#!/usr/bin/ruby

# frozen_string_literal: true

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


def read_config(path = 'config.yaml')
  p "Reading config from #{path}"
  YAML.load_file(path)
rescue Psych::SyntaxError => e
  warn "Parsing configfile failed: #{e}"
  raise
rescue Errno::ENOENT => e
  warn "IO failed: #{e}"
  raise
end

def ensure_cert_dir(path = './certs')
  unless File.exist?(path)
    puts 'Certificate directory does not exist. Creating with secure permissions.'
    Dir.mkdir(path, 0o0700)
  end
  File.world_writable?(path) && warn('WARNING! Certificate directory is world writable! This could be a serious security issue!')
  File.world_readable?(path) && warn('WARNING! Certificate directory is world readable! This could be a serious security issue!')
  File.file?(path) && raise('Certificate directory is not a directory but a file. Aborting.')
  File.writable?(path) || raise('Certificate directory is not writable. Aborting.')
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)
  elsif File.exist?(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
  return private_key
end

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

def lookup_ns(domain)
  p "Domain #{domain}: Creating recursor object for checking challenge propagation"
  rec = Dnsruby::Resolver.new
  p "Domain #{domain}: Getting NS records for #{domain}"
  rec.query_no_validation_or_recursion(domain, 'NS')
rescue StandardError => e
  warn "Domain #{domain}: NS lookup during deploy failed: #{e}"
  raise
end

def lookup_soa(domain)
  rec = Dnsruby::Resolver.new
  p "Domain #{domain}: Getting SOA records for #{domain}"
  rec.query_no_validation_or_recursion(domain, 'SOA')
rescue StandardError => e
  warn "Domain #{domain}: SOA lookup during deploy failed: #{e}"
  raise
end

def find_apex_domain(domain)
  domain_soa_resp = lookup_soa(domain)
  if domain_soa_resp.answer.empty?
    domain_soa_resp.authority[0].name
  else
    domain_soa_resp.answer[0].name
  end
end

def build_dns_update_packet(apex, authzs)
  update = Dnsruby::Update.new(apex)

  authzs.each do |auth|
    chal = auth.dns01
    update.delete("#{chal.record_name}.#{auth.domain}", chal.record_type)
    update.add("#{chal.record_name}.#{auth.domain}", chal.record_type, 3, chal.record_content)
  end
  return update
end

def build_tsig_object(apex, config)
  p "Domain #{apex}: Looking up TSIG parameters"
  tsig_name = config.dig('domains', apex, 'tsig_key') || config.dig('defaults', 'domains', 'tsig_key')
  tsig_key = config.dig('tsig_keys', tsig_name, 'key')
  tsig_alg = config.dig('tsig_keys', tsig_name, 'algorithm')

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

def deploy_dns_tokens_on_apex(apex, authzs, nameserver, config)
  update_packet = build_dns_update_packet(apex, authzs)

  p "Domain #{apex}: Creating object for contacting nameserver"
  res = Dnsruby::Resolver.new(nameserver)
  res.dnssec = false

  tsig = build_tsig_object(apex, config)

  p "Domain #{apex}: Signing DNS UPDATE packet with TSIG object"
  tsig.apply(update_packet)

  p "Domain #{apex}: Sending UPDATE to nameserver"
  res.send_message(update_packet)
rescue StandardError => e
  warn "Domain #{apex}: DNS Update failed: #{e}"
  raise
end

def deploy_dns01_challenge_token(domain, challenge, nameserver, config)
  p "Domain #{domain}: Creating DNS UPDATE packet"

  apex_domain = find_apex_domain(domain)

  update = Dnsruby::Update.new(apex_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 "Domain #{domain}: Creating object for contacting nameserver"
  res = Dnsruby::Resolver.new(nameserver)
  res.dnssec = false

  tsig = build_tsig_object(domain, config)

  p "Domain #{domain}: Signing DNS UPDATE packet with TSIG object"
  tsig.apply(update)

  p "Domain #{domain}: Sending UPDATE to nameserver"
  res.send_message(update)
rescue StandardError => e
  warn "Domain #{domain}: DNS Update failed: #{e}"
  raise
end

def wait_for_challenge_propagation(domain, challenge)
  apex_domain = find_apex_domain(domain)
  domain_auth_ns = lookup_ns(apex_domain)

  p "Domain #{domain}: Checking challenge status on all NS"

  threads = []

  domain_auth_ns.answer.each do |ns|
    threads << Thread.new(ns) do |my_ns|
      nameserver = my_ns.rdata.to_s
      p "Domain #{domain}: Creating resolver object for checking propagation on #{nameserver}"
      res = Dnsruby::Resolver.new(nameserver)
      res.dnssec = false
      res.do_caching = false
      loop do
        p "Domain #{domain}: Querying ACME challenge record"
        result = res.query_no_validation_or_recursion("_acme-challenge.#{domain}", 'TXT')
        propagated = result.answer.any? do |answer|
          answer.rdata[0] == challenge.record_content
        end
        break if propagated

