////using Newtonsoft.Json;
////using Amazon.DynamoDBv2.DocumentModel;
////using System;
////using System.Collections.Generic;
////using System.Linq;
////using System.Text;
////using System.Threading.Tasks;
////using Google.Protobuf.WellKnownTypes;

////namespace ServerCommon.DB
////{
////    public enum EMailType
////    { 
////        RECEIVED_MAIL = 1,
////        SENDED_MAIL = 2,
////    }

////    public class MailEntityAttr
////    {
////        public string mailKey = string.Empty;
////        public bool isRead;
////        public bool isGetItem;
////        public bool isSystemMail;
////        public string senderNickName = string.Empty;
////        public string senderGuid = string.Empty;
////        public string receiverNickName = string.Empty;
////        public string receiverGuid = string.Empty;
////        public string title = string.Empty;
////        public string text = string.Empty;
////        public Timestamp createTime = new();
////        public Timestamp expireTime = new();
////        public List<MailItem> ItemList = new();
////    }

////    public class MailEntity
////    {
////        public string PK_Guid { get; private set; } = string.Empty;
////        public string SK_DateSequence { get; private set; } = string.Empty;
////        public MailEntityAttr Attr { get; private set; } = new();
////        public string TTL { get; private set; } = string.Empty; //MUSTBE: TTL에 의해 메일이 삭제될 경우 메일 삭제 비즈니스 로그를 남기지 못한다. !!! - kangms

////        public EEntityType entityType { get; protected set; } = EEntityType.ReceivedMail;

////        public MailEntity()
////        {
////        }
////        public MailEntity(Document document)
////        {
////            ReadFrom(document);
////        }

////        public void ReadFrom(Document document)
////        {
////            PK_Guid = document["PK"].AsString().Replace(MainDB.GetPKPrefix(entityType), "");
////            SK_DateSequence = document["SK"].AsString().Replace(MainDB.GetSKPrefix(entityType), "");
////            if (document.ContainsKey("TTL"))
////            {
////                document["TTL"].AsString();
////            }
////            else TTL = string.Empty;
            

////            MailEntityAttr? attr = JsonConvert.DeserializeObject<MailEntityAttr>(document["Attr"].AsString());
////            if (attr == null)
////                throw new Exception("Attr DeserializeObject error");

////            Attr = attr;
////        }

////        public Document DocumentForUpdate()
////        {
////            var document = new Document();
////            document["PK"] = MainDB.MakePK(entityType, PK_Guid);
////            document["SK"] = MainDB.MakeSK(entityType, SK_DateSequence);
////            document["TTL"] = TTL;
////            document["Attr"] = JsonConvert.SerializeObject(Attr);
////            return document;
////        }
////        public Document DocumentForDelete()
////        {
////            var document = new Document();
////            document["PK"] = MainDB.MakePK(entityType, PK_Guid);
////            document["SK"] = MainDB.MakeSK(entityType, SK_DateSequence);
////            return document;
////        }
////    }

////    public class ReceivedMailEntity : MailEntity
////    {
////        public ReceivedMailEntity(Document document)
////        {
////            entityType = EEntityType.ReceivedMail;
////            ReadFrom(document);
////        }
////    }

////    public class SendedMailEntity : MailEntity
////    {
////        public SendedMailEntity(Document document)
////        {
////            entityType = EEntityType.SendedMail;
////            ReadFrom(document);
////        }
////    }
////}