#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 log4net.DateFormatter;
using log4net.Core;

namespace log4net.Util.PatternStringConverters;

/// <summary>
/// Write the current date to the output
/// </summary>
/// <remarks>
/// <para>
/// Date pattern converter, uses a <see cref="IDateFormatter"/> to format 
/// the current date and time to the writer as a string.
/// </para>
/// <para>
/// The value of the <see cref="PatternConverter.Option"/> determines 
/// the formatting of the date. The following values are allowed:
/// <list type="definition">
///    <listheader>
///     <term>Option value</term>
///     <description>Output</description>
///   </listheader>
///    <item>
///     <term>ISO8601</term>
///     <description>
///     Uses the <see cref="Iso8601DateFormatter"/> formatter. 
///     Formats using the <c>"yyyy-MM-dd HH:mm:ss,fff"</c> pattern.
///     </description>
///   </item>
///   <item>
///     <term>DATE</term>
///     <description>
///     Uses the <see cref="DateTimeDateFormatter"/> formatter. 
///     Formats using the <c>"dd MMM yyyy HH:mm:ss,fff"</c> for example, <c>"06 Nov 1994 15:49:37,459"</c>.
///     </description>
///   </item>
///   <item>
///     <term>ABSOLUTE</term>
///     <description>
///     Uses the <see cref="AbsoluteTimeDateFormatter"/> formatter. 
///     Formats using the <c>"HH:mm:ss,fff"</c> for example, <c>"15:49:37,459"</c>.
///     </description>
///   </item>
///   <item>
///     <term>other</term>
///     <description>
///     Any other pattern string uses the <see cref="SimpleDateFormatter"/> formatter. 
///     This formatter passes the pattern string to the <see cref="DateTime"/> 
///     <see cref="DateTime.ToString(string)"/> method.
///     For details on valid patterns see 
///     <a href="http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfsystemglobalizationdatetimeformatinfoclasstopic.asp">DateTimeFormatInfo Class</a>.
///     </description>
///   </item>
/// </list>
/// </para>
/// <para>
/// The date and time is in the local time zone and is rendered in that zone.
/// To output the time in Universal time see <see cref="UtcDatePatternConverter"/>.
/// </para>
/// </remarks>
/// <author>Nicko Cadell</author>
internal class DatePatternConverter : PatternConverter, IOptionHandler
{
  /// <summary>
  /// The <see cref="IDateFormatter"/> used to render the date to a string
  /// </summary>
  // ReSharper disable once InconsistentNaming
  protected IDateFormatter? m_dateFormatter;

  /// <summary>
  /// Initialize the converter 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>
  public void ActivateOptions()
  {
    string dateFormatStr = Option ?? AbsoluteTimeDateFormatter.Iso8601TimeDateFormat;

    if (SystemInfo.EqualsIgnoringCase(dateFormatStr, AbsoluteTimeDateFormatter.Iso8601TimeDateFormat))
    {
      m_dateFormatter = new Iso8601DateFormatter();
    }
    else if (SystemInfo.EqualsIgnoringCase(dateFormatStr, AbsoluteTimeDateFormatter.AbsoluteTimeDateFormat))
    {
      m_dateFormatter = new AbsoluteTimeDateFormatter();
    }
    else if (SystemInfo.EqualsIgnoringCase(dateFormatStr, AbsoluteTimeDateFormatter.DateAndTimeDateFormat))
    {
      m_dateFormatter = new DateTimeDateFormatter();
    }
    else
    {
      try
      {
        m_dateFormatter = new SimpleDateFormatter(dateFormatStr);
      }
      catch (Exception e) when (!e.IsFatal())
      {
        LogLog.Error(_declaringType, $"Could not instantiate SimpleDateFormatter with [{dateFormatStr}]", e);
        m_dateFormatter = new Iso8601DateFormatter();
      }
    }
  }

  /// <summary>
  /// Write the current date to the output
  /// </summary>
  /// <param name="writer"><see cref="TextWriter" /> that will receive the formatted result.</param>
  /// <param name="state">null, state is not set</param>
  /// <remarks>
  /// <para>
  /// Pass the current date and time to the <see cref="IDateFormatter"/>
  /// for it to render it to the writer.
  /// </para>
  /// <para>
  /// The date and time passed is in the local time zone.
  /// </para>
  /// </remarks>
  public override void Convert(TextWriter writer, object? state)
  {
    try
    {
      m_dateFormatter?.FormatDate(DateTime.Now, writer);
    }
    catch (Exception e) when (!e.IsFatal())
    {
      LogLog.Error(_declaringType, "Error occurred while converting date.", e);
    }
  }

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