#!/usr/bin/python2
# coding: utf-8
#
# pkgdistcache daemon v0.3.1
# by Alessio Bianchi <venator85@gmail.com>
#
# Daemon code by Chad J. Schroeder
# http://code.activestate.com/recipes/278731/
#

import sys
import os
import os.path
import subprocess
import string
import avahi
import dbus
import gobject
import dbus.glib
import SimpleHTTPServer
import BaseHTTPServer
import signal
import socket

avahi_service = None

def terminate(signum, frame):
	avahi_service.unpublish()
	sys.exit(0)

# Run a command synchronously, redirecting stdout and stderr to strings
def runcmd(cmd, cwd=None):
	pipe = subprocess.Popen(cmd, shell=True, cwd=cwd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
	(stdout, stderr) = pipe.communicate()	# wait for process to terminate and return stdout and stderr
	return {'stdout': stdout.strip(), 'stderr': stderr.strip(), 'retcode': pipe.returncode}

# Detach a process from the controlling terminal and run it in the background as a daemon
def daemonize():
	try:
		pid = os.fork()
	except OSError, e:
		raise Exception, "%s [%d]" % (e.strerror, e.errno)

	if (pid == 0):	# The first child.
		os.setsid()
		try:
			pid = os.fork()	# Fork a second child.
		except OSError, e:
			raise Exception, "%s [%d]" % (e.strerror, e.errno)

		if (pid != 0):	# The second child.
			os._exit(0)	# Exit parent (the first child) of the second child.
	else:
		os._exit(0)	# Exit parent of the first child.

	import resource		# Resource usage information.
	maxfd = resource.getrlimit(resource.RLIMIT_NOFILE)[1]
	if (maxfd == resource.RLIM_INFINITY):
		maxfd = 1024
	
	# Iterate through and close all file descriptors.
	for fd in range(0, maxfd):
		try:
			os.close(fd)
		except OSError:	# ERROR, fd wasn't open to begin with (ignored)
			pass

	# The standard I/O file descriptors are redirected to /dev/null by default.
	os.open("/dev/null", os.O_RDWR)	# standard input (0)
	os.dup2(0, 1)			# standard output (1)
	os.dup2(0, 2)			# standard error (2)
	return(0)

class AvahiPublisher:
	#Based on http://avahi.org/wiki/PythonPublishExample
	def __init__(self, name, stype, host, port):
		self.name = name
		self.stype = stype
		self.domain = 'local'
		self.host = host
		self.port = port
		self.systemBus = dbus.SystemBus()
		self.server = dbus.Interface(self.systemBus.get_object(avahi.DBUS_NAME, avahi.DBUS_PATH_SERVER), avahi.DBUS_INTERFACE_SERVER)

	def publish(self):
		self.group = dbus.Interface(
			self.systemBus.get_object(avahi.DBUS_NAME, self.server.EntryGroupNew()),
			avahi.DBUS_INTERFACE_ENTRY_GROUP)

		self.group.AddService(
			avahi.IF_UNSPEC,	#interface
			avahi.PROTO_UNSPEC,	#protocol
			dbus.UInt32(0),		#flags
			self.name, self.stype,
			self.domain, self.host,
			dbus.UInt16(self.port),
			avahi.string_array_to_txt_array([]))
		self.group.Commit()

	def unpublish(self):
		self.group.Reset()

class HTTPServerV6(BaseHTTPServer.HTTPServer):
  address_family = socket.AF_INET6

def main(args):
	import optparse
	parser = optparse.OptionParser()
	parser.add_option("-F", "--foreground", action="store_true", dest="no_daemon", default=False,
		              help="run pkgdistcache-daemon in foreground")
	(options, args) = parser.parse_args()
	if options.no_daemon == False:
		# fork daemon in background
		daemonize()

	# load configuration file
	conf_file = '/etc/pkgdistcache.conf'
	if os.path.isfile(conf_file):
		config = eval(open(conf_file).read())
	else:
		printerr("Config file " + conf_file + " not found")
		return 2
	
	port = config['port']
	hostname = runcmd('hostname')['stdout']
	global avahi_service
	avahi_service = AvahiPublisher(hostname, '_pkgdistcache._tcp', '', port)
	avahi_service.publish()
	
	os.chdir('/var/cache/pacman/pkg')
	handler = SimpleHTTPServer.SimpleHTTPRequestHandler
	httpd = HTTPServerV6(('', port), handler)

	try:
		httpd.serve_forever()
	except KeyboardInterrupt:
		avahi_service.unpublish()

	return 0

if __name__ == '__main__':
	signal.signal(signal.SIGTERM, terminate)
	main(sys.argv)