﻿#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.Collections;
using System.IO;

using log4net.Core;
using log4net.Layout.Pattern;
using log4net.Util;

namespace log4net.Layout
{
  /// <summary>
  /// A flexible layout configurable with pattern string that re-evaluates on each call.
  /// </summary>
  /// <remarks>
  /// <para>This class is built on <see cref="PatternLayout"></see> and provides all the
  /// features and capabilities of PatternLayout.  PatternLayout is a 'static' class
  /// in that its layout is done once at configuration time.  This class will recreate
  /// the layout on each reference.</para>
  /// <para>One important difference between PatternLayout and DynamicPatternLayout is the
  /// treatment of the Header and Footer parameters in the configuration.  The Header and Footer
  /// parameters for DynamicPatternLayout must be syntactically in the form of a PatternString,
  /// but should not be marked as type log4net.Util.PatternString.  Doing so causes the
  /// pattern to be statically converted at configuration time and causes DynamicPatternLayout
  /// to perform the same as PatternLayout.</para>
  /// <para>Please see <see cref="PatternLayout"/> for complete documentation.</para>
  /// <example>
  ///  &lt;layout type="log4net.Layout.DynamicPatternLayout"&gt;
  ///   &lt;param name="Header" value="%newline**** Trace Opened     Local: %date{yyyy-MM-dd HH:mm:ss.fff}     UTC: %utcdate{yyyy-MM-dd HH:mm:ss.fff} ****%newline" /&gt;
  ///   &lt;param name="Footer" value="**** Trace Closed %date{yyyy-MM-dd HH:mm:ss.fff} ****%newline" /&gt;
  /// &lt;/layout&gt;
  /// </example>
  /// </remarks>
  public class DynamicPatternLayout : PatternLayout
  {
    #region Member Variables
    /// <summary>
    /// The header PatternString
    /// </summary>
    private PatternString m_headerPatternString = new PatternString("");

    /// <summary>
    /// The footer PatternString
    /// </summary>
    private PatternString m_footerPatternString = new PatternString("");
    #endregion

    #region Constructors
    /// <summary>
    /// Constructs a DynamicPatternLayout using the DefaultConversionPattern
    /// </summary>
    /// <remarks>
    /// <para>
    /// The default pattern just produces the application supplied message.
    /// </para>
    /// </remarks>
    public DynamicPatternLayout()
      : base()
    {
    }

    /// <summary>
    /// Constructs a DynamicPatternLayout using the supplied conversion pattern
    /// </summary>
    /// <param name="pattern">the pattern to use</param>
    /// <remarks>
    /// </remarks>
    public DynamicPatternLayout(string pattern)
      : base(pattern)
    {
    }
    #endregion

    #region Override implementation of LayoutSkeleton
    /// <summary>
    /// The header for the layout format.
    /// </summary>
    /// <value>the layout header</value>
    /// <remarks>
    /// <para>
    /// The Header text will be appended before any logging events
    /// are formatted and appended.
    /// </para>
    /// The pattern will be formatted on each get operation.
    /// </remarks>
    public override string Header
    {
      get
      {
        return m_headerPatternString.Format();
      }
      set
      {
        base.Header = value;
        m_headerPatternString = new PatternString(value);
      }
    }   /* property DynamicPatternLayout Header */

    /// <summary>
    /// The footer for the layout format.
    /// </summary>
    /// <value>the layout footer</value>
    /// <remarks>
    /// <para>
    /// The Footer text will be appended after all the logging events
    /// have been formatted and appended.
    /// </para>
    /// The pattern will be formatted on each get operation.
    /// </remarks>
    public override string Footer
    {
      get
      {
        return m_footerPatternString.Format();
      }
      set
      {
        base.Footer = value;
        m_footerPatternString = new PatternString(value);
      }
    }   /* property DynamicPatternLayout Footer */
    #endregion
  }      /* class DynamicPatternLayout */
}        /* namespace log4net.Layout */