class Globetrotter

# File lib/globetrotter.rb, line 12
def initialize(options)
  @ns_max_age_minutes = options.ns_max_age_minutes
  @ns_count_to_check = options.ns_count_to_check
  @timeout_seconds = options.timeout_seconds
  @query = options.domain
  @concurrency = options.ns_query_concurrency
  @ns_ips = fetch_ns_ips
  @file = GlobetrotterFile.new(options.file) if options.file
end

# File lib/globetrotter.rb, line 80
def self.run(options)
  new(options).run
end

# File lib/globetrotter.rb, line 22
def run
  ns_count = @ns_ips.count
  @ns_count_to_check = ns_count if @ns_count_to_check > ns_count
  @ns_ips = @ns_ips.sample(@ns_count_to_check)

  message = "Found #{ns_count} nameserver#{'s' unless ns_count.size == 1}. "\
            "Querying #{@ns_count_to_check} of those "\
            "for '#{query}', #{@concurrency} at a time, "\
            "with a timeout of #{@timeout_seconds} second#{'s' unless @timeout_seconds == 1}."
  $stderr.puts message

  EM.run do
    if @file
      result_ips = @file.set
      size_before = result_ips.size
    else
      result_ips = Set.new
    end
    ok = 0
    nok = 0
    EM::Iterator.new(@ns_ips, @concurrency).each(
      proc do |ns_ip, iter|
        resolver = RubyDNS::Resolver.new(
          [[:udp, ns_ip.to_s, 53]],
          timeout: @timeout_seconds
        )
        resolver.query(query) do |response|
          case response
          when RubyDNS::Message
            response.answer.each do |answer|
              address = IPAddr.new(answer[2].address.to_s)
              result_ips.add(address)
            end
            ok += 1
            iter.next
          when RubyDNS::ResolutionFailure
            nok += 1
            iter.next
          end
        end
      end,
      proc do
        EM.stop
        if @file
          size_after = result_ips.size
          new_results = size_after - size_before
          @file.set = result_ips
          @file.write
        else
          result_ips.each { |ip| puts ip }
        end
        $stderr.puts "#{ok} succeeded, #{nok} failed (#{ok + nok} total)"
        $stderr.puts "Wrote #{new_results} new unique result#{'s' unless new_results.size == 1} to #{@file}" if @file
      end
    )
  end
end

# File lib/globetrotter.rb, line 88
def fetch_ns_ips
  Wrest.logger = Logger.new(STDERR)
  uri = "http://public-dns.tk/nameservers.json".to_uri
  nameservers = uri.get.deserialise.map { |data| Nameserver.new(data) }
  nameservers.select do |ns|
    ns.valid? && ns.ipv4? && (ns.age_minutes <= @ns_max_age_minutes)
  end.map(&:ip)
end

# File lib/globetrotter.rb, line 97
def resolve_with_nameserver(query, nameserver)
  resolver = RubyDNS::Resolver.new([[:udp, nameserver, 53]])
  resolver.query(query)
end