# frozen_string_literal: true

# lib/facter/dns_records.rb
#
# Reports this host's expected DNS records (assembled by profiles::dns::updater
# into its records file) versus what is currently deployed on the authoritative
# server, so puppet can detect drift and re-apply.
#
# Structured value:
#   { server, count, expected => [{zone,fqdn,type,ttl,value}], in_sync,
#     drift => [{...,deployed => [...]}] }

# Helpers for the dns_records fact.
module DnsRecordsFact
  RECORDS_FILE = '/var/lib/dns-updater/records'
  SERVER_FILE  = '/var/lib/dns-updater/server'

  module_function

  # normalise a value for comparison: strip, drop trailing dot, downcase
  def norm(value)
    value.to_s.strip.chomp('.').downcase
  end

  def server
    File.exist?(SERVER_FILE) ? File.read(SERVER_FILE).strip : nil
  end

  # a name relative to a zone (or @) as a fully-qualified name
  def to_fqdn(name, zone)
    return "#{zone}." if name.to_s.empty? || name == '@'

    "#{name}.#{zone}."
  end

  # parse one "zone|name|type|ttl|value" line into a record hash (nil to skip)
  def parse_line(line)
    line = line.strip
    return nil if line.empty? || line.start_with?('#')

    zone, name, type, ttl, value = line.split('|', 5)
    return nil unless zone && type && value

    { 'zone' => zone, 'fqdn' => to_fqdn(name, zone), 'type' => type, 'ttl' => ttl, 'value' => value }
  end

  # parse the records file into record hashes
  def expected
    return [] unless File.exist?(RECORDS_FILE)

    File.readlines(RECORDS_FILE).filter_map { |line| parse_line(line) }
  end

  # the values currently deployed for a record, per the authoritative server
  def deployed(record, srv)
    cmd = ['dig', '+short', '+time=2', '+tries=1']
    cmd << "@#{srv}" if srv && !srv.empty?
    cmd += [record['fqdn'], record['type']]
    out = Facter::Core::Execution.execute(cmd.join(' '), on_fail: '')
    out.to_s.split("\n").map { |line| norm(line) }.reject(&:empty?)
  end

  def report
    srv = server
    exp = expected
    drift = exp.filter_map do |record|
      dep = deployed(record, srv)
      record.merge('deployed' => dep) unless dep.include?(norm(record['value']))
    end
    { 'server' => srv, 'count' => exp.length, 'expected' => exp, 'in_sync' => drift.empty?, 'drift' => drift }
  end
end

Facter.add(:dns_records) do
  confine kernel: 'Linux'
  setcode do
    File.exist?(DnsRecordsFact::RECORDS_FILE) ? DnsRecordsFact.report : nil
  end
end

# Convenience boolean for `if $facts['dns_records_insync']` guards.
Facter.add(:dns_records_insync) do
  confine kernel: 'Linux'
  setcode do
    v = Facter.value(:dns_records)
    v.nil? ? nil : v['in_sync']
  end
end