#!/bin/bash

if [ "$UID" != "0" ]; then
	echo Need to be root.
	exit 1
fi

declare -A results_target

usage() {
	cat << EOF
usage: systemd-sysv-convert [-h] [--save] [--show] [--apply]
                            SERVICE [SERVICE ...]
EOF
}

help() {
	usage
	cat << EOF
Save and Restore SysV Service Runlevel Information

positional arguments:
  SERVICE	Service names

optional arguments:
  -h, --help	show this help message and exit
  --save	Save SysV runlevel information for one or more services
  --show	Show saved SysV runlevel information for one or more services
  --apply 	Apply saved SysV runlevel information for one or more services
  		to systemd counterparts
EOF
}

find_service() {
	local service=$1
	local rcnd=$2

	case $rcnd in
	boot.d)		[ -L /etc/rc.d/$rcnd/S??boot.$service ] ;;
	*)		[ -L /etc/rc.d/$rcnd/S??$service ]
	esac
}

lookup_database() {
	local services=$@
	local service
	local runlevel
	local priority

	# 'priority' field is not used but is kept for backward compat
	# reason.
	while read service runlevel priority; do
		for s in $services ; do
			if [ $s == $service ]; then
				results_target[$service]+=" runlevel$runlevel.target"
				break
			fi
		done
	done < /var/lib/systemd/sysv-convert/database
}

declare -i fail=0
case "$1" in
	-h|--help)
		help
		exit 0
		;;
	--save)
		shift
		for service in $@ ; do
			if [ ! -r /etc/init.d/$service ] && [ ! -r /etc/init.d/boot.$service ]; then
				echo "SysV service $service does not exist, skipping"
				continue
			fi
			for rcnd in rc2.d rc3.d rc4.d rc5.d boot.d; do
				case $rcnd in
				rc*.d)	runlevel=${rcnd:2:1} ;;
				boot.d)	runlevel=3 ;;
				esac

				# Write a dumb priority as it is not used.
				find_service $service $rcnd &&
				echo "$service	$runlevel 50" >>/var/lib/systemd/sysv-convert/database
			done
		done
		;;
	--show)
		shift
		services=$@
		lookup_database $services
		for service in $services; do
  			if [ -z "${results_target[$service]}" ]; then
				echo "No information about service $service found." >/dev/stderr
				let fail++
				continue
			fi
			for target in ${results_target[$service]}; do
				echo "SysV service '$service' is pulled by $target"
			done
		done
		;;
	--apply)
		shift
		services=$@
		for service in $services; do
			if [ ! -f "/lib/systemd/system/$service.service" -a ! -f "/usr/lib/systemd/system/$service.service" ]; then
				echo systemd service $service.service does not exist. >/dev/stderr
				exit 1
			fi
		done

		#
		# The database might no have been created by a previous --save
		# call. This can happen when:
		#
		#  - we're upgrading a package which initially didn't
		#    have any unit file nor sysv init script and now
		#    start shipping one or more unit files (bsc#982303).
		#
		#  - the sysv init service wasn't enabled at all before
		#    being migrated to a native unit file (bsc#982211).
		#
		if [ -e /var/lib/systemd/sysv-convert/database ]; then
			lookup_database $services
			for service in $services; do
				[ -f "/lib/systemd/system/$service.service" ] && unit="/lib/systemd/system/$service.service"
				[ -f "/usr/lib/systemd/system/$service.service" ] && unit="/usr/lib/systemd/system/$service.service"

				# If $service is not present in the database,
				# then it simply means that the sysv init
				# service was not enabled at all.
				for target in ${results_target[$service]}; do
					echo ln -sf $unit /etc/systemd/system/$target.wants/$service.service >/dev/stderr
					mkdir -p "/etc/systemd/system/$target.wants"
					/bin/ln -sf $unit /etc/systemd/system/$target.wants/$service.service
				done
			done
		fi
		;;
	*)
 		usage
		let fail=2
		;;
esac

exit $fail