/*
    * Copyright 2012 The Netty Project
    *
    * The Netty Project 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.jboss.netty.handler.logging;
  
  import org.jboss.netty.buffer.ChannelBuffer;
  import org.jboss.netty.channel.ChannelDownstreamHandler;
  import org.jboss.netty.channel.ChannelEvent;
  import org.jboss.netty.channel.ChannelHandler;
  import org.jboss.netty.channel.ChannelHandler.Sharable;
  import org.jboss.netty.channel.ChannelHandlerContext;
  import org.jboss.netty.channel.ChannelUpstreamHandler;
  import org.jboss.netty.channel.ExceptionEvent;
  import org.jboss.netty.channel.MessageEvent;
  import org.jboss.netty.logging.InternalLogLevel;
  import org.jboss.netty.logging.InternalLogger;
  import org.jboss.netty.logging.InternalLoggerFactory;
  
  /**
   * A {@link ChannelHandler} that logs all events via {@link InternalLogger}.
   * By default, all events are logged at <tt>DEBUG</tt> level.  You can extend
   * this class and override {@link #log(ChannelEvent)} to change the default
   * behavior.
   * @apiviz.landmark
   */
  @Sharable
  public class LoggingHandler implements ChannelUpstreamHandler, ChannelDownstreamHandler {
  
      private static final InternalLogLevel DEFAULT_LEVEL = InternalLogLevel.DEBUG;
      private static final String NEWLINE = String.format("%n");
  
      private static final String[] BYTE2HEX = new String[256];
      private static final String[] HEXPADDING = new String[16];
      private static final String[] BYTEPADDING = new String[16];
      private static final char[] BYTE2CHAR = new char[256];
  
      static {
          int i;
  
          // Generate the lookup table for byte-to-hex-dump conversion
          for (i = 0; i < 10; i ++) {
              StringBuilder buf = new StringBuilder(3);
              buf.append(" 0");
              buf.append(i);
              BYTE2HEX[i] = buf.toString();
          }
          for (; i < 16; i ++) {
              StringBuilder buf = new StringBuilder(3);
              buf.append(" 0");
              buf.append((char) ('a' + i - 10));
              BYTE2HEX[i] = buf.toString();
          }
          for (; i < BYTE2HEX.length; i ++) {
              StringBuilder buf = new StringBuilder(3);
              buf.append(' ');
              buf.append(Integer.toHexString(i));
              BYTE2HEX[i] = buf.toString();
          }
  
          // Generate the lookup table for hex dump paddings
          for (i = 0; i < HEXPADDING.length; i ++) {
              int padding = HEXPADDING.length - i;
              StringBuilder buf = new StringBuilder(padding * 3);
              for (int j = 0; j < padding; j ++) {
                  buf.append("   ");
              }
              HEXPADDING[i] = buf.toString();
          }
  
          // Generate the lookup table for byte dump paddings
          for (i = 0; i < BYTEPADDING.length; i ++) {
              int padding = BYTEPADDING.length - i;
              StringBuilder buf = new StringBuilder(padding);
              for (int j = 0; j < padding; j ++) {
                  buf.append(' ');
              }
              BYTEPADDING[i] = buf.toString();
          }
  
          // Generate the lookup table for byte-to-char conversion
          for (i = 0; i < BYTE2CHAR.length; i ++) {
              if (i <= 0x1f || i >= 0x7f) {
                  BYTE2CHAR[i] = '.';
              } else {
                  BYTE2CHAR[i] = (char) i;
              }
          }
     }
 
     private final InternalLogger logger;
     private final InternalLogLevel level;
     private final boolean hexDump;
 
     /**
      * Creates a new instance whose logger name is the fully qualified class
      * name of the instance with hex dump enabled.
      */
     public LoggingHandler() {
         this(true);
     }
 
     /**
      * Creates a new instance whose logger name is the fully qualified class
      * name of the instance.
      *
      * @param level   the log level
      */
     public LoggingHandler(InternalLogLevel level) {
         this(level, true);
     }
 
     /**
      * Creates a new instance whose logger name is the fully qualified class
      * name of the instance.
      *
      * @param hexDump {@code true} if and only if the hex dump of the received
      *                message is logged
      */
     public LoggingHandler(boolean hexDump) {
         this(DEFAULT_LEVEL, hexDump);
     }
 
     /**
      * Creates a new instance whose logger name is the fully qualified class
      * name of the instance.
      *
      * @param level   the log level
      * @param hexDump {@code true} if and only if the hex dump of the received
      *                message is logged
      */
     public LoggingHandler(InternalLogLevel level, boolean hexDump) {
         if (level == null) {
             throw new NullPointerException("level");
         }
 
         logger = InternalLoggerFactory.getInstance(getClass());
         this.level = level;
         this.hexDump = hexDump;
     }
 
     /**
      * Creates a new instance with the specified logger name and with hex dump
      * enabled.
      */
     public LoggingHandler(Class<?> clazz) {
         this(clazz, true);
     }
 
     /**
      * Creates a new instance with the specified logger name.
      *
      * @param hexDump {@code true} if and only if the hex dump of the received
      *                message is logged
      */
     public LoggingHandler(Class<?> clazz, boolean hexDump) {
         this(clazz, DEFAULT_LEVEL, hexDump);
     }
 
