Get DateTimes relative Now from Parsing text period, e.g. "Sun 18:00 - Mon 06:00" provided current datetime

DatePeriod.cs

using System;
using System.Globalization;

public class Program
{
	public static void Main()
	{
		//string inputStr = "Tue 18:00-Wed 06:00";
		string inputStr = "Sat 18:00-Mon 06:00";
		var now = DateTime.Parse("2021-08-30 06:01:00");
		Console.WriteLine("now " + now);
		var p = GetPeriod(now, inputStr);
		Console.WriteLine(p.Start + " " + p.End);
	}

	private static int GetDayIndex(string dayNameAbbreviation)
	{
		return (Array.IndexOf(CultureInfo.InvariantCulture.DateTimeFormat.AbbreviatedDayNames, dayNameAbbreviation) + 6) % 7;
	}

	private static Period GetPeriod(DateTime now, string input)
	{
		var interval = input.Split("-");
		var start = new DowTime(GetDayIndex(interval[0].Split(" ")[0]), TimeSpan.Parse(interval[0].Split(" ")[1]));
		var end = new DowTime(GetDayIndex(interval[1].Split(" ")[0]), TimeSpan.Parse(interval[1].Split(" ")[1]));
		var pStart = GetNearestDate(now, start, true);
		var pEnd = GetNearestDate(now, end, false);
		var p = new Period()
		{Start = pStart, End = pEnd};
		Console.WriteLine("org " + pStart + " " + pEnd);
		// diff can't be more than a week 
		var dDiff = pEnd.Subtract(pStart);
		if (dDiff.Days >= 7) p.Start = pStart.AddDays(7);
		return p;
	}

	private static DateTime GetNearestDate(DateTime now, DowTime input, bool isStart)
	{
		var d = new DateTime(now.Year, now.Month, now.Day, input.Time.Hours, input.Time.Minutes, 0);
		Console.WriteLine("d " + d);
		var nowDow = ((int)now.DayOfWeek + 6) % 7;
		Console.WriteLine("nowDow " + nowDow + " input dow " + input.DayOfWeek + " d " + d);
		var added = 0;
		while (added < 7) {
			if (((int)d.DayOfWeek+6)%7 == input.DayOfWeek && (isStart?(d<=now):(d>now)))
				break;
			else {
				if (isStart) d = d.AddDays(-1);
				else if (!isStart) d = d.AddDays(1);
				added++;
			}
		}
		Console.WriteLine(added+" "+((int)d.DayOfWeek+6)%7+" "+input.DayOfWeek);
		return d;
	}
}

public class DowTime
{
	public int DayOfWeek
	{
		get;
		set;
	}

	public TimeSpan Time
	{
		get;
		set;
	}

	public DowTime(int dow, TimeSpan t)
	{
		DayOfWeek = dow;
		Time = t;
	}
}

public class Period
{
	public DateTime Start
	{
		get;
		set;
	}

	public DateTime End
	{
		get;
		set;
	}
}