#region Apache License
//
// 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.
//
#endregion

using System;
using System.Text;
using System.Xml;
using System.IO;

using log4net.Core;
using log4net.Util;

namespace log4net.Layout
{
  /// <summary>
  /// Layout that formats the log events as XML elements compatible with the log4j schema
  /// </summary>
  /// <remarks>
  /// <para>
  /// Formats the log events according to the http://logging.apache.org/log4j schema.
  /// </para>
  /// </remarks>
  /// <author>Nicko Cadell</author>
  public class XmlLayoutSchemaLog4j : XmlLayoutBase
  {
    #region Static Members

    /// <summary>
    /// The 1st of January 1970 in UTC
    /// </summary>
    private static readonly DateTime s_date1970 = new DateTime(1970, 1, 1);

    #endregion

    #region Constructors

    /// <summary>
    /// Constructs an XMLLayoutSchemaLog4j
    /// </summary>
    public XmlLayoutSchemaLog4j() : base()
    {
    }

    /// <summary>
    /// Constructs an XMLLayoutSchemaLog4j.
    /// </summary>
    /// <remarks>
    /// <para>
    /// 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. 
    /// </para>
    /// <para>
    /// If you are embedding this layout within an SMTPAppender
    /// then make sure to set the <b>LocationInfo</b> option of that 
    /// appender as well.
    /// </para>
    /// </remarks>
    public XmlLayoutSchemaLog4j(bool locationInfo) : base(locationInfo)
    {
    }

    #endregion

    #region Public Properties

    /// <summary>
    /// The version of the log4j schema to use.
    /// </summary>
    /// <remarks>
    /// <para>
    /// Only version 1.2 of the log4j schema is supported.
    /// </para>
    /// </remarks>
    public string Version
    {
      get { return "1.2"; }
      set
      {
        if (value != "1.2")
        {
          throw new ArgumentException("Only version 1.2 of the log4j schema is currently supported");
        }
      }
    }

    #endregion

    /* Example log4j schema event

<log4j:event logger="first logger" level="ERROR" thread="Thread-3" timestamp="1051494121460">
  <log4j:message><![CDATA[errormsg 3]]></log4j:message>
  <log4j:NDC><![CDATA[third]]></log4j:NDC>
  <log4j:MDC>
    <log4j:data name="some string" value="some valuethird"/>
  </log4j:MDC>
  <log4j:throwable><![CDATA[java.lang.Exception: someexception-third
   at org.apache.log4j.chainsaw.Generator.run(Generator.java:94)
]]></log4j:throwable>
  <log4j:locationInfo class="org.apache.log4j.chainsaw.Generator"
method="run" file="Generator.java" line="94"/>
  <log4j:properties>
    <log4j:data name="log4jmachinename" value="windows"/>
    <log4j:data name="log4japp" value="udp-generator"/>
  </log4j:properties>
</log4j:event>

    */

    /* Since log4j 1.3 the log4j:MDC has been combined into the log4j:properties element */

    /// <summary>
    /// Actually do the writing of the xml
    /// </summary>
    /// <param name="writer">the writer to use</param>
    /// <param name="loggingEvent">the event to write</param>
    /// <remarks>
    /// <para>
    /// Generate XML that is compatible with the log4j schema.
    /// </para>
    /// </remarks>
    protected override void FormatXml(XmlWriter writer, LoggingEvent loggingEvent)
    {
      // Translate logging events for log4j

      // Translate hostname property
      if (loggingEvent.LookupProperty(LoggingEvent.HostNameProperty) != null &&
        loggingEvent.LookupProperty("log4jmachinename") == null)
      {
        loggingEvent.GetProperties()["log4jmachinename"] = loggingEvent.LookupProperty(LoggingEvent.HostNameProperty);
      }

      // translate appdomain name
      if (loggingEvent.LookupProperty("log4japp") == null &&
        loggingEvent.Domain != null &&
        loggingEvent.Domain.Length > 0)
      {
        loggingEvent.GetProperties()["log4japp"] = loggingEvent.Domain;
      }

      // translate identity name
      if (loggingEvent.Identity != null &&
        loggingEvent.Identity.Length > 0 &&
        loggingEvent.LookupProperty(LoggingEvent.IdentityProperty) == null)
      {
        loggingEvent.GetProperties()[LoggingEvent.IdentityProperty] = loggingEvent.Identity;
      }

