package org.slf4j.impl;

import org.slf4j.MDC;
import org.slf4j.helpers.BasicMDCAdapter;

import java.util.logging.Formatter;
import java.util.logging.LogRecord;
import java.util.Set;
import java.util.Arrays;

/**
 * Implementation of {@link java.util.logging.Formatter} that generates xml in the log4j format.
 * <p>
 * The generated xml corresponds 100% with what is generated by
 * log4j's <a href=http://logging.apache.org/log4j/1.2/apidocs/org/apache/log4j/xml/XMLLayout.html">XMLLayout</a>
 * <p>
 * The MDC properties will only be correct when <code>format</code> is called from the same thread
 * that generated the LogRecord.
 * <p>
 * The file and line attributes in the locationInfo element will always be "?"
 * since LogRecord does not provide that info.
 * <p>
 * The implementation is heavily based on XMLLayout
 * </p>
 */
public class Log4jXmlFormatter extends Formatter {

  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.
   * @param flag whether locationInfo should be output by this layout
   **/
  public void setLocationInfo(boolean flag) {
    locationInfo = flag;
  }

  /**
   Returns the current value of the <b>LocationInfo</b> option.
   * @return whether locationInfo will be output by this layout
   */
  public boolean getLocationInfo() {
    return locationInfo;
  }

  /**
   * Sets whether MDC key-value pairs should be output, default false.
   * @param flag new value.
   */
  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.
   */
  public boolean getProperties() {
    return properties;
  }

  public String format(final LogRecord record) {

    // 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);
    }
    buf.append("<log4j:event logger=\"");
    buf.append(Transform.escapeTags(record.getLoggerName()));
    buf.append("\" timestamp=\"");
    buf.append(record.getMillis());
    buf.append("\" level=\"");

    buf.append(Transform.escapeTags(record.getLevel().getName()));
    buf.append("\" thread=\"");
    buf.append(String.valueOf(record.getThreadID()));
    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, record.getMessage());
    buf.append("]]></log4j:message>\r\n");

    if (record.getThrown() != null) {
      String[] s = Transform.getThrowableStrRep(record.getThrown());
      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) {
      buf.append("<log4j:locationInfo class=\"");
      buf.append(Transform.escapeTags(record.getSourceClassName()));
      buf.append("\" method=\"");
      buf.append(Transform.escapeTags(record.getSourceMethodName()));
      buf.append("\" file=\"?\" line=\"?\"/>\r\n");
    }

    if (properties) {
      if (MDC.getMDCAdapter() instanceof BasicMDCAdapter) {
        BasicMDCAdapter mdcAdapter = (BasicMDCAdapter) MDC.getMDCAdapter();
        Set keySet = mdcAdapter.getKeys();
        if (keySet != null && 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 = mdcAdapter.get(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();
  }



}