#!/bin/sh

set -eu

actions_icons='/usr/share/icons/gnome/16x16/actions'
awk_who='
	BEGIN {
		display_ere = " [(]" display "[)]$";
		printed = 0;
	}
	NR == 1 {
		headings = $0;
	}
	NR > 1 {
		if (!match($0, display_ere)) {
			if (!printed) {
				print("\n\nThe following other sessions " \
					"will be hung up:\n");
				print("<tt><small>    " headings \
					"</small></tt>");
				printed = 1;
			}
			print("<tt><small>    " $0 "</small></tt>");
		}
	}
	'

do_logout()
{
	zenity --question --title='Log Out' \
		--window-icon="${actions_icons}/system-log-out.png" \
		--text='Are you sure you want to log out?' \
		--ok-label='Log Out' --cancel-label='Cancel' && \
		printf 'quit\n' >~/.xsessionmanage

	return 0
}

do_shutdown()
{
	zenity --question --title='Shut Down' \
		--window-icon="${actions_icons}/system-shutdown.png" \
		--text="Are you sure you want to shut down this system?$(\
			who -H | awk -v "display=${DISPLAY}" "${awk_who}")" \
		--ok-label='Shut Down' --cancel-label='Cancel' && \
		sudo shutdown -hP now

	return 0
}

do_reboot()
{
	zenity --question --title='Reboot' \
		--window-icon="${actions_icons}/system-shutdown.png" \
		--text="Are you sure you want to reboot this system?$(\
			who -H | awk -v "display=${DISPLAY}" "${awk_who}")" \
		--ok-label='Reboot' --cancel-label='Cancel' && \
		sudo reboot

	return 0
}

do_s2mem()
{
	zenity --question --title='Suspend' \
		--window-icon="${actions_icons}/media-playback-pause.png" \
		--text='Are you sure you want to suspend this system?' \
		--ok-label='Suspend' --cancel-label='Cancel' && \
		sudo dd of='/sys/power/state' <<-EOF
			mem
			EOF

	return 0
}

do_s2disk()
{
	zenity --question --title='Hibernate' \
		--window-icon="${actions_icons}/media-playback-pause.png" \
		--text='Are you sure you want to hibernate this system?' \
		--ok-label='Hibernate' --cancel-label='Cancel' && \
		sudo dd of='/sys/power/state' <<-EOF
			disk
			EOF

	return 0
}

usage()
{
	printf 'Usage: %s {logout|shutdown|reboot|s2mem|s2disk}\n' "${0}"

	return 0
}

main()
{
	local action=

	if [ ${#} -ne 1 ]; then
		usage 1>&2
		return 1
	fi
	action="${1}"
	shift 1

	read -r DISPLAY 0<~/.xdisplay

	case "${action}" in
		'logout' | 'shutdown' | 'reboot' | 's2mem' | 's2disk')
			"do_${action}"
			;;
		*)
			usage 1>&2
			return 1
			;;
	esac

	return 0
}

main "${@}"