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

namespace Wood.Util
{
    public static class CommonHelper
    {
        public static Guid NewGuid
        {
            get
            {
                return Guid.NewGuid();
            }
        }

        public static string NewGuidStr
        {
            get
            {
                return Guid.NewGuid().ToString();
            }
        }

        public static DateTime CurrentTime
        {
            get
            {
                return DateTime.Now;
            }
        }

        public static string CurrentTimeStr
        {
            get
            {
                DateTime dt = CurrentTime;
                return dt.ToString("yyyy-MM-dd HH:mm:ss");
            }
        }

        public static string CurrentMachineName
        {
            get
            {
                return Environment.MachineName;
            }
        }

        public static string UserName
        {
            get
            {
                return "Admin";
            }
        }
    }

    /// <summary>
    /// Expression动态拼接+泛型缓存
    /// </summary>
    /// <typeparam name="TIn"></typeparam>
    /// <typeparam name="TOut"></typeparam>
    public class ExpressionGenericMapper<TIn, TOut>//Mapper`2
    {
        private static Func<TIn, TOut> _FUNC = null;
        static ExpressionGenericMapper()
        {
            ParameterExpression parameterExpression = Expression.Parameter(typeof(TIn), "p");
            List<MemberBinding> memberBindingList = new List<MemberBinding>();
            foreach (var item in typeof(TOut).GetProperties())
            {
                MemberExpression property = Expression.Property(parameterExpression, typeof(TIn).GetProperty(item.Name));
                MemberBinding memberBinding = Expression.Bind(item, property);
                memberBindingList.Add(memberBinding);
            }
            foreach (var item in typeof(TOut).GetFields())
            {
                MemberExpression property = Expression.Field(parameterExpression, typeof(TIn).GetField(item.Name));
                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
            });
            _FUNC = lambda.Compile();//拼装是一次性的
        }
        public static TOut Trans(TIn t)
        {
            return _FUNC(t);
        }
    }
}