/*
 *  Copyright(c)2003 Forward Computing and Control Pty. Ltd.
 *  ACN 003 669 994, NSW, Australia      All rights Reserved
 *
 *  Written by Dr. M.P. Ford
 *
 */
package au.com.forward.logging;
import java.nio.charset.Charset;
import au.com.forward.utils.StringUtils;
import java.util.*;
import java.util.logging.*;

/**
 *  This class provides a robust xml formatter.
 *
 *@author     Matthew Ford
 *@created    3 Oct 2003
 */
public class LoggingXMLFormatter extends RobustFormatter {

  /**
   *  Returns the newLine setting for this class for XML use \n for new lines
   *
   *@return    the string to use for new lines.
   */
  protected String newLineString() {
    return "\n";
  }


  /**
   *  Return the header string for a set of XML formatted records.
   *
   *@param  h  The target handler.
   *@return    header string
   */
  public String getHead(Handler h) {
    StringBuffer sb = new StringBuffer();
    sb.append("<?xml version=\"1.0\"");

    String encoding = h.getEncoding();

    if (encoding == null) {
      // Figure out the default encoding.
      encoding = sun.io.Converters.getDefaultEncodingName();
    }

    // Try to map the encoding name to a canonical name.
    try {
      Charset cs = Charset.forName(encoding);
      encoding = cs.name();
    } catch (Exception ex) {
      // We hit problems finding a canonical name.
      // Just use the raw encoding name.
    }

    sb.append(" encoding=\"");
    sb.append(encoding);
    sb.append("\"");
    sb.append(" standalone=\"no\"?>\n");
    sb.append("<!DOCTYPE log SYSTEM \"logger.dtd\">\n");
    sb.append("<?xml-stylesheet type=\"text/xsl\" href=\"logger.xsl\"?>\n");
    sb.append("<log>\n");

    return sb.toString();
  }


  /**
   *  Return the tail string for a set of XML formatted records.
   *
   *@param  h  The target handler.
   *@return    tail string
   */
  public String getTail(Handler h) {
    return "</log>\n";
  }


  /**
   *  Format the given message to XML.
   *
   *@param  record  the log record to be formatted.
   *@return         a formatted log record
   */
  public String format(LogRecord record) {
    StringBuffer sb = new StringBuffer(500);
    sb.append("<record>\n");

    sb.append("  <date>");
    appendISO8601(sb, record.getMillis());
    sb.append("</date>\n");

    sb.append("  <millis>");
    sb.append(record.getMillis());
    sb.append("</millis>\n");

    sb.append("  <sequence>");
    sb.append(record.getSequenceNumber());
    sb.append("</sequence>\n");

    String name = record.getLoggerName();
    if (name != null) {
      sb.append("  <logger>");
      escape(sb, name);
      sb.append("</logger>\n");
    }

    sb.append("  <level>");
    escape(sb, record.getLevel().toString());
    sb.append("</level>\n");

    if (record.getSourceClassName() != null) {
      sb.append("  <class>");
      escape(sb, record.getSourceClassName());
      sb.append("</class>\n");
    }

    if (record.getSourceMethodName() != null) {
      sb.append("  <method>");
      escape(sb, record.getSourceMethodName());
      sb.append("</method>\n");
    }

    sb.append("  <thread>");
    sb.append(record.getThreadID());
    sb.append("</thread>\n");

    String message = "";

    if (record.getMessage() != null) {
      // Format the message string and its accompanying parameters.
      message = formatMessage(record);
    }

    if (record.getThrown() != null) {
      Throwable th = record.getThrown();
      if (message.length() > 0) {
        message += "\n";
      }
      message = StringUtils.toString(th);
    }

    sb.append("  <message>");
    escape(sb, message);
    sb.append("</message>");
    sb.append("\n");
    sb.append("</record>\n");
    return sb.toString();
  }



  /**
   *  Append to the given StringBuffer an escaped version of the given text
   *  string where XML special characters have been escaped. For a null string we
   *  append "<null>"
   *
   *@param  sb    the StringBuffer to append to
   *@param  text  the text to be escaped.
   */
  private void escape(StringBuffer sb, String text) {
    if (text == null) {
      text = "<null>";
    }
    for (int i = 0; i < text.length(); i++) {
      char ch = text.charAt(i);
      if (ch == '<') {
        sb.append("&lt;");
      } else if (ch == '>') {
        sb.append("&gt;");
      } else if (ch == '&') {
        sb.append("&amp;");
      } else {
        sb.append(ch);
      }
    }
  }


  /**
   *  Append the time and date in ISO 8601 format java.text.SimpleDateFormat
   *  dateFormat = new java.text.SimpleDateFormat("yyyy-mm-ddTHH:mm:ss"); stops
   *  this class from loading ??
   *
   *@param  sb      StringBuffer to append to
   *@param  millis  the time in milliseconds
   */
  private void appendISO8601(StringBuffer sb, long millis) {
    GregorianCalendar calendar = new GregorianCalendar();
    calendar.setTimeInMillis(millis);
    sb.append(calendar.get(Calendar.YEAR));
    sb.append('-');
    a2(sb, calendar.get(Calendar.MONTH) + 1);
    sb.append('-');
    a2(sb, calendar.get(Calendar.DAY_OF_MONTH));
    sb.append('T');
    a2(sb, calendar.get(Calendar.HOUR_OF_DAY));
    sb.append(':');
    a2(sb, calendar.get(Calendar.MINUTE));
    sb.append(':');
    a2(sb, calendar.get(Calendar.SECOND));
  }



  /**
   *  Append a two digit number.
   *
   *@param  sb  output buffer to append to
   *@param  x   int to format
   */
  private void a2(StringBuffer sb, int x) {
    if (x < 10) {
      sb.append('0');
    }
    sb.append(x);
  }

}