#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>
/// Property pattern converter
/// </summary>
/// <remarks>
/// <para>
/// Writes out the value of a named property. The property name
/// should be set in the <see cref="log4net.Util.PatternConverter.Option"/>
/// property.
/// </para>
/// <para>
/// If the <see cref="log4net.Util.PatternConverter.Option"/> is set to <c>null</c>
/// then all the properties are written as key value pairs.
/// </para>
/// </remarks>
/// <author>Nicko Cadell</author>
internal sealed class PropertyPatternConverter : PatternLayoutConverter
{
  /// <summary>
  /// Write the property value 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>
  /// Writes out the value of a named property. The property name
  /// should be set in the <see cref="log4net.Util.PatternConverter.Option"/>
  /// property.
  /// </para>
  /// <para>
  /// If the <see cref="log4net.Util.PatternConverter.Option"/> is set to <c>null</c>
  /// then all the properties are written as key value pairs.
  /// </para>
  /// </remarks>
  protected override void Convert(TextWriter writer, LoggingEvent loggingEvent)
  {
    if (Option is not null)
    {
      // Write the value for the specified key
      WriteObject(writer, loggingEvent.Repository, loggingEvent.LookupProperty(Option));
    }
    else
    {
      // Write all the key value pairs
      WriteDictionary(writer, loggingEvent.Repository, loggingEvent.GetProperties());
    }
  }
}
