##
## Copyright (C) 2006 Gajim Team
##
## 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; version 2 only.
##
## 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.
##

"""
Handles Jingle sessions (XEP 0166)
"""

#TODO:
# * 'senders' attribute of 'content' element
# * security preconditions
# * actions:
#   - content-modify
#   - session-info
#   - security-info
#   - transport-accept, transport-reject
#   - Tie-breaking
# * timeout

import gajim #Get rid of that?
import xmpp
from jingle_transport import get_jingle_transport
from jingle_content import get_jingle_content, JingleContentSetupException
from common.connection_handlers_events import *

# FIXME: Move it to JingleSession.States?
class JingleStates(object):
    """
    States in which jingle session may exist
    """
    ended = 0
    pending = 1
    active = 2

class OutOfOrder(Exception):
    """
    Exception that should be raised when an action is received when in the wrong
    state
    """

class TieBreak(Exception):
    """
    Exception that should be raised in case of a tie, when we overrule the other
    action
    """

class JingleSession(object):
    """
    This represents one jingle session, that is, one or more content types
    negotiated between an initiator and a responder.
    """

    def __init__(self, con, weinitiate, jid, sid=None):
        """
        con -- connection object,
        weinitiate -- boolean, are we the initiator?
        jid - jid of the other entity
        """
        self.contents = {} # negotiated contents
        self.connection = con # connection to use
        # our full jid
        #FIXME: Get rid of gajim here?
        self.ourjid = gajim.get_jid_from_account(self.connection.name)
        if con.server_resource:
            self.ourjid = self.ourjid + '/' + con.server_resource
        self.peerjid = jid # jid we connect to
        # jid we use as the initiator
        self.initiator = weinitiate and self.ourjid or self.peerjid
        # jid we use as the responder
        self.responder = weinitiate and self.peerjid or self.ourjid
        # are we an initiator?
        self.weinitiate = weinitiate
        # what state is session in? (one from JingleStates)
        self.state = JingleStates.ended
        if not sid:
            sid = con.connection.getAnID()
        self.sid = sid # sessionid

        self.accepted = True # is this session accepted by user

        # callbacks to call on proper contents
        # use .prepend() to add new callbacks, especially when you're going
        # to send error instead of ack
        self.callbacks = {
                'content-accept':       [self.__on_content_accept, self.__broadcast,
                        self.__ack],
                'content-add':          [self.__on_content_add, self.__broadcast,
                        self.__ack], #TODO
                'content-modify':       [self.__ack], #TODO
                'content-reject':       [self.__ack, self.__on_content_remove], #TODO
                'content-remove':       [self.__ack, self.__on_content_remove],
                'description-info':     [self.__broadcast, self.__ack], #TODO
                'security-info':        [self.__ack], #TODO
                'session-accept':       [self.__on_session_accept, self.__on_content_accept,
                        self.__broadcast, self.__ack],
                'session-info':         [self.__broadcast, self.__on_session_info, self.__ack],
                'session-initiate':     [self.__on_session_initiate, self.__broadcast,
                        self.__ack],
                'session-terminate':    [self.__on_session_terminate, self.__broadcast_all,
                        self.__ack],
                'transport-info':       [self.__broadcast, self.__ack],
                'transport-replace':    [self.__broadcast, self.__on_transport_replace], #TODO
                'transport-accept':     [self.__ack], #TODO
                'transport-reject':     [self.__ack], #TODO
                'iq-result':            [],
                'iq-error':             [self.__on_error],
        }

    def approve_session(self):
        """
        Called when user accepts session in UI (when we aren't the initiator)
        """
        self.accept_session()

    def decline_session(self):
        """
        Called when user declines session in UI (when we aren't the initiator)
        """
        reason = xmpp.Node('reason')
        reason.addChild('decline')
        self._session_terminate(reason)

    def approve_content(self, media):
        content = self.get_content(media)
        if content:
            content.accepted = True
            self.on_session_state_changed(content)

    def reject_content(self, media):
        content = self.get_content(media)
        if content:
            if self.state == JingleStates.active:
                self.__content_reject(content)
            content.destroy()
            self.on_session_state_changed()

    def end_session(self):
        """
        Called when user stops or cancel session in UI
        """
        reason = xmpp.Node('reason')
        if self.state == JingleStates.active:
            reason.addChild('success')
        else:
            reason.addChild('cancel')
        self._session_terminate(reason)

    def get_content(self, media=None):
        if media is None:
            return

        for content in self.contents.values():
            if content.media == media:
                return content

    def add_content(self, name, content, creator='we'):
        """
        Add new content to session. If the session is active, this will send
        proper stanza to update session

