using System;
using BS.Shared.Extensions;
using DevExpress.XtraScheduler;

namespace BS.Shared.Core
{
    public static class DateTimeUtils
    {
        public static AnzahlMonate GetTotalMonths(DateTime start, DateTime end)
        {
            int restTageStart = 0;
            int restTageEnd = 0;

            DateTime startDt = start;
            DateTime endDt = end;

            if (startDt.Day > 1)
            {
                var endMonat = new DateTime(startDt.Year, startDt.Month, 1).AddMonths(1).AddDays(-1);

                if (endDt < endMonat)
                {
                    endMonat = endDt;
                }
                restTageStart = endMonat.Subtract(startDt).Days + 1;
                startDt = endMonat.AddDays(1);
            }
            if (startDt <= endDt && endDt.AddDays(1).Day != 1)
            {
                var startMonat = new DateTime(endDt.Year, endDt.Month, 1);

                restTageEnd += endDt.Subtract(startMonat).Days + 1;

                endDt = startMonat;
            }

            int fullMonths = 0;
            while (startDt < endDt)
            {
                fullMonths++;
                startDt = startDt.AddMonths(1);
            }

            decimal monthsTotal = fullMonths;


            if (restTageStart != 0)
            {
                monthsTotal += restTageStart / (decimal)DateTime.DaysInMonth(start.Date.Year, start.Date.Month);

            }
            if (restTageEnd != 0)
            {
                monthsTotal += restTageEnd / (decimal)DateTime.DaysInMonth(end.Date.Year, end.Date.Month);

            }

            var am = new AnzahlMonate();
            am.GanzeMonate = fullMonths;
            am.RestTageAnfang = restTageStart;
            am.RestTageEnde = restTageEnd;
            am.AnzahlMonateGesamt = monthsTotal;

            return am;
        }

        public static WeekDays GetWeekDays(int number)
        {
            switch (number)
            {
                case 1:
                    return WeekDays.Sunday;
                case 2:
                    return WeekDays.Monday;
                case 4:
                    return WeekDays.Tuesday;
                case 8:
                    return WeekDays.Wednesday;
                case 16:
                    return WeekDays.Thursday;
                case 32:
                    return WeekDays.Friday;
                case 62:
                    return WeekDays.WorkDays;
                case 64:
                    return WeekDays.Saturday;
                case 65:
                    return WeekDays.WeekendDays;
                case 127:
                    return WeekDays.EveryDay;
                default:
                    return WeekDays.Monday;
            }
        }

        public static DayOfWeek ConvertWeekDaysToDayOfWeek(WeekDays weekDays)
        {
            try
            {
                if((int) weekDays <= 64)
                {
                    return (DayOfWeek) Convert.ToString((int) weekDays, 2).Length - 1;
                }
            }
            catch(Exception)
            {
                return DayOfWeek.Sunday;
            }

            return DayOfWeek.Sunday;
        }

        public static int GetNumberOfWeekEndDaysInBetween(DateTime pStart, DateTime pEnd)
        {
            var numberOfWeekEndDays = 0;
            var currentDate = pStart.Date;

            var b = pEnd.Date;

            while (currentDate <= b)
            {
                if (currentDate.DayOfWeek == DayOfWeek.Saturday || currentDate.DayOfWeek == DayOfWeek.Sunday)
                {
                    numberOfWeekEndDays++;
                }

                currentDate = currentDate.AddDays(1);
            }

            return numberOfWeekEndDays;
        }

        public static DateTime GetNthDayOfWeekInMonth(DateTime date, int number, DayOfWeek dayOfWeek)
        {
            if (number <= 0)
            {
                throw new ArgumentOutOfRangeException();
            }

            // Letzter Wochentag im Monat
            if (number > 3)
            {
                return GetNthDayOfWeekInMonth(date.AddMonths(1), 1, dayOfWeek).AddDays(-7);
            }

            var firstDayOfMonth = new DateTime(date.Year, date.Month, 1);

            var counter = 1;

            do
            {
                if (firstDayOfMonth.DayOfWeek == dayOfWeek)
                {
                    if (counter == number)
                    {
                        return firstDayOfMonth;
                    }

                    counter++;
                }

                firstDayOfMonth = firstDayOfMonth.AddDays(1);
            } while (counter <= number);

            return firstDayOfMonth;
        }

        public static DayOfWeek ConvertAppointmentDayOfWeekToDayOfWeek(AppointmentDayOfWeek appointmentDayOfWeek)
        {
            return (DayOfWeek) (((int) appointmentDayOfWeek + 1) % 7);
        }

        public static ArbeitszeitEintragDateTimeObject GetAssistanceTimeComparisonDateTime(string uhrzeitVon, string uhrzeitBis, DateTime date)
        {
            var day = date.GetShortDateTime();

            var isStartSuccessfullyParsed = DateTime.TryParse($"{day:dd.MM.yyyy} {uhrzeitVon}", out var start);
            var isEndSuccessfullyParsed = DateTime.TryParse($"{day:dd.MM.yyyy} {uhrzeitBis}", out var end);

            if (isStartSuccessfullyParsed && isEndSuccessfullyParsed)
            {
                return new ArbeitszeitEintragDateTimeObject(start, end);
            }

            return new ArbeitszeitEintragDateTimeObject(start, end);
        }
    }

    public class AnzahlMonate
    {
        public decimal AnzahlMonateGesamt { get; set; }
        public int GanzeMonate { get; set; }
        public decimal RestTageAnfang { get; set; }
        public decimal RestTageEnde { get; set; }
    }
}