# frozen_string_literal: true

require_relative 'duration/iso8601_parser'

module FacultyHelpers
  # Helpers to handle Postgres Intervals in ruby.
  # This will only work with dates, since that is all that is required right now.
  # This is a much simplified version of how rails handles durations - I'm sure there are some edge cases that are
  # not handled here. But this should be enough for us to use date durations without including the whole of
  # activesupport.
  class Duration
    def self.parse(string)
      new(Duration::ISO8601Parser.new(string).parse!)
    end

    def initialize(parts)
      @parts = parts
    end

    def -@
      Duration.new(@parts.transform_values(&:-@))
    end

    def add_to(date)
      date >>= (@parts[:years] * 12) if @parts[:years]
      date >>= @parts[:months] if @parts[:months]
      date += @parts[:weeks] * 7 if @parts[:weeks]
      date += @parts[:days] if @parts[:days]

      date
    end

    def subtract_from(date)
      (-self).add_to(date)
    end
  end
end