using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Text;
using System.Threading.Tasks;

namespace Ant.Core.Utils
{
    /// <summary>
    /// 高效实体转换（浅拷贝）（反射+表达式目录树+静态缓存 方式）
    /// </summary>
    /// <typeparam name="TIn"></typeparam>
    /// <typeparam name="TOut"></typeparam>
    public static class SafeClone<TIn, TOut>
    {
        private static readonly Func<TIn, TOut> cache = GetFunc();

        private static Func<TIn, TOut> GetFunc()
        {
            ParameterExpression parameterExpression = Expression.Parameter(typeof(TIn), "p");
            List<MemberBinding> memberBindingList = new List<MemberBinding>();

            foreach (var item in typeof(TOut).GetProperties())
            {
                if (!item.CanWrite) continue;

                var tInProperty = typeof(TIn).GetProperties().FirstOrDefault(x => x.Name == item.Name);
                if (tInProperty != null && tInProperty.PropertyType == item.PropertyType)
                {
                    MemberExpression property = Expression.Property(parameterExpression, tInProperty);
                    MemberBinding memberBinding = Expression.Bind(item, property);
                    memberBindingList.Add(memberBinding);
                }
            }

            MemberInitExpression memberInitExpression = Expression.MemberInit(Expression.New(typeof(TOut)), memberBindingList.ToArray());
            Expression<Func<TIn, TOut>> lambda = Expression.Lambda<Func<TIn, TOut>>(memberInitExpression, new ParameterExpression[] { parameterExpression });

            return lambda.Compile();
        }

        public static TOut Trans(TIn tIn)
        {
            return cache(tIn);
        }
    }
}