        p "Domain #{domain}: Not yet propagated, still old value, sleeping before checking again"
        sleep(0.5)
      rescue Dnsruby::NXDomain
        p "Domain #{domain}: Not yet propagated, NXdomain, sleeping before checking again"
        sleep(0.5)
        retry
      rescue StandardError => e
        warn "Domain #{domain}: ACME challenge lookup failed: #{e}"
        raise
      end
    end
  end

  threads.each(&:join)
end

def acme_request_with_retries(retries: 10, &block)
  # p "Retries: #{retries}"
  block.call(self)
rescue Acme::Client::Error::BadNonce
  raise unless retries.positive?

  p 'Retrying because of invalid nonce.'
  acme_request_with_retries(retries: retries - 1, &block)
end

def unvalidated_domains(d_a)
  d_a.select do |d, a|
    p "#{d} status #{a['auth'].dns01.status}"
    p a['auth'].dns01.status
    acme_request_with_retries { a['auth'].dns01.reload }
    a['auth'].dns01.status != 'valid'
  end
end

def wait_for_challenge_validation(challenge, cert_name)
  p 'Requesting validation of challenge'
  p challenge.object_id
  acme_request_with_retries { challenge.request_validation }

  while challenge.status == 'pending'
    p "Cert #{cert_name}: challenge validation is pending, sleeping before checking again"
    sleep(0.1)
    acme_request_with_retries { challenge.reload }
  end
  # pp challenge
end

def get_cert(order, cert_name, domains, domain_key)
  path = "./certs/#{cert_name}/"
  crt_file = "#{path}/cert.pem"
  p "Cert #{cert_name}: Creating CSR object"
  csr = Acme::Client::CertificateRequest.new(
    private_key: domain_key,
    names: domains,
    subject: { common_name: domains[0] }
  )
  p "Cert #{cert_name}: Finalize cert order"
  # pp order
  # TODO: this seems unnecessary?
  # acme_request_with_retries { order.reload }
  acme_request_with_retries { order.finalize(csr: csr) }
  while order.status == 'processing'
    p "Cert #{cert_name}: Sleep while order is processing"
    sleep(0.1)
    p "Cert #{cert_name}: Rechecking order status"
    acme_request_with_retries { order.reload }
  end
  # p "order status: #{order.status}"
  # pp order
  cert = acme_request_with_retries { order.certificate }

  p "Cert #{cert_name}: Writing cert"
  cert_file = File.new("#{path}#{Time.now.to_i}.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")
  elsif File.file?("#{File.dirname(cert_file)}/current.crt")
    raise 'Could not place symlink for "current.crt" because that is already a normal file.'
  end
  return cert
end

def find_ca_for_cert(cert_name, cert_opts, config)
  cert_ca_account = cert_opts['ca_account'] || config.dig('defaults', 'certs', 'ca_account')
  # cert_ca_name = config.dig('ca_accounts', cert_ca_account, 'ca')
  # cert_ca_identity = config.dig('ca_accounts', cert_ca_account, 'identity')
  #
  # p "Cert #{cert_name}: Finding directory URL for CA"
  # acme_directory_url = config.dig('CAs', cert_ca_name, 'directory_url')
  #
  # p "Cert #{cert_name}: Finding account to use for cert #{cert_name} from CA #{cert_ca_name}"
  # account = config.dig('identities', cert_ca_account_name)
  # email = account['email']
  { cert_name => cert_ca_account }
  #   {
  #     'ca' => cert_ca_name,
  #     'account' => cert_ca_account_name,
  #   },
  # }
end

def make_client_for_ca_account(ca, id)
  p "CA #{ca['name']}: Finding directory URL for CA"
  acme_directory_url = ca['directory_url']

  private_key = read_account_key(id['keyfile'])

  p "CA #{ca['name']}: Creating client object for communication with CA"
  client = Acme::Client.new(private_key: private_key, directory: acme_directory_url)

  email = id['email']

