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

namespace Helpers
{
  public class DateHelper
  {
    public static string TimeAgoInWords(DateTime fromTime)
    {
      return DistanceOfTimeInWords(fromTime, DateTime.Now);
    }

    public static string TimeAgoInWords(DateTime fromTime, bool includeSeconds)
    {
      return DistanceOfTimeInWords(fromTime, DateTime.Now, includeSeconds);
    }

    public static string DistanceOfTimeInWords(DateTime fromTime, DateTime toTime)
    {
      return DistanceOfTimeInWords(fromTime, toTime, false);
    }

    public static string DistanceOfTimeInWords(DateTime fromTime, DateTime toTime, bool includeSeconds)
    {
      TimeSpan ts = (toTime - fromTime).Duration();
      int distanceInMinutes = (int)ts.TotalMinutes;
      int distanceInSeconds = (int)ts.TotalSeconds;

      string inWords = string.Empty;

      if (distanceInMinutes <= 1)
      {
        if (includeSeconds)
        {
          if (InRange(0, 4, distanceInSeconds)) { inWords = Resources.LessThanFiveSeconds; }
          else if (InRange(5, 9, distanceInSeconds)) { inWords = Resources.LessThanTenSeconds; }
          else if (InRange(10, 19, distanceInSeconds)) { inWords = Resources.LessThanTwentySeconds; }
          else if (InRange(20, 39, distanceInSeconds)) { inWords = Resources.HalfAMinute; }
          else if (InRange(40, 59, distanceInSeconds)) { inWords = Resources.LessThanAMinute; }
          else { inWords = Resources.OneMinute; }
        }
        else
        {
          inWords = distanceInMinutes == 0 ? Resources.LessThanAMinute : Resources.OneMinute;
        }
      }
      else
      {
        if (InRange(2, 44, distanceInMinutes)) { inWords = string.Format(Resources.MultipleMinutes, distanceInMinutes); }
        else if (InRange(45, 89, distanceInMinutes)) { inWords = Resources.AboutOneHour; }
        else if (InRange(90, 1439, distanceInMinutes)) 
        { 
          inWords = string.Format(Resources.AboutMultipleHours, RoundedDistance(distanceInMinutes, 60)); 
        }
        else if (InRange(1440, 2879, distanceInMinutes)) { inWords = Resources.OneDay; }
        else if (InRange(2880, 43199, distanceInMinutes)) { inWords = string.Format(Resources.MultipleDays, RoundedDistance(distanceInMinutes, 1440)); }
        else if (InRange(43200, 86399, distanceInMinutes)) { inWords = Resources.AboutOneMonth; }
        else if (InRange(86400, 525599, distanceInMinutes)) { inWords = string.Format(Resources.MultipleMonths, RoundedDistance(distanceInMinutes, 43200)); }
        else if (InRange(525600, 1051199, distanceInMinutes)) { inWords = Resources.AboutOneYear; }
        else { inWords = string.Format(Resources.MultipleYears, RoundedDistance(distanceInMinutes, 525600)); }
      }

      return inWords;
    }

    private static int RoundedDistance(int value, double dividedBy)
    {
      return (int)decimal.Round(Convert.ToDecimal(value / dividedBy), MidpointRounding.AwayFromZero);
    }

    private static bool InRange(int low, int high, int value)
    {
      return (value >= low && value <= high);
    }

  }
}