#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.IO;

using log4net.Core;

namespace log4net.Layout.Pattern
{
  /// <summary>
  /// Converter to include event NDC
  /// </summary>
  /// <remarks>
  /// <para>
  /// Outputs the value of the event property named <c>NDC</c>.
  /// </para>
  /// <para>
  /// The <see cref="PropertyPatternConverter"/> should be used instead.
  /// </para>
  /// </remarks>
  /// <author>Nicko Cadell</author>
  internal sealed class NdcPatternConverter : PatternLayoutConverter
  {
    /// <summary>
    /// Write the event NDC to the output
    /// </summary>
    /// <param name="writer"><see cref="TextWriter" /> that will receive the formatted result.</param>
    /// <param name="loggingEvent">the event being logged</param>
    /// <remarks>
    /// <para>
    /// As the thread context stacks are now stored in named event properties
    /// this converter simply looks up the value of the <c>NDC</c> property.
    /// </para>
    /// <para>
    /// The <see cref="PropertyPatternConverter"/> should be used instead.
    /// </para>
    /// </remarks>
    protected override void Convert(TextWriter writer, LoggingEvent loggingEvent)
    {
      // Write the value for the specified key
      WriteObject(writer, loggingEvent.Repository, loggingEvent.LookupProperty("NDC"));
    }
  }
}
