#!/usr/bin/env ruby
require_relative "utils"
require "netaddr"

class RdnsZone
  def initialize(data, subnet)
    @data = data
    @subnet = NetAddr::CIDR.create(subnet)
  end
  attr_reader :data

  def [](key)
    (data["zone"] || {})[key]
  end

  def pointers(&blk)
    version = @subnet.version

    @data["network"].each do |name, host|
      ip = host["ipv#{version}"]
      next unless ip
      arpa = NetAddr::CIDR.create(ip).arpa
      next unless arpa.end_with?(@subnet.arpa)
      host_part = arpa[0, arpa.size - @subnet.arpa.size - 1]
      yield name, host_part
    end
  end

  def name
    @subnet.arpa.gsub(/\.$/, "")
  end

  def write_zone_file(root_path)
    zone_template = Template.new(root_path.join("templates/rdns-zone.erb"))
    rdns_path = root_path.join("zones", name)
    atomic_write(rdns_path, zone_template.render(zone: self))
  end
end

registry = Registry.new
root_path = Pathname.new(File.expand_path("../..", __FILE__))
zone_template = Template.new(root_path.join("templates/dn42-zone.erb"))
result = zone_template.render(data: registry.data)
atomic_write(root_path.join("zones/dn42.zone"), result)

if subnet = try(registry.data, "zone", "v4_subnet")
  RdnsZone.new(registry.data, subnet).write_zone_file(root_path)
end

if subnet = try(registry.data, "zone", "v6_subnet")
  RdnsZone.new(registry.data, subnet).write_zone_file(root_path)
end