/*
    * 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.File;
  import java.io.IOException;
  import java.io.OutputStream;
  import java.io.RandomAccessFile;
  import java.io.Serializable;
  import java.nio.ByteBuffer;
  import java.util.HashMap;
  import java.util.Map;
  
  import org.apache.logging.log4j.core.Layout;
  import org.apache.logging.log4j.core.util.NullOutputStream;
  
  /**
   * Extends OutputStreamManager but instead of using a buffered output stream,
   * this class uses a {@code ByteBuffer} and a {@code RandomAccessFile} to do the
   * I/O.
   */
  public class RandomAccessFileManager extends OutputStreamManager {
      static final int DEFAULT_BUFFER_SIZE = 256 * 1024;
  
      private static final RandomAccessFileManagerFactory FACTORY = new RandomAccessFileManagerFactory();
  
      private final boolean isImmediateFlush;
      private final String advertiseURI;
      private final RandomAccessFile randomAccessFile;
      private final ByteBuffer buffer;
      private final ThreadLocal<Boolean> isEndOfBatch = new ThreadLocal<Boolean>();
  
      protected RandomAccessFileManager(final RandomAccessFile file,
              final String fileName, final OutputStream os,
              final boolean immediateFlush, final int bufferSize,
              final String advertiseURI, final Layout<? extends Serializable> layout) {
          super(os, fileName, layout);
          this.isImmediateFlush = immediateFlush;
          this.randomAccessFile = file;
          this.advertiseURI = advertiseURI;
          this.isEndOfBatch.set(Boolean.FALSE);
          this.buffer = ByteBuffer.allocate(bufferSize);
      }
  
      /**
       * Returns the RandomAccessFileManager.
       *
       * @param fileName The name of the file to manage.
       * @param append true if the file should be appended to, false if it should
       *            be overwritten.
       * @param isFlush true if the contents should be flushed to disk on every
       *            write
       * @param bufferSize The buffer size.
       * @param advertiseURI the URI to use when advertising the file
       * @param layout The layout.
       * @return A RandomAccessFileManager for the File.
       */
      public static RandomAccessFileManager getFileManager(final String fileName, final boolean append,
              final boolean isFlush, final int bufferSize, final String advertiseURI,
              final Layout<? extends Serializable> layout) {
          return (RandomAccessFileManager) getManager(fileName, new FactoryData(append,
                  isFlush, bufferSize, advertiseURI, layout), FACTORY);
      }
  
      public Boolean isEndOfBatch() {
          return isEndOfBatch.get();
      }
  
      public void setEndOfBatch(final boolean isEndOfBatch) {
          this.isEndOfBatch.set(Boolean.valueOf(isEndOfBatch));
      }
  
      @Override
      protected synchronized void write(final byte[] bytes, int offset, int length) {
          super.write(bytes, offset, length); // writes to dummy output stream
  
          int chunk = 0;
          do {
              if (length > buffer.remaining()) {
                  flush();
              }
              chunk = Math.min(length, buffer.remaining());
              buffer.put(bytes, offset, chunk);
              offset += chunk;
              length -= chunk;
         } while (length > 0);
 
         if (isImmediateFlush || isEndOfBatch.get() == Boolean.TRUE) {
             flush();
         }
     }
 
     @Override
     public synchronized void flush() {
         buffer.flip();
         try {
             randomAccessFile.write(buffer.array(), 0, buffer.limit());
         } catch (final IOException ex) {
             final String msg = "Error writing to RandomAccessFile " + getName();
             throw new AppenderLoggingException(msg, ex);
         }
         buffer.clear();
     }
 
     @Override
     public synchronized void close() {
         flush();
         try {
             randomAccessFile.close();
         } catch (final IOException ex) {
             LOGGER.error("Unable to close RandomAccessFile " + getName() + ". "
                     + ex);
         }
     }
 
     /**
      * Returns the name of the File being managed.
      *
      * @return The name of the File being managed.
      */
     public String getFileName() {
         return getName();
     }
     
     /**
      * Returns the buffer capacity.
      * @return the buffer size
      */
     public int getBufferSize() {
         return buffer.capacity();
     }
 
     /**
      * Gets this FileManager's content format specified by:
      * <p>
      * Key: "fileURI" Value: provided "advertiseURI" param.
      * </p>
      * 
      * @return Map of content format keys supporting FileManager
      */
     @Override
     public Map<String, String> getContentFormat() {
         final Map<String, String> result = new HashMap<String, String>(
                 super.getContentFormat());
         result.put("fileURI", advertiseURI);
         return result;
     }
 
     /**
      * Factory Data.
      */
     private static class FactoryData {
         private final boolean append;
         private final boolean immediateFlush;
         private final int bufferSize;
         private final String advertiseURI;
         private final Layout<? extends Serializable> layout;
 
         /**
          * Constructor.
          *
          * @param append Append status.
          * @param bufferSize TODO
          */
         public FactoryData(final boolean append, final boolean immediateFlush,
                 final int bufferSize, final String advertiseURI, final Layout<? extends Serializable> layout) {
             this.append = append;
             this.immediateFlush = immediateFlush;
             this.bufferSize = bufferSize;
             this.advertiseURI = advertiseURI;
             this.layout = layout;
         }
     }
 
     /**
      * Factory to create a RandomAccessFileManager.
      */
     private static class RandomAccessFileManagerFactory implements
             ManagerFactory<RandomAccessFileManager, FactoryData> {
 
         /**
          * Create a RandomAccessFileManager.
          *
          * @param name The name of the File.
          * @param data The FactoryData
          * @return The RandomAccessFileManager for the File.
          */
         @Override
         public RandomAccessFileManager createManager(final String name, final FactoryData data) {
             final File file = new File(name);
             final File parent = file.getParentFile();
             if (null != parent && !parent.exists()) {
                 parent.mkdirs();
             }
             if (!data.append) {
                 file.delete();
             }
 
             final OutputStream os = NullOutputStream.NULL_OUTPUT_STREAM;
             RandomAccessFile raf;
             try {
                 raf = new RandomAccessFile(name, "rw");
                 if (data.append) {
                     raf.seek(raf.length());
                 } else {
                     raf.setLength(0);
                 }
                 return new RandomAccessFileManager(raf, name, os, data.immediateFlush,
                         data.bufferSize, data.advertiseURI, data.layout);
             } catch (final Exception ex) {
                 LOGGER.error("RandomAccessFileManager (" + name + ") " + ex);
             }
             return null;
         }
     }
 
 }