        Creator must be one of ('we', 'peer', 'initiator', 'responder')
        """
        assert creator in ('we', 'peer', 'initiator', 'responder')

        if (creator == 'we' and self.weinitiate) or (creator == 'peer' and \
        not self.weinitiate):
            creator = 'initiator'
        elif (creator == 'peer' and self.weinitiate) or (creator == 'we' and \
        not self.weinitiate):
            creator = 'responder'
        content.creator = creator
        content.name = name
        self.contents[(creator, name)] = content

        if (creator == 'initiator') == self.weinitiate:
            # The content is from us, accept it
            content.accepted = True

    def remove_content(self, creator, name, reason=None):
        """
        Remove the content `name` created by `creator`
        by sending content-remove, or by sending session-terminate if
        there is no content left.
        """
        if (creator, name) in self.contents:
            content = self.contents[(creator, name)]
            self.__content_remove(content, reason)
            self.contents[(creator, name)].destroy()

    def modify_content(self, creator, name, *someother):
        """
        We do not need this now
        """
        pass

    def on_session_state_changed(self, content=None):
        if self.state == JingleStates.ended:
            # Session not yet started, only one action possible: session-initiate
            if self.is_ready() and self.weinitiate:
                self.__session_initiate()
        elif self.state == JingleStates.pending:
            # We can either send a session-accept or a content-add
            if self.is_ready() and not self.weinitiate:
                self.__session_accept()
            elif content and (content.creator == 'initiator') == self.weinitiate:
                self.__content_add(content)
            elif content and self.weinitiate:
                self.__content_accept(content)
        elif self.state == JingleStates.active:
            # We can either send a content-add or a content-accept
            if not content:
                return
            if (content.creator == 'initiator') == self.weinitiate:
                # We initiated this content. It's a pending content-add.
                self.__content_add(content)
            else:
                # The other side created this content, we accept it.
                self.__content_accept(content)

    def is_ready(self):
        """
        Return True when all codecs and candidates are ready (for all contents)
        """
        return (any((content.is_ready() for content in self.contents.itervalues()))
                and self.accepted)

    def accept_session(self):
        """
        Mark the session as accepted
        """
        self.accepted = True
        self.on_session_state_changed()

    def start_session(self):
        """
        Mark the session as ready to be started
        """
        self.accepted = True
        self.on_session_state_changed()

    def send_session_info(self):
        pass

    def send_content_accept(self, content):
        assert self.state != JingleStates.ended
        stanza, jingle = self.__make_jingle('content-accept')
        jingle.addChild(node=content)
        self.connection.connection.send(stanza)

    def send_transport_info(self, content):
        assert self.state != JingleStates.ended
        stanza, jingle = self.__make_jingle('transport-info')
        jingle.addChild(node=content)
        self.connection.connection.send(stanza)

    def send_description_info(self, content):
        assert self.state != JingleStates.ended
        stanza, jingle = self.__make_jingle('description-info')
        jingle.addChild(node=content)
        self.connection.connection.send(stanza)

    def on_stanza(self, stanza):
        """
        A callback for ConnectionJingle. It gets stanza, then tries to send it to
        all internally registered callbacks. First one to raise
        xmpp.NodeProcessed breaks function
        """
        jingle = stanza.getTag('jingle')
        error = stanza.getTag('error')
        if error:
            # it's an iq-error stanza
            action = 'iq-error'
        elif jingle:
            # it's a jingle action
            action = jingle.getAttr('action')
            if action not in self.callbacks:
                self.__send_error(stanza, 'bad-request')
                return
            # FIXME: If we aren't initiated and it's not a session-initiate...
            if action != 'session-initiate' and self.state == JingleStates.ended:
                self.__send_error(stanza, 'item-not-found', 'unknown-session')
                return
        else:
            # it's an iq-result (ack) stanza
            action = 'iq-result'

        callables = self.callbacks[action]

        try:
            for callable in callables:
                callable(stanza=stanza, jingle=jingle, error=error, action=action)
        except xmpp.NodeProcessed:
            pass
        except TieBreak:
            self.__send_error(stanza, 'conflict', 'tiebreak')
        except OutOfOrder:
            # FIXME
            self.__send_error(stanza, 'unexpected-request', 'out-of-order')

    def __ack(self, stanza, jingle, error, action):
        """
        Default callback for action stanzas -- simple ack and stop processing
        """
        response = stanza.buildReply('result')
        self.connection.connection.send(response)

    def __on_error(self, stanza, jingle, error, action):
        # FIXME
        text = error.getTagData('text')
        error_name = None
        for child in error.getChildren():
            if child.getNamespace() == xmpp.NS_JINGLE_ERRORS:
                error_name = child.getName()
                break
            elif child.getNamespace() == xmpp.NS_STANZAS:
                error_name = child.getName()
        self.__dispatch_error(error_name, text, error.getAttr('type'))
        # FIXME: Not sure when we would want to do that...

