#!/usr/bin/env ruby

require 'rubygems'
require 'pp'
require 'arvados'
require 'etc'
require 'fileutils'
require 'yaml'

req_envs = %w(ARVADOS_API_HOST ARVADOS_API_TOKEN ARVADOS_VIRTUAL_MACHINE_UUID)
req_envs.each do |k|
  unless ENV[k]
    abort "Fatal: These environment vars must be set: #{req_envs}"
  end
end

exclusive_mode = ARGV.index("--exclusive")
exclusive_banner = "#######################################################################################
#  THIS FILE IS MANAGED BY #{$0} -- CHANGES WILL BE OVERWRITTEN  #
#######################################################################################\n\n"
start_banner = "### BEGIN Arvados-managed keys -- changes between markers will be overwritten\n"
end_banner = "### END Arvados-managed keys -- changes between markers will be overwritten\n"

keys = ''

seen = Hash.new

begin
  uids = Hash[Etc.to_enum(:passwd).map { |ent| [ent.name, ent.uid] }]
  gids = Hash[Etc.to_enum(:group).map { |ent| [ent.name, ent.gid] }]
  arv = Arvados.new({ :suppress_ssl_warnings => false })

  vm_uuid = ENV['ARVADOS_VIRTUAL_MACHINE_UUID']

  logins = arv.virtual_machine.logins(:uuid => vm_uuid)[:items]
  logins = [] if logins.nil?
  logins = logins.reject { |l| l[:username].nil? or l[:hostname].nil? or l[:public_key].nil? or l[:virtual_machine_uuid] != vm_uuid }

  # No system users
  uid_min = 1000
  open("/etc/login.defs", encoding: "utf-8") do |login_defs|
    login_defs.each_line do |line|
      next unless match = /^UID_MIN\s+(\S+)$/.match(line)
      if match[1].start_with?("0x")
        base = 16
      elsif match[1].start_with?("0")
        base = 8
      else
        base = 10
      end
      new_uid_min = match[1].to_i(base)
      uid_min = new_uid_min if (new_uid_min > 0)
    end
  end
  logins.reject! { |l| (uids[l[:username]] || 65535) < uid_min }

  keys = Hash.new()

  # Collect all keys
  logins.each do |l|
    keys[l[:username]] = Array.new() if not keys.has_key?(l[:username])
    key = l[:public_key]
    # Handle putty-style ssh public keys
    key.sub!(/^(Comment: "r[^\n]*\n)(.*)$/m,'ssh-rsa \2 \1')
    key.sub!(/^(Comment: "d[^\n]*\n)(.*)$/m,'ssh-dss \2 \1')
    key.gsub!(/\n/,'')
    key.strip

    keys[l[:username]].push(key) if not keys[l[:username]].include?(key)
  end

  seen = Hash.new()
  devnull = open("/dev/null", "w")

  logins.each do |l|
    next if seen[l[:username]]
    seen[l[:username]] = true if not seen.has_key?(l[:username])

    unless uids[l[:username]]
      STDERR.puts "Creating account #{l[:username]}"
      groups = l[:groups] || []
      # Adding users to the FUSE group has long been hardcoded behavior.
      groups << "fuse"
      groups.select! { |name| gids[name] }
      # Create new user
      next unless system("useradd", "-m",
                         "-c", l[:username],
                         "-s", "/bin/bash",
                         "-G", groups.join(","),
                         l[:username],
                         out: devnull)
    end
    # Create .ssh directory if necessary
    @homedir = Etc.getpwnam(l[:username]).dir
    userdotssh = File.join(@homedir, ".ssh")
    Dir.mkdir(userdotssh) if !File.exists?(userdotssh)
    newkeys = keys[l[:username]].join("\n") + "\n"
    keysfile = File.join(userdotssh, "authorized_keys")

    if File.exists?(keysfile)
      oldkeys = IO::read(keysfile)
    else
      oldkeys = ""
    end

    if exclusive_mode
      newkeys = exclusive_banner + newkeys
    elsif oldkeys.start_with?(exclusive_banner)
      newkeys = start_banner + newkeys + end_banner
    elsif (m = /^(.*?\n|)#{start_banner}(.*?\n|)#{end_banner}(.*)/m.match(oldkeys))
      newkeys = m[1] + start_banner + newkeys + end_banner + m[3]
    else
      newkeys = start_banner + newkeys + end_banner + oldkeys
    end

    if oldkeys != newkeys then
      f = File.new(keysfile, 'w')
      f.write(newkeys)
      f.close()
    end
    FileUtils.chown_R(l[:username], nil, userdotssh)
    File.chmod(0700, userdotssh)
    File.chmod(0750, @homedir)
    File.chmod(0600, keysfile)
  end

  devnull.close
rescue Exception => bang
  puts "Error: " + bang.to_s
  puts bang.backtrace.join("\n")
  exit 1
end