using System.Globalization;

namespace View_by_Distance.Shared.Models.Stateless.Methods;

internal abstract class PersonBirthday
{

    // ...

    internal static Models.PersonBirthday? GetPersonBirthday(string personBirthdayFormat, string personKeyFormatted)
    {
        Models.PersonBirthday? result;
        DateTime? dateTime;
        if (personKeyFormatted.Length != personBirthdayFormat.Length)
            result = null;
        else
        {
            dateTime = IPersonBirthday.GetDateTime(personBirthdayFormat, personKeyFormatted);
            if (dateTime is null)
                result = null;
            else
                result = new(dateTime.Value);
        }
        return result;
    }

    internal static TimeSpan? GetTimeSpan(long minimumDateTimeTicks, bool? isWrongYear, Models.PersonBirthday personBirthday)
    {
        TimeSpan? timeSpan;
        bool isWrongYearFilterOrCounterPersonBirthday = IPersonBirthday.IsWrongYearFilterOrCounterPersonBirthday(isWrongYear, personBirthday);
        if (isWrongYearFilterOrCounterPersonBirthday)
            timeSpan = null;
        else
            timeSpan = new(minimumDateTimeTicks - personBirthday.Value.Ticks);
        return timeSpan;
    }

    internal static TimeSpan? GetTimeSpan(DateTime minimumDateTime, bool? isWrongYear, Models.PersonBirthday personBirthday)
    {
        TimeSpan? timeSpan = GetTimeSpan(minimumDateTime.Ticks, isWrongYear, personBirthday);
        return timeSpan;
    }

    internal static (int, TimeSpan) GetAge(long dateTimeTicks, Models.PersonBirthday birthday)
    {
        TimeSpan result;
        int years;
        if (birthday?.Value is null)
            throw new NullReferenceException(nameof(birthday.Value));
        (years, result) = Age.GetAge(dateTimeTicks, birthday.Value);
        return (years, result);
    }

    internal static (int, TimeSpan) GetAge(DateTime dateTime, Models.PersonBirthday birthday)
    {
        TimeSpan result;
        int years;
        if (birthday?.Value is null)
            throw new NullReferenceException(nameof(birthday.Value));
        (years, result) = Age.GetAge(dateTime, birthday.Value);
        return (years, result);
    }

    internal static (int, double) GetAge(DateTime dateTime, DateTime dayBeforeLeapDate, Models.PersonBirthday birthday)
    {
        double result;
        (int years, TimeSpan timeSpan) = GetAge(dateTime, birthday);
        if (!DateTime.IsLeapYear(dateTime.Year) || dateTime < dayBeforeLeapDate.AddDays(1))
            result = timeSpan.TotalDays / 365;
        else
            result = timeSpan.TotalDays / 366;
        return (years, result);
    }

    internal static double? GetAge(Models.PersonBirthday birthday)
    {
        double? result;
        if (birthday is null)
            result = null;
        else
        {
            DateTime dateTime = DateTime.Now;
            DateTime dayBeforeLeapDate = new(dateTime.Year, 2, 28);
            (int years, double r) = GetAge(dateTime, dayBeforeLeapDate, birthday);
            result = years + r;
        }
        return result;
    }

    internal static List<(string, Models.PersonBirthday)> GetPersonBirthdays(string personBirthdayFormat, string[] personKeyDirectories, string personDisplayDirectoryName)
    {
        List<(string, Models.PersonBirthday)> results = new();
        string personKeyFormatted;
        Models.PersonBirthday? personBirthday;
        foreach (string personKeyDirectory in personKeyDirectories)
        {
            personKeyFormatted = Path.GetFileName(personKeyDirectory);
            if (!DateTime.TryParseExact(personKeyFormatted, "MM.dd.yyyy", CultureInfo.InvariantCulture, DateTimeStyles.None, out DateTime birthday))
                personBirthday = IPersonBirthday.GetPersonBirthday(personBirthdayFormat, personKeyFormatted);
            else
                // (personBirthday, personKeyFormatted) = Person.Get(personBirthdayFormat, personDisplayDirectory, personKeyDirectory, birthday);
                continue;
            if (personBirthday is null)
                continue;
            if (!IPersonBirthday.IsCounterPersonBirthday(personBirthday) && ((!personKeyDirectory.Contains('#') && (personDisplayDirectoryName.Contains('~') || personDisplayDirectoryName.Contains('#'))) || (personKeyDirectory.Contains('#') && !personDisplayDirectoryName.Contains('#'))))
                throw new NotSupportedException();
            results.Add(new(personKeyFormatted, personBirthday));
        }
        return results;
    }

