#!/usr/bin/env python3


# SAT plugin for managing gateways (xep-0047)
# Copyright (C) 2009-2026 Jérôme Poisson (goffi@goffi.org)

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero 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 Affero General Public License for more details.

# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

from libervia.backend.core.i18n import _
from libervia.backend.core.log import getLogger

log = getLogger(__name__)
from libervia.backend.core.constants import Const as C
from libervia.backend.core import exceptions
from twisted.words.protocols.jabber import jid
from twisted.words.protocols.jabber import xmlstream
from twisted.words.protocols.jabber import error
from twisted.internet import reactor
from twisted.internet import defer
from twisted.python import failure

from tx_xmpp import disco, itx_xmpp

from zope.interface import implementer

import base64

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

MESSAGE = "/message"
IQ_SET = '/iq[@type="set"]'
NS_IBB = "http://jabber.org/protocol/ibb"
IBB_OPEN = IQ_SET + '/open[@xmlns="' + NS_IBB + '"]'
IBB_CLOSE = IQ_SET + '/close[@xmlns="' + NS_IBB + '" and @sid="{}"]'
IBB_IQ_DATA = IQ_SET + '/data[@xmlns="' + NS_IBB + '" and @sid="{}"]'
IBB_MESSAGE_DATA = MESSAGE + '/data[@xmlns="' + NS_IBB + '" and @sid="{}"]'
TIMEOUT = 120  # timeout for workflow
DEFER_KEY = "finished"  # key of the deferred used to track session end

PLUGIN_INFO = {
    C.PI_NAME: "In-Band Bytestream Plugin",
    C.PI_IMPORT_NAME: "XEP-0047",
    C.PI_TYPE: "XEP",
    C.PI_MODES: C.PLUG_MODE_BOTH,
    C.PI_PROTOCOLS: ["XEP-0047"],
    C.PI_MAIN: "XEP_0047",
    C.PI_HANDLER: "yes",
    C.PI_DESCRIPTION: _("""Implementation of In-Band Bytestreams"""),
}


class XEP_0047(object):
    NAMESPACE = NS_IBB
    BLOCK_SIZE = 4096

    def __init__(self, host):
        log.info(_("In-Band Bytestreams plugin initialization"))
        self.host = host

    def get_handler(self, client):
        return XEP_0047_handler(self)

    def profile_connected(self, client):
        client.xep_0047_current_stream = {}  # key: stream_id, value: data(dict)

    def _time_out(self, sid, client):
        """Delete current_stream id, called after timeout

        @param sid(unicode): session id of client.xep_0047_current_stream
        @param client: %(doc_client)s
        """
        log.info(
            "In-Band Bytestream: TimeOut reached for id {sid} [{profile}]".format(
                sid=sid, profile=client.profile
            )
        )
        self._kill_session(sid, client, "TIMEOUT")

    def _kill_session(self, sid, client, failure_reason=None):
        """Delete a current_stream id, clean up associated observers

        @param sid(unicode): session id
        @param client: %(doc_client)s
        @param failure_reason(None, unicode): if None the session is successful
            else, will be used to call failure_cb
        """
        try:
            session = client.xep_0047_current_stream[sid]
        except KeyError:
            log.warning("kill id called on a non existant id")
            return

        try:
            observer_cb = session["observer_cb"]
        except KeyError:
            pass
        else:
            client.xmlstream.removeObserver(session["event_data"], observer_cb)

        if session["timer"].active():
            session["timer"].cancel()

        del client.xep_0047_current_stream[sid]

        success = failure_reason is None
        stream_d = session[DEFER_KEY]

        if success:
            stream_d.callback(None)
        else:
            stream_d.errback(failure.Failure(exceptions.DataError(failure_reason)))

    def create_session(self, *args, **kwargs):
        """like [_create_session] but return the session deferred instead of the whole session

        session deferred is fired when transfer is finished
        """
        return self._create_session(*args, **kwargs)[DEFER_KEY]

    def _create_session(self, client, stream_object, local_jid, to_jid, sid):
        """Called when a bytestream is imminent

        @param stream_object(IConsumer): stream object where data will be written
        @param local_jid(jid.JID): same as [start_stream]
        @param to_jid(jid.JId): jid of the other peer
        @param sid(unicode): session id
        @return (dict): session data
        """
        if sid in client.xep_0047_current_stream:
            raise exceptions.ConflictError("A session with this id already exists !")
        session_data = client.xep_0047_current_stream[sid] = {
            "id": sid,
            DEFER_KEY: defer.Deferred(),
            "local_jid": local_jid,
            "to": to_jid,
            "stream_object": stream_object,
            "seq": -1,
            "timer": reactor.callLater(TIMEOUT, self._time_out, sid, client),
        }

        return session_data

    def _on_ibb_open(self, iq_elt, client):
        """ "Called when an IBB <open> element is received

