#!/bin/bash
# Debian gdm package pre-removal script
# Copyright 2001 Branden Robinson.
# Licensed under the GNU General Public License, version 2.  See the file
# /usr/share/common-licenses/GPL or <http://www.gnu.org/copyleft/gpl.txt>.
# Acknowlegements to Stephen Early, Mark Eichin, and Manoj Srivastava.

set -e

THIS_PACKAGE=gdm3
DEFAULT_DISPLAY_MANAGER_FILE=/etc/X11/default-display-manager

if [ "$1" = "remove" -o "$1" = "deconfigure" ]; then
  if [ -e /usr/share/debconf/confmodule ]; then
    . /usr/share/debconf/confmodule
    # disown this question
    db_unregister shared/default-x-display-manager || true
    # does the question still exist?
    if db_get shared/default-x-display-manager; then
      db_metaget shared/default-x-display-manager owners
      db_subst shared/default-x-display-manager choices "$RET"
      db_get shared/default-x-display-manager
      # are we removing the currently selected display manager?
      if [ "$THIS_PACKAGE" = "$RET" ]; then
        if [ -e "$DEFAULT_DISPLAY_MANAGER_FILE" ]; then
          db_get "$RET"/daemon_name
          if [ "$(cat $DEFAULT_DISPLAY_MANAGER_FILE)" = "$RET" ]; then
            rm "$DEFAULT_DISPLAY_MANAGER_FILE"
          fi
        fi
        # ask the user to choose a new default
        db_fset shared/default-x-display-manager seen false
        db_input critical shared/default-x-display-manager || true
        db_go
        # if the display manager file doesn't exist, write it with the path
        # to the new default display manager
        if [ ! -e $DEFAULT_DISPLAY_MANAGER_FILE ]; then
          db_get shared/default-x-display-manager
          echo "Please be sure to run \"dpkg-reconfigure $RET\"."
          db_get "$RET"/daemon_name
          echo "$RET" > "$DEFAULT_DISPLAY_MANAGER_FILE"
        fi
      fi
    fi
  fi

  DEFAULT_SERVICE=/etc/systemd/system/display-manager.service
  # set default-display-manager systemd service link according to our config
  if [ -e "$DEFAULT_DISPLAY_MANAGER_FILE" ]; then
    SERVICE=/lib/systemd/system/$(basename $(cat "$DEFAULT_DISPLAY_MANAGER_FILE")).service
    if [ -h "$DEFAULT_SERVICE" ] && [ $(readlink "$DEFAULT_SERVICE") = /dev/null ]; then
      echo "Display manager service is masked" >&2
    elif [ -e "$SERVICE" ]; then
      ln -sf "$SERVICE" "$DEFAULT_SERVICE"
    else
      echo "WARNING: $SERVICE is the selected default display manager but does not exist" >&2
      rm -f "$DEFAULT_SERVICE"
    fi
  else
    rm -f "$DEFAULT_SERVICE"
  fi
fi