    private static string? GetMonthShortForm(string month)
    {
        string? result = month.ToLower()[0] switch
        {
            // 'j' => "jan",
            'f' => "feb",
            // 'm' => "mar",
            // 'a' => "apr",
            // 'm' => "may",
            // 'j' => "jun",
            // 'j' => "jul",
            // 'a' => "aug",
            's' => "sep",
            'o' => "oct",
            'n' => "nov",
            'd' => "dec",
            _ => null
        };
        return result;
    }

    internal static DateTime? GetDate(string month, string day, string year)
    {
        DateTime? result;
        DateTime dayDateTime;
        DateTime yearDateTime;
        DateTime monthDateTime;
        string? monthShortHand = string.IsNullOrEmpty(month) ? "x" : GetMonthShortForm(month);
        if (month.Length > 3)
        {
            if (!DateTime.TryParseExact($"{month},1,1500", "MMMM,d,yyyy", CultureInfo.InvariantCulture, DateTimeStyles.None, out monthDateTime))
                monthDateTime = DateTime.MinValue;
        }
        else if (month.Length == 3)
        {
            if (!DateTime.TryParseExact($"{month},1,1500", "MMM,d,yyyy", CultureInfo.InvariantCulture, DateTimeStyles.None, out monthDateTime))
                monthDateTime = DateTime.MinValue;
        }
        else if (month.Length == 1 && monthShortHand is not null)
        {
            if (!DateTime.TryParseExact($"{monthShortHand},1,1500", "MMM,d,yyyy", CultureInfo.InvariantCulture, DateTimeStyles.None, out monthDateTime))
                monthDateTime = DateTime.MinValue;
        }
        else if (int.TryParse(month, out int _))
        {
            if (!DateTime.TryParseExact($"{month.PadLeft(2, '0')[..2]},1,1500", "MM,d,yyyy", CultureInfo.InvariantCulture, DateTimeStyles.None, out monthDateTime))
                monthDateTime = DateTime.MinValue;
        }
        else
            monthDateTime = DateTime.MinValue;
        if (!int.TryParse(day, out int _))
            dayDateTime = DateTime.MinValue;
        else
        {
            if (!DateTime.TryParseExact($"01,{day.PadLeft(2, '0')[..2]},1500", "MM,d,yyyy", CultureInfo.InvariantCulture, DateTimeStyles.None, out dayDateTime))
                dayDateTime = DateTime.MinValue;
        }
        if (year.Length == 2 && int.TryParse(year, out int _))
        {
            if (!DateTime.TryParseExact($"01,01,{year.PadLeft(4, '0')[..4]}", "MM,dd,yy", CultureInfo.InvariantCulture, DateTimeStyles.None, out yearDateTime))
                yearDateTime = DateTime.MinValue;
        }
        else if (year.Length == 4 && int.TryParse(year, out int _))
        {
            if (!DateTime.TryParseExact($"01,01,{year.PadLeft(4, '0')[..4]}", "MM,dd,yyyy", CultureInfo.InvariantCulture, DateTimeStyles.None, out yearDateTime))
                yearDateTime = DateTime.MinValue;
        }
        else
            yearDateTime = DateTime.MinValue;
        result = monthDateTime == DateTime.MinValue ? null : dayDateTime == DateTime.MinValue ? null : yearDateTime == DateTime.MinValue ? null : new(yearDateTime.Year, monthDateTime.Month, dayDateTime.Day);
        return result;
    }

}