using System;

using System.Text.RegularExpressions;

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        var IterationType = ScheduleIterationType.Weekly;

        var IterationKind = ScheduleIterationKind.Local;

        var dateTime = DateTime.Now;

        string windowStart = "16T15:50:00+0200";

        string windowEnd = "16T16:00:00+0200";

        var periodicSchedule = new PeriodicSchedule(IterationType, IterationKind, dateTime);

        var start = string.IsNullOrEmpty(windowStart) ? periodicSchedule.GetNthPeriodStart(0) : new PartialDateTime(windowStart, IterationType).CompleteWith(dateTime);

        var end = string.IsNullOrEmpty(windowEnd) ? periodicSchedule.GetNthPeriodStart(1) : new PartialDateTime(windowEnd, IterationType).CompleteWith(dateTime);

        Console.WriteLine(start <= dateTime && dateTime < end);

        Console.WriteLine(periodicSchedule.GetNthPeriodStart(0));

    }

​

    public enum ScheduleIterationType

    {

        None,

        Yearly,

        Monthly,

        Weekly,

        Daily,

        Hourly,

        Minutely

    }

​

    public enum ScheduleIterationKind

    {

        Local,

        Utc

    }

​

    public class PeriodicSchedule

    {

        private ScheduleIterationType IterationType;

        private ScheduleIterationKind IterationKind;

        private DateTime StartTime;

        public PeriodicSchedule(ScheduleIterationType iterationType, ScheduleIterationKind iterationKind, DateTime startTime)

        {

            IterationType = iterationType;

            IterationKind = iterationKind;

            StartTime = startTime;

        }

​

        public PeriodicSchedule(ScheduleIterationType iterationType, DateTime startTime)

        {

            IterationType = iterationType;

            IterationKind = ScheduleIterationKind.Local;

            StartTime = startTime;

        }

​

        public DateTime GetNthPeriodStart(int nth)

        {

            var frenchTimeZone = TimeZoneInfo.FindSystemTimeZoneById("CET");

            var referenceDateTime = TimeZoneInfo.ConvertTime(StartTime, frenchTimeZone);

            switch (IterationType)

            {

                case ScheduleIterationType.Yearly:

                    return new DateTimeOffset(referenceDateTime.Year, 1, 1, 0, 0, 0, frenchTimeZone.BaseUtcOffset).AddYears(nth).UtcDateTime;

                case ScheduleIterationType.Monthly:

                    return new DateTimeOffset(referenceDateTime.Year, referenceDateTime.Month, 1, 0, 0, 0, frenchTimeZone.BaseUtcOffset).AddMonths(nth).UtcDateTime;

                case ScheduleIterationType.Weekly:

                    var periodStartDate = new DateTimeOffset(referenceDateTime.Year, referenceDateTime.Month, referenceDateTime.Day, 0, 0, 0, frenchTimeZone.BaseUtcOffset);

                    var dayOfTheWeek = ((int)periodStartDate.DayOfWeek + 6) % 7; //Normalized day, 0=monday,6=sunday

                    periodStartDate = periodStartDate.AddDays(-dayOfTheWeek + 7 * nth);

                    return periodStartDate.UtcDateTime;

                case ScheduleIterationType.Daily:

                    return new DateTimeOffset(referenceDateTime.Year, referenceDateTime.Month, referenceDateTime.Day, 0, 0, 0, frenchTimeZone.BaseUtcOffset).AddDays(nth).UtcDateTime;

                case ScheduleIterationType.Hourly:

                    return new DateTimeOffset(referenceDateTime.Year, referenceDateTime.Month, referenceDateTime.Day, referenceDateTime.Hour, 0, 0, frenchTimeZone.BaseUtcOffset).AddHours(nth).UtcDateTime;

                case ScheduleIterationType.Minutely:

                    return new DateTimeOffset(referenceDateTime.Year, referenceDateTime.Month, referenceDateTime.Day, referenceDateTime.Hour, referenceDateTime.Minute, 0, frenchTimeZone.BaseUtcOffset).AddMinutes(nth).UtcDateTime;

                default:

                    return referenceDateTime;

