#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.IO;

using System.Text;

using System.Xml;



using log4net.Util;

using log4net.Core;



namespace log4net.Layout

{

	/// <summary>

	/// Layout that formats the log events as XML elements.

	/// </summary>

	/// <remarks>

	/// <para>

	/// This is an abstract class that must be subclassed by an implementation 

	/// to conform to a specific schema.

	/// </para>

	/// <para>

	/// Deriving classes must implement the <see cref="FormatXml"/> method.

	/// </para>

	/// </remarks>

	/// <author>Nicko Cadell</author>

	/// <author>Gert Driesen</author>

	abstract public class XmlLayoutBase : LayoutSkeleton

	{

		#region Protected Instance Constructors



		/// <summary>

		/// Protected constructor to support subclasses

		/// </summary>

		/// <remarks>

		/// <para>

		/// Initializes a new instance of the <see cref="XmlLayoutBase" /> class

		/// with no location info.

		/// </para>

		/// </remarks>

		protected XmlLayoutBase() : this(false)

		{

			IgnoresException = false;

		}



		/// <summary>

		/// Protected constructor to support subclasses

		/// </summary>

		/// <remarks>

		/// <para>

		/// The <paramref name="locationInfo" /> parameter determines whether 

		/// location information will be output by the layout. If 

		/// <paramref name="locationInfo" /> is set to <c>true</c>, 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>

		protected XmlLayoutBase(bool locationInfo)

		{

			IgnoresException = false;

			m_locationInfo = locationInfo;

		}



		#endregion Protected Instance Constructors



		#region Public Instance Properties



		/// <summary>

		/// Gets a value indicating whether to include location information in 

		/// the XML events.

		/// </summary>

		/// <value>

		/// <c>true</c> if location information should be included in the XML 

		/// events; otherwise, <c>false</c>.

		/// </value>

		/// <remarks>

		/// <para>

		/// If <see cref="LocationInfo" /> is set to <c>true</c>, 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 <c>SMTPAppender</c>

		/// then make sure to set the <b>LocationInfo</b> option of that 

		/// appender as well.

		/// </para>

		/// </remarks>

		public bool LocationInfo

		{

			get { return m_locationInfo; }

			set { m_locationInfo = value; }

		}

		/// <summary>

		/// The string to replace characters that can not be expressed in XML with.

		/// <remarks>

		/// <para>

		/// Not all characters may be expressed in XML. This property contains the

		/// string to replace those that can not with. This defaults to a ?. Set it

		/// to the empty string to simply remove offending characters. For more

		/// details on the allowed character ranges see http://www.w3.org/TR/REC-xml/#charsets

		/// Character replacement will occur in  the log message, the property names 

		/// and the property values.

		/// </para>

		/// </remarks>

		/// </summary>

		public string InvalidCharReplacement

		{

			get {return m_invalidCharReplacement;}

			set {m_invalidCharReplacement=value;}

		}

		#endregion



		#region Implementation of IOptionHandler



		/// <summary>

		/// Initialize layout options

		/// </summary>

		/// <remarks>

		/// <para>

		/// This is part of the <see cref="IOptionHandler"/> delayed object

		/// activation scheme. The <see cref="ActivateOptions"/> method must 

		/// be called on this object after the configuration properties have

		/// been set. Until <see cref="ActivateOptions"/> is called this

		/// object is in an undefined state and must not be used. 

		/// </para>

		/// <para>

		/// If any of the configuration properties are modified then 

		/// <see cref="ActivateOptions"/> must be called again.

		/// </para>

		/// </remarks>

		override public void ActivateOptions() 

		{

			// nothing to do

		}



		#endregion Implementation of IOptionHandler



		#region Override implementation of LayoutSkeleton



		/// <summary>

		/// Gets the content type output by this layout. 

		/// </summary>

		/// <value>

		/// As this is the XML layout, the value is always <c>"text/xml"</c>.

		/// </value>

		/// <remarks>

		/// <para>

		/// As this is the XML layout, the value is always <c>"text/xml"</c>.

		/// </para>

		/// </remarks>

		override public string ContentType

		{

			get { return "text/xml"; }

		}



		/// <summary>

		/// Produces a formatted string.

		/// </summary>

		/// <param name="loggingEvent">The event being logged.</param>

		/// <param name="writer">The TextWriter to write the formatted event to</param>

		/// <remarks>

		/// <para>

		/// Format the <see cref="LoggingEvent"/> and write it to the <see cref="TextWriter"/>.

		/// </para>

		/// <para>

		/// This method creates an <see cref="XmlTextWriter"/> that writes to the

		/// <paramref name="writer"/>. The <see cref="XmlTextWriter"/> is passed 

		/// to the <see cref="FormatXml"/> method. Subclasses should override the

		/// <see cref="FormatXml"/> method rather than this method.

		/// </para>

		/// </remarks>

		override public void Format(TextWriter writer, LoggingEvent loggingEvent) 

		{

			if (loggingEvent == null)

			{

				throw new ArgumentNullException("loggingEvent");

			}



			// Attach the protected writer to the TextWriter passed in

			m_protectCloseTextWriter.Attach(writer);



			XmlTextWriter xmlWriter = new XmlTextWriter(m_protectCloseTextWriter);

			xmlWriter.Formatting = Formatting.None;

			xmlWriter.Namespaces = false;



			// Write the event to the writer

			FormatXml(xmlWriter, loggingEvent);



			xmlWriter.WriteWhitespace(SystemInfo.NewLine);



			// Close on xmlWriter will ensure xml is flushed

			// the protected writer will ignore the actual close

			xmlWriter.Close();



			// detach from the writer

			m_protectCloseTextWriter.Attach(null);

		}



		#endregion Override implementation of LayoutSkeleton



		#region Protected Instance Methods



		/// <summary>

		/// Does the actual writing of the XML.

		/// </summary>

		/// <param name="writer">The writer to use to output the event to.</param>

		/// <param name="loggingEvent">The event to write.</param>

		/// <remarks>

		/// <para>

		/// Subclasses should override this method to format

		/// the <see cref="LoggingEvent"/> as XML.

		/// </para>

		/// </remarks>

		abstract protected void FormatXml(XmlWriter writer, LoggingEvent loggingEvent);



		#endregion Protected Instance Methods



		#region Private Instance Fields

  

		/// <summary>

		/// Flag to indicate if location information should be included in

		/// the XML events.

		/// </summary>

		private bool m_locationInfo = false;



		/// <summary>

		/// Writer adapter that ignores Close

		/// </summary>

		private readonly ProtectCloseTextWriter m_protectCloseTextWriter = new ProtectCloseTextWriter(null);



		/// <summary>

		/// The string to replace invalid chars with

		/// </summary>

		private string m_invalidCharReplacement="?";



		#endregion Private Instance Fields

	}

}