    def __on_transport_replace(self, stanza, jingle, error, action):
        for content in jingle.iterTags('content'):
            creator = content['creator']
            name = content['name']
            if (creator, name) in self.contents:
                transport_ns = content.getTag('transport').getNamespace()
                if transport_ns == xmpp.JINGLE_ICE_UDP:
                    # FIXME: We don't manage anything else than ICE-UDP now...
                    # What was the previous transport?!?
                    # Anyway, content's transport is not modifiable yet
                    pass
                else:
                    stanza, jingle = self.__make_jingle('transport-reject')
                    content = jingle.setTag('content', attrs={'creator': creator,
                            'name': name})
                    content.setTag('transport', namespace=transport_ns)
                    self.connection.connection.send(stanza)
                    raise xmpp.NodeProcessed
            else:
                # FIXME: This ressource is unknown to us, what should we do?
                # For now, reject the transport
                stanza, jingle = self.__make_jingle('transport-reject')
                c = jingle.setTag('content', attrs={'creator': creator,
                        'name': name})
                c.setTag('transport', namespace=transport_ns)
                self.connection.connection.send(stanza)
                raise xmpp.NodeProcessed

    def __on_session_info(self, stanza, jingle, error, action):
        # TODO: ringing, active, (un)hold, (un)mute
        payload = jingle.getPayload()
        if payload:
            self.__send_error(stanza, 'feature-not-implemented', 'unsupported-info', type_='modify')
            raise xmpp.NodeProcessed

    def __on_content_remove(self, stanza, jingle, error, action):
        for content in jingle.iterTags('content'):
            creator = content['creator']
            name = content['name']
            if (creator, name) in self.contents:
                content = self.contents[(creator, name)]
                # TODO: this will fail if content is not an RTP content
                gajim.nec.push_incoming_event(JingleDisconnectedReceivedEvent(
                    None, conn=self.connection, jingle_session=self,
                    media=content.media, reason='removed'))
                content.destroy()
        if not self.contents:
            reason = xmpp.Node('reason')
            reason.setTag('success')
            self._session_terminate(reason)

    def __on_session_accept(self, stanza, jingle, error, action):
        # FIXME
        if self.state != JingleStates.pending:
            raise OutOfOrder
        self.state = JingleStates.active

    def __on_content_accept(self, stanza, jingle, error, action):
        """
        Called when we get content-accept stanza or equivalent one (like
        session-accept)
        """
        # check which contents are accepted
        for content in jingle.iterTags('content'):
            creator = content['creator']
            # TODO
            name = content['name']

    def __on_content_add(self, stanza, jingle, error, action):
        if self.state == JingleStates.ended:
            raise OutOfOrder

        parse_result = self.__parse_contents(jingle)
        contents = parse_result[0]
        rejected_contents = parse_result[1]

        for name, creator in rejected_contents:
            # TODO
            content = JingleContent()
            self.add_content(name, content, creator)
            self.__content_reject(content)
            self.contents[(content.creator, content.name)].destroy()

        gajim.nec.push_incoming_event(JingleRequestReceivedEvent(None,
            conn=self.connection, jingle_session=self, contents=contents))

    def __on_session_initiate(self, stanza, jingle, error, action):
        """
        We got a jingle session request from other entity, therefore we are the
        receiver... Unpack the data, inform the user
        """
        if self.state != JingleStates.ended:
            raise OutOfOrder

        self.initiator = jingle['initiator']
        self.responder = self.ourjid
        self.peerjid = self.initiator
        self.accepted = False   # user did not accept this session yet

        # TODO: If the initiator is unknown to the receiver (e.g., via presence
        # subscription) and the receiver has a policy of not communicating via
        # Jingle with unknown entities, it SHOULD return a <service-unavailable/>
        # error.

