Classe de exemplo para determinar se um estabelecimento está aberto no momento

sample.rb

class Sample
  HOURS = {
    'mon' => [],
    'tue' => [
      ['09:00', '19:00'],
    ],
    'wed' => [
      ['09:00', '19:00'],
    ],
    'thu' => [
      ['09:00', '19:00'],
    ],
    'fri' => [
      ['13:00', '19:00'],
    ],
    'sat' => [
      ['09:00', '15:00'],
      ['17:00', '20:30'],
    ],
    'sun' => [
      ['09:00', '15:00'],
    ],
  }

  def self.open?(datetime)
    weekday = datetime.strftime('%a').downcase
    hour = datetime.strftime('%H:%M')

    ranges = HOURS[weekday].map { |item| Range.new(item.first, item.last) }
    ranges.any? { |item| item.cover?(hour) }
  end
end

Output

irb(main):075:0> Sample.open? Time.new(2018, 12, 31, 14)
=> false
irb(main):076:0> Sample.open? Time.new(2019, 1, 5, 17, 01, 0)
=> true
irb(main):077:0> Sample.open? Time.new(2019, 1, 5, 20, 31, 0)
=> false
irb(main):078:0> Sample.open? Time.now
=> true