#!/usr/bin/env ruby

require 'cgi'

cgi = CGI::new

collection = cgi.params.fetch('collection', 'abt')
number = cgi.params.fetch('episode', 1)

if number.kind_of?(Array) then
  number = number[0]
end

if number < 100 then
  number = "%02d" % [number]
else
  number = "%03d" % [number]
end

def get_episode(coll, num)
  collection_templates = {
    'abt' => '%s.???',
    'iwtbf' => 'iwtbf-%s.PNG'
  }

  Dir[collection_templates[coll] % [num]][0]
end

puts get_episode(collection, number)