        # Check if there's already a session with this user:
        for session in self.connection.iter_jingle_sessions(self.peerjid):
            if not session is self:
                reason = xmpp.Node('reason')
                alternative_session = reason.setTag('alternative-session')
                alternative_session.setTagData('sid', session.sid)
                self.__ack(stanza, jingle, error, action)
                self._session_terminate(reason)
                raise xmpp.NodeProcessed

        # Lets check what kind of jingle session does the peer want
        contents, contents_rejected, reason_txt = self.__parse_contents(jingle)

        # If there's no content we understand...
        if not contents:
            # TODO: http://xmpp.org/extensions/xep-0166.html#session-terminate
            reason = xmpp.Node('reason')
            reason.setTag(reason_txt)
            self.__ack(stanza, jingle, error, action)
            self._session_terminate(reason)
            raise xmpp.NodeProcessed

        self.state = JingleStates.pending

        # Send event about starting a session
        gajim.nec.push_incoming_event(JingleRequestReceivedEvent(None,
            conn=self.connection, jingle_session=self, contents=contents))

    def __broadcast(self, stanza, jingle, error, action):
        """
        Broadcast the stanza contents to proper content handlers
        """
        for content in jingle.iterTags('content'):
            name = content['name']
            creator = content['creator']
            if (creator, name) not in self.contents:
                text = 'Content %s (created by %s) does not exist' % (name, creator)
                self.__send_error(stanza, 'bad-request', text=text, type_='_modify')
                raise xmpp.NodeProcessed
            else:
                cn = self.contents[(creator, name)]
                cn.on_stanza(stanza, content, error, action)

    def __on_session_terminate(self, stanza, jingle, error, action):
        self.connection.delete_jingle_session(self.sid)
        reason, text = self.__reason_from_stanza(jingle)
        if reason not in ('success', 'cancel', 'decline'):
            self.__dispatch_error(reason, text)
        if text:
            text = '%s (%s)' % (reason, text)
        else:
            # TODO
            text = reason
        gajim.nec.push_incoming_event(JingleDisconnectedReceivedEvent(None,
            conn=self.connection, jingle_session=self, media=None,
            reason=text))

    def __broadcast_all(self, stanza, jingle, error, action):
        """
        Broadcast the stanza to all content handlers
        """
        for content in self.contents.itervalues():
            content.on_stanza(stanza, None, error, action)

    def __parse_contents(self, jingle):
        # TODO: Needs some reworking
        contents = []
        contents_rejected = []
        reasons = set()

        for element in jingle.iterTags('content'):
            transport = get_jingle_transport(element.getTag('transport'))
            content_type = get_jingle_content(element.getTag('description'))
            if content_type:
                try:
                    if transport:
                        content = content_type(self, transport)
                        self.add_content(element['name'],
                                content, 'peer')
                        contents.append((content.media,))
                    else:
                        reasons.add('unsupported-transports')
                        contents_rejected.append((element['name'], 'peer'))
                except JingleContentSetupException:
                    reasons.add('failed-application')
            else:
                contents_rejected.append((element['name'], 'peer'))
                reasons.add('unsupported-applications')

        failure_reason = None

        # Store the first reason of failure
        for reason in ('failed-application', 'unsupported-transports',
                'unsupported-applications'):
            if reason in reasons:
                failure_reason = reason
                break

        return (contents, contents_rejected, failure_reason)

    def __dispatch_error(self, error=None, text=None, type_=None):
        if text:
            text = '%s (%s)' % (error, text)
        if type_ != 'modify':
            gajim.nec.push_incoming_event(JingleErrorReceivedEvent(None,
                conn=self.connection, jingle_session=self,
                reason=text or error))

    def __reason_from_stanza(self, stanza):
        # TODO: Move to GUI?
        reason = 'success'
        reasons = ['success', 'busy', 'cancel', 'connectivity-error',
                'decline', 'expired', 'failed-application', 'failed-transport',
                'general-error', 'gone', 'incompatible-parameters', 'media-error',
                'security-error', 'timeout', 'unsupported-applications',
                'unsupported-transports']
        tag = stanza.getTag('reason')
        text = ''
        if tag:
            text = tag.getTagData('text')
            for r in reasons:
                if tag.getTag(r):
                    reason = r
                    break
        return (reason, text)

    def __make_jingle(self, action, reason=None):
        stanza = xmpp.Iq(typ='set', to=xmpp.JID(self.peerjid))
        attrs = {'action': action,
                'sid': self.sid}
        if action == 'session-initiate':
            attrs['initiator'] = self.initiator
        elif action == 'session-accept':
            attrs['responder'] = self.responder
        jingle = stanza.addChild('jingle', attrs=attrs, namespace=xmpp.NS_JINGLE)
        if reason is not None:
            jingle.addChild(node=reason)
        return stanza, jingle

