require 'net/http'
require 'uri'
require 'nokogiri'

URL = 'http://www.fos.kuis.kyoto-u.ac.jp/~igarashi/CoPL/index.cgi'

DEFAULT_FORM_DATA = {
  command: 'answer',
  no: 0
}

DEFAULT_GAME = 'Nat'

def post_sandbox(user, derivation, game = DEFAULT_GAME)
  uri = URI.parse(URL)
  req = Net::HTTP::Post.new(uri.request_uri)
  req.add_field('Cookie', "loginas=#{user};")
  form_data = DEFAULT_FORM_DATA.merge(game: game, derivation: derivation)
  req.set_form_data(form_data)
  Net::HTTP.new(uri.host).request(req)
end

def parse_result(html)
  doc = Nokogiri::HTML.parse(html)
  {
    title: doc.at_css('h1')&.inner_text&.strip,
    message: doc.at_css('#main > pre')&.inner_text&.strip
  }
end

def main
  raise("usage: #{$0} user derivation_path [game]") if ARGV.size < 2
  user, derivation_path, game = ARGV
  game ||= DEFAULT_GAME

  derivation = File.open(derivation_path, &:read)
  res = post_sandbox(user, derivation, game)
  raise res.code unless res.is_a? Net::HTTPOK

  puts parse_result(res.body).values.join("\n")
end

if __FILE__ == $0
  main
end