#!/usr/bin/env ruby

class MegaGreeter
  attr_accessor :names

  def initialize(names = "World")
    @names = names
  end

  def say_hi
    if @names.nil?
      puts "..."
    elsif @names.respond_to?("each")
      @names.each do |name|
        puts "Hello #{name}!"
      end
    else
      puts "Hello #{@names}!"
    end
  end

  def say_bye
    if @names.nil?
      puts "..."
    elsif @names.respond_to?("join")
      puts "Goodbye #{@names.join(", ")}. Come back soon!"
    else
      puts "Goodbye #{@names}. Come back soon!"
    end
  end
end

if __FILE__ == $PROGRAM_NAME
  greeter = MegaGreeter.new
  greeter.say_hi
  greeter.say_bye

  greeter.names = "Zeke"
  greeter.say_hi
  greeter.say_bye

  greeter.names = ["Albert", "Brenda", "Charles", "Dave", "Engelbert"]
  greeter.say_hi
  greeter.say_bye

  greeter.names = nil
  greeter.say_hi
  greeter.say_bye
end