distance_of_time_in_words.rb

def distance_of_time_in_words(from_time, to_time = 0, include_seconds_or_options = {}, options = {})
  if include_seconds_or_options.is_a?(Hash)
    options = include_seconds_or_options
  else
    ActiveSupport::Deprecation.warn "distance_of_time_in_words and time_ago_in_words now accept :include_seconds " +
                                    "as a part of options hash, not a boolean argument"
    options[:include_seconds] ||= !!include_seconds_or_options
  end

  options = {
    scope: :'datetime.distance_in_words'
  }.merge!(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)
  from_time, to_time = to_time, from_time if from_time > to_time
  distance_in_minutes = ((to_time - from_time)/60.0).round
  distance_in_seconds = (to_time - from_time).round

  I18n.with_options :locale => options[:locale], :scope => options[:scope] 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 options[: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...45           then locale.t :x_minutes,      :count => distance_in_minutes
      when 45...90          then locale.t :about_x_hours,  :count => 1
      # 90 mins up to 24 hours
      when 90...1440        then locale.t :about_x_hours,  :count => (distance_in_minutes.to_f / 60.0).round
      # 24 hours up to 42 hours
      when 1440...2520      then locale.t :x_days,         :count => 1
      # 42 hours up to 30 days
      when 2520...43200     then locale.t :x_days,         :count => (distance_in_minutes.to_f / 1440.0).round
      # 30 days up to 60 days
      when 43200...86400    then locale.t :about_x_months, :count => (distance_in_minutes.to_f / 43200.0).round
      # 60 days up to 365 days
      when 86400...525600   then locale.t :x_months,       :count => (distance_in_minutes.to_f / 43200.0).round
      else
        if from_time.acts_like?(:time) && to_time.acts_like?(:time)
          fyear = from_time.year
          fyear += 1 if from_time.month >= 3
          tyear = to_time.year
          tyear -= 1 if to_time.month < 3
          leap_years = (fyear > tyear) ? 0 : (fyear..tyear).count{|x| Date.leap?(x)}
          minute_offset_for_leap_year = leap_years * 1440
          # Discount the leap year days when calculating year distance.
          # e.g. if there are 20 leap year days between 2 dates having the same day
          # and month then the based on 365 days calculation
          # the distance in years will come out to over 80 years when in written
          # english it would read better as about 80 years.
          minutes_with_offset = distance_in_minutes - minute_offset_for_leap_year
        else
          minutes_with_offset = distance_in_minutes
        end
        remainder                   = (minutes_with_offset % 525600)
        distance_in_years           = (minutes_with_offset.div 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