#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.Generic;
using log4net.Util;

namespace log4net.Core
{
  /// <summary>
  /// provides method information without actually referencing a System.Reflection.MethodBase
  /// as that would require that the containing assembly is loaded.
  /// </summary>
  /// 
  [Log4NetSerializable]
  public class MethodItem
  {
    /// <summary>
    /// constructs a method item for an unknown method.
    /// </summary>
    public MethodItem()
    {
      Name = NA;
      Parameters = Array.Empty<string>();
    }

    /// <summary>
    /// constructs a method item from the name of the method.
    /// </summary>
    /// <param name="name"></param>
    public MethodItem(string name)
      : this()
    {
      Name = name;
    }

    /// <summary>
    /// constructs a method item from the name of the method and its parameters.
    /// </summary>
    /// <param name="name"></param>
    /// <param name="parameters"></param>
    public MethodItem(string name, string[] parameters)
      : this(name)
    {
      Parameters = parameters;
    }

    /// <summary>
    /// constructs a method item from a method base by determining the method name and its parameters.
    /// </summary>
    /// <param name="methodBase"></param>
    public MethodItem(System.Reflection.MethodBase methodBase)
      : this(methodBase.Name, GetMethodParameterNames(methodBase))
    {
    }

    private static string[] GetMethodParameterNames(System.Reflection.MethodBase methodBase)
    {
      var methodParameterNames = new List<string>();
      try
      {
        System.Reflection.ParameterInfo[] methodBaseGetParameters = methodBase.GetParameters();

        int methodBaseGetParametersCount = methodBaseGetParameters.GetUpperBound(0);

        for (int i = 0; i <= methodBaseGetParametersCount; i++)
        {
          methodParameterNames.Add(methodBaseGetParameters[i].ParameterType + " " + methodBaseGetParameters[i].Name);
        }
      }
      catch (Exception ex)
      {
        LogLog.Error(declaringType, "An exception ocurred while retreiving method parameters.", ex);
      }

      return methodParameterNames.ToArray();
    }

    /// <summary>
    /// Gets the method name of the caller making the logging 
    /// request.
    /// </summary>
    /// <value>
    /// The method name of the caller making the logging 
    /// request.
    /// </value>
    /// <remarks>
    /// <para>
    /// Gets the method name of the caller making the logging 
    /// request.
    /// </para>
    /// </remarks>
    public string Name { get; }

    /// <summary>
    /// Gets the method parameters of the caller making
    /// the logging request.
    /// </summary>
    /// <value>
    /// The method parameters of the caller making
    /// the logging request
    /// </value>
    /// <remarks>
    /// <para>
    /// Gets the method parameters of the caller making
    /// the logging request.
    /// </para>
    /// </remarks>
    public string[] Parameters { get; }

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

    /// <summary>
    /// When location information is not available the constant
    /// <c>NA</c> is returned. Current value of this string
    /// constant is <b>?</b>.
    /// </summary>
    private const string NA = "?";
  }
}
