#!/usr/bin/env python3

# SàT plugin for Jingle File Transfer (XEP-0234)
# Copyright (C) 2009-2021 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 collections import namedtuple
import mimetypes
import os.path

from twisted.internet import defer
from twisted.internet import reactor
from twisted.internet import error as internet_error
from twisted.python import failure
from twisted.words.protocols.jabber import jid
from twisted.words.protocols.jabber.xmlstream import XMPPHandler
from twisted.words.xish import domish
from wokkel import disco, iwokkel
from zope.interface import implementer

from libervia.backend.core import exceptions
from libervia.backend.core.constants import Const as C
from libervia.backend.core.core_types import SatXMPPEntity
from libervia.backend.core.i18n import D_, _
from libervia.backend.core.log import getLogger
from libervia.backend.tools import xml_tools
from libervia.backend.tools import utils
from libervia.backend.tools import stream
from libervia.backend.tools.common import date_utils
from libervia.backend.tools.common import regex

from .plugin_xep_0166 import BaseApplicationHandler


log = getLogger(__name__)

NS_JINGLE_FT = "urn:xmpp:jingle:apps:file-transfer:5"

PLUGIN_INFO = {
    C.PI_NAME: "Jingle File Transfer",
    C.PI_IMPORT_NAME: "XEP-0234",
    C.PI_TYPE: "XEP",
    C.PI_MODES: C.PLUG_MODE_BOTH,
    C.PI_PROTOCOLS: ["XEP-0234"],
    C.PI_DEPENDENCIES: ["XEP-0166", "XEP-0300", "FILE"],
    C.PI_MAIN: "XEP_0234",
    C.PI_HANDLER: "yes",
    C.PI_DESCRIPTION: _("""Implementation of Jingle File Transfer"""),
}

EXTRA_ALLOWED = {"path", "namespace", "file_desc", "file_hash", "hash_algo"}
Range = namedtuple("Range", ("offset", "length"))


class XEP_0234(BaseApplicationHandler):
    # TODO: assure everything is closed when file is sent or session terminate is received
    # TODO: call self._f.unregister when unloading order will be managing (i.e. when
    #   dependencies will be unloaded at the end)
    Range = Range  # we copy the class here, so it can be used by other plugins
    name = PLUGIN_INFO[C.PI_NAME]
    human_name = D_("file transfer")

    def __init__(self, host):
        log.info(_("plugin Jingle File Transfer initialization"))
        self.host = host
        host.register_namespace("jingle-ft", NS_JINGLE_FT)
        self._j = host.plugins["XEP-0166"]  # shortcut to access jingle
        self._j.register_application(NS_JINGLE_FT, self)
        self._f = host.plugins["FILE"]
        self._f.register(self, priority=10000)
        self._hash = self.host.plugins["XEP-0300"]
        host.bridge.add_method(
            "file_jingle_send",
            ".plugin",
            in_sign="ssssa{ss}s",
            out_sign="",
            method=self._file_send,
            async_=True,
        )
        host.bridge.add_method(
            "file_jingle_request",
            ".plugin",
            in_sign="sssssa{ss}s",
            out_sign="s",
            method=self._file_jingle_request,
            async_=True,
        )

    def get_handler(self, client):
        return XEP_0234_handler()

    def get_progress_id(self, session, content_name):
        """Return a unique progress ID

        @param session(dict): jingle session
        @param content_name(unicode): name of the content
        @return (unicode): unique progress id
        """
        return "{}_{}".format(session["id"], content_name)

    async def can_handle_file_send(self, client, peer_jid, filepath):
        if peer_jid.resource:
            return await self.host.hasFeature(client, NS_JINGLE_FT, peer_jid)
        else:
            # if we have a bare jid, Jingle Message Initiation will be tried
            return True

    # generic methods

    def build_file_element(
        self, client, name=None, file_hash=None, hash_algo=None, size=None,
        mime_type=None, desc=None, modified=None, transfer_range=None, path=None,
        namespace=None, file_elt=None, **kwargs):
        """Generate a <file> element with available metadata

