getBaseResource().openStream();
     }
 
     /**
      * Setup the <code>InputStream</code> for URL with nested segments.
      *
      * @throws java.io.IOException If an I/O error occurs.
      */
     protected void setupPathedInputStream() throws IOException {
         InputStream curIn = getBaseResource().openStream();
 
         for (int i = 0; i < this.segments.length; ++i) {
             curIn = getSegmentInputStream(curIn, segments[i]);
         }
 
         this.in = curIn;
     }
 
     /**
      * Retrieve the <code>InputStream</code> for the nesting
      * segment relative to a base <code>InputStream</code>.
      *
      * @param baseIn  The base input-stream.
      * @param segment The nesting segment path.
      * @return The input-stream to the segment.
      * @throws java.io.IOException If an I/O error occurs.
      */
     protected InputStream getSegmentInputStream(InputStream baseIn, String segment) throws IOException {
         JarInputStream jarIn = new JarInputStream(baseIn);
         JarEntry entry;
 
         while (jarIn.available() != 0) {
             entry = jarIn.getNextJarEntry();
 
             if (entry == null) {
                 break;
             }
 
             if (("/" + entry.getName()).equals(segment)) {
                 return jarIn;
             }
         }
 
         throw new IOException("unable to locate segment: " + segment);
     }
 
     /**
      * @see java.net.URLConnection
      */
     public InputStream getInputStream() throws IOException {
         if (this.in == null) {
             connect();
         }
         return this.in;
     }
 
     /**
      * @return JarFile
      * @throws java.io.IOException
      * @see java.net.JarURLConnection#getJarFile()
      */
     public JarFile getJarFile() throws IOException {
         String url = baseResource.toExternalForm();
 
         if (url.startsWith("file:/")) {
             url = url.substring(6);
         }
 
         return new JarFile(URLDecoder.decode(url, "UTF-8"));
     }
 
     private static String normalizeUrlPath(String name) {
         if (name.startsWith("/")) {
             name = name.substring(1);
         }
 
         // Looking for org/codehaus/werkflow/personality/basic/../common/core-idioms.xml
         //                                               |    i  |
         //                                               +-------+ remove
         //
         int i = name.indexOf("/..");
 
         // Can't be at the beginning because we have no root to refer to so
         // we start at 1.
         if (i > 0) {
             int j = name.lastIndexOf("/", i - 1);
 
             name = name.substring(0, j) + name.substring(i + 3);
         }
 
         return name;
     }
 
 }