require 'active_support/core_ext/object/blank' require 'active_support/core_ext/hash/transform_values' module ActiveSupport class Duration # Serializes duration to string according to ISO 8601 Duration format. class ISO8601Serializer def initialize(duration, precision: nil) @duration = duration @precision = precision end # Builds and returns output string. def serialize output = 'P' parts, sign = normalize output << "#{parts[:years]}Y" if parts.key?(:years) output << "#{parts[:months]}M" if parts.key?(:months) output << "#{parts[:weeks]}W" if parts.key?(:weeks) output << "#{parts[:days]}D" if parts.key?(:days) time = '' time << "#{parts[:hours]}H" if parts.key?(:hours) time << "#{parts[:minutes]}M" if parts.key?(:minutes) if parts.key?(:seconds) time << "#{sprintf(@precision ? "%0.0#{@precision}f" : '%g', parts[:seconds])}S" end output << "T#{time}" if time.present? "#{sign}#{output}" end private # Return pair of duration's parts and whole duration sign. # Parts are summarized (as they can become repetitive due to addition, etc). # Zero parts are removed as not significant. # If all parts are negative it will negate all of them and return minus as a sign. def normalize parts = @duration.parts.each_with_object(Hash.new(0)) do |(k,v),p| p[k] += v unless v.zero? end # If all parts are negative - let's make a negative duration sign = '' if parts.values.all? { |v| v < 0 } sign = '-' parts.transform_values!(&:-@) end [parts, sign] end end end end