#!/usr/bin/env bash
# Script to setup screens on login and lid-switch-action
# Uses autorandr to determine which screens are connected and which to setup.
#
# Per default a configuration named "default" will be used, if the computer is
# a laptop and not docked.
# A configuration named "docked-closed" will be used during login, when the lid
# is closed and docked.
# A configuration named "docked-all" will be used during login, when the lid
# is open and docked.

set -e -u

lid_state=""
fingerprint=""
action=""
x_user=""
display=""
current_user=""
path=""

# get DISPLAY number
get_display()
{
  display=$(pgrep -a Xorg|cut -d':' -f2| cut -d' ' -f1)
}

# get current user running X
get_x_user()
{
  x_user="$(loginctl list-sessions --no-legend| grep "seat"| awk '{print $3}')"
}

# get current user running this script
get_current_user()
{
  current_user="$(whoami)"
}

# get full path to this script
get_path()
{
  path="$0"
}

# Get current lid state ("open" or "closed")
function get_lid_state()
{
  if [ -r "/proc/acpi/button/lid/LID/state" ]; then
    lid_state="$(awk '{print $2}' /proc/acpi/button/lid/LID/state)"
  fi
}

# Get current docking state ("true" or "false")
function is_docked()
{
  if command -v busctl > /dev/null; then
    busctl introspect org.freedesktop.login1 /org/freedesktop/login1| grep -E '^.Docked'| awk '{print $4}'
  else
    echo false
  fi
}

# Get the md5sum of the current autorandr fingerprint
function get_setup_fingerprint()
{
  fingerprint="$(autorandr --fingerprint| md5sum| cut -d ' ' -f 1)"
}

# Get the md5sum of a autorandr configuration
function get_configuration_fingerprint()
{
  local fingerprint=""
  if [ -r "$HOME/.config/autorandr/$1/setup" ]; then
    fingerprint="$(md5sum "$HOME/.config/autorandr/$1/setup"| cut -d ' ' -f 1)"
  fi
  echo "$fingerprint"
}

function set_configuration()
{
  local state=0
  # if the computer is docked
  if is_docked ; then
    # if there's a lid-switch action
    if [ -n "$action" ]; then
      case "$action" in 
        "open")
          if [ "$(get_configuration_fingerprint 'docked-all')"  == "$fingerprint" ]; then
            echo "Loading docked-all."
            state=1
            autorandr -l docked-all
          fi
          ;;
        "close")
          if [ "$(get_configuration_fingerprint 'docked-closed')" == "$fingerprint" ]; then
            echo "Loading docked-closed."
            state=1
            autorandr -l docked-closed
          fi
          ;;
      esac
    else
      # check the lid state
      case "$lid_state" in
        "open")
          if [[ $(get_configuration_fingerprint "docked-all") == "$fingerprint" ]]; then
            echo "Loading docked-all."
            state=1
            autorandr -l docked-all
          fi
          ;;
        "closed")
          if [[ $(get_configuration_fingerprint "docked-closed") == "$fingerprint" ]]; then
            echo "Loading docked-closed."
            state=1
            autorandr -l docked-closed
          fi
          ;;
          *)
            echo "Your computer is docked but has no lid?!"
            exit 1
          ;;
      esac
    fi
  # else if not docked
  else
    if [ "$action" = "open" ]; then
      if [[ $(get_configuration_fingerprint "external") == "$fingerprint" ]]; then
        echo "Loading external."
        state=1
        autorandr -l external
      fi
    fi
  fi
  # if the screen still has not been setup, try using default
  if [ $state -ne 1 ]; then
    if [[ $(get_configuration_fingerprint "default") == "$fingerprint" ]]; then
      echo "Loading default."
      autorandr -l default
    fi
  fi
}

# check if autorandr is installed
if [ ! -x "/usr/bin/autorandr" ]; then
  echo "Autorandr is not installed."
  exit 1
fi

# get (lid-switch) action from parameter ("open" or "close")
if [ "$#" -eq 1 ]; then
  action="$1"
fi

logger "Calling 'setup_screens'"
get_x_user
get_display
get_current_user
get_path

# Export Xorg DISPLAY and XAUTHORITY
export DISPLAY=":$display"
export XAUTHORITY="/home/$x_user/.Xauthority"

# if the script caller is the current X user or root (and lightdm is the current X user)
if [ "$current_user" == "$x_user" ]; then
  get_lid_state
  get_setup_fingerprint
  set_configuration
elif [ "$current_user" == "root" ]; then
    logger "Running $path as user $x_user now."
    runuser -l "$x_user" -c "$path"
else
    echo "$current_user is not currently running X and is not allowed to let the current X user run this script."
    exit 1
fi

exit 0