using System;
using System.Collections.Generic;
using System.Linq;

namespace Sony.Filtr.Utility.Extensions
{
    public static class DateTimeExtensions
    {
        public static IEnumerable<DateTime> GetDateRangeTo(this DateTime start, DateTime endDate)
        {
            for (var dt = start; dt <= endDate; dt = dt.AddDays(1))
            {
                yield return dt.Date;
            }
        }

        public static IEnumerable<DateTime> GetDateRangeToNow(this DateTime startDate)
        {
            if (startDate > DateTime.UtcNow) { return Enumerable.Empty<DateTime>(); }

            return startDate.GetDateRangeTo(DateTime.UtcNow);
        }

        public static string ToNeutralShortDateString(this DateTime dateTime)
        {
            return dateTime.ToString("yyyy-MM-dd");
        }

        public static string ToNeutralShortDateString(this DateTime? dateTime)
        {
            return dateTime?.ToString("yyyy-MM-dd");
        }

        public static bool IsYesterday(this DateTime dt)
        {
            return dt.Date == DateTime.Now.AddDays(-1).Date;
        }

        public static DateTime FromVendorTimestamp(this double vendorTimestamp)
        {
            // Unix timestamp is seconds past epoch
            System.DateTime dtDateTime = new DateTime(1970, 1, 1, 0, 0, 0, 0, System.DateTimeKind.Utc);
            dtDateTime = dtDateTime.AddSeconds(vendorTimestamp / 100).ToLocalTime();
            
            return dtDateTime;
        }
    }
}