#!/usr/bin/ruby

require 'yaml'
require 'openssl'
require 'acme-client'
require 'dnsruby'
require 'time'


def read_config( path = 'config.yaml' )
  p "Reading config from #{path}"
  begin
    config = YAML.load_file( path )
  rescue Psych::SyntaxError
    $stderr.puts "Parsing configfile failed: " + $!.to_s
    raise
  rescue Errno::ENOENT
    $stderr.puts "IO failed: " + $!.to_s
    raise
  end
  return config
end

def read_account_key( path = 'pkey.pem' )
  p "Reading account key from #{path}"
  if File.readable?( path )
    p "File #{path} is readable, trying to parse"
    privatekey_string = File.read( path )
    private_key = OpenSSL::PKey::EC.new( privatekey_string )
  else
    if File.exists?( path )
      raise( "The file #{path} exists but is not readable. Make it readable or specify different path" )
    else
      p "File #{path} does not exist, trying to create"
      private_key = OpenSSL::PKey::EC.generate( "prime256v1" )
      File.write( path, private_key.private_to_pem )
    end
  end
  return private_key
end

def read_cert_key( domain )
  folder = "./certs/#{domain}/"
  path = "#{folder}/current.key"
  p "Reading cert key from #{path}"
  if File.readable?( path )
    p "File #{path} is readable, trying to parse"
    privatekey_string = File.read( path )
    private_key = OpenSSL::PKey::EC.new( privatekey_string )
  else
    if File.exists?( path )
      raise( "The file #{path} exists but is not readable. Make it readable or specify different path" )
    else
      p "File #{path} does not exist, trying to create"
      private_key = OpenSSL::PKey::EC.generate( "prime256v1" )
      pkey_file = File.new( folder + Time.now.to_i.to_s + ".key", 'w' )
      pkey_file.write( private_key.private_to_pem )
      File.symlink( File.basename( pkey_file ), File.dirname( pkey_file ) + "/current.key" )
    end
  end
  return private_key
end

def deploy_dns01_challenge_token( domain, challenge, nameserver, config )
  p 'Creating DNS UPDATE packet'
  update = Dnsruby::Update.new( domain )
  # TODO: delete challenge token record after validation
  update.delete( challenge.record_name + "." + domain, challenge.record_type )
  update.add( challenge.record_name + "." + domain, challenge.record_type, 10, challenge.record_content )

  p 'Creating object for contacting nameserver'
  res = Dnsruby::Resolver.new( nameserver )
  res.dnssec = false

  p 'Looking up TSIG parameters'
  tsig_name = config['domains'][domain]['tsig_key']
  tsig_key = config['tsig_keys'][tsig_name]['key']
  tsig_alg = config['tsig_keys'][tsig_name]['algorithm']

  p 'Creating TSIG object'
  tsig = Dnsruby::RR.create(
    {
      name: tsig_name,
      type: 'TSIG',
      key: tsig_key,
      algorithm: tsig_alg,
    }
  )

  p 'Signing DNS UPDATE packet with TSIG object'
  tsig.apply(update)

  p 'Sending UPDATE to nameserver'
  response = res.send_message(update)
end

def wait_for_challenge_propagation( domain, challenge )
  p 'Creating recursor object for checking challenge propagation'
  rec = Dnsruby::Recursor.new
  p "Getting NS records for #{domain}"
  domain_auth_ns = rec.query_no_validation_or_recursion( domain, "NS" )

  p 'Checking challenge status on all NS'
  domain_auth_ns.answer.each do |ns|
    nameserver = ns.rdata.to_s
    p "Creating resolver object for checking propagation on #{nameserver}"
    res = Dnsruby::Resolver.new( nameserver )
    res.dnssec = false
    res.do_caching = false
    begin
      p 'Querying ACME challenge record'
      result = res.query_no_validation_or_recursion( "_acme-challenge." + domain, "TXT" )
      p result
      propagated = result.answer.any? do |answer|
        answer.rdata[0] == challenge.record_content
      end
      unless propagated
        p 'Not yet propagated, sleeping before checking again'
        sleep(1)
      end
    end until propagated
  end
end

def wait_for_challenge_validation( challenge )
  p 'Requesting validation of challenge'
  challenge.request_validation

  while challenge.status == 'pending'
    p 'Sleeping because challenge validation is pending'
    sleep(1)
    p 'Checking again'
    challenge.reload
  end
end

def get_cert( order, domains, domain_key )
  path = "./certs/#{domains[0]}/"
  crt_file = "#{path}/cert.pem"
  p 'Creating CSR object'
  csr = Acme::Client::CertificateRequest.new(
    private_key: domain_key,
    names: domains,
    subject: { common_name: "#{domains[0]}" }
  )
  p 'Finalize cert order'
  order.finalize(csr: csr)
  while order.status == 'processing'
    p 'Sleep while order is processing'
    sleep(1)
    p 'Rechecking order status'
    order.reload
  end
  cert = order.certificate

  p 'Writing cert'
  cert_file = File.new( path + Time.now.to_i.to_s + ".crt", 'w' )
  cert_file.write( cert )
  if File.symlink?( File.dirname( cert_file ) + "/current.crt" )
    File.unlink( File.dirname( cert_file ) + "/current.crt" )
    File.symlink( File.basename( cert_file ), File.dirname( cert_file ) + "/current.crt" )
  else
    raise StandardError
  end
  return cert
end


config = read_config

# iterate over configured certs
# TODO: make this one thread per cert
config['certs'].each_pair do |cert_name, cert_opts|
  p "Finding CA to use for cert #{cert_name}"
  acme_directory_url = config['CAs'][cert_opts['ca']['name']]['directory_url']

  p "Finding account to use for cert #{cert_name} from CA #{cert_opts['ca']['name']}"
  account = config['ca_accounts'][cert_opts['ca']['account']]
  email = account['email']

  private_key = read_account_key( account['keyfile'] )

  p 'Creating client object for communication with CA'
  client = Acme::Client.new( private_key: private_key, directory: acme_directory_url )

  client.new_account(contact: "mailto:#{email}", terms_of_service_agreed: true)

  p "Creating order object for cert #{cert_name}"
  order = client.new_order(identifiers: cert_opts['domain_names'] )
  if order.status != 'ready'
    p 'Order is not ready, we need to authorize first'

    p 'Iterating over required authorizations'
    order.authorizations.each do |auth|
      p "Processing authorization for #{auth.domain}"
      p "Finding challenge type for #{auth.domain}"
      challenge = auth.dns01
      deploy_dns01_challenge_token( auth.domain, challenge, config['domains'][auth.domain]['primary_ns'], config )
      wait_for_challenge_propagation( auth.domain, challenge )
      wait_for_challenge_validation( challenge )
    end
  else
    p 'Order is ready, we don’t need to authorize'
  end
  domain_key = read_cert_key( cert_opts['domain_names'][0] )

  get_cert( order, cert_opts['domain_names'], domain_key )
end