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

class DhcpRegistry < Registry
  def add_lease(name, macaddress, ipv4, ipv6)
    data["network"][name] ||= {}
    host = data["network"][name]
    host["macaddress"] = macaddress
    host["ipv4"] = ipv4 if ipv4
    host["ipv6"] = ipv6 if ipv6
  end

  def remove_lease(name)
    if data["network"].delete(name).nil?
      die "no such lease name #{name} in registry.json"
    end
  end

  def update_leases
    template_path = Pathname.new(File.expand_path("../../templates", __FILE__))
    dhcp_template = Template.new(template_path.join("dhcp.conf.erb"))
    static_leases = data["network"].select do |name, data|
      data["mac"] && (data["ipv4"] || data["ipv6"])
    end.map do |name, data|
      TemplateContext.new(data.merge(name: name))
    end
    dhcp_path = Pathname.new(File.expand_path("../../dhcp.peers.conf", __FILE__))
    File.open(dhcp_path, "w+").write(dhcp_template.render(leases: static_leases))

    reload_dhcp
  end

  def reload_dhcp
    command = try(data, "host", "reload_command")
    if command.nil?
      puts "skip to reload dhcpd because reload_command is not defined"
    else
      sh(command)
    end
  end
end

GLOBAL_OPTIONS = OptionParser.new do |opts|
  opts.banner = "Usage: dhcp [options] [subcommand [options]]"
  opts.separator ""
  opts.separator <<HELP
Available subcommands:
add [options] NAME MACADDRESS: add dhcp lease
remove [options] NAME:         remove dhcp static lease
regenerate:                    regenerate dhcp configuration

See 'dhcp COMMAND --help' for more information on a specific command.
HELP
end

class Application
  def run(args)
    GLOBAL_OPTIONS.order!(args)
    @registry = DhcpRegistry.new
    case command = args.shift
    when "add"
      add_command
    when "remove"
      remove_command
    when nil
      puts(GLOBAL_OPTIONS.help())
      exit(0)
    when "regenerate" # fall through
    else
      die "unknown subcommand #{command}"
    end

    registry.save
    registry.update_leases
  end

  private
    def add_command(args)
      ipv4, ipv6 = nil, nil
      parser = OptionParser.new do |opts|
        opts.banner = "Usage: dhcp add [options] NAME MACADDRESS"
        opts.on("-4", "--ipv4 ADDRESS", "set fixed ipv4 address") do |address|
          ipv4 = address
        end
        opts.on("-6", "--ipv6 ADDRESS", "set fixed ipv6 address") do |address|
          ipv6 = address
        end
      end.order!(args)
      if ARGV.size < 2
        $stderr.puts "no enough arguments"
        die(parser.help)
      end
      name, macaddress = args
      @registry.add_lease(name, macaddress, ipv4, ipv6)
    end

    def remove_command(args)
      parser = OptionParser.new do |opts|
        opts.banner = "Usage: dhcp remove NAME"
      end.order!(args)
      if args.empty?
        $stderr.puts "no enough arguments"
        die(parser.help)
      end
      @registry.remove_lease(args.first)
    end
end

Application.new.run(ARGV)