        @param file_hash(unicode, None): hash of the file
            empty string to set <hash-used/> element
        @param hash_algo(unicode, None): hash algorithm used
            if file_hash is None and hash_algo is set, a <hash-used/> element will be
            generated
        @param transfer_range(Range, None): where transfer must start/stop
        @param modified(int, unicode, None): date of last modification
            0 to use current date
            int to use an unix timestamp
            else must be an unicode string which will be used as it (it must be an XMPP
            time)
        @param file_elt(domish.Element, None): element to use
            None to create a new one
        @param **kwargs: data for plugin extension (ignored by default)
        @return (domish.Element): generated element
        @trigger XEP-0234_buildFileElement(file_elt, extra_args): can be used to extend
            elements to add
        """
        if file_elt is None:
            file_elt = domish.Element((NS_JINGLE_FT, "file"))
        for name, value in (
            ("name", name),
            ("size", size),
            ("media-type", mime_type),
            ("desc", desc),
            ("path", path),
            ("namespace", namespace),
        ):
            if value is not None:
                file_elt.addElement(name, content=str(value))

        if modified is not None:
            if isinstance(modified, int):
                file_elt.addElement("date", utils.xmpp_date(modified or None))
            else:
                file_elt.addElement("date", modified)
        elif "created" in kwargs:
            file_elt.addElement("date", utils.xmpp_date(kwargs.pop("created")))

        range_elt = file_elt.addElement("range")
        if transfer_range is not None:
            if transfer_range.offset is not None:
                range_elt["offset"] = transfer_range.offset
            if transfer_range.length is not None:
                range_elt["length"] = transfer_range.length
        if file_hash is not None:
            if not file_hash:
                file_elt.addChild(self._hash.build_hash_used_elt())
            else:
                file_elt.addChild(self._hash.build_hash_elt(file_hash, hash_algo))
        elif hash_algo is not None:
            file_elt.addChild(self._hash.build_hash_used_elt(hash_algo))
        self.host.trigger.point(
            "XEP-0234_buildFileElement", client, file_elt, extra_args=kwargs)
        if kwargs:
            for kw in kwargs:
                log.debug("ignored keyword: {}".format(kw))
        return file_elt

    def build_file_element_from_dict(self, client, file_data, **kwargs):
        """like build_file_element but get values from a file_data dict

        @param file_data(dict): metadata to use
        @param **kwargs: data to override
        """
        if kwargs:
            file_data = file_data.copy()
            file_data.update(kwargs)
        try:
            file_data["mime_type"] = (
                f'{file_data.pop("media_type")}/{file_data.pop("media_subtype")}'
            )
        except KeyError:
            pass
        return self.build_file_element(client, **file_data)

    async def parse_file_element(
            self, client, file_elt, file_data=None, given=False, parent_elt=None,
            keep_empty_range=False):
        """Parse a <file> element and file dictionary accordingly

        @param file_data(dict, None): dict where the data will be set
            following keys will be set (and overwritten if they already exist):
                name, file_hash, hash_algo, size, mime_type, desc, path, namespace, range
            if None, a new dict is created
        @param given(bool): if True, prefix hash key with "given_"
        @param parent_elt(domish.Element, None): parent of the file element
            if set, file_elt must not be set
        @param keep_empty_range(bool): if True, keep empty range (i.e. range when offset
            and length are None).
            Empty range is useful to know if a peer_jid can handle range
        @return (dict): file_data
        @trigger XEP-0234_parseFileElement(file_elt, file_data): can be used to parse new
            elements
        @raise exceptions.NotFound: there is not <file> element in parent_elt
        @raise exceptions.DataError: if file_elt uri is not NS_JINGLE_FT
        """
        if parent_elt is not None:
            if file_elt is not None:
                raise exceptions.InternalError(
                    "file_elt must be None if parent_elt is set"
                )
            try:
                file_elt = next(parent_elt.elements(NS_JINGLE_FT, "file"))
            except StopIteration:
                raise exceptions.NotFound()
        else:
            if not file_elt or file_elt.uri != NS_JINGLE_FT:
                raise exceptions.DataError(
                    "invalid <file> element: {stanza}".format(stanza=file_elt.toXml())
                )

