using System.Collections.Generic;
using System.Linq;

namespace EC.Utils
{
	/// <summary>
	/// 泛型Distinct比较
	/// Data.Distinct(new ExtList<T>("字段")).ToList();
	/// 版 本：V3.0.0
	/// 版 权：EasyCode
	/// 作 者：LXC
	/// </summary>
	/// <typeparam name="T"></typeparam>
	public class ExtList<T> : IEqualityComparer<T> where T : class, new()
	{
		private string[] comparintFiledName = { };

		public ExtList(params string[] comparintFiledName)
		{
			this.comparintFiledName = comparintFiledName;
		}

		bool IEqualityComparer<T>.Equals(T x, T y)
		{
			if (x == null && y == null)
			{
				return false;
			}
			if (comparintFiledName.Length == 0)
			{
				return x.Equals(y);
			}
			bool result = true;
			var typeX = x.GetType();//获取类型
			var typeY = y.GetType();
			foreach (var filedName in comparintFiledName)
			{
				var xPropertyInfo = (from p in typeX.GetProperties() where p.Name.Equals(filedName) select p).FirstOrDefault();
				var yPropertyInfo = (from p in typeY.GetProperties() where p.Name.Equals(filedName) select p).FirstOrDefault();

				result = result
					&& xPropertyInfo != null && yPropertyInfo != null
					&& xPropertyInfo.GetValue(x, null).ToString().Equals(yPropertyInfo.GetValue(y, null));
			}
			return result;
		}

		int IEqualityComparer<T>.GetHashCode(T obj)
		{
			return obj.ToString().GetHashCode();
		}
	}
}