# frozen_string_literal: true

module Facter
  module Resolvers
    class Hostname < BaseResolver
      # :fqdn
      # :domain
      # :hostname

      init_resolver

      class << self
        private

        def post_resolve(fact_name, _options)
          @fact_list.fetch(fact_name) { retrieve_info(fact_name) }
        end

        def retrieve_info(fact_name)
          require 'socket'
          output = Socket.gethostname
          hostname, domain = retrieve_from_fqdn(output)

          fqdn = retrieve_with_addrinfo(hostname) if hostname_and_no_domain?(hostname, domain)

          _, domain = retrieve_from_fqdn(fqdn) if exists_and_valid_fqdn?(fqdn, hostname)

          domain = read_domain unless exists_and_not_empty?(domain)

          construct_fact_list(hostname, domain, fqdn)
          @fact_list[fact_name]
        end

        def retrieve_from_fqdn(output)
          if output =~ /(.*?)\.(.+$)/
            log.debug("Managed to read hostname: #{Regexp.last_match(1)} and domain: #{Regexp.last_match(2)}")
            [Regexp.last_match(1), Regexp.last_match(2)]
          else
            log.debug("Only managed to read hostname: #{output}, no domain was found.")
            [output, '']
          end
        end

        def retrieve_with_addrinfo(host)
          begin
            name = Socket.getaddrinfo(host, 0, Socket::AF_UNSPEC, Socket::SOCK_STREAM, nil, Socket::AI_CANONNAME)[0]
          rescue StandardError => e
            @log.debug("Socket.getaddrinfo failed to retrieve fqdn for hostname #{host} with: #{e}")
            return
          end
          return if name.nil? || name.empty? || host == name[2] || name[2] == name[3]

          name[2]
        end

        def exists_and_valid_fqdn?(fqdn, hostname)
          exists_and_not_empty?(fqdn) && fqdn.start_with?("#{hostname}.")
        end

        def hostname_and_no_domain?(hostname, domain)
          domain.empty? && !hostname.empty?
        end

        def read_domain
          file_content = Facter::Util::FileHelper.safe_read('/etc/resolv.conf')
          if file_content =~ /^domain\s+(\S+)/
            Regexp.last_match(1)
          elsif file_content =~ /^search\s+(\S+)/
            Regexp.last_match(1)
          end
        end

        def construct_fqdn(host, domain, fqdn)
          return fqdn if exists_and_not_empty?(fqdn)
          return if host.nil? || host.empty?

          exists_and_not_empty?(domain) ? "#{host}.#{domain}" : host
        end

        def construct_fact_list(hostname, domain, fqdn)
          @fact_list[:hostname] = hostname
          @fact_list[:domain] = domain
          @fact_list[:fqdn] = construct_fqdn(@fact_list[:hostname], @fact_list[:domain], fqdn)
        end

        def exists_and_not_empty?(variable)
          variable && !variable.empty?
        end
      end
    end
  end
end
