using System;
using System.Collections.Generic;
using System.Configuration;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;

namespace CommonTool
{
	/// <summary>
	/// 反射帮助类
	/// </summary>
	public class ReflectionHelper
	{

		public  static ReflectionHelper Instance { get; } = new ReflectionHelper();


		public Type GetType(string className)
		{
			return GetType(AssemblyName, NameSpace,className);
		}

		public Type GetType(string assemblyName, string nameSpace, string className)
		{
			string fullName = nameSpace + "." + className;
			string path = fullName + "," + assemblyName;
			return Type.GetType(path);
		}

		/// <summary>
		/// 创建对象实例
		/// </summary>
		/// <param name="className">类型名</param>
		/// <returns></returns>
		public object CreateInstance(string className)
		{
			return CreateInstance(AssemblyName, NameSpace, className);
		}

		/// <summary>
		/// 创建对象实例
		/// </summary>
		/// <typeparam name="T"></typeparam>
		/// <param name="assemblyName">程序集</param>
		/// <param name="nameSpace">类型所在命名空间</param>
		/// <param name="className">类型名</param>
		/// <returns></returns>
		public object CreateInstance(string assemblyName, string nameSpace, string className)
			
		{
			string fullName = nameSpace + "." + className;
			string path = fullName + "," + assemblyName;//命名空间.类型名,程序集
			Type o = Type.GetType(path);//加载类型
			if (o != null)
			{
				object obj = Activator.CreateInstance(o, true);//根据类型创建实例
				return obj;//类型转换并返回
			}
			return null;
		}

		/// <summary>
		/// 创建对象实例
		/// </summary>
		/// <typeparam name="T">要创建对象的类型</typeparam>
		/// <param name="className">类型名</param>
		/// <returns></returns>
		public T CreateInstance<T>(string className)
		{
			return CreateInstance<T>(AssemblyName, NameSpace, className);
		}

		/// <summary>
		/// 创建对象实例
		/// </summary>
		/// <typeparam name="T">要创建对象的类型</typeparam>
		/// <param name="assemblyName">类型所在程序集名称</param>
		/// <param name="nameSpace">类型所在命名空间</param>
		/// <param name="className">类型名</param>
		/// <returns></returns>
		public T CreateInstance<T>(string assemblyName, string nameSpace, string className)
		{
			try
			{
				string fullName = nameSpace + "." + className;//命名空间.类型名
															  //此为第一种写法
				object ect = Assembly.Load(assemblyName).CreateInstance(fullName);//加载程序集，创建程序集里面的 命名空间.类型名 实例
				return (T)ect;//类型转换并返回
							  //下面是第二种写法
							  //string path = fullName + "," + assemblyName;//命名空间.类型名,程序集
							  //Type o = Type.GetType(path);//加载类型
							  //object obj = Activator.CreateInstance(o, true);//根据类型创建实例
							  //return (T)obj;//类型转换并返回
			}
			catch
			{
				//发生异常，返回类型的默认值
				return default(T);
			}
		}

		private string AssemblyName => ConfigurationManager.AppSettings["AssemblyName"];
		private string NameSpace => ConfigurationManager.AppSettings["NameSpace"];
		private string FullName => NameSpace + "." + AssemblyName;

		
	}
}