        if file_data is None:
            file_data = {}

        for name in ("name", "desc", "path", "namespace"):
            try:
                file_data[name] = str(next(file_elt.elements(NS_JINGLE_FT, name)))
            except StopIteration:
                pass

        name = file_data.get("name")
        if name == "..":
            # we don't want to go to parent dir when joining to a path
            name = "--"
            file_data["name"] = name
        elif name is not None and ("/" in name or "\\" in name):
            file_data["name"] = regex.path_escape(name)

        try:
            file_data["mime_type"] = str(
                next(file_elt.elements(NS_JINGLE_FT, "media-type"))
            )
        except StopIteration:
            pass

        try:
            file_data["size"] = int(
                str(next(file_elt.elements(NS_JINGLE_FT, "size")))
            )
        except StopIteration:
            pass

        try:
            file_data["modified"] = date_utils.date_parse(
                next(file_elt.elements(NS_JINGLE_FT, "date"))
            )
        except StopIteration:
            pass

        try:
            range_elt = next(file_elt.elements(NS_JINGLE_FT, "range"))
        except StopIteration:
            pass
        else:
            offset = range_elt.getAttribute("offset")
            length = range_elt.getAttribute("length")
            if offset or length or keep_empty_range:
                file_data["transfer_range"] = Range(offset=offset, length=length)

        prefix = "given_" if given else ""
        hash_algo_key, hash_key = "hash_algo", prefix + "file_hash"
        try:
            file_data[hash_algo_key], file_data[hash_key] = self._hash.parse_hash_elt(
                file_elt
            )
        except exceptions.NotFound:
            pass

        self.host.trigger.point("XEP-0234_parseFileElement", client, file_elt, file_data)

        return file_data

    # bridge methods

    def _file_send(
        self,
        peer_jid,
        filepath,
        name="",
        file_desc="",
        extra=None,
        profile=C.PROF_KEY_NONE,
    ):
        client = self.host.get_client(profile)
        return defer.ensureDeferred(self.file_send(
            client,
            jid.JID(peer_jid),
            filepath,
            name or None,
            file_desc or None,
            extra or None,
        ))

    async def file_send(
        self, client, peer_jid, filepath, name, file_desc=None, extra=None
    ):
        """Send a file using jingle file transfer

        @param peer_jid(jid.JID): destinee jid
        @param filepath(str): absolute path of the file
        @param name(unicode, None): name of the file
        @param file_desc(unicode, None): description of the file
        @return (D(unicode)): progress id
        """
        progress_id_d = defer.Deferred()
        if extra is None:
            extra = {}
        if file_desc is not None:
            extra["file_desc"] = file_desc
        encrypted = extra.pop("encrypted", False)
        await self._j.initiate(
            client,
            peer_jid,
            [
                {
                    "app_ns": NS_JINGLE_FT,
                    "senders": self._j.ROLE_INITIATOR,
                    "app_kwargs": {
                        "filepath": filepath,
                        "name": name,
                        "extra": extra,
                        "progress_id_d": progress_id_d,
                    },
                }
            ],
            encrypted = encrypted
        )
        return await progress_id_d

    def _file_jingle_request(
            self, peer_jid, filepath, name="", file_hash="", hash_algo="", extra=None,
            profile=C.PROF_KEY_NONE):
        client = self.host.get_client(profile)
        return defer.ensureDeferred(self.file_jingle_request(
            client,
            jid.JID(peer_jid),
            filepath,
            name or None,
            file_hash or None,
            hash_algo or None,
            extra or None,
        ))

    async def file_jingle_request(
            self, client, peer_jid, filepath, name=None, file_hash=None, hash_algo=None,
            extra=None):
        """Request a file using jingle file transfer