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

def handle_apex_authzs(apex, authzs, config)
  p "apex: #{apex}"
  primary_ns = config.dig('domains', authzs[0].domain, 'primary_ns') || config.dig('defaults', 'domains', 'primary_ns')
  deploy_dns_tokens_on_apex(apex, authzs, primary_ns, config)
end


config = read_config

cert_dir = config.dig('global', 'cert_dir') || './certs/'

ensure_cert_dir(cert_dir)


domains = config['certs'].map { |_certname, cert_opts| cert_opts['domain_names'] }.flatten
domain_attrs = domains.to_h { |d| [d, {}] }


domain_apex_threads = {}
domains.map do |d|
  domain_apex_threads[d] = Thread.new(d) do |d|
    p "finding apex for domain #{d}"
    find_apex_domain(d).to_s
  end
end
domain_apex_threads.each(&:join)

domain_attrs.keys.each do |domain|
  domain_attrs[domain][:apex] = domain_apex_threads[domain].value
end

apex_domains = domain_attrs.map do |_, v|
  apex = v[:apex]
  domains_under_apex = domain_attrs.filter { |d,v| v[:apex] == apex }.keys
  [apex, { :domains => domains_under_apex }]
end.uniq.to_h


apex_domain_ns_threads = {}
apex_domains.keys.map do |d|
  apex_domain_ns_threads[d] = Thread.new(d) do |d|
    p "finding ns for apex domain #{d}"
    res = lookup_ns(d)
    ns_names = res.answer.map do |answer|
      answer.rdata.to_s
    end
  end
end
apex_domain_ns_threads.each(&:join)

apex_domains.keys.each do |domain|
  apex_domains[domain][:ns] = apex_domain_ns_threads[domain].value
  # p "#{domain}: #{apex_domains[domain][:ns]}"
end
# p apex_domains


certs = config['certs']
certs.each_pair do |name, opts|
  opts['ca_account'] || certs[name]['ca_account'] = config.dig('defaults', 'certs', 'ca_account')
end


ca_accounts = certs.map { |_, opts| opts['ca_account'] }.uniq


account_threads = []
ca_accounts.each do |ca_account|
  account_threads << Thread.new(ca_account) do |ca_account|
    ca_name = config.dig('ca_accounts', ca_account, 'ca')
    ca = config.dig('CAs', ca_name)
    ca_identity = config.dig('ca_accounts', ca_account, 'identity')
    identity = config.dig('identities', ca_identity)
    client = make_client_for_ca_account(ca, identity)
    {
      ca_account => client
    }
  end
end
account_threads.each(&:join)

ca_clients = account_threads.map { |t| t.value }
ca_clients = ca_clients[0].merge(*ca_clients[1..])


certs.each_pair do |cert_name, cert_opts|
  client = ca_clients[cert_opts['ca_account']]
  domains = cert_opts['domain_names']
  certs[cert_name]['order_thread'] = Thread.new(cert_name, client, domains) do |cert_name, client, domains|
    p "Cert #{cert_name}: Creating order object for cert #{cert_name}"
    acme_request_with_retries { client.new_order(identifiers: domains) }
  end
end

certs.each_pair do |cert_name, cert_opts|
  t = cert_opts['order_thread']
  t.join
  certs[cert_name]['order'] = t.value
end


certs.each_pair do |cert, opts|
  order_authorizations = acme_request_with_retries { opts['order'].authorizations }
  order_authorizations.each do |auth|
    domain_attrs[auth.domain]['auth'] = auth
  end
end

all_authorizations = domain_attrs.map do |d, attrs|
  attrs['auth']
end

authzs_by_apex = all_authorizations.group_by do |auth|
  domain_attrs[auth.domain][:apex]
end

authzs_by_apex.each_pair do |apex, authzs|
  handle_apex_authzs(apex, authzs, config)
end

propagation_threads = []
domain_attrs.each_pair do |d, attrs|
  domain_attrs[d][:propagation_thread] = Thread.new(attrs['auth']) do |auth|
    wait_for_challenge_propagation(auth.domain, auth.dns01)
  end
  propagation_threads << domain_attrs[d][:propagation_thread]
end

propagation_threads.each(&:join)

# validation_threads = {}
p 'Finding unvalidated domains, initial run'
unvalidated_domains = unvalidated_domains(domain_attrs)
until unvalidated_domains.empty?
  unvalidated_domains.each_pair do |_, attrs|
  # WARNING: for some reason threading does not really work here!
  # domain_attrs.each_pair do |d, attrs|
    # domain_attrs[d][:auth_thread] = Thread.new(attrs) do |attrs|
    # validation_threads[d] = Thread.new(attrs) do |attrs|
      # wait_for_challenge_validation(auth.domain, auth.dns01)
      # pp auth.dns01
      # pp auth.dns01
      # p attrs['auth'].object_id
      # wait_for_challenge_validation(attrs['auth'].dns01, attrs['auth'].domain)
    # acme_request_with_retries { attrs['auth'].dns01.reload }
    p 'Requesting validation of challenge'
    acme_request_with_retries { attrs['auth'].dns01.request_validation }
  end
  # validation_threads[d] = domain_attrs[d][:auth_thread]
  p 'Finding unvalidated domains, next run'
  unvalidated_domains = unvalidated_domains(domain_attrs)
  sleep(0.2)
end

# validation_threads.each_pair { |d, t| t.join }

certs.each_pair do |name, opts|
  cert_key = read_cert_key(name)
  get_cert(opts['order'], name, opts['domain_names'], cert_key)
end