using System;

using Bogus;

using System.Linq;

using System.Diagnostics;

using System.Collections.Generic;

using System.Collections.Concurrent;

using System.Threading.Tasks;

​

​

public class Program

{

    public static void Main()

    {

        //Setup Fake Data

        var setting = new Faker<EzEmployee>()

            .RuleFor(p => p.RowId, f => Guid.NewGuid().ToString())

            .RuleFor(p => p.EmailAddress, (f, p) => f.Internet.Email())

            .RuleFor(p => p.Status, f => f.PickRandom<EzStatus>().ToString());

        var emps = setting.Generate(15000);

        Console.WriteLine("Total Distinct Email Count:" + emps.Select(x => x.EmailAddress).Distinct().Count());

        Console.WriteLine(String.Empty);

        /*

            原始資料描述：

                一個 E-Mail 可能有多筆 Record，最終的結果一個 E-Mail 只能有一筆資料

            順序規則：

            - 一個 E-Mail 如果有 ACTIVE 則就使用 ACTIVE 的那筆資料

            - 一個 E-Mail 如果沒有 ACTIVE 則使用比對出 INACTIVE 的那筆資料

            - 一個 E-Mail 如果沒有 ACTIVE 或 INACTIVE 的資料則代表異常則跳過 

            考題：

            - 前提：假資料筆數固定 15000

            - 請參考 GoForeachList 寫出一個新 Function 

                - 最終執行時間要小於 GoForeachList Function

                - 資料筆數要等同於 Total Distinct Email Count And 邏輯要符合上述描述

                - 最終的物件型別為 List<EzEmployee>

        */

        GoForeachList(emps);

    }

    public static void GoForeachList(List<EzEmployee> data)

    {

        var watch = new Stopwatch();

​

        watch.Start();

​

        /*  

        var acEmployees = data.Where(x => x.Status == "ACTIVE");

        var inacEmployees = data.Where(x => x.Status == "INACTIVE");

        var employees = acEmployees.Union(inacEmployees);

​

        var result = employees

            .GroupBy(x => x.EmailAddress)

            .Select(x => x.First()).ToList();

        */

​

        var result = Enumerable.Empty<EzEmployee>();

        var emails = data.GroupBy(x => x.EmailAddress);

        result = emails.Select(x => x.FirstOrDefault(y => y.Status.Equals("active", StringComparison.OrdinalIgnoreCase))).Where(x => x != null);

        result = result.Concat(emails.Where(x => x.All(y => y.Status.Equals("inactive", StringComparison.OrdinalIgnoreCase))).Select(x => x.First()));

        watch.Stop();

​

        Console.WriteLine("========= Foreach List =========");

        Console.WriteLine("Exec total Milliseconds:" + watch.ElapsedMilliseconds);

        Console.WriteLine("Exec total count:" + result.Count());

    }

    public enum EzStatus

    {

        ACTIVE,

        INACTIVE

    }

​

    public class EzEmployee

    {

        public int Id { get; set; }

        public string RowId { get; set; }

        public string EmailAddress { get; set; }

        public string Status { get; set; }

    }

}