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

namespace LINQDictionaryJoin
{
    class Program
    {
        static void Main(string[] args)
        {
            var bl = new IPersonBasicBL();
            var result = bl.Get();

            new IPersonChangeContentBL().SetPersonInfo(result);

        }
    }

    public class IPersonBasicBL
    {
        public IEnumerable<Person> Get()
        {
            List<Person> result = new List<Person>();
            result.Add(new Person { Id = 1, Name = "Name", ChangeContentId = new Guid(), EffectiveDate = DateTime.Today });
            return result;
        }
    }

    public interface IPersonBasic
    {
        int Id { get; set; }
        string Name { get; set; }
    }

    public class IPersonChangeContentBL
    {
        public void SetPersonInfo(IEnumerable<IPersonChangeContent> datas)
        {
            var ids = datas.Select(d => d.ChangeContentId);
            var personChangeContentDict = new PersonChangeContentRepository()
                                                .Get(ids)
                                                .ToDictionary(n => n.ChangeContentId);

            foreach (var item in datas)
            {
                item.EffectiveDate = personChangeContentDict.GetValue(item.ChangeContentId).EffectiveDate;
            }
        }
    }

    public class PersonChangeContentRepository
    {
        internal IEnumerable<IPersonChangeContent> Get(IEnumerable<Guid> ids)
        {
            List<IPersonChangeContent> result = new List<IPersonChangeContent>();
            result.Add(new Person { Id = 1, Name = "Name", ChangeContentId = new Guid(), EffectiveDate = DateTime.Today });
            return result;
        }
    }

    public interface IPersonChangeContent
    {
        Guid ChangeContentId { get; set; }
        DateTime EffectiveDate { get; set; }
    }

    public class Person : IPersonBasic, IPersonChangeContent
    {
        public int Id { get; set; }
        public string Name { get; set; }

        public Guid ChangeContentId { get; set; }
        public DateTime EffectiveDate { get; set; }
    }

    public static class Helers
    {
        public static T2 GetValue<T1, T2>(this Dictionary<T1, T2> dict, T1 key)
        {
            T2 result = default(T2);

            dict.TryGetValue(key, out result);

            return result;
        }
    }
}