#!/bin/bash
# vim:ts=2:sts=2:sw=2

#
# Run a command as the currently active X11 user
#

seat="seat0"

# determine location of loginctl
LOGINCTL=$(command -v loginctl || command -v systemd-loginctl)
if [[ -e LOGINCTL ]]; then
  echo "Error: Unable to find loginctl executable"
  exit 1
fi

get_session_info() {
  local session="$1"
  local varname="$2"
  local IFS=$'\n'
  eval declare -Ag $varname
  for row in $(loginctl show-session "$session"); do
    key="$(echo "${row}"|cut -d= -f1)"
    val="$(echo "${row}"|cut -d= -f2-)"
    eval ${varname}[\"${key}\"]=\"${val}\"
  done
}

escape() {
  for arg in "$@" ; do
    printf "%q " "$arg";
  done;
}

session_list="$(loginctl --no-legend | grep "$seat" | awk '{print $1}')"
found_active_session=""
for session in $session_list; do
  get_session_info "$session" session_info
  if [[ "${session_info[Active]}" = "yes" ]]; then
    found_active_session="yes"
    break
  fi
done
if [ -z "${found_active_session}" ]; then
  echo "Error: Unable to determine active session"
  exit 1
fi

if [[ "${session_info[Type]}" != "x11" ]]; then
  echo "Error: Active session is not x11"
  exit 2
fi

current_user="$(id -u -n)"

if [[ ${current_user} == ${session_info[Name]} ]]; then
  # already correct user, no need to su
  DISPLAY="${session_info[Display]}" "$@"
else
  # run command as user
  DISPLAY="${session_info[Display]}" su -c - "${session_info[Name]}" "$(escape "$@")"
fi