    def __send_error(self, stanza, error, jingle_error=None, text=None, type_=None):
        err_stanza = xmpp.Error(stanza, '%s %s' % (xmpp.NS_STANZAS, error))
        err = err_stanza.getTag('error')
        if type_:
            err.setAttr('type', type_)
        if jingle_error:
            err.setTag(jingle_error, namespace=xmpp.NS_JINGLE_ERRORS)
        if text:
            err.setTagData('text', text)
        self.connection.connection.send(err_stanza)
        self.__dispatch_error(jingle_error or error, text, type_)

    def __append_content(self, jingle, content):
        """
        Append <content/> element to <jingle/> element, with (full=True) or
        without (full=False) <content/> children
        """
        jingle.addChild('content',
                attrs={'name': content.name, 'creator': content.creator})

    def __append_contents(self, jingle):
        """
        Append all <content/> elements to <jingle/>
        """
        # TODO: integrate with __appendContent?
        # TODO: parameters 'name', 'content'?
        for content in self.contents.values():
            if content.is_ready():
                self.__append_content(jingle, content)

    def __session_initiate(self):
        assert self.state == JingleStates.ended
        stanza, jingle = self.__make_jingle('session-initiate')
        self.__append_contents(jingle)
        self.__broadcast(stanza, jingle, None, 'session-initiate-sent')
        self.connection.connection.send(stanza)
        self.state = JingleStates.pending

    def __session_accept(self):
        assert self.state == JingleStates.pending
        stanza, jingle = self.__make_jingle('session-accept')
        self.__append_contents(jingle)
        self.__broadcast(stanza, jingle, None, 'session-accept-sent')
        self.connection.connection.send(stanza)
        self.state = JingleStates.active

    def __session_info(self, payload=None):
        assert self.state != JingleStates.ended
        stanza, jingle = self.__make_jingle('session-info')
        if payload:
            jingle.addChild(node=payload)
        self.connection.connection.send(stanza)

    def _session_terminate(self, reason=None):
        assert self.state != JingleStates.ended
        stanza, jingle = self.__make_jingle('session-terminate', reason=reason)
        self.__broadcast_all(stanza, jingle, None, 'session-terminate-sent')
        if self.connection.connection and self.connection.connected >= 2:
            self.connection.connection.send(stanza)
        # TODO: Move to GUI?
        reason, text = self.__reason_from_stanza(jingle)
        if reason not in ('success', 'cancel', 'decline'):
            self.__dispatch_error(reason, text)
        if text:
            text = '%s (%s)' % (reason, text)
        else:
            text = reason
        self.connection.delete_jingle_session(self.sid)
        gajim.nec.push_incoming_event(JingleDisconnectedReceivedEvent(None,
            conn=self.connection, jingle_session=self, media=None,
            reason=text))

    def __content_add(self, content):
        # TODO: test
        assert self.state != JingleStates.ended
        stanza, jingle = self.__make_jingle('content-add')
        self.__append_content(jingle, content)
        self.__broadcast(stanza, jingle, None, 'content-add-sent')
        self.connection.connection.send(stanza)

    def __content_accept(self, content):
        # TODO: test
        assert self.state != JingleStates.ended
        stanza, jingle = self.__make_jingle('content-accept')
        self.__append_content(jingle, content)
        self.__broadcast(stanza, jingle, None, 'content-accept-sent')
        self.connection.connection.send(stanza)

    def __content_reject(self, content):
        assert self.state != JingleStates.ended
        stanza, jingle = self.__make_jingle('content-reject')
        self.__append_content(jingle, content)
        self.connection.connection.send(stanza)
        # TODO: this will fail if content is not an RTP content
        gajim.nec.push_incoming_event(JingleDisconnectedReceivedEvent(None,
            conn=self.connection, jingle_session=self, media=content.media,
            reason='rejected'))

    def __content_modify(self):
        assert self.state != JingleStates.ended

    def __content_remove(self, content, reason=None):
        assert self.state != JingleStates.ended
        if self.connection.connection and self.connection.connected > 1:
            stanza, jingle = self.__make_jingle('content-remove', reason=reason)
            self.__append_content(jingle, content)
            self.connection.connection.send(stanza)
        # TODO: this will fail if content is not an RTP content
        gajim.nec.push_incoming_event(JingleDisconnectedReceivedEvent(None,
            conn=self.connection, jingle_session=self, media=content.media,
            reason='removed'))

    def content_negotiated(self, media):
        gajim.nec.push_incoming_event(JingleConnectedReceivedEvent(None,
            conn=self.connection, jingle_session=self, media=media))
