#!/usr/bin/python
# -*- coding: utf-8 -*-

"""
SAT plugin for managing xep-0115
Copyright (C) 2009, 2010, 2011  Jérôme Poisson (goffi@goffi.org)

This program 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, either version 3 of the License, or
(at your option) any later version.

This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
"""

from logging import debug, info, error, warning
from twisted.words.xish import domish
from twisted.words.protocols.jabber import client, jid, xmlstream
from twisted.words.protocols.jabber import error as jab_error
from twisted.words.protocols.jabber.xmlstream import IQ
import os.path
import types

from zope.interface import implements

from wokkel import disco, iwokkel

from hashlib import sha1
from base64 import b64encode

try:
    from twisted.words.protocols.xmlstream import XMPPHandler
except ImportError:
    from wokkel.subprotocols import XMPPHandler

PRESENCE = '/presence'
NS_ENTITY_CAPABILITY = 'http://jabber.org/protocol/caps'
CAPABILITY_UPDATE = PRESENCE + '/c[@xmlns="' +  NS_ENTITY_CAPABILITY + '"]'

PLUGIN_INFO = {
"name": "XEP 0115 Plugin",
"import_name": "XEP_0115",
"type": "XEP",
"protocols": ["XEP-0115"],
"dependencies": [],
"main": "XEP_0115",
"handler": "yes",
"description": _("""Implementation of entity capabilities""")
}

class HashGenerationError(Exception):
    pass

class ByteIdentity(object):
    """This class manage identity as bytes (needed for i;octet sort),
    it is used for the hash generation"""

    def __init__(self, identity, lang=None):
        assert isinstance(identity, disco.DiscoIdentity)
        self.category = identity.category.encode('utf-8')
        self.idType = identity.type.encode('utf-8')
        self.name = identity.name.encode('utf-8') if identity.name else ''
        self.lang = lang.encode('utf-8') if lang else ''

    def __str__(self):
        return "%s/%s/%s/%s" % (self.category, self.idType, self.lang, self.name)
           

class XEP_0115():
    cap_hash = None

    def __init__(self, host):
        info(_("Plugin XEP_0115 initialization"))
        self.host = host
        host.trigger.add("Disco Handled", self.checkHash)
        self.hash_cache = host.memory.getPrivate("entity_capabilities_cache") or {}  #key = hash or jid
        self.jid_hash = {} #jid to hash mapping, map to a discoInfo if the hash method is unknown 

    def checkHash(self, profile):
        if not XEP_0115.cap_hash:
            XEP_0115.cap_hash = self.generateHash(profile)
        else:
            self.presenceHack(profile)
        return True
        
    def getHandler(self, profile):
        return XEP_0115_handler(self, profile)

    def presenceHack(self, profile):
        """modify SatPresenceProtocol to add capabilities data"""
        client=self.host.getClient(profile)
        presenceInst = client.presence
        c_elt = domish.Element((NS_ENTITY_CAPABILITY,'c'))
        c_elt['hash']='sha-1'
        c_elt['node']='http://wiki.goffi.org/wiki/Salut_%C3%A0_Toi'
        c_elt['ver']=XEP_0115.cap_hash
        presenceInst._c_elt = c_elt
        if "_legacy_send" in dir(presenceInst):
            debug('capabilities already added to presence instance')
            return
        def hacked_send(self, obj):
            obj.addChild(self._c_elt)
            self._legacy_send(obj)
        new_send = types.MethodType(hacked_send, presenceInst, presenceInst.__class__)
        presenceInst._legacy_send = presenceInst.send
        presenceInst.send = new_send


    def generateHash(self, profile_key="@DEFAULT@"):
        """This method generate a sha1 hash as explained in xep-0115 #5.1
        it then store it in XEP_0115.cap_hash"""
        profile = self.host.memory.getProfileName(profile_key)
        if not profile:
            error ('Requesting hash for an inexistant profile')
            raise HashGenerationError

        client = self.host.getClient(profile_key)
        if not client:
            error ('Requesting hash for an inexistant client')
            raise HashGenerationError
        
        def generateHash_2(services, profile):
            _s=[]
            byte_identities = [ByteIdentity(identity) for identity in filter(lambda x:isinstance(x,disco.DiscoIdentity),services)] #FIXME: lang must be managed here
            byte_identities.sort(key=lambda i:i.lang)
            byte_identities.sort(key=lambda i:i.idType)
            byte_identities.sort(key=lambda i:i.category)
            for identity in byte_identities:
                _s.append(str(identity))
                _s.append('<')
            byte_features = [feature.encode('utf-8') for feature in filter(lambda x:isinstance(x,disco.DiscoFeature),services)]
            byte_features.sort() #XXX: the default sort has the same behaviour as the requested RFC 4790 i;octet sort
            for feature in byte_features:
                _s.append(feature)
                _s.append('<')
            #TODO: manage XEP-0128 data form here
            XEP_0115.cap_hash = b64encode(sha1(''.join(_s)).digest())
            debug(_('Capability hash generated: [%s]') % XEP_0115.cap_hash)
            self.presenceHack(profile)
            
        services = client.discoHandler.info(client.jid, client.jid, '').addCallback(generateHash_2, profile)
   
class XEP_0115_handler(XMPPHandler):
    implements(iwokkel.IDisco)
   
    def __init__(self, plugin_parent, profile):
        self.plugin_parent = plugin_parent
        self.host = plugin_parent.host
        self.profile = profile

    def connectionInitialized(self):
        self.xmlstream.addObserver(CAPABILITY_UPDATE, self.update)
    
    def getDiscoInfo(self, requestor, target, nodeIdentifier=''):
        return [disco.DiscoFeature(NS_ENTITY_CAPABILITY)]

    def getDiscoItems(self, requestor, target, nodeIdentifier=''):
        return []

    def _updateCache(self, discoResult, from_jid, key):
        """Actually update the cache
        @param discoResult: result of the requestInfo
        @param known_hash: True if it's a hash method we know, we don't save the cache else"""
        if key:
            self.plugin_parent.jid_hash[from_jid] = key
            self.plugin_parent.hash_cache[key] = discoResult
        else:
            #No key, that mean unknown hash method
            self.plugin_parent.jid_hash[from_jid] = discoResult
        self.host.memory.setPrivate("entity_capabilities_cache", self.plugin_parent.hash_cache)


    def update(self, presence):
        """
        Manage the capabilities of the entity
        Check if we know the version of this capatilities
        and get the capibilities if necessary
        """
        from_jid = jid.JID(presence['from'])
        c_elem = filter (lambda x:x.name == "c", presence.elements())[0] #We only want the "c" element
        try:
            ver=c_elem['ver']
            hash=c_elem['hash']
            node=c_elem['node']
        except KeyError:
            warning('Received invalid capabilities tag')
            return
        if not self.plugin_parent.jid_hash.has_key(from_jid):
            if self.plugin_parent.hash_cache.has_key(ver):
                #we know that hash, we just link it with the jid
                self.plugin_parent.jid_hash[from_jid] = ver
            else:
                if hash!='sha-1':
                    #unknown hash method
                    warning('Unknown hash for entity capabilities: [%s]' % hash)
                self.parent.disco.requestInfo(from_jid).addCallback(self._updateCache, from_jid, ver if hash=='sha-1' else None )
        #TODO: me must manage the full algorithm described at XEP-0115 #5.4 part 3