module Padrino::Helpers::FormatHelpers

distance_of_time_in_words(Time.now, Time.now) # => less than a minute
distance_of_time_in_words(to_time, from_time, true) # => about 6 years
distance_of_time_in_words(from_time, to_time, true) # => about 6 years
to_time = Time.now + 6.years + 19.days

distance_of_time_in_words(from_time, from_time + 4.years + 9.days + 30.minutes + 5.seconds) # => about 4 years
distance_of_time_in_words(from_time, from_time + 3.years + 6.months) # => over 3 years
distance_of_time_in_words(from_time, from_time + 1.year + 3.days) # => about 1 year
distance_of_time_in_words(from_time, 76.seconds.from_now) # => 1 minute
distance_of_time_in_words(from_time, from_time - 45.seconds, true) # => less than a minute
distance_of_time_in_words(from_time, from_time + 45.seconds, true) # => less than a minute
distance_of_time_in_words(from_time, from_time + 60.hours) # => about 3 days
distance_of_time_in_words(from_time, 3.years.from_now) # => about 3 years
distance_of_time_in_words(from_time, from_time + 15.seconds, true) # => less than 20 seconds
distance_of_time_in_words(from_time, from_time + 15.seconds) # => less than a minute
distance_of_time_in_words(from_time, 50.minutes.from_now) # => about 1 hour
distance_of_time_in_words(from_time, from_time + 50.minutes) # => about 1 hour
from_time = Time.now

==== Examples

60-89 secs # => 1 minute
40-59 secs # => less than a minute
20-39 secs # => half a minute
10-19 secs # => less than 20 seconds
5-9 secs # => less than 10 seconds
0-4 secs # => less than 5 seconds
With include_seconds = true and the difference < 1 minute 29 seconds:

2 yrs <-> max time or date # => (same rules as 1 yr)
1 yr, 9 months <-> 2 yr minus 1 sec # => almost 2 years
1 yr, 3 months <-> 1 yr, 9 months # => over 1 year
1 yr <-> 1 yr, 3 months # => about 1 year
59 days, 23 hrs, 59 mins, 30 secs <-> 1 yr minus 1 sec # => [2..12] months
29 days, 23 hrs, 59 mins, 30 secs <-> 59 days, 23 hrs, 59 mins, 29 secs # => about 1 month
47 hrs, 59 mins, 29 secs <-> 29 days, 23 hrs, 59 mins, 29 secs # => [2..29] days
23 hrs, 59 mins, 29 secs <-> 47 hrs, 59 mins, 29 secs # => 1 day
89 mins, 29 secs <-> 23 hrs, 59 mins, 29 secs # => about [2..24] hours
44 mins, 30 secs <-> 89 mins, 29 secs # => about 1 hour
1 min, 30 secs <-> 44 mins, 29 secs # => [2..44] minutes
30 secs <-> 1 min, 29 secs # => 1 minute
0 <-> 29 secs # => less than a minute

Distances are reported based on the following table:
Set include_seconds to true if you want more detailed approximations when distance < 1 min, 29 secs
Reports the approximate distance in time between two Time or Date objects or integers as seconds.
#

def distance_of_time_in_words(from_time, to_time = 0, include_seconds = false, options = {})
  from_time = from_time.to_time if from_time.respond_to?(:to_time)
  to_time = to_time.to_time if to_time.respond_to?(:to_time)
  distance_in_minutes = (((to_time - from_time).abs)/60).round
  distance_in_seconds = ((to_time - from_time).abs).round
  I18n.with_options :locale => options[:locale], :scope => :'datetime.distance_in_words' do |locale|
    case distance_in_minutes
      when 0..1
        return distance_in_minutes == 0 ?
               locale.t(:less_than_x_minutes, :count => 1) :
               locale.t(:x_minutes, :count => distance_in_minutes) unless include_seconds
        case distance_in_seconds
          when 0..4   then locale.t :less_than_x_seconds, :count => 5
          when 5..9   then locale.t :less_than_x_seconds, :count => 10
          when 10..19 then locale.t :less_than_x_seconds, :count => 20
          when 20..39 then locale.t :half_a_minute
          when 40..59 then locale.t :less_than_x_minutes, :count => 1
          else             locale.t :x_minutes,           :count => 1
        end
      when 2..44           then locale.t :x_minutes,      :count => distance_in_minutes
      when 45..89          then locale.t :about_x_hours,  :count => 1
      when 90..1439        then locale.t :about_x_hours,  :count => (distance_in_minutes.to_f / 60.0).round
      when 1440..2529      then locale.t :x_days,         :count => 1
      when 2530..43199     then locale.t :x_days,         :count => (distance_in_minutes.to_f / 1440.0).round
      when 43200..86399    then locale.t :about_x_months, :count => 1
      when 86400..525599   then locale.t :x_months,       :count => (distance_in_minutes.to_f / 43200.0).round
      else
        distance_in_years           = distance_in_minutes / 525600
        minute_offset_for_leap_year = (distance_in_years / 4) * 1440
        remainder                   = ((distance_in_minutes - minute_offset_for_leap_year) % 525600)
        if remainder < 131400
          locale.t(:about_x_years,  :count => distance_in_years)
        elsif remainder < 394200
          locale.t(:over_x_years,   :count => distance_in_years)
        else
          locale.t(:almost_x_years, :count => distance_in_years + 1)
        end
    end
  end
end