using System;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        //=================================================================================================

        //Get hours & days of operation

        //These normally come from a config file, but hardcoding them here for demo

        int availableChatStartHour = 13; //7am CST in UTC time

        int availableChatDuration = 12;  //12 hours from 7am CST is 7pm CST

        string[] availableDaysForChat = "monday,tuesday,wednesday,thursday,friday".ToUpper().Split(',');

        //=================================================================================================

        //The current timezone-agnostic time.

        var now = DateTime.UtcNow;

        //Convert times to a date object

        //-------------------------------------------------

        //I THINK THIS IS WHERE MY BUG IS

        var startTime = new DateTime(now.Year, now.Month, now.Day, availableChatStartHour, 0, 0, DateTimeKind.Utc);

        //-------------------------------------------------

        var endTime = startTime.AddHours(availableChatDuration);

        //Company HQ is located in the central time zone

        //The central time zone can experience daylight saving time.

        //We need to determine if DST is currently active or not in CST

        var cstZone = TimeZoneInfo.FindSystemTimeZoneById("Central Standard Time");

        var cstTime = TimeZoneInfo.ConvertTimeFromUtc(now, cstZone);

        var isDstActive = cstZone.IsDaylightSavingTime(cstTime);

        //If DST is active, then we need to subtract an hour from the start and end times.

        if (isDstActive)

        {

            startTime = startTime.AddHours(-1);

            endTime = endTime.AddHours(-1);

        }

        //Determine if the day of the week (in CST time) is available for chat

        var isDayAvilable = availableDaysForChat.Contains(cstTime.DayOfWeek.ToString().ToUpper());

        //Make sure the time of day is within the acceptable range

        var isAfterStartTime = now > startTime;

        var isBeforeEndTime = now < endTime;

        //Now take everything into account and see if the chat is available

        //return isDayAvilable && isAfterStartTime && isBeforeEndTime;

        Console.WriteLine("NOW:   "+ now);

        Console.WriteLine("START: "+ startTime);

        Console.WriteLine("END:   "+ endTime);

        Console.WriteLine("-------------------------------------");

        Console.WriteLine("Day Available:       "+isDayAvilable);

        Console.WriteLine("Is After Start Time: "+ isAfterStartTime);

        Console.WriteLine("Is Before End Time:  "+ isBeforeEndTime);

        Console.WriteLine("-------------------------------------");

        Console.WriteLine("FINAL RESULT:        "+ (isDayAvilable && isAfterStartTime && isBeforeEndTime));

​

    }

}