/*
    * 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.
   */
  
  // Contributors:   Mathias Bogaert
  
  package org.apache.log4j.xml;
  
  import org.apache.log4j.Layout;
  import org.apache.log4j.helpers.Transform;
  import org.apache.log4j.spi.LocationInfo;
  import org.apache.log4j.spi.LoggingEvent;
  
  import java.util.Set;
  import java.util.Arrays;
  
  /**
   * The output of the XMLLayout consists of a series of log4j:event
   * elements as defined in the <a
   * href="log4j.dtd">log4j.dtd</a>. It does not output a
   * complete well-formed XML file. The output is designed to be
   * included as an <em>external entity</em> in a separate file to form
   * a correct XML file.
   *
   * <p>For example, if <code>abc</code> is the name of the file where
   * the XMLLayout ouput goes, then a well-formed XML file would be:
   *
    <pre>
     &lt;?xml version="1.0" ?&gt;
   
    &lt;!DOCTYPE log4j:eventSet PUBLIC "-//APACHE//DTD LOG4J 1.2//EN" "log4j.dtd" [&lt;!ENTITY data SYSTEM "abc"&gt;]&gt;
   
    &lt;log4j:eventSet version="1.2" xmlns:log4j="http://jakarta.apache.org/log4j/"&gt;
   	&nbsp;&nbsp;&data;
    &lt;/log4j:eventSet&gt;
    </pre>
   
   * <p>This approach enforces the independence of the XMLLayout and the
   * appender where it is embedded.
   *
   * <p>The <code>version</code> attribute helps components to correctly
   * intrepret output generated by XMLLayout. The value of this
   * attribute should be "1.1" for output generated by log4j versions
   * prior to log4j 1.2 (final release) and "1.2" for relase 1.2 and
   * later.
   *
   * Appenders using this layout should have their encoding
   * set to UTF-8 or UTF-16, otherwise events containing
   * non ASCII characters could result in corrupted
   * log files. 
   *
   * @author Ceki  G&uuml;lc&uuml;
   * @since 0.9.0 
   * */
  public class XMLLayout extends Layout {
  
    private  final int DEFAULT_SIZE = 256;
    private final int UPPER_LIMIT = 2048;
  
    private StringBuffer buf = new StringBuffer(DEFAULT_SIZE);
    private boolean locationInfo = false;
    private boolean properties = false;
   
    /**
     * The <b>LocationInfo</b> option takes a boolean value. By default,
     * it is set to false which means there will be no location
     * information output by this layout. If the the option is set to
     * true, then the file name and line number of the statement at the
     * origin of the log statement will be output.
     *
     * <p>If you are embedding this layout within an {@link
     * org.apache.log4j.net.SMTPAppender} then make sure to set the
     * <b>LocationInfo</b> option of that appender as well.
     * */
    public void setLocationInfo(boolean flag) {
      locationInfo = flag;
    }
    
    /**
       Returns the current value of the <b>LocationInfo</b> option.
     */
    public boolean getLocationInfo() {
      return locationInfo;
    }
  
      /**
      * Sets whether MDC key-value pairs should be output, default false.
      * @param flag new value.
      * @since 1.2.15
      */
   public void setProperties(final boolean flag) {
       properties = flag;
   }
 
     /**
      * Gets whether MDC key-value pairs should be output.
      * @return true if MDC key-value pairs are output.
      * @since 1.2.15
      */
   public boolean getProperties() {
       return properties;
   }
 
   /** No options to activate. */
   public void activateOptions() {
   }
 
 
   /**
    * Formats a {@link org.apache.log4j.spi.LoggingEvent} in conformance with the log4j.dtd.
    * */
   public String format(final LoggingEvent event) {
 
     // Reset working buffer. If the buffer is too large, then we need a new
     // one in order to avoid the penalty of creating a large array.
     if(buf.capacity() > UPPER_LIMIT) {
       buf = new StringBuffer(DEFAULT_SIZE);
     } else {
       buf.setLength(0);
     }
     
     // We yield to the \r\n heresy.
 
     buf.append("<log4j:event logger=\"");
     buf.append(Transform.escapeTags(event.getLoggerName()));
     buf.append("\" timestamp=\"");
     buf.append(event.timeStamp);
     buf.append("\" level=\"");
     buf.append(Transform.escapeTags(String.valueOf(event.getLevel())));
     buf.append("\" thread=\"");
     buf.append(Transform.escapeTags(event.getThreadName()));
     buf.append("\">\r\n");
 
     buf.append("<log4j:message><![CDATA[");
     // Append the rendered message. Also make sure to escape any
     // existing CDATA sections.
     Transform.appendEscapingCDATA(buf, event.getRenderedMessage());
     buf.append("]]></log4j:message>\r\n");       
     
     String ndc = event.getNDC();
     if(ndc != null) {
       buf.append("<log4j:NDC><![CDATA[");
       Transform.appendEscapingCDATA(buf, ndc);
       buf.append("]]></log4j:NDC>\r\n");       
     }
     
     String[] s = event.getThrowableStrRep();
     if(s != null) {
       buf.append("<log4j:throwable><![CDATA[");
       for(int i = 0; i < s.length; i++) {
           Transform.appendEscapingCDATA(buf, s[i]);
 	      buf.append("\r\n");
       }
       buf.append("]]></log4j:throwable>\r\n");
     }
     
     if(locationInfo) { 
       LocationInfo locationInfo = event.getLocationInformation();	
       buf.append("<log4j:locationInfo class=\"");
       buf.append(Transform.escapeTags(locationInfo.getClassName()));
       buf.append("\" method=\"");
       buf.append(Transform.escapeTags(locationInfo.getMethodName()));
       buf.append("\" file=\"");
       buf.append(Transform.escapeTags(locationInfo.getFileName()));
       buf.append("\" line=\"");
       buf.append(locationInfo.getLineNumber());
       buf.append("\"/>\r\n");
     }
 
     if (properties) {
         Set keySet = event.getPropertyKeySet();
         if (keySet.size() > 0) {
             buf.append("<log4j:properties>\r\n");
             Object[] keys = keySet.toArray();
             Arrays.sort(keys);
             for (int i = 0; i < keys.length; i++) {
                 String key = keys[i].toString();
                 Object val = event.getMDC(key);
                 if (val != null) {
                     buf.append("<log4j:data name=\"");
                     buf.append(Transform.escapeTags(key));
                     buf.append("\" value=\"");
                     buf.append(Transform.escapeTags(String.valueOf(val)));
                     buf.append("\"/>\r\n");
                 }
             }
             buf.append("</log4j:properties>\r\n");
         }
     }
     
     buf.append("</log4j:event>\r\n\r\n");
     
     return buf.toString();
   }
   
   /**
      The XMLLayout prints and does not ignore exceptions. Hence the
      return value <code>false</code>.
   */
   public boolean ignoresThrowable() {
     return false;
   }
 }