A TimeOfDay class for leftylink on IRC

time_of_day.rb

# frozen_string_literal: true

class TimeOfDay
  include Comparable

  SEPARATOR = ':'
  HOURS_MATCH = /\A\d+/.freeze
  MINUTES_MATCH = /(?<=#{SEPARATOR})\d+/o.freeze

  attr_reader :hour
  attr_reader :minute

  def self.[](time)
    unless time.respond_to? :to_str
      raise TypeError, "no implicit conversion of #{time.class} into String"
    end

    time_str = time.to_str

    new hour: time_str[HOURS_MATCH].to_i, minute: time_str[MINUTES_MATCH].to_i
  end

  def initialize(hour:, minute:)
    @hour = hour
    @minute = minute

    freeze
  end

  def <=>(other)
    to_i <=> other.to_i
  end

  def to_s
    "#{hour}#{SEPARATOR}#{minute}"
  end

  def to_i
    @hour * 60 + @minute
  end

  def +(other)
    hours, minutes = (to_i + other).divmod(60)

    self.class.new hour: hours, minute: minutes
  end

  def -(other)
    hours, minutes = (to_i - other).divmod(60)

    self.class.new hour: hours, minute: minutes
  end

  def succ
    self + 1
  end
end

before = TimeOfDay['12:00']
#=> #<TimeOfDay:0x0000000114e43490 @hour=12, @minute=0>

after = TimeOfDay['12:05']
#=> #<TimeOfDay:0x0000000115305050 @hour=12, @minute=5>

before < after
#=> true

(before..after).count
#=> 6

before - 42
#=> #<TimeOfDay:0x00000001153435f8 @hour=11, @minute=18>