#!/usr/bin/env python3.1

import postgresql.api, re, sys

# wrapper around syslog, can be muted
class Logger:
	__slots__ = frozenset(['_syslog'])

	def __init__(self):
		config.section('log')

	def notice(self, message):
		if self._syslog:
			self._syslog.syslog(self._syslog.LOG_NOTICE, message)

# wrapper around database
class tagDB:
	__slots__ = frozenset(('_check_stmt', '_db', '_dump_stmt'))

	def __init__(self):
		config.section('database')
		self._db = postgresql.open(
			'pq://{}:{}@{}/{}'.format(
				config['user'],
				config['password'],
				config['host'],
				config['database'],
		) )
		self._check_stmt = None
		self._dump_stmt = None

	def check(self, site, ip_address):
		if self._check_stmt == None:
			self._check_stmt = self._db.prepare("select redirect_url, regexp from site_rule where site <@ tripdomain($1) and netmask >> $2::text::inet order by array_length(site, 1) desc")
		return(self._check_stmt(site, ip_address))

	def dump(self):
		if self._dump_stmt == None:
			self._dump_stmt = self._db.prepare("select untrip(site), tag, regexp from urls natural join site natural join tag order by site, tag")
		return(self._dump_stmt())

# abstract class with basic checking functionality
class Checker:
	__slots__ = frozenset(['_db', '_log'])

	def __init__(self):
		self._db = tagDB()
		self._log = Logger()

			self.check(line)

# threaded checking facility
class CheckerThread(Checker):
	__slots__ = frozenset(['_lock', '_lock_exit', '_lock_queue', '_queue'])

	def __init__(self):
		import _thread

		# basic initialisation
		Checker.__init__(self)

		# Spin lock. Loop acquires it on start then releases it when holding queue
		# lock. This way the thread proceeds without stops while queue has data and
		# gets stalled when no data present. The lock is released by queue writer
		# after storing something into the queue

	def process(self, id, site, ip_address, url_path, line):
		# simply adding data to the queue
		self._queue.append((id, site, ip_address, url_path))
		self._log.info('request {} queued ({})\n'.format(id, line))

# this classes processes config file and substitutes default values
class Config:
	__slots__ = frozenset(['_config', '_default', '_section', 'options'])
	_default = {
		'reactor': {
			'reactor': 'thread',
		},
		'log': {
			'silent': 'no',
		},
		'database': {
			'host': 'localhost',
			'database': 'squidTag',
	},}

	# function to read in config file
	def __init__(self):
		import configparser, optparse, os

		parser = optparse.OptionParser()
		parser.add_option('-c', '--config', dest = 'config',
			help = 'config file location', metavar = 'FILE',
			default = '/usr/local/etc/squid-tagger.conf')
		parser.add_option('-d', '--dump', dest = 'dump',
			help = 'dump database', action = 'store_true', metavar = 'bool',
			default = False)

		(self.options, args) = parser.parse_args()

		assert os.access(self.options.config, os.R_OK), "Fatal error: can't read {}".format(self.options.config)

		self._config = configparser.ConfigParser()
		self._config.readfp(open(self.options.config))

	# function to select config file section or create one
	def section(self, section):
		if not self._config.has_section(section):
			self._config.add_section(section)
		self._section = section

			else:
				self._config.set(self._section, name, None)
		return(self._config.get(self._section, name))

# initializing and reading in config file
config = Config()

if config.options.dump:
	# dumping database
	import csv

	tagdb = tagDB()

	csv_writer = csv.writer(sys.stdout)
	csv_writer.writerow(['site', 'tags', 'regexp'])
	for row in tagdb.dump():
		csv_writer.writerow([row[0], '{' + ','.join(row[1]) + '}', row[2]])

else:
	# main loop
	config.section('reactor')
	if config['reactor'] == 'thread':
		checker = CheckerThread()
	elif config['reactor'] == 'plain':
		checker = Checker()
	elif config['reactor'] == 'kqueue':
		checker = CheckerKqueue()

	checker.loop()