#!/usr/bin/env ruby
require 'net/http'
require 'netaddr'
require 'json'
require 'pathname'

LXC_ROOT = Pathname.new("/etc/lxc")
CONTAINER_DATA = LXC_ROOT.join("container.json")

class Hetzner
  BASE_URI = URI("https://robot-ws.your-server.de")
  def initialize(user, password)
    @user = user
    @password = password
  end

  def get(path)
    resp = perform_request(Net::HTTP::Get.new(uri_for(path)))
    JSON.parse(resp.body)
  end

  def post(path, params={})
    req = Net::HTTP::Post.new(uri_for(path))
    req.set_form_data(params)
    resp = perform_request(req)
    JSON.parse(resp.body)
  end

  def put(path, params={})
    req = Net::HTTP::Put.new(uri_for(path))
    req.set_form_data(params)
    resp = perform_request(req)
    JSON.parse(resp.body)
  end

  def delete(path)
    perform_request(Net::HTTP::Delete.new(uri_for(path)))
  end

private
  def uri_for(path)
    u = BASE_URI.clone
    u.path = path
    u
  end

  def perform_request(req)
    req.basic_auth(@user, @password)
    resp = Net::HTTP.start(BASE_URI.hostname,
                           BASE_URI.port,
                           use_ssl: true) do |http|
      http.request(req)
    end
    if resp.code.start_with? "2"
      return resp
    else
      raise StandardError.new("failed to perform request: #{resp.inspect}")
    end
  end
end
def update_hetzner_rdns6(user, password, json)
  api = Hetzner.new(user, password)
  rdns = api.get("/rdns")
  records = {}
  rdns.each do |val|
    rec = val["rdns"]
    cidr = NetAddr::CIDR.create(rec["ip"])
    next if cidr.version == 4
    records[cidr.ip] = rec["ptr"]
  end
  json["network"].each do |host, data|
    cidr = data["ipv6"]
    next if cidr.nil?
    ipv6 = NetAddr::CIDR.create(cidr).ip
    hostname = data["rdns6"] || "#{host}.higgsboson.tk"
    ptr = records.delete(ipv6)
    if ptr.nil? or ptr != hostname
      api.post("/rdns/#{ipv6}", ptr: hostname)
    end
  end
  records.each do |ip, ptr|
    api.delete("/rnds/#{ip}")
  end
end

credentials = File.read("/etc/lxc/hetzner.key")
json = JSON.load(File.open(CONTAINER_DATA))
user, password = credentials.split(":")
update_hetzner_rdns6(user, password, json)
puts("ok")