        @param peer_jid(jid.JID): destinee jid
        @param filepath(str): absolute path where the file will be downloaded
        @param name(unicode, None): name of the file
        @param file_hash(unicode, None): hash of the file
        @return (D(unicode)): progress id
        """
        progress_id_d = defer.Deferred()
        if extra is None:
            extra = {}
        if file_hash is not None:
            if hash_algo is None:
                raise ValueError(_("hash_algo must be set if file_hash is set"))
            extra["file_hash"] = file_hash
            extra["hash_algo"] = hash_algo
        else:
            if hash_algo is not None:
                raise ValueError(_("file_hash must be set if hash_algo is set"))
        await self._j.initiate(
            client,
            peer_jid,
            [
                {
                    "app_ns": NS_JINGLE_FT,
                    "senders": self._j.ROLE_RESPONDER,
                    "app_kwargs": {
                        "filepath": filepath,
                        "name": name,
                        "extra": extra,
                        "progress_id_d": progress_id_d,
                    },
                }
            ],
        )
        return await progress_id_d

    # jingle callbacks

    async def jingle_preflight(
        self,
        client: SatXMPPEntity,
        session: dict,
        description_elt: domish.Element
    ) -> None:
        """Perform preflight checks for an incoming call session.

        Check if the calls is audio only or audio/video, then, prompts the user for
        confirmation.

        @param client: The client instance.
        @param session: Jingle session.
        @param description_elt: The description element. It's parent attribute is used to
            determine check siblings to see if it's an audio only or audio/video call.

        @raises exceptions.CancelError: If the user doesn't accept the incoming call.
        """
        session_id = session["id"]
        peer_jid = session["peer_jid"]
        # FIXME: has been moved from XEP-0353, but it doesn't handle correctly file
        #   transfer (metadata are not used). We must check with other clients what is
        #   actually send, and if XEP-0353 is used, and do a better integration.

        if client.roster and peer_jid.userhostJID() not in client.roster:
            confirm_msg = D_(
                "Somebody not in your contact list ({peer_jid}) wants to do a "
                '"{human_name}" session with you, this would leak your presence and '
                "possibly you IP (internet localisation), do you accept?"
            ).format(peer_jid=peer_jid, human_name=self.human_name)
            confirm_title = D_("File sent from an unknown contact")
            action_type = C.META_TYPE_NOT_IN_ROSTER_LEAK
            action_subtype = None
        else:
            confirm_msg = D_(
                "{peer_jid} wants to send a file to you, do you accept?"
            ).format(peer_jid=peer_jid)
            confirm_title = D_("File Proposed")
            action_type = C.META_TYPE_CONFIRM
            action_subtype = C.META_TYPE_FILE
        action_extra = {
            "type": action_type,
            "session_id": session_id,
            "from_jid": peer_jid.full(),
        }
        if action_subtype is not None:
            action_extra["subtype"] = action_subtype
        accepted = await xml_tools.defer_confirm(
            self.host,
            confirm_msg,
            confirm_title,
            profile=client.profile,
            action_extra=action_extra
        )
        if accepted:
            session["file_accepted"] = True
        return accepted

    async def jingle_preflight_info(
        self,
        client: SatXMPPEntity,
        session: dict,
        info_type: str,
        info_data: dict|None = None
    ) -> None:
        pass

    async def jingle_preflight_cancel(
        self,
        client: SatXMPPEntity,
        session: dict,
        cancel_error: exceptions.CancelError
    ) -> None:
        pass

    def jingle_description_elt(
        self, client, session, content_name, filepath, name, extra, progress_id_d
    ):
        return domish.Element((NS_JINGLE_FT, "description"))

    def jingle_session_init(
        self, client, session, content_name, filepath, name, extra, progress_id_d
    ):
        if extra is None:
            extra = {}
        else:
            if not EXTRA_ALLOWED.issuperset(extra):
                raise ValueError(
                    _("only the following keys are allowed in extra: {keys}").format(
                        keys=", ".join(EXTRA_ALLOWED)
                    )
                )
        progress_id_d.callback(self.get_progress_id(session, content_name))
        content_data = session["contents"][content_name]
        application_data = content_data["application_data"]
        assert "file_path" not in application_data
        application_data["file_path"] = filepath
        file_data = application_data["file_data"] = {}
        desc_elt = self.jingle_description_elt(
            client, session, content_name, filepath, name, extra, progress_id_d)
        file_elt = desc_elt.addElement("file")

