using System;
using System.Reflection;
using System.Reflection.Emit;
using System.Runtime.CompilerServices;
using System.Threading;

namespace AspClassic.Scripting.Utils;

internal static class ReflectionUtils
{
	public const char GenericArityDelimiter = '`';

	private static AssemblyBuilder _assembly;

	private static ModuleBuilder _modBuilder;

	private static int _typeCount;

	private static readonly Type[] _DelegateCtorSignature = new Type[2]
	{
		typeof(object),
		typeof(IntPtr)
	};

	private static TypeBuilder DefineDelegateType(string name)
	{
		if (_assembly == null)
		{
			Interlocked.CompareExchange(ref _assembly, AppDomain.CurrentDomain.DefineDynamicAssembly(new AssemblyName("DynamicDelegates"), AssemblyBuilderAccess.Run), null);
			lock (_assembly)
			{
				if (_modBuilder == null)
				{
					_modBuilder = _assembly.DefineDynamicModule("DynamicDelegates");
				}
			}
		}
		return _modBuilder.DefineType(name + Interlocked.Increment(ref _typeCount), TypeAttributes.Public | TypeAttributes.Sealed | TypeAttributes.AutoClass, typeof(MulticastDelegate));
	}

	public static Type GetObjectCallSiteDelegateType(int paramCnt)
	{
		switch (paramCnt)
		{
		case 0:
			return typeof(Func<CallSite, object, object>);
		case 1:
			return typeof(Func<CallSite, object, object, object>);
		case 2:
			return typeof(Func<CallSite, object, object, object, object>);
		case 3:
			return typeof(Func<CallSite, object, object, object, object, object>);
		case 4:
			return typeof(Func<CallSite, object, object, object, object, object, object>);
		case 5:
			return typeof(Func<CallSite, object, object, object, object, object, object, object>);
		case 6:
			return typeof(Func<CallSite, object, object, object, object, object, object, object, object>);
		case 7:
			return typeof(Func<CallSite, object, object, object, object, object, object, object, object, object>);
		case 8:
			return typeof(Func<CallSite, object, object, object, object, object, object, object, object, object, object>);
		case 9:
			return typeof(Func<CallSite, object, object, object, object, object, object, object, object, object, object, object>);
		case 10:
			return typeof(Func<CallSite, object, object, object, object, object, object, object, object, object, object, object, object>);
		case 11:
			return typeof(Func<CallSite, object, object, object, object, object, object, object, object, object, object, object, object, object>);
		case 12:
			return typeof(Func<CallSite, object, object, object, object, object, object, object, object, object, object, object, object, object, object>);
		case 13:
			return typeof(Func<CallSite, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object>);
		case 14:
			return typeof(Func<CallSite, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object, object>);
		default:
		{
			Type[] array = new Type[paramCnt + 2];
			array[0] = typeof(CallSite);
			array[1] = typeof(object);
			for (int i = 0; i < paramCnt; i++)
			{
				array[i + 2] = typeof(object);
			}
			TypeBuilder typeBuilder = DefineDelegateType("Delegate");
			typeBuilder.DefineConstructor(MethodAttributes.Public | MethodAttributes.HideBySig | MethodAttributes.RTSpecialName, CallingConventions.Standard, _DelegateCtorSignature).SetImplementationFlags(MethodImplAttributes.CodeTypeMask);
			typeBuilder.DefineMethod("Invoke", MethodAttributes.Public | MethodAttributes.Virtual | MethodAttributes.HideBySig | MethodAttributes.VtableLayoutMask, typeof(object), array).SetImplementationFlags(MethodImplAttributes.CodeTypeMask);
			return typeBuilder.CreateType();
		}
		}
	}
}