/* 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 java.io.PrintWriter;
   import java.io.IOException;
   import java.io.Writer;
   
  /**
   * Provides a PrintWriter that routes through to another PrintWriter, 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.
   * <p>
   * Borrowed from sitemesh.
   *
   * @author Joe Walnes
   * @version $Revision: 1.1 $
   */
  public class RoutablePrintWriter extends PrintWriter {
  
      private PrintWriter 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 {
          PrintWriter activateDestination() throws IOException;
      }
  
      public RoutablePrintWriter(DestinationFactory factory, Runnable callBeforeUse) {
          super(new NullWriter());
          this.factory = factory;
          this.callBeforeUse = callBeforeUse;
      }
  
      public RoutablePrintWriter(DestinationFactory factory) {
          this(factory, doNothing);
      }
  
      private PrintWriter getDestination() {
          if (destination == null) {
              try {
                  destination = factory.activateDestination();
              } catch (IOException e) {
                  setError();
              }
          }
  
          callBeforeUse.run();
  
          return destination;
      }
  
      public void updateDestination(DestinationFactory factory) {
          destination = null;
          this.factory = factory;
      }
  
      public void close() {
          getDestination().close();
      }
  
      public void println(Object x) {
          getDestination().println(x);
      }
  
      public void println(String x) {
          getDestination().println(x);
      }
  
      public void println(char x[]) {
          getDestination().println(x);
      }
  
      public void println(double x) {
          getDestination().println(x);
      }
  
      public void println(float x) {
          getDestination().println(x);
      }
  
      public void println(long x) {
          getDestination().println(x);
      }
  
      public void println(int x) {
          getDestination().println(x);
      }
  
     public void println(char x) {
         getDestination().println(x);
     }
 
     public void println(boolean x) {
         getDestination().println(x);
     }
 
     public void println() {
         getDestination().println();
     }
 
     public void print(Object obj) {
         getDestination().print(obj);
     }
 
     public void print(String s) {
         getDestination().print(s);
     }
 
     public void print(char s[]) {
         getDestination().print(s);
     }
 
     public void print(double d) {
         getDestination().print(d);
     }
 
     public void print(float f) {
         getDestination().print(f);
     }
 
     public void print(long l) {
         getDestination().print(l);
     }
 
     public void print(int i) {
         getDestination().print(i);
     }
 
     public void print(char c) {
         getDestination().print(c);
     }
 
     public void print(boolean b) {
         getDestination().print(b);
     }
 
     public void write(String s) {
         getDestination().write(s);
     }
 
     public void write(String s, int off, int len) {
         getDestination().write(s, off, len);
     }
 
     public void write(char buf[]) {
         getDestination().write(buf);
     }
 
     public void write(char buf[], int off, int len) {
         getDestination().write(buf, off, len);
     }
 
     public void write(int c) {
         getDestination().write(c);
     }
 
     public boolean checkError() {
         return getDestination().checkError();
     }
 
     public void flush() {
         getDestination().flush();
     }
 
     /**
      * Just to keep super constructor for PrintWriter happy - it's never actually used.
      */
     private static class NullWriter extends Writer {
 
         protected NullWriter() {
             super();
         }
 
         public void write(char cbuf[], int off, int len) throws IOException {
             throw new UnsupportedOperationException();
         }
 
         public void flush() throws IOException {
             throw new UnsupportedOperationException();
         }
 
         public void close() throws IOException {
             throw new UnsupportedOperationException();
         }
 
     }
 
 }