using System;
using System.Globalization;

namespace Xylem.Common.Utils.DateTimeServer
{

    /// <summary>
    /// Class for international time settings and conversions
    /// </summary>
    [Serializable]
    public static class DateTimeServer
    {
        /// <summary>
        /// Convert date time offset to local date as string.
        /// </summary>
        /// <param name="dto">date time offset needed to extract the local date</param>
        /// <param name="cI">culture info for local information of date and time offset</param>
        /// <returns>Date string</returns>
        /// <remarks date="2021-Feb-25" author="Thomas Wiedebusch">
        /// - Initial.
        /// </remarks>
        public static String GetDateStringFromDateTimeOffset(DateTimeOffset dto, CultureInfo cI)
        {
            var date = dto.Date;
            return date.ToShortDateString();
        }

        /// <summary>
        /// Convert date time to sortable string.
        /// </summary>
        /// <param name="dt">date time offset needed to extract the local date</param>
        /// <param name="cI">culture info for local information of date and time offset</param>
        /// <returns>Date string</returns>
        /// <remarks date="2022-Jun-30" author="Thomas Wiedebusch">
        /// - Initial.
        /// </remarks>
        public static String GetSortableDateStringFromDateTime(DateTime dt, CultureInfo cI)
        {
            var culturePattern = @"yyyy/MM/dd";
            if (cI.IetfLanguageTag.Contains("de-"))
            {
                culturePattern = @"yyyy-MM-dd";
            }
            return dt.ToString(culturePattern);
        }

        /// <summary>
        /// Convert date string to date time.
        /// </summary>
        /// <param name="date">as string</param>
        /// <param name="cI"></param>
        /// <returns>validation date as date time offset</returns>
        /// <remarks date="2021-Mar-23" author="Thomas Wiedebusch">
        /// - Initial.
        /// </remarks>
        public static DateTime GetDateTimeFromDateString(String date, CultureInfo cI)
        {
            try
            {
                if (DateTime.TryParse(date, out var localDateTime))
                {
                    var localTimeOffset = TimeZone.CurrentTimeZone.GetUtcOffset(localDateTime);
                    var dateTimeOffset = new DateTimeOffset(localDateTime, localTimeOffset);
                    var dateTime = dateTimeOffset.DateTime;
                    return dateTime;
                }

                return DateTime.Now;
            }
            catch (Exception)
            {
                return DateTime.Now;
            }
        }

        /// <summary>
        /// Convert date string to date time offset adding always 23:59:59
        /// </summary>
        /// <param name="date">as string</param>
        /// <returns>validation date as date time offset</returns>
        /// <remarks date="2021-Feb-25" author="Thomas Wiedebusch">
        /// - Initial.
        /// </remarks>
        public static DateTimeOffset GetDateTimeOffsetFromDateString(String date)
        {
            try
            {
                if (DateTime.TryParse(date, out var dateTime))
                {
                    var localTimeOffset = TimeZone.CurrentTimeZone.GetUtcOffset(dateTime);
                    return new DateTimeOffset(dateTime.Year, dateTime.Month, dateTime.Day,
                        23, 59, 59, localTimeOffset);
                }
                return DateTimeOffset.Now;
            }
            catch (Exception)
            {
                return DateTimeOffset.Now;
            }
        }
        /// <summary>
        /// Set a validation date to the current local date time 
        /// </summary>
        /// <param name="validDays">days to extend the validation</param>
        /// <returns>validation date as date time offset</returns>
        /// <remarks date="2021-Feb-25" author="Thomas Wiedebusch">
        /// - Initial.
        /// </remarks>
        public static DateTimeOffset SetValidationDate(Double validDays)
        {
            try
            {
                var localDateTime = DateTime.Now;
                var localTimeOffset = TimeZone.CurrentTimeZone.GetUtcOffset(localDateTime);
                var todayValidDateTime = new DateTimeOffset(localDateTime.Year, localDateTime.Month,
                    localDateTime.Day, 23, 59, 59, localTimeOffset);

                // add the validate date to the current time span
                return todayValidDateTime.AddDays(validDays);
            }
            catch (Exception)
            {
                return DateTimeOffset.Now;
            }
        }
        /// <summary>
        /// Get the data time until midnight for date time validation purposes as otherwise
        /// the time may count up and today is always false in comparison wit DataTime.Now!
        /// </summary>
        /// <returns>date time of today until midnight</returns>
        /// <remarks date="2021-Apr-14" author="Thomas Wiedebusch">
        /// - Initial.
        /// </remarks>
        public static DateTime GetDateTimeTodayUntilMidnight()
        {
            try
            {
                var localDateTime = DateTime.Now;
                var localTimeOffset = TimeZone.CurrentTimeZone.GetUtcOffset(localDateTime);
                var todayUntilMidnightDateTime = new DateTimeOffset(localDateTime.Year, localDateTime.Month,
                    localDateTime.Day, 23, 59, 59, localTimeOffset);

                var dateTime = todayUntilMidnightDateTime.DateTime;
                return dateTime;
            }
            catch (Exception)
            {
                return DateTime.Now;
            }
        }
    }
}