ICD.Common.Utils/ICD.Common.Utils/Extensions/ReflectionExtensions.cs

using System;
using System.Collections.Generic;
using System.Linq;
using ICD.Common.Properties;
#if SIMPLSHARP
using Crestron.SimplSharp.Reflection;
#else
using System.Reflection;
#endif

namespace ICD.Common.Utils.Extensions
{
	/// <summary>
	/// Extension methods for use with reflection objects.
	/// </summary>
	public static class ReflectionExtensions
	{
		/// <summary>
		/// Returns the custom attributes attached to the member.
		/// </summary>
		/// <typeparam name="T"></typeparam>
		/// <param name="extends"></param>
		/// <returns></returns>
		public static IEnumerable<T> GetCustomAttributes<T>([NotNull] this ICustomAttributeProvider extends)
		{
			if (extends == null)
				throw new ArgumentNullException("extends");

			return extends.GetCustomAttributes<T>(false);
		}

		/// <summary>
		/// Returns the custom attributes attached to the member.
		/// </summary>
		/// <typeparam name="T"></typeparam>
		/// <param name="extends"></param>
		/// <param name="inherits"></param>
		/// <returns></returns>
		public static IEnumerable<T> GetCustomAttributes<T>([NotNull] this ICustomAttributeProvider extends,
		                                                    bool inherits)
		{
			if (extends == null)
				throw new ArgumentNullException("extends");

			try
			{
				return extends.GetCustomAttributes(typeof(T), inherits).Cast<T>();
			}
			// Crestron bug?
			catch (ArgumentNullException)
			{
				return Enumerable.Empty<T>();
			}
		}

		/// <summary>
		/// Returns the custom attribute attached to the member.
		/// </summary>
		/// <typeparam name="T"></typeparam>
		/// <param name="extends"></param>
		/// <returns></returns>
		public static T GetCustomAttribute<T>([NotNull] this ICustomAttributeProvider extends)
		{
			if (extends == null)
				throw new ArgumentNullException("extends");

			return extends.GetCustomAttribute<T>(false);
		}

		/// <summary>
		/// Returns the custom attribute attached to the member.
		/// </summary>
		/// <typeparam name="T"></typeparam>
		/// <param name="extends"></param>
		/// <param name="inherits"></param>
		/// <returns></returns>
		public static T GetCustomAttribute<T>([NotNull] this ICustomAttributeProvider extends, bool inherits)
		{
			if (extends == null)
				throw new ArgumentNullException("extends");

			return extends.GetCustomAttributes<T>(inherits).First();
		}

#if NETSTANDARD
		/// <summary>
		/// Returns the custom attributes attached to the member.
		/// </summary>
		/// <typeparam name="T"></typeparam>
		/// <param name="extends"></param>
		/// <returns></returns>
		public static IEnumerable<T> GetCustomAttributesIncludingBaseInterfaces<T>([NotNull] this Type extends)
			where T : Attribute
		{
			if (extends == null)
				throw new ArgumentNullException("extends");

			return extends.GetCustomAttributes<T>(true)
			              .Union(extends.GetInterfaces()
			                            .SelectMany(interfaceType => interfaceType
				                                        .GetCustomAttributes<T>(true)))
			              .Distinct();
		}

		/// <summary>
		/// Returns the custom attributes attached to the member.
		/// </summary>
		/// <typeparam name="T"></typeparam>
		/// <param name="extends"></param>
		/// <returns></returns>
		public static IEnumerable<T> GetCustomAttributesIncludingBaseInterfaces<T>([NotNull] this MemberInfo extends)
			where T : Attribute
		{
			if (extends == null)
				throw new ArgumentNullException("extends");

			return extends.GetCustomAttributes<T>(true)
			              .Union(extends.DeclaringType?
			                            .GetInterfaces()
			                            .SelectMany(interfaceType => interfaceType
			                                                         .GetMember(extends.Name,
			                                                                    extends.MemberType,
			                                                                    BindingFlags.Instance)
			                                                         .FirstOrDefault()?
			                                                         .GetCustomAttributes<T>(true) ??
			                                                         Enumerable.Empty<T>())?
			                            .Except(null) ?? Enumerable.Empty<T>())
			              .Distinct();
		}
#endif

		/// <summary>
		/// Gets the EventArgs Type for the given event.
		/// </summary>
		/// <param name="extends"></param>
		/// <returns></returns>
		public static Type GetEventArgsType([NotNull] this EventInfo extends)
		{
			if (extends == null)
				throw new ArgumentNullException("extends");

			Type eventHandlerType = extends.EventHandlerType;
			return eventHandlerType == typeof(EventHandler)
				       ? typeof(EventArgs)
				       : eventHandlerType.GetInnerGenericTypes(typeof(EventHandler<>))
				                         .First();
		}
	}
}