/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements. See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache license, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License. You may obtain a copy of the License at
    *
    *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the license for the specific language governing permissions and
   * limitations under the license.
   */
  package org.apache.logging.log4j.core.appender;
  
  import java.io.IOException;
  import java.io.OutputStream;
  
  import org.apache.logging.log4j.core.Layout;
  
  /**
   * Manages an OutputStream so that it can be shared by multiple Appenders and will
   * allow appenders to reconfigure without requiring a new stream.
   */
  public class OutputStreamManager extends AbstractManager {
  
      private volatile OutputStream os;
      protected final Layout<?> layout;
  
      protected OutputStreamManager(final OutputStream os, final String streamName, final Layout<?> layout) {
          super(streamName);
          this.os = os;
          this.layout = layout;
          if (layout != null) {
              final byte[] header = layout.getHeader();
              if (header != null) {
                  try {
                      this.os.write(header, 0, header.length);
                  } catch (final IOException ioe) {
                      LOGGER.error("Unable to write header", ioe);
                  }
              }
          }
      }
  
      /**
       * Creates a Manager.
       *
       * @param name The name of the stream to manage.
       * @param data The data to pass to the Manager.
       * @param factory The factory to use to create the Manager.
       * @param <T> The type of the OutputStreamManager.
       * @return An OutputStreamManager.
       */
      public static <T> OutputStreamManager getManager(final String name, final T data,
                                                   final ManagerFactory<? extends OutputStreamManager, T> factory) {
          return AbstractManager.getManager(name, factory, data);
      }
  
      /**
       * Default hook to write footer during close.
       */
      @Override
      public void releaseSub() {
          writeFooter();
          close();
      }
  
      /**
       * Writes the footer.
       */
      protected void writeFooter() {
          if (layout == null) {
              return;
          }
          final byte[] footer = layout.getFooter();
          if (footer != null) {
              write(footer);
          }
      }
  
      /**
       * Returns the status of the stream.
       * @return true if the stream is open, false if it is not.
       */
      public boolean isOpen() {
          return getCount() > 0;
      }
  
      protected OutputStream getOutputStream() {
          return os;
      }
  
      protected void setOutputStream(final OutputStream os) {
          final byte[] header = layout.getHeader();
          if (header != null) {
             try {
                 os.write(header, 0, header.length);
                 this.os = os; // only update field if os.write() succeeded
             } catch (final IOException ioe) {
                 LOGGER.error("Unable to write header", ioe);
             }
         } else {
             this.os = os;
         }
     }
 
     /**
      * Some output streams synchronize writes while others do not. Synchronizing here insures that
      * log events won't be intertwined.
      * @param bytes The serialized Log event.
      * @param offset The offset into the byte array.
      * @param length The number of bytes to write.
      * @throws AppenderLoggingException if an error occurs.
      */
     protected synchronized void write(final byte[] bytes, final int offset, final int length)  {
         //System.out.println("write " + count);
         try {
             os.write(bytes, offset, length);
         } catch (final IOException ex) {
             final String msg = "Error writing to stream " + getName();
             throw new AppenderLoggingException(msg, ex);
         }
     }
 
     /**
      * Some output streams synchronize writes while others do not.
      * @param bytes The serialized Log event.
      * @throws AppenderLoggingException if an error occurs.
      */
     protected void write(final byte[] bytes)  {
         write(bytes, 0, bytes.length);
     }
 
     protected synchronized void close() {
         final OutputStream stream = os; // access volatile field only once per method
         if (stream == System.out || stream == System.err) {
             return;
         }
         try {
             stream.close();
         } catch (final IOException ex) {
             LOGGER.error("Unable to close stream " + getName() + ". " + ex);
         }
     }
 
     /**
      * Flushes any buffers.
      */
     public synchronized void flush() {
         try {
             os.flush();
         } catch (final IOException ex) {
             final String msg = "Error flushing stream " + getName();
             throw new AppenderLoggingException(msg, ex);
         }
     }
 }