Date converter utility for things that want shitty Unix timestamps

dt.rb

#!/usr/bin/ruby

# This program converts dates (from a semi-memorable, short format similar to the standard `date` utility).
# It will output them as unix timestamps (it will also accept ISO dates for this conversion).
# Or, it can output them in ISO8601, but this will always be in UTC because timezones are pointless.

require 'date'

class Usage < StandardError
end

Debug = false
Full = ARGV.delete('-d') or ARGV.delete('--date')

def date
	y=mo=d=h=mi=s=nil
	raise Usage unless ARGV.length == 1
	i = ARGV[0]
	more, s = i.split ?.

	if more.match /\A[\d-]+T[\d:]+(Z|\+.*)\Z/
		return more  # Already an ISO date
	end
	raise Usage unless more.length % 2 == 0

	now = DateTime.now.new_offset(0)

	more = more.scan /../

	case more.length
	when 1
		h, = more
	when 2
		h, mi = more
	when 3
		d, h, mi = more
	when 4
		mo, d, h, mi = more
	when 5
		mo, d, h, mi, _y = more
		y = now.year - (now.year % 100) + _y.to_i
	when 6
		mo, d, h, mi, _c, _y = more
		y = _c.to_i * 100 + _y.to_i
	else
		raise Usage
	end

	Debug and p y, mo, d, h, mi, s
	y ||= now.year
	mo ||= now.month
	d ||= now.day
	mi ||= '00'
	s ||= '00'
	
	Debug and puts
	Debug and p y, mo, d, h, mi, s
	return "#{y}-#{mo}-#{d}T#{h}:#{mi}:#{s}Z"

rescue Usage
	$stderr.puts "Usage: #{$0} [-d|--date] [[MM]DD]hhmm[[CC]YY][.ss]"
	$stderr.puts
	$stderr.puts "  --date: Print UTC (Z) ISO date string instead of timestamp"
	exit 1
end

if Full
	puts DateTime.parse(date).new_offset(0).iso8601.sub('+00:00','Z')
else
	puts DateTime.parse(date).to_time.to_i
end