# -*- coding:utf-8 -*-
## src/common/caps.py
##
## Copyright (C) 2007 Tomasz Melcer <liori AT exroot.org>
##                    Travis Shirk <travis AT pobox.com>
## Copyright (C) 2007-2008 Yann Leboulanger <asterix AT lagaule.org>
## Copyright (C) 2008 Brendan Taylor <whateley AT gmail.com>
##                    Jonathan Schleifer <js-gajim AT webkeks.org>
## Copyright (C) 2008-2009 Stephan Erb <steve-e AT h3c.de>
##
## This file is part of Gajim.
##
## Gajim is free software; you can redistribute it and/or modify
## it under the terms of the GNU General Public License as published
## by the Free Software Foundation; version 3 only.
##
## Gajim is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
## GNU General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with Gajim. If not, see <http://www.gnu.org/licenses/>.
##

'''
Module containing all XEP-115 (Entity Capabilities) related classes 

Basic Idea:
CapsCache caches features to hash relationships. The cache is queried
through ClientCaps objects which are hold by contact instances. 
''' 

import gajim
import helpers

from common.xmpp import NS_XHTML_IM, NS_RECEIPTS, NS_ESESSION, NS_CHATSTATES
# Features where we cannot safely assume that the other side supports them
FEATURE_BLACKLIST = [NS_CHATSTATES, NS_XHTML_IM, NS_RECEIPTS, NS_ESESSION]


class AbstractClientCaps(object):
	'''
	Base class representing a client and its capabilities as advertised by
	a caps tag in a presence. 
	'''
	def __init__(self, caps_hash, node):
		self._hash = caps_hash
		self._node = node
		
	def get_discover_strategy(self):
		return self._discover
							
	def _discover(self, connection, jid):
		''' To be implemented by subclassess '''
		raise NotImplementedError()
	
	def get_cache_lookup_strategy(self):
		return self._lookup_in_cache
	
	def _lookup_in_cache(self, caps_cache):
		''' To be implemented by subclassess '''
		raise NotImplementedError()
	
	def get_hash_validation_strategy(self):
		return self._is_hash_valid
					
	def _is_hash_valid(self, identities, features, dataforms):
		raise NotImplementedError()		
	
	
class ClientCaps(AbstractClientCaps):
	''' The current XEP-115 implementation '''
	
	def __init__(self, caps_hash, node, hash_method):
		AbstractClientCaps.__init__(self, caps_hash, node)
		assert hash_method != 'old'
		self._hash_method = hash_method
	
	def _lookup_in_cache(self, caps_cache):
		return caps_cache[(self._hash_method, self._hash)]
	
	def _discover(self, connection, jid):
		connection.discoverInfo(jid, '%s#%s' % (self._node, self._hash))
				
	def _is_hash_valid(self, identities, features, dataforms):
		computed_hash = helpers.compute_caps_hash(identities, features,
				dataforms=dataforms, hash_method=self._hash_method)
		return computed_hash == self._hash	
	
	
class OldClientCaps(AbstractClientCaps):
	''' Old XEP-115 implemtation. Kept around for background competability.  '''
	
	def __init__(self, caps_hash, node):
		AbstractClientCaps.__init__(self, caps_hash, node)

	def _lookup_in_cache(self, caps_cache):
		return caps_cache[('old', self._node + '#' + self._hash)]
	
	def _discover(self, connection, jid):
		connection.discoverInfo(jid)
		
	def _is_hash_valid(self, identities, features, dataforms):
		return True	
		
		
class NullClientCaps(AbstractClientCaps):
	'''
	This is a NULL-Object to streamline caps handling if a client has not
	advertised any caps or has advertised them in an improper way. 
	
	Assumes (almost) everything is supported.
	''' 
	
	def __init__(self):
		AbstractClientCaps.__init__(self, None, None)
	
	def _lookup_in_cache(self, caps_cache):
		return caps_cache[('old', '')]
	
	def _discover(self, connection, jid):
		pass

	def _is_hash_valid(self, identities, features, dataforms):
		return False	


class CapsCache(object):
	''' 
	This object keeps the mapping between caps data and real disco
	features they represent, and provides simple way to query that info.
	'''
	def __init__(self, logger=None):
		# our containers:
		# __cache is a dictionary mapping: pair of hash method and hash maps
		#   to CapsCacheItem object
		# __CacheItem is a class that stores data about particular
		#   client (hash method/hash pair)
		self.__cache = {}

		class CacheItem(object):
			# __names is a string cache; every string long enough is given
			#   another object, and we will have plenty of identical long
			#   strings. therefore we can cache them
			__names = {}
			
			def __init__(self, hash_method, hash_, logger):
				# cached into db
				self.hash_method = hash_method
				self.hash = hash_
				self._features = []
				self._identities = []
				self._logger = logger

