using System;
using System.Collections.Generic;
using System.Dynamic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using AutoMapper;

namespace Server.Utils
{
    /// <summary>
    /// 动态属性
    /// </summary>
    /// <typeparam name="T"></typeparam>
    /// <typeparam name="TDestination"></typeparam>
    public class DynamicCustomResolver<TSource, TDestination, TMember> : IValueResolver<TSource, TDestination, TMember>
    {
        public DynamicCustomResolver(string name, Func<object, TMember> resolverValueFunc)
        {
            Name = name;
            this.MemberType = typeof(TDestination).GetProperty(name).PropertyType;
            this.ResolverValueFunc = resolverValueFunc;
        }
        /// <summary>
        /// 属性的名称
        /// </summary>
        public string Name { get; set; }
        /// <summary>
        /// 成员类型
        /// </summary>
        public Type MemberType { get; set; }
        /// <summary>
        /// 自定义转换值
        /// </summary>
        public Func<object, TMember> ResolverValueFunc { get; set; }
        /// <summary>
        /// 转换
        /// </summary>
        /// <param name="source"></param>
        /// <param name="destination"></param>
        /// <param name="destMember"></param>
        /// <param name="context"></param>
        /// <returns></returns>
        public TMember Resolve(TSource source, TDestination destination, TMember destMember, ResolutionContext context)
        {
            try
            {
                var dny = source as ExpandoObject;
                var item = dny.FirstOrDefault(w => w.Key == Name);
                var val = item.Value;
                //如果自定义了转换器，就调用
                if (ResolverValueFunc != null)
                {
                    return ResolverValueFunc(val);
                }
                if (item.Value == DBNull.Value)
                {
                    val = null;
                }
                if (this.MemberType.IsEnum)//枚举
                {
                    if (val == null)
                    {
                        return (TMember)Enum.ToObject(this.MemberType, 0);
                    }
                    return (TMember)Enum.ToObject(this.MemberType, val);
                }
                if (this.MemberType == typeof(string))
                {
                    if (val == null)
                    {
                        return default(TMember);
                    }
                    return (TMember)Convert.ChangeType(val, this.MemberType);
                }
                if (this.MemberType.IsValueType)
                {
                    if (val == null)
                    {
                        return default(TMember);
                    }
                }
                return (TMember)Convert.ChangeType(val, this.MemberType);
            }
            catch (Exception e)
            {
                throw new Exception(this.Name + "转换错误 " + source, e);
            }
        }
    }
}