#!/bin/sh
##
##  List installed packages if they are likely to be useful in a Xen
##  instance.
##


function packages {
  equery --quiet list
}


##  a helper function, to parse multiline token lists into regex alternations
function tokens_to_alternation {
  echo $1 | sed -r 's/[[:space:]]/|/g'
}


##  filters out packages in the 'do not want' categories
function category_filter {
  do_not_want="
    sys-kernel x11- virtual gnome- media-video media-sound net-wireless
    dev-java
    "
  egrep -v "^("`tokens_to_alternation "$do_not_want"`")"
}


##  eliminate packages with any of the 'do_not_want' tokens in their names
function name_filter {
  do_not_want="
    mozilla gimp scim uim xvid
    x11 xorg
    opengl mesa glut 
    gtk cairo gnome 
    "
  egrep -v `tokens_to_alternation "$do_not_want"`
}


##  this is by far the most expensive operation, making multiple calls to
##  equery and writing to a tmp file after every one
function use_flag_filter {
  c=/tmp/has_gui_cache
  [ -f $c ] && rm $c
  touch $c

  do_not_want="
    xorg xv X gnome kde xfs xft glut gtk gtk2 qt qt3 qt4 opengl
    "
  for flag in $do_not_want
  do
    equery --quiet hasuse $flag | sort >> $c
  done
  sort $c | uniq > /tmp/has_gui

  comm -2 -3 - /tmp/has_gui
}


packages | category_filter | name_filter | use_flag_filter