uuids.rb

#!/usr/bin/env ruby

require "optparse"
require "uuidtools"

DEFAULT_COUNT = 20
RANDOM_FUNC = -> { $options[:count].times { puts UUIDTools::UUID.random_create } }

$options = {
  count: DEFAULT_COUNT,
  func: RANDOM_FUNC,
  namespace: UUIDTools::UUID_X500_NAMESPACE
}

OptionParser.new do |opts|
  opts.banner = "Generates various UUIDs using SecureRandom and UUIDTools modules."
  opts.separator "Usage:
    #{opts.program_name} [options] [count]
Examples:
    uuids             Generates #{DEFAULT_COUNT} random UUIDs
    uuids N           Generates N random UUIDs
    uuids -t N        Generates N timestamp UUIDs
    uuids -m STRING   Generates MD5 hash for STRING as UUID
    uuids -s STRING   Generates SHA1 hash for STRING as UUID
Options:
"
  opts.on("-m", "--md5 NAME", "Generate UUID using MD5 hash (version 3)") do |something|
    $options[:func] = -> { puts UUIDTools::UUID.md5_create($options[:namespace], something) }
  end
  opts.on("-n", "--namespace name-or-uuid", "Specify DNS, OID, URL, X500 (default), or custom UUID namespace") do |something|
    $options[:namespace] = case something.downcase
      when "d", "dns"
        UUIDTools::UUID_DNS_NAMESPACE
      when "o", "oid"
        UUIDTools::UUID_OID_NAMESPACE
      when "u", "url"
        UUIDTools::UUID_URL_NAMESPACE
      when "x", "x500"
        UUIDTools::UUID_X500_NAMESPACE
      else
        begin
          UUIDTools::UUID.parse(something)
        rescue ArgumentError
          puts "\"#{something}\" is not a valid UUID string suitable for use as custom namespace"
          exit
        end
      end
  end
  opts.on("-r", "--random [count]", "Generate some random UUIDs (default: #{DEFAULT_COUNT})") do |count|
    $options[:count] = count.to_i if count
    $options[:func] = RANDOM_FUNC
  end
  opts.on("-s", "--sha1 NAME", "Generate UUID using SHA1 hash") do |something|
    $options[:func] = -> { puts UUIDTools::UUID.sha1_create($options[:namespace], something) }
  end
  opts.on("-t", "--timestamp [count]", "Generate some timestamp-based UUIDs (default: #{DEFAULT_COUNT})") do |count|
    $options[:count] = count.to_i if count
    $options[:func] = -> { $options[:count].times { puts UUIDTools::UUID.timestamp_create } }
  end
end.parse!

# If we are generating random UUIDs and some argument is present, then convert it to a number, and we will then
# generate as many random UUIDs as is specified
$options[:count] = ARGV.first.to_i if !ARGV.empty? && $options[:func] == RANDOM_FUNC

# Genrate UUID(s)
$options[:func].call