        @param iq_elt(domish.Element): the whole <iq> stanza
        """
        log.debug(_("IBB stream opening"))
        iq_elt.handled = True
        open_elt = next(iq_elt.elements(NS_IBB, "open"))
        block_size = open_elt.getAttribute("block-size")
        sid = open_elt.getAttribute("sid")
        stanza = open_elt.getAttribute("stanza", "iq")
        if not sid or not block_size or int(block_size) > 65535:
            return self._sendError("not-acceptable", sid or None, iq_elt, client)
        if not sid in client.xep_0047_current_stream:
            log.warning(_("Ignoring unexpected IBB transfer: %s" % sid))
            return self._sendError("not-acceptable", sid or None, iq_elt, client)
        session_data = client.xep_0047_current_stream[sid]
        if session_data["to"] != jid.JID(iq_elt["from"]):
            log.warning(
                _("sended jid inconsistency (man in the middle attack attempt ?)")
            )
            return self._sendError("not-acceptable", sid, iq_elt, client)

        # at this stage, the session looks ok and will be accepted

        # we reset the timeout:
        session_data["timer"].reset(TIMEOUT)

        # we save the xmlstream, events and observer data to allow observer removal
        session_data["event_data"] = event_data = (
            IBB_MESSAGE_DATA if stanza == "message" else IBB_IQ_DATA
        ).format(sid)
        session_data["observer_cb"] = observer_cb = self._on_ibb_data
        event_close = IBB_CLOSE.format(sid)
        # we now set the stream observer to look after data packet
        # FIXME: if we never get the events, the observers stay.
        #        would be better to have generic observer and check id once triggered
        client.xmlstream.addObserver(event_data, observer_cb, client=client)
        client.xmlstream.addOnetimeObserver(
            event_close, self._on_ibb_close, client=client
        )
        # finally, we send the accept stanza
        iq_result_elt = xmlstream.toResponse(iq_elt, "result")
        client.send(iq_result_elt)

    def _on_ibb_close(self, iq_elt, client):
        """ "Called when an IBB <close> element is received

        @param iq_elt(domish.Element): the whole <iq> stanza
        """
        iq_elt.handled = True
        log.debug(_("IBB stream closing"))
        close_elt = next(iq_elt.elements(NS_IBB, "close"))
        # XXX: this observer is only triggered on valid sid, so we don't need to check it
        sid = close_elt["sid"]

        iq_result_elt = xmlstream.toResponse(iq_elt, "result")
        client.send(iq_result_elt)
        self._kill_session(sid, client)

    def _on_ibb_data(self, element, client):
        """Observer called on <iq> or <message> stanzas with data element

        Manage the data elelement (check validity and write to the stream_object)
        @param element(domish.Element): <iq> or <message> stanza
        """
        element.handled = True
        data_elt = next(element.elements(NS_IBB, "data"))
        sid = data_elt["sid"]

        try:
            session_data = client.xep_0047_current_stream[sid]
        except KeyError:
            log.warning(_("Received data for an unknown session id"))
            return self._sendError("item-not-found", None, element, client)

        from_jid = session_data["to"]
        stream_object = session_data["stream_object"]

        if from_jid.full() != element["from"]:
            log.warning(
                _(
                    "sended jid inconsistency (man in the middle attack attempt ?)\ninitial={initial}\ngiven={given}"
                ).format(initial=from_jid, given=element["from"])
            )
            if element.name == "iq":
                self._sendError("not-acceptable", sid, element, client)
            return

        session_data["seq"] = (session_data["seq"] + 1) % 65535
        if int(data_elt.getAttribute("seq", -1)) != session_data["seq"]:
            log.warning(_("Sequence error"))
            if element.name == "iq":
                reason = "not-acceptable"
                self._sendError(reason, sid, element, client)
            self.terminate_stream(session_data, client, reason)
            return

        # we reset the timeout:
        session_data["timer"].reset(TIMEOUT)

        # we can now decode the data
        try:
            stream_object.write(base64.b64decode(str(data_elt)))
        except TypeError:
            # The base64 data is invalid
            log.warning(_("Invalid base64 data"))
            if element.name == "iq":
                self._sendError("not-acceptable", sid, element, client)
            self.terminate_stream(session_data, client, reason)
            return

        # we can now ack success
        if element.name == "iq":
            iq_result_elt = xmlstream.toResponse(element, "result")
            client.send(iq_result_elt)

    def _sendError(self, error_condition, sid, iq_elt, client):
        """Send error stanza