      // translate user name
      if (loggingEvent.UserName != null &&
        loggingEvent.UserName.Length > 0 &&
        loggingEvent.LookupProperty(LoggingEvent.UserNameProperty) == null)
      {
        loggingEvent.GetProperties()[LoggingEvent.UserNameProperty] = loggingEvent.UserName;
      }

      // Write the start element
#if NETSTANDARD
      writer.WriteStartElement("log4j", "event", "log4net");
#else
      writer.WriteStartElement("log4j:event");
#endif
      writer.WriteAttributeString("logger", loggingEvent.LoggerName);

      // Calculate the timestamp as the number of milliseconds since january 1970
      // 
      // We must convert the TimeStamp to UTC before performing any mathematical
      // operations. This allows use to take into account discontinuities
      // caused by daylight savings time transitions.
      TimeSpan timeSince1970 = loggingEvent.TimeStampUtc - s_date1970;

      writer.WriteAttributeString("timestamp", XmlConvert.ToString((long)timeSince1970.TotalMilliseconds));
      writer.WriteAttributeString("level", loggingEvent.Level.DisplayName);
      writer.WriteAttributeString("thread", loggingEvent.ThreadName);

      // Append the message text
#if NETSTANDARD
      writer.WriteStartElement("log4j", "message", "log4net");
#else
      writer.WriteStartElement("log4j:message");
#endif
      Transform.WriteEscapedXmlString(writer, loggingEvent.RenderedMessage, this.InvalidCharReplacement);
      writer.WriteEndElement();

      object ndcObj = loggingEvent.LookupProperty("NDC");
      if (ndcObj != null)
      {
        string valueStr = loggingEvent.Repository.RendererMap.FindAndRender(ndcObj);

        if (valueStr != null && valueStr.Length > 0)
        {
          // Append the NDC text
#if NETSTANDARD
          writer.WriteStartElement("log4j", "NDC", "log4net");
#else
          writer.WriteStartElement("log4j:NDC");
#endif
          Transform.WriteEscapedXmlString(writer, valueStr, this.InvalidCharReplacement);
          writer.WriteEndElement();
        }
      }

      // Append the properties text
      PropertiesDictionary properties = loggingEvent.GetProperties();
      if (properties.Count > 0)
      {
#if NETSTANDARD
        writer.WriteStartElement("log4j", "properties", "log4net");
#else
        writer.WriteStartElement("log4j:properties");
#endif
        foreach (System.Collections.DictionaryEntry entry in properties)
        {
#if NETSTANDARD
          writer.WriteStartElement("log4j", "data", "log4net");
#else
          writer.WriteStartElement("log4j:data");
#endif
          writer.WriteAttributeString("name", (string)entry.Key);

          // Use an ObjectRenderer to convert the object to a string
          string valueStr = loggingEvent.Repository.RendererMap.FindAndRender(entry.Value);
          writer.WriteAttributeString("value", valueStr);

          writer.WriteEndElement();
        }
        writer.WriteEndElement();
      }

      string exceptionStr = loggingEvent.GetExceptionString();
      if (exceptionStr != null && exceptionStr.Length > 0)
      {
        // Append the stack trace line
#if NETSTANDARD
        writer.WriteStartElement("log4j", "throwable", "log4net");
#else
        writer.WriteStartElement("log4j:throwable");
#endif
        Transform.WriteEscapedXmlString(writer, exceptionStr, this.InvalidCharReplacement);
        writer.WriteEndElement();
      }

      if (LocationInfo)
      {
        LocationInfo locationInfo = loggingEvent.LocationInformation;

#if NETSTANDARD
        writer.WriteStartElement("log4j", "locationInfo", "log4net");
#else
        writer.WriteStartElement("log4j:locationInfo");
#endif
        writer.WriteAttributeString("class", locationInfo.ClassName);
        writer.WriteAttributeString("method", locationInfo.MethodName);
        writer.WriteAttributeString("file", locationInfo.FileName);
        writer.WriteAttributeString("line", locationInfo.LineNumber);
        writer.WriteEndElement();
      }

      writer.WriteEndElement();
    }
  }
}