# erfordert Ruby 1.9

require "csv"
require "fileutils"
require "set"

csv_file = ARGV.first
raise "specify a user CSV" if csv_file.nil?

raise "must be run as root" unless Process.uid == 0

def invalid_login?(login)
  return false if login =~ /^[a-z0-9]+$/
  warn "invalid login: #{login.inspect}"
  true
end

$existing_logins = CSV.readlines("/etc/passwd", :col_sep => ":").map(&:first).to_set
def existing_login?(login)
  return false unless $existing_logins.include?(login)
  warn "existing login: #{login.inspect}"
  true
end

new_users = CSV.readlines(csv_file).reject { |(login, _, _)| invalid_login?(login) or existing_login?(login) }

exit 0 if new_users.empty?

lines_by_file_name = {"passwd" => [], "group" => [], "shadow" => []}

new_users.each_with_index do |(login, lastname, firstname), i|
  uid = i + 1001
  lines_by_file_name["passwd"] << [login, "x", uid, uid, "#{lastname}, #{firstname}", "/bin/bash"].join(":")
  lines_by_file_name["group"]  << [login, "x", uid, login].join(":")
  lines_by_file_name["shadow"] << [login, "!", "", "", "", "", "", "", ""].join(":")
end

lines_by_file_name.each do |file_name, lines|
  File.open("/etc/#{file_name}", "a") { |f| f.puts lines }
end

new_users.each do |(login, _, _)|
  home_dir = "/home/#{login}"
  FileUtils.mkdir_p(home_dir, :mode => 0700)
  FileUtils.cp_r("/etc/skel/.", home_dir)
end