/**
    * Logback: the reliable, generic, fast and flexible logging framework.
    * Copyright (C) 1999-2015, QOS.ch. All rights reserved.
    *
    * This program and the accompanying materials are dual-licensed under
    * either the terms of the Eclipse Public License v1.0 as published by
    * the Eclipse Foundation
    *
    *   or (per the licensee's choosing)
   *
   * under the terms of the GNU Lesser General Public License version 2.1
   * as published by the Free Software Foundation.
   */
  package ch.qos.logback.core;
  
  import static ch.qos.logback.core.CoreConstants.CODES_URL;
  
  import java.io.IOException;
  import java.io.OutputStream;
  import java.util.concurrent.locks.ReentrantLock;
  
  import ch.qos.logback.core.encoder.Encoder;
  import ch.qos.logback.core.encoder.LayoutWrappingEncoder;
  import ch.qos.logback.core.spi.DeferredProcessingAware;
  import ch.qos.logback.core.status.ErrorStatus;
  
  /**
   * OutputStreamAppender appends events to a {@link OutputStream}. This class
   * provides basic services that other appenders build upon.
   * 
   * For more information about this appender, please refer to the online manual
   * at http://logback.qos.ch/manual/appenders.html#OutputStreamAppender
   * 
   * @author Ceki Gülcü
   */
  public class OutputStreamAppender<E> extends UnsynchronizedAppenderBase<E> {
  
      /**
       * It is the encoder which is ultimately responsible for writing the event to an
       * {@link OutputStream}.
       */
      protected Encoder<E> encoder;
  
      /**
       * All synchronization in this class is done via the lock object.
       */
      protected final ReentrantLock streamWriteLock = new ReentrantLock(false);
  
      /**
       * This is the {@link OutputStream outputStream} where output will be written.
       */
      private OutputStream outputStream;
  
      boolean immediateFlush = true;
  
      /**
       * The underlying output stream used by this appender.
       * 
       * @return
       */
      public OutputStream getOutputStream() {
          return outputStream;
      }
  
      /**
       * Checks that requires parameters are set and if everything is in order,
       * activates this appender.
       */
      public void start() {
          int errors = 0;
          if (this.encoder == null) {
              addStatus(new ErrorStatus("No encoder set for the appender named \"" + name + "\".", this));
              errors++;
          }
  
          if (this.outputStream == null) {
              addStatus(new ErrorStatus("No output stream set for the appender named \"" + name + "\".", this));
              errors++;
          }
          // only error free appenders should be activated
          if (errors == 0) {
              super.start();
          }
      }
  
      public void setLayout(Layout<E> layout) {
          addWarn("This appender no longer admits a layout as a sub-component, set an encoder instead.");
          addWarn("To ensure compatibility, wrapping your layout in LayoutWrappingEncoder.");
          addWarn("See also " + CODES_URL + "#layoutInsteadOfEncoder for details");
          LayoutWrappingEncoder<E> lwe = new LayoutWrappingEncoder<E>();
          lwe.setLayout(layout);
          lwe.setContext(context);
          this.encoder = lwe;
      }
  
      @Override
      protected void append(E eventObject) {
          if (!isStarted()) {
              return;
         }
 
         subAppend(eventObject);
     }
 
     /**
      * Stop this appender instance. The underlying stream or writer is also closed.
      * 
      * <p>
      * Stopped appenders cannot be reused.
      */
     public void stop() {
         if(!isStarted())
             return;
 
         streamWriteLock.lock();
         try {
             closeOutputStream();
             super.stop();
         } finally {
             streamWriteLock.unlock();
         }
     }
 
     /**
      * Close the underlying {@link OutputStream}.
      */
     protected void closeOutputStream() {
         if (this.outputStream != null) {
             try {
                 // before closing we have to output out layout's footer
                 encoderClose();
                 this.outputStream.close();
                 this.outputStream = null;
             } catch (IOException e) {
                 addStatus(new ErrorStatus("Could not close output stream for OutputStreamAppender.", this, e));
             }
         }
     }
 
     void encoderClose() {
         if (encoder != null && this.outputStream != null) {
             try {
                 byte[] footer = encoder.footerBytes();
                 writeBytes(footer);
             } catch (IOException ioe) {
                 this.started = false;
                 addStatus(new ErrorStatus("Failed to write footer for appender named [" + name + "].", this, ioe));
             }
         }
     }
 
     /**
      * <p>
      * Sets the @link OutputStream} where the log output will go. The specified
      * <code>OutputStream</code> must be opened by the user and be writable. The
      * <code>OutputStream</code> will be closed when the appender instance is
      * closed.
      * 
      * @param outputStream An already opened OutputStream.
      */
     public void setOutputStream(OutputStream outputStream) {
         streamWriteLock.lock();
         try {
             // close any previously opened output stream
             closeOutputStream();
             this.outputStream = outputStream;
             if (encoder == null) {
                 addWarn("Encoder has not been set. Cannot invoke its init method.");
                 return;
             }
 
             encoderInit();
         } finally {
             streamWriteLock.unlock();
         }
     }
 
     void encoderInit() {
         if (encoder != null && this.outputStream != null) {
             try {
                 byte[] header = encoder.headerBytes();
                 writeBytes(header);
             } catch (IOException ioe) {
                 this.started = false;
                 addStatus(
                         new ErrorStatus("Failed to initialize encoder for appender named [" + name + "].", this, ioe));
             }
         }
     }
 
     protected void writeOut(E event) throws IOException {
         byte[] byteArray = this.encoder.encode(event);
         writeBytes(byteArray);
     }
 
     private void writeBytes(byte[] byteArray) throws IOException {
         if (byteArray == null || byteArray.length == 0)
             return;
 
         streamWriteLock.lock();
         try {
             writeByteArrayToOutputStreamWithPossibleFlush(byteArray);
         } finally {
             streamWriteLock.unlock();
         }
     }
 
     /**
      * A simple method to write to an outputStream and flush the stream if immediateFlush is set to true.
      *
      * @since 1.3.9/1.4.9
      */
     protected final void writeByteArrayToOutputStreamWithPossibleFlush(byte[] byteArray) throws IOException {
         this.outputStream.write(byteArray);
         if (immediateFlush) {
             this.outputStream.flush();
         }
     }
 
     /**
      * Actual writing occurs here.
      * <p>
      * Most subclasses of <code>WriterAppender</code> will need to override this
      * method.
      * 
      * @since 0.9.0
      */
     protected void subAppend(E event) {
         if (!isStarted()) {
             return;
         }
         try {
             // this step avoids LBCLASSIC-139
             if (event instanceof DeferredProcessingAware) {
                 ((DeferredProcessingAware) event).prepareForDeferredProcessing();
             }
             writeOut(event);
 
         } catch (IOException ioe) {
             // as soon as an exception occurs, move to non-started state
             // and add a single ErrorStatus to the SM.
             this.started = false;
             addStatus(new ErrorStatus("IO failure in appender", this, ioe));
         }
     }
 
     public Encoder<E> getEncoder() {
         return encoder;
     }
 
     public void setEncoder(Encoder<E> encoder) {
         this.encoder = encoder;
     }
 
     public boolean isImmediateFlush() {
         return immediateFlush;
     }
 
     public void setImmediateFlush(boolean immediateFlush) {
         this.immediateFlush = immediateFlush;
     }
 
 }