     /**
      * Creates a new instance with the specified logger name.
      *
      * @param level   the log level
      */
     public LoggingHandler(Class<?> clazz, InternalLogLevel level) {
         this(clazz, level, true);
     }
 
     /**
      * Creates a new instance with the specified logger name.
      *
      * @param level   the log level
      * @param hexDump {@code true} if and only if the hex dump of the received
      *                message is logged
      */
     public LoggingHandler(Class<?> clazz, InternalLogLevel level, boolean hexDump) {
         if (clazz == null) {
             throw new NullPointerException("clazz");
         }
         if (level == null) {
             throw new NullPointerException("level");
         }
         logger = InternalLoggerFactory.getInstance(clazz);
         this.level = level;
         this.hexDump = hexDump;
     }
 
     /**
      * Creates a new instance with the specified logger name and with hex dump
      * enabled.
      */
     public LoggingHandler(String name) {
         this(name, true);
     }
 
     /**
      * Creates a new instance with the specified logger name.
      *
      * @param hexDump {@code true} if and only if the hex dump of the received
      *                message is logged
      */
     public LoggingHandler(String name, boolean hexDump) {
         this(name, DEFAULT_LEVEL, hexDump);
     }
 
     /**
      * Creates a new instance with the specified logger name.
      *
      * @param level   the log level
      * @param hexDump {@code true} if and only if the hex dump of the received
      *                message is logged
      */
     public LoggingHandler(String name, InternalLogLevel level, boolean hexDump) {
         if (name == null) {
             throw new NullPointerException("name");
         }
         if (level == null) {
             throw new NullPointerException("level");
         }
         logger = InternalLoggerFactory.getInstance(name);
         this.level = level;
         this.hexDump = hexDump;
     }
 
     /**
      * Returns the {@link InternalLogger} that this handler uses to log
      * a {@link ChannelEvent}.
      */
     public InternalLogger getLogger() {
         return logger;
     }
 
     /**
      * Returns the {@link InternalLogLevel} that this handler uses to log
      * a {@link ChannelEvent}.
      */
     public InternalLogLevel getLevel() {
         return level;
     }
 
     /**
      * Logs the specified event to the {@link InternalLogger} returned by
      * {@link #getLogger()}. If hex dump has been enabled for this handler,
      * the hex dump of the {@link ChannelBuffer} in a {@link MessageEvent} will
      * be logged together.
      */
     public void log(ChannelEvent e) {
         if (getLogger().isEnabled(level)) {
             String msg = e.toString();
 
             // Append hex dump if necessary.
             if (hexDump && e instanceof MessageEvent) {
                 MessageEvent me = (MessageEvent) e;
                 if (me.getMessage() instanceof ChannelBuffer) {
                     msg += formatBuffer((ChannelBuffer) me.getMessage());
                 }
             }
 
             // Log the message (and exception if available.)
             if (e instanceof ExceptionEvent) {
                 getLogger().log(level, msg, ((ExceptionEvent) e).getCause());
             } else {
                 getLogger().log(level, msg);
             }
         }
     }
 
     private static String formatBuffer(ChannelBuffer buf) {
         int length = buf.readableBytes();
         int rows = length / 16 + (length % 15 == 0? 0 : 1) + 4;
         StringBuilder dump = new StringBuilder(rows * 80);
 
         dump.append(
                 NEWLINE + "         +-------------------------------------------------+" +
                 NEWLINE + "         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |" +
                 NEWLINE + "+--------+-------------------------------------------------+----------------+");
 
         final int startIndex = buf.readerIndex();
         final int endIndex = buf.writerIndex();
 
         int i;
         for (i = startIndex; i < endIndex; i ++) {
             int relIdx = i - startIndex;
             int relIdxMod16 = relIdx & 15;
             if (relIdxMod16 == 0) {
                 dump.append(NEWLINE);
                 dump.append(Long.toHexString(relIdx & 0xFFFFFFFFL | 0x100000000L));
                 dump.setCharAt(dump.length() - 9, '|');
                 dump.append('|');
             }
             dump.append(BYTE2HEX[buf.getUnsignedByte(i)]);
             if (relIdxMod16 == 15) {
                 dump.append(" |");
                 for (int j = i - 15; j <= i; j ++) {
                     dump.append(BYTE2CHAR[buf.getUnsignedByte(j)]);
                 }
                 dump.append('|');
             }
         }
 
         if ((i - startIndex & 15) != 0) {
             int remainder = length & 15;
             dump.append(HEXPADDING[remainder]);
             dump.append(" |");
             for (int j = i - remainder; j < i; j ++) {
                 dump.append(BYTE2CHAR[buf.getUnsignedByte(j)]);
             }
             dump.append(BYTEPADDING[remainder]);
             dump.append('|');
         }
 
         dump.append(
                 NEWLINE + "+--------+-------------------------------------------------+----------------+");
 
         return dump.toString();
     }
 
     public void handleUpstream(ChannelHandlerContext ctx, ChannelEvent e)
             throws Exception {
         log(e);
         ctx.sendUpstream(e);
     }
 
     public void handleDownstream(ChannelHandlerContext ctx, ChannelEvent e)
             throws Exception {
         log(e);
         ctx.sendDownstream(e);
     }
 }