        if content_data["senders"] == self._j.ROLE_INITIATOR:
            # we send a file
            if name is None:
                name = os.path.basename(filepath)
            file_data["date"] = utils.xmpp_date()
            file_data["desc"] = extra.pop("file_desc", "")
            file_data["name"] = name
            mime_type = mimetypes.guess_type(name, strict=False)[0]
            if mime_type is not None:
                file_data["mime_type"] = mime_type
            file_data["size"] = os.path.getsize(filepath)
            if "namespace" in extra:
                file_data["namespace"] = extra["namespace"]
            if "path" in extra:
                file_data["path"] = extra["path"]
            self.build_file_element_from_dict(
                client, file_data, file_elt=file_elt, file_hash="")
        else:
            # we request a file
            file_hash = extra.pop("file_hash", "")
            if not name and not file_hash:
                raise ValueError(_("you need to provide at least name or file hash"))
            if name:
                file_data["name"] = name
            if file_hash:
                file_data["file_hash"] = file_hash
                file_data["hash_algo"] = extra["hash_algo"]
            else:
                file_data["hash_algo"] = self._hash.get_default_algo()
            if "namespace" in extra:
                file_data["namespace"] = extra["namespace"]
            if "path" in extra:
                file_data["path"] = extra["path"]
            self.build_file_element_from_dict(client, file_data, file_elt=file_elt)

        return desc_elt

    async def jingle_request_confirmation(
        self,
        client: SatXMPPEntity,
        action: str,
        session: dict,
        content_name: str,
        desc_elt: domish.Element,
    ):
        """This method request confirmation for a jingle session"""
        content_data = session["contents"][content_name]
        senders = content_data["senders"]
        if senders not in (self._j.ROLE_INITIATOR, self._j.ROLE_RESPONDER):
            log.warning("Bad sender, assuming initiator")
            senders = content_data["senders"] = self._j.ROLE_INITIATOR
        # first we grab file informations
        try:
            file_elt = next(desc_elt.elements(NS_JINGLE_FT, "file"))
        except StopIteration:
            raise failure.Failure(exceptions.DataError)
        file_data = {"progress_id": self.get_progress_id(session, content_name)}

        if senders == self._j.ROLE_RESPONDER:
            # we send the file
            return await self._file_sending_request_conf(
                client, session, content_data, content_name, file_data, file_elt
            )
        else:
            # we receive the file
            return await self._file_receiving_request_conf(
                client, session, content_data, content_name, file_data, file_elt
            )

    async def _file_sending_request_conf(
        self, client, session, content_data, content_name, file_data, file_elt
    ):
        """parse file_elt, and handle file retrieving/permission checking"""
        await self.parse_file_element(client, file_elt, file_data)
        content_data["application_data"]["file_data"] = file_data
        finished_d = content_data["finished_d"] = defer.Deferred()

        # confirmed_d is a deferred returning confimed value (only used if cont is False)
        cont, confirmed_d = self.host.trigger.return_point(
            "XEP-0234_fileSendingRequest",
            client,
            session,
            content_data,
            content_name,
            file_data,
            file_elt,
        )
        if not cont:
            confirmed = await confirmed_d
            if confirmed:
                args = [client, session, content_name, content_data]
                finished_d.addCallbacks(
                    self._finished_cb, self._finished_eb, args, None, args
                )
            return confirmed

        log.warning(_("File continue is not implemented yet"))
        return False

    async def _file_receiving_request_conf(
        self, client, session, content_data, content_name, file_data, file_elt
    ):
        """parse file_elt, and handle user permission/file opening"""
        await self.parse_file_element(client, file_elt, file_data, given=True)
        try:
            hash_algo, file_data["given_file_hash"] = self._hash.parse_hash_elt(file_elt)
        except exceptions.NotFound:
            try:
                hash_algo = self._hash.parse_hash_used_elt(file_elt)
            except exceptions.NotFound:
                raise failure.Failure(exceptions.DataError)

        if hash_algo is not None:
            file_data["hash_algo"] = hash_algo
            file_data["hash_hasher"] = hasher = self._hash.get_hasher(hash_algo)
            file_data["data_cb"] = lambda data: hasher.update(data)

        try:
            file_data["size"] = int(file_data["size"])
        except ValueError:
            raise failure.Failure(exceptions.DataError)

