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

OPTION_PARSER = OptionParser.new do |opts|
  opts.banner = "Usage: jails [options] [subcommand [options]]"
  opts.separator ""
  opts.separator <<HELP
Available subcommands:
add [options] NAME [ipaddress[,ipaddress,...]]: add jail
regenerate: regenerate configuration

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

def usage
  puts(OPTION_PARSER.help)
  exit(0)
end

ROOT_PATH = Pathname.new(File.expand_path("../.." ,__FILE__))
EZJAIL_CONFIG_PATH = Pathname.new("/usr/local/etc/ezjail/")

class Jail
  def initialize(name, properties={})
    @name = name
    @properties = properties
  end
  attr_accessor :name, :properties

  def ip4
    extract_ip("ip4")
  end
  def ip6
    extract_ip("ip6")
  end

  private
  def extract_ip(type)
    ips = @properties[type] || []
    ips.map do |addr|
      # example: em0|192.168.67.0 -> 192.168.67.0
      addr =~ /\|?([^|]+)$/
      $1
    end
  end
end

class JailRegistry < Registry
  def add(name)
    data["jails"] ||= {}
    data["settings"] ||= {}

    ip4 = next_address("ip4")
    ip6 = next_address("ip6")
    data["jails"][name] = {
      "ip4" => [ip4],
      "ip6" => [ip6]
    }
    ipconfig = "#{ip4},#{ip6}"
    flavour = []
    if settings["flavour"]
      flavour = ["-f", settings["flavour"]]
    end
    sh("ezjail-admin", "create", *flavour, name, ipconfig)
  end

  def env(name)
    jail_data = data["jails"][name] or die("no jail with name #{name} found")
    jail_data = default_jail_conf.merge(jail_data)
    templ = Template.new(ROOT_PATH.join("templates/jail_env.erb"))
    properties = jail_properties(name, jail_data)
    puts(templ.render(name: name, properties: properties))
  end

  def update_pf_vars
    templ = Template.new(ROOT_PATH.join("templates/pf.erb"))
    path = ROOT_PATH.join("pf_vars.conf")

    atomic_write(path, templ.render(jails: jails))
  end

  def update_config_symlinks
    conf_path = ROOT_PATH.join("scripts/jail_conf")
    FileUtils.mkdir_p(EZJAIL_CONFIG_PATH)
    jails.each do |jail|
      FileUtils.ln_sf(conf_path, EZJAIL_CONFIG_PATH.join(jail.name))
    end
  end

  def update_fstabs
    templ = Template.new(ROOT_PATH.join("templates/fstab.erb"))
    jails.each do |jail|
      fstab = settings["fstab"].dup
      fstab.concat(jail.properties["fstab"] || [])
      fstab.map! do |entry|
        entry % { name: jail.name }
      end

      path = "/etc/fstab.#{jail.name}"
      atomic_write(path, templ.render(fstab: fstab))
    end
  end

  private
    def settings
      {
        "ip4_subnet" => "192.168.10.0/24",
        "ip6_subnet" => "fd7d:aed0:18aa::/48",
        "fstab" => [
          "/usr/jails/basejail /usr/jails/%{name}/basejail nullfs ro 0 0",
        ],
      }.merge(data["settings"])
    end

    def default_jail_conf
      {
        "exec_start" => "/bin/sh /etc/rc",
        "exec_stop" => nil,
        "hostname" => "%{name}",
        "rootdir" => "/usr/jails/%{name}",
        "mount_enable" => true,
        "devfs_ruleset" => "devfsrules_jails",
        "procfs_enable" => true,
        "fdescfs_enable" => true,
        "image" => nil,
        "imagetype" => nil,
        "attachparams" => nil,
        "attachblocking" => nil,
        "forceblocking" => nil,
        "zfs_datasets" => nil,
        "cpuset" => nil,
        "fib" => nil,
        "parentzfs" => nil,
        "parameters" => nil,
        "post_start_script" => nil,
        "retention_policy" => nil
      }.merge(data["default_jail_conf"])
    end

    def jail_properties(name, properties)
      props = properties.dup

      ips = props.delete("ip4") || []
      ips.concat(props.delete("ip6") || [])
      unless ips.empty?
        props["ip"] = ips.join(",")
      end
      props.each do |prop, value|
        props[prop] = serialize_property(name, value)
      end

      props
    end

    def serialize_property(name, value)
      str = case value
      when TrueClass
        return value ? "YES" : "NO"
      when String
        value % { name: name }
      else
        value
      end
      Shellwords.escape(str)
    end

    def jails
      data["jails"].map do |name, properties|
        Jail.new(name, properties)
      end
    end

    def next_address(type)
      subnets = []
      data["jails"].each do |k,v|
        if v[type].is_a? Array
          v[type].each do |subnet|
            subnets << NetAddr::CIDR.create(subnet)
          end
        end
      end
      subnet = settings["#{type}_subnet"]
      next_free_subnet(NetAddr::CIDR.create(subnet), subnets)
    end
end

def main(args)
  OPTION_PARSER.order!(args)

  usage if args.size < 1

  registry = JailRegistry.new

  case command = args.shift
  when "add"
    name = args.first or die "name required"
    registry.add(name)
    registry.save
  when nil
    usage
  when "regenerate"
  when "env"
    name = args.first or die "name required"
    registry.env(name)
  else
    die "unknown subcommand #{command}"
  end
  registry.update_pf_vars
  registry.update_fstabs
  registry.update_config_symlinks
end

main(ARGV)