package com.atlassian.plugin;
   
   import org.apache.commons.lang.Validate;
   import org.apache.commons.io.IOUtils;
   
   import java.util.jar.JarFile;
   import java.util.zip.ZipEntry;
   import java.io.*;
   
  /**
   * The implementation of PluginArtifact that is backed by a jar file.
   *
   * @see PluginArtifact
   * @since 2.0.0
   */
  public class JarPluginArtifact implements PluginArtifact
  {
      private final File jarFile;
  
      public JarPluginArtifact(File jarFile)
      {
          Validate.notNull(jarFile);
          this.jarFile = jarFile;
      }
  
      public boolean doesResourceExist(String name)
      {
          InputStream in = null;
          try
          {
              in = getResourceAsStream(name);
              return (in != null);
          }
          finally
          {
              IOUtils.closeQuietly(in);
          }
      }
  
      /**
       * @return an input stream for the this file in the jar. Closing this stream also closes the jar file this stream comes from.
       */
      public InputStream getResourceAsStream(String fileName) throws PluginParseException
      {
          Validate.notNull(fileName, "The file name must not be null");
          final JarFile jar;
          final ZipEntry entry;
          try
          {
              jar = new JarFile(jarFile);
              entry = jar.getEntry(fileName);
              if (entry == null)
              {
                  jar.close();
                  return null;
              }
          }
          catch (IOException e)
          {
              throw new PluginParseException("Cannot open JAR file for reading: " + jarFile, e);
          }
  
          InputStream descriptorStream;
          try
          {
              descriptorStream = new BufferedInputStream(jar.getInputStream(entry)) {
  
                  // because we do not expose a handle to the jar file this stream is associated with, we need to make sure
                  // we explicitly close the jar file when we're done with the stream (else we'll have a file handle leak)
                  public void close() throws IOException
                  {
                      super.close();
                      jar.close();
                  }
              };
          }
          catch (IOException e)
          {
              throw new PluginParseException("Cannot retrieve " + fileName + " from plugin JAR [" + jarFile + "]", e);
          }
          return descriptorStream;
      }
  
      public String getName()
      {
          return jarFile.getName();
      }
  
      @Override
      public String toString()
      {
          return getName();
      }
  
      /**
       * @return a buffered file input stream of the file on disk. This input stream
       * is not resettable.
       */
      public InputStream getInputStream()
     {
         try
         {
             return new BufferedInputStream(new FileInputStream(jarFile));
         }
         catch (FileNotFoundException e)
         {
             throw new RuntimeException("Could not open JAR file for reading: " + jarFile, e);
         }
     }
 
     public File toFile()
     {
         return jarFile;
     }
 }