module DurationHelper

  # Takes a number of seconds as input and returns a formatted string. See
  # tests for examples.
  def format_duration(seconds, options = {})
    return "0 seconds" if seconds.floor == 0
    options.reverse_merge!(:parts_to_show => 4, :word_style => :short, :specific_end => false)

    description = (options[:word_style] == :short) ?
                    [ ['sec',    60], ['min',    60], ['hr',   24], ['day'] ] :
                    [ ['second', 60], ['minute', 60], ['hour', 24], ['day'] ]

    components = []
    units = seconds.floor
    description.each do |component, max|
      if max
        components.unshift([units % max, component])
        break unless units >= max
        units = units.to_f / max
      else
        components.unshift([units, component])
      end
    end

    parts_shown = 0
    results = components.map do |c|
      next if parts_shown >= options[:parts_to_show]
      parts_shown += 1
      number = c.first
      if options[:specific_end].present? && parts_shown == options[:parts_to_show] && c.last =~ /^(hr|hour|day)/
        number = number.round_at(1).to_i_if_whole
      else
        number = number.floor
      end
      next if number == 0
      "#{number} #{number == 1 ? c.last : c.last.pluralize}"
    end
    results.compact.join(' ')
  end

end