using System;

namespace InABox.Mobile
{
    public class DateTimeToAgeConverter : AbstractConverter<DateTime, String>
    {
        
        public static string FormatTime(DateTime date)
        {
            DateTime now = DateTime.Now;
            String prefix = date > now ? "In" : "";
            String suffix = date <= now ? "ago" : "";
            TimeSpan span = date > now ? date - now : now - date;
            
            if (span.Days > 365)
            {
                int years = (span.Days / 365);
                if (span.Days % 365 != 0)
                    years += 1;
                return String.Format("{0} {1} {2} {3}", 
                    prefix,
                    years, 
                    years == 1 ? "year" : "years",
                    suffix).Trim();
            }
            
            if (span.Days > 30)
            {
                int months = (span.Days / 30);
                if (span.Days % 31 != 0)
                    months += 1;
                return String.Format("{0} {1} {2} {3}", 
                    prefix,
                    months,
                    months == 1 ? "month" : "months",
                    suffix).Trim();
            }
            
            if (span.Days > 0)
                return String.Format("{0} {1} {2} {3}", 
                    prefix,
                    span.Days, 
                    span.Days == 1 ? "day" : "days",
                    suffix).Trim();
            
            if (span.Hours > 0)
                return String.Format("{0} about {1} {2} {3}", 
                    prefix,
                    span.Hours, 
                    span.Hours == 1 ? "hour" : "hours",
                    suffix);
            
            if (span.Minutes > 0)
                return String.Format("{0} {1} {2} {3}",
                    prefix,
                    span.Minutes, 
                    span.Minutes == 1 ? "minute" : "minutes",
                    suffix).Trim();
            
            if (span.Seconds > 5)
                return String.Format("{0} {1} seconds {2}", 
                    prefix,
                    span.Seconds,
                    suffix).Trim();
            
            if (span.Seconds <= 5)
                return date > now
                    ? "Imminently" 
                    : "Just now";
            
            return string.Empty;
        }
        
        protected override string Convert(DateTime value, object? parameter = null)
        {
            return FormatTime(value);
        }
    }
}