#!/usr/bin/env zsh

export XDG_CURRENT_DESKTOP=sway
export XDG_SESSION_DESKTOP="${XDG_SESSION_DESKTOP:-sway}"
export XDG_SESSION_TYPE=wayland
VARIABLES="DESKTOP_SESSION XDG_CURRENT_DESKTOP XDG_SESSION_DESKTOP XDG_SESSION_TYPE"
VARIABLES="${VARIABLES} DISPLAY I3SOCK SWAYSOCK WAYLAND_DISPLAY"
VARIABLES="${VARIABLES} XCURSOR_THEME XCURSOR_SIZE"
SESSION_TARGET="sway-session.target"
SESSION_SHUTDOWN_TARGET="sway-session-shutdown.target"
SWAY_UNIT="sway.scope"

print_usage() {
	cat <<EOF
Usage: $0 <setup|cleanup> [ARGS]
  --help              Show this help message and exit.
  --add-env=NAME, -E NAME
                      Add an variable to the environment imported into
                      systemd and purged on exit.

  setup               Perform sway session systemd setup. This will fail
                      if the command is not run as a child of 'sway' (via
                      an 'exec' or 'exec_always' directive or command).
  cleanup             Meant to be called by the service manager as a part
                      of sway-session-shutdown.target.
EOF
}

while [ $# -gt 0 ]; do
	case "$1" in
		--help)
			print_usage
			exit 0 ;;
		--add-env=?*)
			VARIABLES="${VARIABLES} ${1#*=}" ;;
		--add-env | -E)
			shift
			VARIABLES="${VARIABLES} ${1}" ;;
		cleanup)
			TASK=cleanup ;;
		setup)
			TASK=setup ;;
		-*)
			echo "Unexpected option: $1" >&2
			print_usage
			exit 1 ;;
		*)
			break ;;
	esac
	shift
done

function setup() {
	# Get process stack
	ppid=$(ps -o ppid= $$ | sed 's/ //g')
	ppcomm=$(ps -o comm= $ppid)

	if [[ $ppcomm == 'sh' ]]; then
	  # sway exec command (a shell) forked before exec, get its parent
		ppid=$(ps -o ppid= $ppid | sed 's/ //g')
		ppcomm=$(ps -o comm= $ppid)
	fi
	
	if ! [[ $ppcomm == 'sway' ]]; then
		echo "Error: attempting to run setup while not invoked by sway!"
		exit 2
	fi

	# Reset failed units
	systemctl --user reset-failed
	
	# Import environment
	echo $VARIABLES | xargs -- systemctl --user import-environment
	echo $VARIABLES | xargs -- dbus-update-activation-environment

	# Load scope unit
	busctl --user call org.freedesktop.systemd1 /org/freedesktop/systemd1 org.freedesktop.systemd1.Manager StartTransientUnit 'ssa(sv)a(sa(sv))' \
				 "$SWAY_UNIT" \
				 fail \
				 7 \
				 PIDs au 1 $ppid \
				 Slice s session.slice \
				 Wants as 1 $SESSION_TARGET \
				 Before as 1 $SESSION_TARGET \
				 PropagatesStopTo as 1 $SESSION_TARGET \
				 OnSuccess as 1 $SESSION_SHUTDOWN_TARGET \
				 OnFailure as 1 $SESSION_SHUTDOWN_TARGET \
				 0
}

function cleanup() {
	systemctl --user unset-environment $VARIABLES
}

case $TASK in
	setup)
		setup ;;
	cleanup)
		cleanup ;;
esac