Find out wich hours are convenient for the meeting for different people working from the defferent timezones: `ruby convenient_hours.rb +2 +3 +8`

convenient_hours.rb

#! /usr/bin/env ruby

def format_time_zone(tz)
  format('%06.2f', tz.gsub(/:/, '.')).gsub(/^0/, '+').gsub(/\./, ':')
end

TIMEZONES = ARGV.map { |tz| format_time_zone(tz) }.freeze

WORKING_HOURS = (7..19).freeze

def build_time(hour, zone)
  Time.new(2019, 1, 1, hour, 0, 0, zone)
end

def working_hours?(time)
  WORKING_HOURS.include?(time.hour)
end

def check_for_convenient_hours(hour)
  initial_time = build_time(hour, TIMEZONES[0])
  convenient_for_all = true
  convenient_times = TIMEZONES.map do |tz|
    local_time = initial_time.dup.localtime(tz)
    is_convenient = working_hours?(local_time)
    convenient_for_all &= is_convenient

    [tz, local_time.hour]
  end

  convenient_times if convenient_for_all
end

def print_convenient_hours(convenient_hours)
  convenient_hours.reduce('') do |acc, (tz, hour)|
    acc << ' ' unless acc == ''
    acc << "[#{tz}]: #{format('%04.2f', hour)}"
  end
end

WORKING_HOURS.each do |hour|
  if convenient_hours = check_for_convenient_hours(hour)
    puts print_convenient_hours(convenient_hours)
  end
end