require 'formula'

class IscDhcp < Formula
  homepage 'http://www.isc.org/software/dhcp'
  url 'http://ftp.isc.org/isc/dhcp/4.2.4-P1/dhcp-4.2.4-P1.tar.gz'
  sha256 'd3baabef27fc006e1ce1c4e3d03d7e5c4b6a34d5a2f45fa47d69235ed25ad420'
  version '4.2.4-P1'

  def install
    # use one dir under var for all runtime state.
    dhcpd_dir = var+'dhcpd'

    # Change the locations of various files to match Homebrew
    # we pass these in through CFLAGS since some cannot be changed
    # via configure args.
    path_opts = {
      '_PATH_DHCPD_CONF'    => etc+'dhcpd.conf',
      '_PATH_DHCLIENT_CONF' => etc+'dhclient.conf',
      '_PATH_DHCPD_DB'      => dhcpd_dir+'dhcpd.leases',
      '_PATH_DHCPD6_DB'     => dhcpd_dir+'dhcpd6.leases',
      '_PATH_DHCLIENT_DB'   => dhcpd_dir+'dhclient.leases',
      '_PATH_DHCLIENT6_DB'  => dhcpd_dir+'dhclient6.leases',
      '_PATH_DHCPD_PID'     => dhcpd_dir+'dhcpd.pid',
      '_PATH_DHCPD6_PID'    => dhcpd_dir+'dhcpd6.pid',
      '_PATH_DHCLIENT_PID'  => dhcpd_dir+'dhclient.pid',
      '_PATH_DHCLIENT6_PID' => dhcpd_dir+'dhclient6.pid',
      '_PATH_DHCRELAY_PID'  => dhcpd_dir+'dhcrelay.pid',
      '_PATH_DHCRELAY6_PID' => dhcpd_dir+'dhcrelay6.pid',
    }

    path_opts.each do |symbol,path|
      ENV.append 'CFLAGS', "-D#{symbol}='\"#{path}\"'"
    end

    # See discussion at: https://gist.github.com/1157223
    if MacOS.version >= :lion
      ENV.append 'CFLAGS', "-D__APPLE_USE_RFC_3542"
    end

    system './configure', "--disable-dependency-tracking",
                          "--prefix=#{prefix}",
                          "--localstatedir=#{dhcpd_dir}"

    # the 'bind' subdirectory doesn't like overly parallel builds
    # so build it sequentially. deparallelizing the whole build
    # can be slow.
    previous_makeflags = ENV['MAKEFLAGS']
    ENV.deparallelize
    system 'make -C bind'
    ENV['MAKEFLAGS'] = previous_makeflags

    # build everything else
    inreplace 'Makefile', 'SUBDIRS = bind', 'SUBDIRS = '
    system 'make'
    system 'make install'

    # rename all the installed sample etc/* files so they don't clobber
    # any existing config files at symlink time.
    Dir.open(prefix+'etc') do |dir|
      dir.each do |f|
        file = "#{dir.path}/#{f}"
        File.rename(file, "#{file}.sample") if File.stat(file).file?
      end
    end

    # create the state dir and lease files else dhcpd will not start up.
    dhcpd_dir.mkpath
    %w(dhcpd dhcpd6 dhclient dhclient6).each do |f|
      file = "#{dhcpd_dir}/#{f}.leases"
      File.new(file, File::CREAT|File::RDONLY).close
    end

    # sample launchd plists
    plist_path.write dhcpd_plist
    plist_path.chmod 0644
    (prefix+'homebrew.mxcl.dhcpd6.plist').write dhcpd6_plist
    (prefix+'homebrew.mxcl.dhcpd6.plist').chmod 0644
  end

  def caveats
    <<-EOCAVEATS.undent
    This install of dhcpd expects config files to be in #{etc}.
    All state files (leases and pids) are stored in #{var}/dhcpd.

    Dhcpd needs to run as root since it listens on privileged ports.
    Sample launchd plists to achieve this have been provided at:
      #{plist_path}
    and:
      #{prefix}/homebrew.mxcl.dhcpd6.plist

    There are two plists because a single dhcpd process may do either
    DHCPv4 or DHCPv6 but not both. Use one or both as needed.

    Copy the plists to /Library/LaunchDaemons and start the services with
      cd /Library/LaunchDaemons
      launchctl load -w #{plist_path.basename}
      launchctl load -w homebrew.mxcl.dhcpd6.plist

    Note that you must create the appropriate config files before starting
    the services or dhcpd will refuse to run.
      DHCPv4: #{etc}/dhcpd.conf
      DHCPv6: #{etc}/dhcpd6.conf

    Sample config files may be found in #{etc}.
    If you change the config, restart dhcpd with one or both of
      launchctl stop #{plist_name}
      launchctl stop homebrew.mxcl.dhcpd6
    EOCAVEATS
  end

  def dhcpd_plist
    <<-EOPLIST.undent
    <?xml version='1.0' encoding='UTF-8'?>
    <!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN"
                    "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
    <plist version='1.0'>
    <dict>
    <key>Label</key><string>#{plist_name}</string>
    <key>ProgramArguments</key>
      <array>
        <string>#{HOMEBREW_PREFIX}/sbin/dhcpd</string>
        <string>-f</string>
      </array>
    <key>Disabled</key><false/>
    <key>KeepAlive</key><true/>
    <key>RunAtLoad</key><true/>
    <key>LowPriorityIO</key><true/>
    </dict>
    </plist>
    EOPLIST
  end

  def dhcpd6_plist
    <<-EOPLIST.undent
    <?xml version='1.0' encoding='UTF-8'?>
    <!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN"
                    "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
    <plist version='1.0'>
    <dict>
    <key>Label</key><string>#{plist_name}</string>
    <key>ProgramArguments</key>
      <array>
        <string>#{HOMEBREW_PREFIX}/sbin/dhcpd</string>
        <string>-f</string>
        <string>-6</string>
        <string>-cf</string>
        <string>#{etc}/dhcpd6.conf</string>
      </array>
    <key>Disabled</key><false/>
    <key>KeepAlive</key><true/>
    <key>RunAtLoad</key><true/>
    <key>LowPriorityIO</key><true/>
    </dict>
    </plist>
    EOPLIST
  end
end