#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>
		override protected 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
			writer.WriteStartElement("log4j:event");
			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
			writer.WriteStartElement("log4j:message");
			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
					writer.WriteStartElement("log4j:NDC");
					Transform.WriteEscapedXmlString(writer, valueStr,this.InvalidCharReplacement);
					writer.WriteEndElement();
				}
			}

			// Append the properties text
			PropertiesDictionary properties = loggingEvent.GetProperties();
			if (properties.Count > 0)
			{
				writer.WriteStartElement("log4j:properties");
				foreach(System.Collections.DictionaryEntry entry in properties)
				{
					writer.WriteStartElement("log4j:data");
					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
				writer.WriteStartElement("log4j:throwable");
				Transform.WriteEscapedXmlString(writer, exceptionStr,this.InvalidCharReplacement);
				writer.WriteEndElement();
			}

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

				writer.WriteStartElement("log4j:locationInfo");
				writer.WriteAttributeString("class", locationInfo.ClassName);
				writer.WriteAttributeString("method", locationInfo.MethodName);
				writer.WriteAttributeString("file", locationInfo.FileName);
				writer.WriteAttributeString("line", locationInfo.LineNumber);
				writer.WriteEndElement();
			}

			writer.WriteEndElement();
		}
	}
}