#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;

namespace log4net.Util.PatternStringConverters
{
  /// <summary>
  /// Write an <see cref="System.Environment.SpecialFolder" /> folder path to the output
  /// </summary>
  /// <remarks>
  /// <para>
  /// Write an special path environment folder path to the output writer.
  /// The value of the <see cref="log4net.Util.PatternConverter.Option"/> determines 
  /// the name of the variable to output. <see cref="log4net.Util.PatternConverter.Option"/>
  /// should be a value in the <see cref="System.Environment.SpecialFolder" /> enumeration.
  /// </para>
  /// </remarks>
  /// <author>Ron Grabowski</author>
  internal sealed class EnvironmentFolderPathPatternConverter : PatternConverter
  {
    /// <summary>
    /// Write an special path environment folder path to the output
    /// </summary>
    /// <param name="writer">the writer to write to</param>
    /// <param name="state">null, state is not set</param>
    /// <remarks>
    /// <para>
    /// Writes the special path environment folder path to the output <paramref name="writer"/>.
    /// The name of the special path environment folder path to output must be set
    /// using the <see cref="log4net.Util.PatternConverter.Option"/>
    /// property.
    /// </para>
    /// </remarks>
    public override void Convert(TextWriter writer, object state)
    {
      try
      {
        if (Option?.Length > 0)
        {
          Environment.SpecialFolder specialFolder =
              (Environment.SpecialFolder)Enum.Parse(typeof(Environment.SpecialFolder), Option, true);

          string envFolderPathValue = Environment.GetFolderPath(specialFolder);
          if (envFolderPathValue?.Length > 0)
            writer.Write(envFolderPathValue);
        }
      }
      catch (System.Security.SecurityException secEx)
      {
        // This security exception will occur if the caller does not have 
        // unrestricted environment permission. If this occurs the expansion 
        // will be skipped with the following warning message.
        LogLog.Debug(declaringType, "Security exception while trying to expand environment variables. Error Ignored. No Expansion.", secEx);
      }
      catch (Exception ex)
      {
        LogLog.Error(declaringType, "Error occurred while converting environment variable.", ex);
      }
    }

    #region Private Static Fields

    /// <summary>
    /// The fully qualified type of the EnvironmentFolderPathPatternConverter class.
    /// </summary>
    /// <remarks>
    /// Used by the internal logger to record the Type of the
    /// log message.
    /// </remarks>
    private static readonly Type declaringType = typeof(EnvironmentFolderPathPatternConverter);

    #endregion Private Static Fields
  }
}