				# not cached into db:
				# have we sent the query?
				# 0 == not queried
				# 1 == queried
				# 2 == got the answer
				self.queried = 0

			def _get_features(self):
				return self._features

			def _set_features(self, value):
				self._features = []
				for feature in value:
					self._features.append(self.__names.setdefault(feature, feature))
					
			features = property(_get_features, _set_features)

			def _get_identities(self):
				list_ = []
				for i in self._identities:
					# transforms it back in a dict
					d = dict()
					d['category'] = i[0]
					if i[1]:
						d['type'] = i[1]
					if i[2]:
						d['xml:lang'] = i[2]
					if i[3]:
						d['name'] = i[3]
					list_.append(d)
				return list_
			
			def _set_identities(self, value):
				self._identities = []
				for identity in value:
					# dict are not hashable, so transform it into a tuple
					t = (identity['category'], identity.get('type'),
						identity.get('xml:lang'), identity.get('name'))
					self._identities.append(self.__names.setdefault(t, t))
					
			identities = property(_get_identities, _set_identities)

			def update(self, identities, features):
				self.identities = identities
				self.features = features
				self._logger.add_caps_entry(self.hash_method, self.hash,
					identities, features)

		self.__CacheItem = CacheItem

		# prepopulate data which we are sure of; note: we do not log these info
		for account in gajim.connections:
			gajimcaps = self[('sha-1', gajim.caps_hash[account])]
			gajimcaps.identities = [gajim.gajim_identity]
			gajimcaps.features = gajim.gajim_common_features + \
				gajim.gajim_optional_features[account]

		# start logging data from the net
		self.logger = logger

	def initialize_from_db(self):
		# get data from logger...
		if self.logger is not None:
			for hash_method, hash_, identities, features in \
			self.logger.iter_caps_data():
				x = self[(hash_method, hash_)]
				x.identities = identities
				x.features = features
				x.queried = 2

	def __getitem__(self, caps):
		if caps in self.__cache:
			return self.__cache[caps]

		hash_method, hash_ = caps

		x = self.__CacheItem(hash_method, hash_, self.logger)
		self.__cache[(hash_method, hash_)] = x
		return x

	def query_client_of_jid_if_unknown(self, connection, jid, client_caps):
		'''
		Start a disco query to determine caps (node, ver, exts).
		Won't query if the data is already in cache.
		'''
		lookup_cache_item = client_caps.get_cache_lookup_strategy()
		q = lookup_cache_item(self)	
		
		if q.queried == 0:
			# do query for bare node+hash pair
			# this will create proper object
			q.queried = 1
			discover = client_caps.get_discover_strategy()
			discover(connection, jid)

gajim.capscache = CapsCache(gajim.logger)


class ConnectionCaps(object):
	'''
	This class highly depends on that it is a part of Connection class.
	'''
	def _capsPresenceCB(self, con, presence):
		'''
		Handle incoming presence stanzas... This is a callback for xmpp
		registered in connection_handlers.py
		'''
		# we will put these into proper Contact object and ask
		# for disco... so that disco will learn how to interpret
		# these caps
		pm_ctrl = None
		try:
			jid = helpers.get_full_jid_from_iq(presence)
		except:
			# Bad jid
			return
		contact = gajim.contacts.get_contact_from_full_jid(self.name, jid)
		if contact is None:
			room_jid, nick = gajim.get_room_and_nick_from_fjid(jid)
			contact = gajim.contacts.get_gc_contact(
				self.name, room_jid, nick)
			pm_ctrl = gajim.interface.msg_win_mgr.get_control(jid, self.name)
			if contact is None:
				# TODO: a way to put contact not-in-roster
				# into Contacts
				return

		caps_tag = presence.getTag('c')
		if not caps_tag:
			# presence did not contain caps_tag
			client_caps = NullClientCaps()
		else:
			hash_method, node, caps_hash = caps_tag['hash'], caps_tag['node'], caps_tag['ver']

			if node is None or caps_hash is None:
				# improper caps in stanza, ignore client capabilities.
				client_caps = NullClientCaps()
			elif hash_method is None:
				client_caps = OldClientCaps(caps_hash, node)
			else:
				client_caps = ClientCaps(caps_hash, node, hash_method)
		
		gajim.capscache.query_client_of_jid_if_unknown(self, jid, client_caps)
		contact.client_caps = client_caps

		if pm_ctrl:
			pm_ctrl.update_contact()

	def _capsDiscoCB(self, jid, node, identities, features, dataforms):		
		contact = gajim.contacts.get_contact_from_full_jid(self.name, jid)
		if not contact:
			room_jid, nick = gajim.get_room_and_nick_from_fjid(jid)
			contact = gajim.contacts.get_gc_contact(self.name, room_jid, nick)
			if contact is None:
				return

		lookup = contact.client_caps.get_cache_lookup_strategy()
		cache_item = lookup(gajim.capscache)	
					
		if cache_item.queried == 2:
			return
		else:
			validate = contact.client_caps.get_hash_validation_strategy()
			hash_is_valid = validate(identities, features, dataforms)
			
			if hash_is_valid:
				cache_item.update(identities, features)
			else:
				contact.client_caps = NullClientCaps()

# vim: se ts=3: