#!/bin/sh
# $1 = task name, $2..$N = packages (from "Packages: list")
# Runtime policy:
#  - language-pack-gnome-* > MATE/GNOME/LXDE
#  - language-pack-kde-*   > KDE (Triskel)
#  - abrowser-/firefox-locale-* > all desktops (MATE/GNOME/LXDE/KDE), not console
#  - libreoffice-l10n-*, icedove-locale-* > MATE/GNOME/KDE; not LXDE/console
#  - skip non-existent candidates (avoid APT 100)

shift 1

debconf_get() {
  [ -x /usr/bin/debconf-communicate ] || return
  printf 'GET %s\n' "$1" | /usr/bin/debconf-communicate 2>/dev/null \
    | awk 'NR==1 && $1==0 { $1=""; sub(/^ /,""); print }'
}

has_pkg() { /usr/bin/dpkg-query -W -f='${Status}\n' "$1" 2>/dev/null | grep -q 'ok installed'; }
exists()  { LC_ALL=C /usr/bin/apt-cache policy "$1" 2>/dev/null | awk '/Candidate:/ {print $2}' | grep -qxv '(none)'; }

sel="$(debconf_get pkgsel/desktop) $(debconf_get tasksel/first)"
case "$sel" in
  *triskel*)          FLAVOR=kde   ;;
  *trisquel-mini*)    FLAVOR=lxde  ;;
  *trisquel-gnome*)   FLAVOR=gnome ;;
  *trisquel-desktop*) FLAVOR=mate  ;;
  *)                  FLAVOR=unknown ;;
esac

if [ "$FLAVOR" = unknown ]; then
  if   has_pkg triskel || has_pkg plasma-desktop; then FLAVOR=kde
  elif has_pkg trisquel-mini || has_pkg lxde-core;    then FLAVOR=lxde
  elif has_pkg trisquel-gnome || has_pkg gnome-shell; then FLAVOR=gnome
  elif has_pkg trisquel-desktop || has_pkg mate-desktop-environment; then FLAVOR=mate
  else FLAVOR=console
  fi
fi

is_kde=false; [ "$FLAVOR" = kde ] && is_kde=true
is_gtk=false; echo "$FLAVOR" | grep -Eq '^(mate|gnome|lxde)$' && is_gtk=true
is_console=false; [ "$FLAVOR" = console ] && is_console=true
is_desktop=true; $is_console && is_desktop=false

emit() {
  p="$1"; [ -n "$p" ] || return
  case "$p" in
    language-pack-gnome-*) $is_gtk || return ;;
    language-pack-kde-*)   $is_kde || return ;;
    abrowser-l10n-*|abrowser-locale-*|firefox-locale-*)
                           $is_desktop || return ;;
    libreoffice-l10n-*)    echo "$FLAVOR" | grep -Eq '^(lxde|console)$' && return ;;
    icedove-locale-*)      echo "$FLAVOR" | grep -Eq '^(lxde|console)$' && return ;;
  esac
  exists "$p" && printf '%s\n' "$p"
}

for p in "$@"; do emit "$p"; done