        name = file_data["name"]
        if "/" in name or "\\" in name:
            log.warning(
                "File name contain path characters, we replace them: {}".format(name)
            )
            file_data["name"] = name.replace("/", "_").replace("\\", "_")

        content_data["application_data"]["file_data"] = file_data

        # now we actualy request permission to user

        # deferred to track end of transfer
        finished_d = content_data["finished_d"] = defer.Deferred()
        confirmed = await self._f.get_dest_dir(
            client, session["peer_jid"], content_data, file_data, stream_object=True
        )
        if confirmed:
            await self.host.trigger.async_point(
                "XEP-0234_file_receiving_request_conf",
                client, session, content_data, file_elt
            )
            args = [client, session, content_name, content_data]
            finished_d.addCallbacks(
                self._finished_cb, self._finished_eb, args, None, args
            )
        return confirmed

    async def jingle_handler(self, client, action, session, content_name, desc_elt):
        content_data = session["contents"][content_name]
        application_data = content_data["application_data"]
        if action in (self._j.A_ACCEPTED_ACK,):
            pass
        elif action == self._j.A_SESSION_INITIATE:
            file_elt = next(desc_elt.elements(NS_JINGLE_FT, "file"))
            try:
                next(file_elt.elements(NS_JINGLE_FT, "range"))
            except StopIteration:
                # initiator doesn't manage <range>, but we do so we advertise it
                # FIXME: to be checked
                log.debug("adding <range> element")
                file_elt.addElement("range")
        elif action == self._j.A_SESSION_ACCEPT:
            assert not "stream_object" in content_data
            file_data = application_data["file_data"]
            file_path = application_data["file_path"]
            senders = content_data["senders"]
            if senders != session["role"]:
                # we are receiving the file
                try:
                    # did the responder specified the size of the file?
                    file_elt = next(desc_elt.elements(NS_JINGLE_FT, "file"))
                    size_elt = next(file_elt.elements(NS_JINGLE_FT, "size"))
                    size = int(str(size_elt))
                except (StopIteration, ValueError):
                    size = None
                # XXX: hash security is not critical here, so we just take the higher
                #      mandatory one
                hasher = file_data["hash_hasher"] = self._hash.get_hasher()
                progress_id = self.get_progress_id(session, content_name)
                try:
                    content_data["stream_object"] = stream.FileStreamObject(
                        self.host,
                        client,
                        file_path,
                        mode="wb",
                        uid=progress_id,
                        size=size,
                        data_cb=lambda data: hasher.update(data),
                    )
                except Exception as e:
                    self.host.bridge.progress_error(
                        progress_id, C.PROGRESS_ERROR_FAILED, client.profile
                    )
                    await self._j.terminate(
                        client, self._j.REASON_FAILED_APPLICATION, session)
                    raise e
            else:
                # we are sending the file
                size = file_data["size"]
                # XXX: hash security is not critical here, so we just take the higher
                #      mandatory one
                hasher = file_data["hash_hasher"] = self._hash.get_hasher()
                content_data["stream_object"] = stream.FileStreamObject(
                    self.host,
                    client,
                    file_path,
                    uid=self.get_progress_id(session, content_name),
                    size=size,
                    data_cb=lambda data: hasher.update(data),
                )
            finished_d = content_data["finished_d"] = defer.Deferred()
            args = [client, session, content_name, content_data]
            finished_d.addCallbacks(self._finished_cb, self._finished_eb, args, None, args)
            await self.host.trigger.async_point(
                "XEP-0234_jingle_handler",
                client, session, content_data, desc_elt
            )
        else:
            log.warning("FIXME: unmanaged action {}".format(action))
        return desc_elt

    def jingle_session_info(self, client, action, session, content_name, jingle_elt):
        """Called on session-info action

