#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.Reflection;

using log4net.Repository;

namespace log4net.Config
{
  /// <summary>
  /// Base class for all log4net configuration attributes.
  /// </summary>
  /// <remarks>
  /// This is an abstract class that must be extended by 
  /// specific configurators. This attribute allows the
  /// configurator to be parameterized by an assembly level
  /// attribute.
  /// </remarks>
  /// <author>Nicko Cadell</author>
  /// <author>Gert Driesen</author>
  [AttributeUsage(AttributeTargets.Assembly)]
  public abstract class ConfiguratorAttribute : Attribute, IComparable
  {
    private readonly int m_priority;

    /// <summary>
    /// Constructor used by subclasses.
    /// </summary>
    /// <param name="priority">the ordering priority for this configurator</param>
    /// <remarks>
    /// <para>
    /// The <paramref name="priority"/> is used to order the configurator
    /// attributes before they are invoked. Higher priority configurators are executed
    /// before lower priority ones.
    /// </para>
    /// </remarks>
    protected ConfiguratorAttribute(int priority)
    {
      m_priority = priority;
    }

    /// <summary>
    /// Configures the <see cref="ILoggerRepository"/> for the specified assembly.
    /// </summary>
    /// <param name="sourceAssembly">The assembly that this attribute was defined on.</param>
    /// <param name="targetRepository">The repository to configure.</param>
    /// <remarks>
    /// <para>
    /// Abstract method implemented by a subclass. When this method is called
    /// the subclass should configure the <paramref name="targetRepository"/>.
    /// </para>
    /// </remarks>
    public abstract void Configure(Assembly sourceAssembly, ILoggerRepository targetRepository);

    /// <summary>
    /// Compare this instance to another ConfiguratorAttribute
    /// </summary>
    /// <param name="obj">the object to compare to</param>
    /// <returns>see <see cref="IComparable.CompareTo"/></returns>
    /// <remarks>
    /// <para>
    /// Compares the priorities of the two <see cref="ConfiguratorAttribute"/> instances.
    /// Sorts by priority in descending order. Objects with the same priority are
    /// randomly ordered.
    /// </para>
    /// </remarks>
    public int CompareTo(object? obj)
    {
      if (ReferenceEquals(this, obj))
      {
        return 0;
      }

      int result = -1;

      if (obj is ConfiguratorAttribute target)
      {
        // Compare the priorities
        result = target.m_priority.CompareTo(m_priority);
        if (result == 0)
        {
          // Same priority, so have to provide some ordering
          result = -1;
        }
      }
      return result;
    }
  }
}