        @param error_condition: one of twisted.words.protocols.jabber.error.STANZA_CONDITIONS keys
        @param sid(unicode,None): jingle session id, or None, if session must not be destroyed
        @param iq_elt(domish.Element): full <iq> stanza
        @param client: %(doc_client)s
        """
        iq_elt = error.StanzaError(error_condition).toResponse(iq_elt)
        log.warning(
            "Error while managing in-band bytestream session, cancelling: {}".format(
                error_condition
            )
        )
        if sid is not None:
            self._kill_session(sid, client, error_condition)
        client.send(iq_elt)

    def start_stream(
        self, client, stream_object, local_jid, to_jid, sid, block_size=None
    ):
        """Launch the stream workflow

        @param stream_object(ifaces.IStreamProducer): stream object to send
        @param local_jid(jid.JID): jid to use as local jid
            This is needed for client which can be addressed with a different jid than
            client.jid if a local part is used (e.g. piotr@file.example.net where
            client.jid would be file.example.net)
        @param to_jid(jid.JID): JID of the recipient
        @param sid(unicode): Stream session id
        @param block_size(int, None): size of the block (or None for default)
        """
        session_data = self._create_session(client, stream_object, local_jid, to_jid, sid)

        if block_size is None:
            block_size = XEP_0047.BLOCK_SIZE
        assert block_size <= 65535
        session_data["block_size"] = block_size

        iq_elt = client.IQ()
        iq_elt["from"] = local_jid.full()
        iq_elt["to"] = to_jid.full()
        open_elt = iq_elt.addElement((NS_IBB, "open"))
        open_elt["block-size"] = str(block_size)
        open_elt["sid"] = sid
        open_elt["stanza"] = "iq"  # TODO: manage <message> stanza ?
        args = [session_data, client]
        d = iq_elt.send()
        d.addCallbacks(self._iq_data_stream_cb, self._iq_data_stream_eb, args, None, args)
        return session_data[DEFER_KEY]

    def _iq_data_stream_cb(self, iq_elt, session_data, client):
        """Called during the whole data streaming

        @param iq_elt(domish.Element): iq result
        @param session_data(dict): data of this streaming session
        @param client: %(doc_client)s
        """
        session_data["timer"].reset(TIMEOUT)

        # FIXME: producer/consumer mechanism is not used properly here
        buffer_ = session_data["stream_object"].file_obj.read(session_data["block_size"])
        if buffer_:
            next_iq_elt = client.IQ()
            next_iq_elt["from"] = session_data["local_jid"].full()
            next_iq_elt["to"] = session_data["to"].full()
            data_elt = next_iq_elt.addElement((NS_IBB, "data"))
            seq = session_data["seq"] = (session_data["seq"] + 1) % 65535
            data_elt["seq"] = str(seq)
            data_elt["sid"] = session_data["id"]
            data_elt.addContent(base64.b64encode(buffer_).decode())
            args = [session_data, client]
            d = next_iq_elt.send()
            d.addCallbacks(
                self._iq_data_stream_cb, self._iq_data_stream_eb, args, None, args
            )
        else:
            self.terminate_stream(session_data, client)

    def _iq_data_stream_eb(self, failure, session_data, client):
        if failure.check(error.StanzaError):
            log.warning("IBB transfer failed: {}".format(failure.value))
        else:
            log.error("IBB transfer failed: {}".format(failure.value))
        self.terminate_stream(session_data, client, "IQ_ERROR")

    def terminate_stream(self, session_data, client, failure_reason=None):
        """Terminate the stream session

        @param session_data(dict): data of this streaming session
        @param client: %(doc_client)s
        @param failure_reason(unicode, None): reason of the failure, or None if steam was successful
        """
        iq_elt = client.IQ()
        iq_elt["from"] = session_data["local_jid"].full()
        iq_elt["to"] = session_data["to"].full()
        close_elt = iq_elt.addElement((NS_IBB, "close"))
        close_elt["sid"] = session_data["id"]
        iq_elt.send()
        self._kill_session(session_data["id"], client, failure_reason)


@implementer(itx_xmpp.IDisco)
class XEP_0047_handler(XMPPHandler):

    def __init__(self, parent):
        self.plugin_parent = parent

    def connectionInitialized(self):
        self.xmlstream.addObserver(
            IBB_OPEN, self.plugin_parent._on_ibb_open, client=self.parent
        )

    def getDiscoInfo(self, requestor, target, nodeIdentifier=""):
        return [disco.DiscoFeature(NS_IBB)]

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