            }

        }

    }

​

    public class PartialDateTime

    {

        private static string pattern = @"((\d\d\d\d)-)?((\d\d)-)?((\d\d)T)?((\d\d):)?((\d\d):)?(\d\d)(\.(\d{3,6}))?(Z|\+(\d\d)(\d\d))";

        private static Regex regex = new Regex(pattern);

        private int year;

        private int month;

        private int day;

        private int hour;

        private int minute;

        private int second;

        private int timezoneHour;

        private int timezoneMinute;

        private string definition;

        private ScheduleIterationType iterationType;

        public PartialDateTime(string definition, ScheduleIterationType iterationType)

        {

            this.definition = definition;

            this.iterationType = iterationType;

            var match = regex.Match(definition);

            if (match.Success == false)

            {

                throw new ArgumentException($"Definition {definition} is not a valid Partial DateTime");

            }

​

            int.TryParse(match.Groups[2].Value, out year);

            int.TryParse(match.Groups[4].Value, out month);

            int.TryParse(match.Groups[6].Value, out day);

            int.TryParse(match.Groups[8].Value, out hour);

            int.TryParse(match.Groups[10].Value, out minute);

            int.TryParse(match.Groups[11].Value, out second);

            int.TryParse(match.Groups[15].Value, out timezoneHour);

            int.TryParse(match.Groups[16].Value, out timezoneMinute);

        }

​

        public DateTime CompleteWith(DateTime dateTime)

        {

            var utcTime = dateTime.ToUniversalTime();

            switch (iterationType)

            {

                case ScheduleIterationType.None:

                    return utcTime;

                case ScheduleIterationType.Yearly:

                    return new DateTime(utcTime.Year, month, day, hour, minute, second, DateTimeKind.Utc).AddHours(-timezoneHour).AddMinutes(-timezoneMinute);

                case ScheduleIterationType.Monthly:

                    return new DateTime(utcTime.Year, utcTime.Month, day, hour, minute, second, DateTimeKind.Utc).AddHours(-timezoneHour).AddMinutes(-timezoneMinute);

                case ScheduleIterationType.Weekly:

                    return new DateTime(utcTime.Year, utcTime.Month, day, hour, minute, second, DateTimeKind.Utc).AddHours(-timezoneHour).AddMinutes(-timezoneMinute);

                case ScheduleIterationType.Daily:

                    return new DateTime(utcTime.Year, utcTime.Month, utcTime.Day, hour, minute, second, DateTimeKind.Utc).AddHours(-timezoneHour).AddMinutes(-timezoneMinute);

                case ScheduleIterationType.Hourly:

                    return new DateTime(utcTime.Year, utcTime.Month, utcTime.Day, utcTime.Hour, minute, second, DateTimeKind.Utc).AddMinutes(-timezoneMinute);

                case ScheduleIterationType.Minutely:

                    return new DateTime(utcTime.Year, utcTime.Month, utcTime.Day, utcTime.Hour, utcTime.Minute, second, DateTimeKind.Utc);

                default:

                    return utcTime;

            }

        }

​

        public static bool IsInside(string start, string end, ScheduleIterationType iterationType, DateTime dateTime)

        {

            var partialStartTime = new PartialDateTime(start, iterationType);

            var partialEndTime = new PartialDateTime(end, iterationType);

            return IsInside(partialStartTime, partialEndTime, dateTime);

        }

​

        public static bool IsInside(PartialDateTime partialStartTime, PartialDateTime partialEndTime, DateTime dateTime)

        {

            var startTime = partialStartTime.CompleteWith(dateTime);

            var endTime = partialEndTime.CompleteWith(dateTime);

            return startTime <= dateTime && dateTime < endTime;

        }

    }

}