#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
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#endregion

using System;

using log4net.Core;
using log4net.Util;

namespace log4net.Filter;

/// <summary>
/// Simple filter to match a string in the event's logger name.
/// </summary>
/// <remarks>
/// <para>
/// The works very similar to the <see cref="LevelMatchFilter"/>. It admits two 
/// options <see cref="LoggerToMatch"/> and <see cref="AcceptOnMatch"/>. If the 
/// <see cref="LoggingEvent.LoggerName"/> of the <see cref="LoggingEvent"/> starts 
/// with the value of the <see cref="LoggerToMatch"/> option, then the 
/// <see cref="Decide"/> method returns <see cref="FilterDecision.Accept"/> in 
/// case the <see cref="AcceptOnMatch"/> option value is set to <c>true</c>, 
/// if it is <c>false</c> then <see cref="FilterDecision.Deny"/> is returned.
/// </para>
/// </remarks>
/// <author>Daniel Cazzulino</author>
public class LoggerMatchFilter : FilterSkeleton
{
  /// <summary>
  /// <see cref="FilterDecision.Accept"/> when matching <see cref="LoggerToMatch"/>
  /// </summary>
  /// <remarks>
  /// <para>
  /// The <see cref="AcceptOnMatch"/> property is a flag that determines
  /// the behavior when a matching <see cref="Level"/> is found. If the
  /// flag is set to true then the filter will <see cref="FilterDecision.Accept"/> the 
  /// logging event, otherwise it will <see cref="FilterDecision.Deny"/> the event.
  /// </para>
  /// <para>
  /// The default is <c>true</c> i.e. to <see cref="FilterDecision.Accept"/> the event.
  /// </para>
  /// </remarks>
  public bool AcceptOnMatch { get; set; } = true;

  /// <summary>
  /// The <see cref="LoggingEvent.LoggerName"/> that the filter will match
  /// </summary>
  /// <remarks>
  /// <para>
  /// This filter will attempt to match this value against logger name in
  /// the following way. The match will be done against the beginning of the
  /// logger name (using <see cref="String.StartsWith(string)"/>). The match is
  /// case sensitive. If a match is found then
  /// the result depends on the value of <see cref="AcceptOnMatch"/>.
  /// </para>
  /// </remarks>
  public string? LoggerToMatch { get; set; }

  /// <summary>
  /// Check if this filter should allow the event to be logged
  /// </summary>
  /// <param name="loggingEvent">the event being logged</param>
  /// <returns>see remarks</returns>
  /// <remarks>
  /// <para>
  /// The rendered message is matched against the <see cref="LoggerToMatch"/>.
  /// If the <see cref="LoggerToMatch"/> equals the beginning of 
  /// the incoming <see cref="LoggingEvent.LoggerName"/> (<see cref="String.StartsWith(string)"/>)
  /// then a match will have occurred. If no match occurs
  /// this function will return <see cref="FilterDecision.Neutral"/>
  /// allowing other filters to check the event. If a match occurs then
  /// the value of <see cref="AcceptOnMatch"/> is checked. If it is
  /// true then <see cref="FilterDecision.Accept"/> is returned otherwise
  /// <see cref="FilterDecision.Deny"/> is returned.
  /// </para>
  /// </remarks>
  public override FilterDecision Decide(LoggingEvent loggingEvent)
  {
    loggingEvent.EnsureNotNull();

    // Check if we have been set up to filter
    if (!string.IsNullOrEmpty(LoggerToMatch) 
        && loggingEvent.LoggerName is not null 
        && loggingEvent.LoggerName.StartsWith(LoggerToMatch))
    {
      // we've got a match
      return AcceptOnMatch ? FilterDecision.Accept : FilterDecision.Deny;
    }
    // We cannot filter so allow the filter chain to continue processing
    return FilterDecision.Neutral;
  }
}