#!/usr/bin/python

# -*- Mode: Python; python-indent: 8; indent-tabs-mode: t -*-

import sys, os, argparse, errno

def find_service(service, runlevel):

	priority = -1

	for l in os.listdir("/etc/rc%i.d" % runlevel):

		if len(l) < 4:

			continue

		if l[0] != 'S' or l[3:] != service:

			continue

		p = int(l[1:3])

		if p >= 0 and p <= 99 and p >= priority:

			priority = p;

	return priority

def lookup_database(services):

	try:

		database = open("/var/lib/systemd/sysv-convert/database", "r")

	except IOError, e:

		if e.errno != errno.ENOENT:

			raise e

		return {}

	found = {}

	k = 0

	for line in database:

		service, r, p = line.strip().split("\t", 3)

		k += 1

		try:

			runlevel = int(r)

			priority = int(p)

		except ValueError, e:

			sys.stderr.write("Failed to parse database line %i. Ignoring." % k)

			continue

		if runlevel not in (2, 3, 4, 5):

			sys.stderr.write("Runlevel out of bounds in database line %i. Ignoring." % k)

			continue

		if priority < 0 or priority > 99:

			sys.stderr.write("Priority out of bounds in database line %i. Ignoring." % k)

			continue

		if service not in services:

			continue

		if service not in found:

			found[service] = {}

		if runlevel not in found[service] or found[service][runlevel] < priority:

			found[service][runlevel] = priority

	return found

def mkdir_p(path):

	try:

		os.makedirs(path, 0755)

	except OSError, e:

		if e.errno != errno.EEXIST:

			raise e

if os.geteuid() != 0:

	sys.stderr.write("Need to be root.\n")

	sys.exit(1)

parser = argparse.ArgumentParser(description='Save and Restore SysV Service Runlevel Information')

parser.add_argument('services', metavar='SERVICE', type=str, nargs='+',

		    help='Service names')

parser.add_argument('--save', dest='save', action='store_const',

		    const=True, default=False,

		    help='Save SysV runlevel information for one or more services')

parser.add_argument('--show', dest='show', action='store_const',

		    const=True, default=False,

		    help='Show saved SysV runlevel information for one or more services')

parser.add_argument('--apply', dest='apply', action='store_const',

		    const=True, default=False,

		    help='Apply saved SysV runlevel information for one or more services to systemd counterparts')

a = parser.parse_args()

if a.save:

	for service in a.services:

		if not os.access("/etc/rc.d/init.d/%s" % service, os.F_OK):

			sys.stderr.write("SysV service %s does not exist.\n" % service)

			sys.exit(1)

	mkdir_p("/var/lib/systemd/sysv-convert")

	database = open("/var/lib/systemd/sysv-convert/database", "a")

	for runlevel in (2, 3, 4, 5):

		priority = find_service(service, runlevel)

		if priority >= 0:

			database.write("%s\t%s\t%s\n" % (service, runlevel, priority))

elif a.show:

	found = lookup_database(a.services)

	if len(found) <= 0:

		sys.stderr.write("No information about passed services found.\n")

		sys.exit(1)

	for service, data in found.iteritems():

		for runlevel, priority in data.iteritems():

			sys.stdout.write("SysV service %s enabled in runlevel %s at priority %s\n" % (service, runlevel, priority))

elif a.apply:

	for service in a.services:

		if not os.access("/lib/systemd/system/%s.service" % service, os.F_OK):

			sys.stderr.write("systemd service %s.service does not exist.\n" % service)

			sys.exit(1)

	found = lookup_database(a.services)

	if len(found) <= 0:

		sys.stderr.write("No information about passed services found.\n")

		sys.exit(1)

	for service, data in found.iteritems():

		for runlevel in data.iterkeys():

			sys.stderr.write("ln -sf /lib/systemd/system/%s.service /etc/systemd/system/runlevel%i.target.wants/%s.service\n" % (service, runlevel, service))

			mkdir_p("/etc/systemd/system/runlevel%i.target.wants" % runlevel)

			try:

				os.symlink("/lib/systemd/system/%s.service" % service,

					   "/etc/systemd/system/runlevel%i.target.wants/%s.service" % (runlevel, service))

			except OSError, e:

				if e.errno != errno.EEXIST:

					raise e

else:

	parser.print_help()