/* This software is published under the terms of the OpenSymphony Software
    * License version 1.1, of which a copy has been included with this
    * distribution in the LICENSE.txt file. */
   package com.atlassian.gzipfilter;
   
   import javax.servlet.ServletOutputStream;
   import java.io.IOException;
   
   /**
   * Provides a ServletOutputStream that routes through to another ServletOutputStream, however the destination
   * can be changed at any point. The destination can be passed in using a factory, so it will not be created
   * until it's actually needed.
   *
   * @author Joe Walnes
   * @version $Revision: 1.1 $
   */
  public class RoutableServletOutputStream extends ServletOutputStream {
  
      private ServletOutputStream destination;
      private DestinationFactory factory;
      private Runnable callBeforeUse;
      private static final Runnable doNothing = new Runnable()
      {
          public void run()
          {
          }
      };
  
      /**
       * Factory to lazily instantiate the destination.
       */
      public static interface DestinationFactory {
          ServletOutputStream create() throws IOException;
      }
  
      public RoutableServletOutputStream(DestinationFactory factory, final Runnable callBeforeUse) {
          this.factory = factory;
          this.callBeforeUse = callBeforeUse;
      }
  
      public RoutableServletOutputStream(final DestinationFactory factory)
      {
          this(factory, doNothing);
      }
  
      private ServletOutputStream getDestination() throws IOException {
          if (destination == null) {
              destination = factory.create();
          }
  
          callBeforeUse.run();
  
          return destination;
      }
  
      public void updateDestination(DestinationFactory factory) {
          destination = null;
          this.factory = factory;
      }
  
      public void close() throws IOException {
          getDestination().close();
      }
  
      public void write(int b) throws IOException {
          getDestination().write(b);
      }
  
      public void print(String s) throws IOException {
          getDestination().print(s);
      }
  
      public void print(boolean b) throws IOException {
          getDestination().print(b);
      }
  
      public void print(char c) throws IOException {
          getDestination().print(c);
      }
  
      public void print(int i) throws IOException {
          getDestination().print(i);
      }
  
      public void print(long l) throws IOException {
          getDestination().print(l);
      }
  
      public void print(float v) throws IOException {
          getDestination().print(v);
      }
  
      public void print(double v) throws IOException {
          getDestination().print(v);
      }
  
      public void println() throws IOException {
          getDestination().println();
      }
 
     public void println(String s) throws IOException {
         getDestination().println(s);
     }
 
     public void println(boolean b) throws IOException {
         getDestination().println(b);
     }
 
     public void println(char c) throws IOException {
         getDestination().println(c);
     }
 
     public void println(int i) throws IOException {
         getDestination().println(i);
     }
 
     public void println(long l) throws IOException {
         getDestination().println(l);
     }
 
     public void println(float v) throws IOException {
         getDestination().println(v);
     }
 
     public void println(double v) throws IOException {
         getDestination().println(v);
     }
 
     public void write(byte b[]) throws IOException {
         getDestination().write(b);
     }
 
     public void write(byte b[], int off, int len) throws IOException {
         getDestination().write(b, off, len);
     }
 
     public void flush() throws IOException {
         getDestination().flush();
     }
 }