RecurrentDateTimeOffset Draft

RecurrentDateTimeOffset.cs

namespace FitLivre.DataStructures
{
    public class RecurrentDateTimeOffset
    {
        private readonly RecurrentDateTimeKind _recurrencyKind;
        private readonly DateTimeOffset[]? _fixedFiniteOccurrences;
        private readonly RecurrentWeekDayAndTime[]? _perWeekOccurrences;
        private readonly RecurrentMonthDayAndTime[]? _perMonthOccurrences;
        private readonly RecurrentYearMonthDayAndTime[]? _perYearOccurrences;
        private readonly TimeSpan _tolerance;

        private readonly TimeSpan _defaultTolerance = TimeSpan.FromHours(1);

        public RecurrentDateTimeOffset(DateTimeOffset[] dateTimeOffsets, TimeSpan? tolerance)
        {
            _tolerance = tolerance ?? _defaultTolerance;
            _recurrencyKind = RecurrentDateTimeKind.FixedFiniteOccurrences;
            _fixedFiniteOccurrences = dateTimeOffsets;
        }

        public RecurrentDateTimeOffset(RecurrentWeekDayAndTime[] perWeekOccurrences, TimeSpan? tolerance)
        {
            _tolerance = tolerance ?? _defaultTolerance;
            _recurrencyKind = RecurrentDateTimeKind.OccurrencesPerWeek;
            _perWeekOccurrences = perWeekOccurrences;
        }

        public RecurrentDateTimeOffset(RecurrentMonthDayAndTime[] perMonthOccurrences, TimeSpan? tolerance)
        {
            _tolerance = tolerance ?? _defaultTolerance;
            _recurrencyKind = RecurrentDateTimeKind.OccurrencesPerMonth;
            _perMonthOccurrences = perMonthOccurrences;
        }

        public RecurrentDateTimeOffset(RecurrentYearMonthDayAndTime[] perYearOccurrences, TimeSpan? tolerance)
        {
            _tolerance = tolerance ?? _defaultTolerance;
            _recurrencyKind = RecurrentDateTimeKind.FixedFiniteOccurrences;
            _perYearOccurrences = perYearOccurrences;
        }

        public bool IsHappening()
        {
            return _recurrencyKind switch
            {
                RecurrentDateTimeKind.FixedFiniteOccurrences => IsHappeningFixedTime(),
                RecurrentDateTimeKind.OccurrencesPerWeek => IsHappeningPerWeek(),
                RecurrentDateTimeKind.OccurrencesPerMonth => IsHappeningPerMonth(),
                RecurrentDateTimeKind.OccurrencesPerYear => IsHappeningPerYear(),
                _ => throw new InvalidOperationException(),
            };
        }

        private bool IsHappeningFixedTime()
        {
            return _fixedFiniteOccurrences!.Any(IsDateTimeOffsetTolerated);
        }

        private bool IsHappeningPerWeek()
        {
            var isHappening = false;
            var currentDateTime = DateTimeOffset.Now;

            foreach (var occurrence in _perWeekOccurrences!)
            {
                var isDayOfWeek = occurrence.DayOfWeek == currentDateTime.DayOfWeek;
                var isCurrentTime = occurrence.TimeOnly < TimeOnly.FromDateTime(currentDateTime.UtcDateTime).Add(_tolerance);

                if (isDayOfWeek && isCurrentTime)
                {
                    isHappening = true;
                }
            }

            return isHappening;
        }

        private bool IsHappeningPerMonth()
        {
            var isHappening = false;
            var currentDateTime = DateTimeOffset.Now;

            foreach (var occurrence in _perMonthOccurrences!)
            {
                var isDayOfMonth = occurrence.DayOfMonth == currentDateTime.Day;
                var isCurrentTime = occurrence.TimeOnly < TimeOnly.FromDateTime(currentDateTime.UtcDateTime).Add(_tolerance);

                if (isDayOfMonth && isCurrentTime)
                {
                    isHappening = true;
                }
            }

            return isHappening;
        }

        private bool IsHappeningPerYear()
        {
            var isHappening = false;
            var currentDateTime = DateTimeOffset.Now;

            foreach (var occurrence in _perYearOccurrences!)
            {
                var isMonth = occurrence.Month == currentDateTime.Month;
                var isDayOfMonth = occurrence.DayOfMonth == currentDateTime.Day;
                var isCurrentTime = occurrence.TimeOnly < TimeOnly.FromDateTime(currentDateTime.UtcDateTime).Add(_tolerance);

                if (isMonth && isDayOfMonth && isCurrentTime)
                {
                    isHappening = true;
                }
            }

            return isHappening;
        }

        private bool IsDateTimeOffsetTolerated(DateTimeOffset current)
        {
            return DateTimeOffset.Now < current + _tolerance;
        }
    }

    public enum RecurrentDateTimeKind
    {
        OccurrencesPerWeek,
        OccurrencesPerMonth,
        OccurrencesPerYear,
        FixedFiniteOccurrences
    }

    public record struct RecurrentWeekDayAndTime(DayOfWeek DayOfWeek, TimeOnly TimeOnly);
    public record struct RecurrentMonthDayAndTime(uint DayOfMonth, TimeOnly TimeOnly);
    public record struct RecurrentYearMonthDayAndTime(uint Month, uint DayOfMonth, TimeOnly TimeOnly);
}