        manage checksum, and ignore <received/> element
        """
        # TODO: manage <received/> element
        content_data = session["contents"][content_name]
        elts = [elt for elt in jingle_elt.elements() if elt.uri == NS_JINGLE_FT]
        if not elts:
            return
        for elt in elts:
            if elt.name == "received":
                pass
            elif elt.name == "checksum":
                # we have received the file hash, we need to parse it
                if content_data["senders"] == session["role"]:
                    log.warning(
                        "unexpected checksum received while we are the file sender"
                    )
                    raise exceptions.DataError
                info_content_name = elt["name"]
                if info_content_name != content_name:
                    # it was for an other content...
                    return
                file_data = content_data["application_data"]["file_data"]
                try:
                    file_elt = next(elt.elements(NS_JINGLE_FT, "file"))
                except StopIteration:
                    raise exceptions.DataError
                algo, file_data["given_file_hash"] = self._hash.parse_hash_elt(file_elt)
                if algo != file_data.get("hash_algo"):
                    log.warning(
                        "Hash algorithm used in given hash ({peer_algo}) doesn't correspond to the one we have used ({our_algo}) [{profile}]".format(
                            peer_algo=algo,
                            our_algo=file_data.get("hash_algo"),
                            profile=client.profile,
                        )
                    )
                else:
                    self._receiver_try_terminate(
                        client, session, content_name, content_data
                    )
            else:
                raise NotImplementedError

    def jingle_terminate(self, client, action, session, content_name, reason_elt):
        if reason_elt.decline:
            # progress is the only way to tell to frontends that session has been declined
            progress_id = self.get_progress_id(session, content_name)
            self.host.bridge.progress_error(
                progress_id, C.PROGRESS_ERROR_DECLINED, client.profile
            )
        elif not reason_elt.success:
            progress_id = self.get_progress_id(session, content_name)
            first_child = reason_elt.firstChildElement()
            if first_child is not None:
                reason = first_child.name
                if reason_elt.text is not None:
                    reason = f"{reason} - {reason_elt.text}"
            else:
                reason = C.PROGRESS_ERROR_FAILED
            self.host.bridge.progress_error(
                progress_id, reason, client.profile
            )

    def _send_check_sum(self, client, session, content_name, content_data):
        """Send the session-info with the hash checksum"""
        file_data = content_data["application_data"]["file_data"]
        hasher = file_data["hash_hasher"]
        hash_ = hasher.hexdigest()
        log.debug("Calculated hash: {}".format(hash_))
        iq_elt, jingle_elt = self._j.build_session_info(client, session)
        checksum_elt = jingle_elt.addElement((NS_JINGLE_FT, "checksum"))
        checksum_elt["creator"] = content_data["creator"]
        checksum_elt["name"] = content_name
        file_elt = checksum_elt.addElement("file")
        file_elt.addChild(self._hash.build_hash_elt(hash_))
        iq_elt.send()

    def _receiver_try_terminate(
        self, client, session, content_name, content_data, last_try=False
    ):
        """Try to terminate the session

        This method must only be used by the receiver.
        It check if transfer is finished, and hash available,
        if everything is OK, it check hash and terminate the session
        @param last_try(bool): if True this mean than session must be terminated even given hash is not available
        @return (bool): True if session was terminated
        """
        if not content_data.get("transfer_finished", False):
            return False
        file_data = content_data["application_data"]["file_data"]
        given_hash = file_data.get("given_file_hash")
        if given_hash is None:
            if last_try:
                log.warning(
                    "sender didn't sent hash checksum, we can't check the file [{profile}]".format(
                        profile=client.profile
                    )
                )
                self._j.delayed_content_terminate(client, session, content_name)
                content_data["stream_object"].close()
                return True
            return False
        hasher = file_data["hash_hasher"]
        hash_ = hasher.hexdigest()

        if hash_ == given_hash:
            log.info(f"Hash checked, file was successfully transfered: {hash_}")
            progress_metadata = {
                "hash": hash_,
                "hash_algo": file_data["hash_algo"],
                "hash_verified": C.BOOL_TRUE,
            }
            error = None
        else:
            log.warning("Hash mismatch, the file was not transfered correctly")
            progress_metadata = None
            error = "Hash mismatch: given={algo}:{given}, calculated={algo}:{our}".format(
                algo=file_data["hash_algo"], given=given_hash, our=hash_
            )

        self._j.delayed_content_terminate(client, session, content_name)
        content_data["stream_object"].close(progress_metadata, error)
        # we may have the last_try timer still active, so we try to cancel it
        try:
            content_data["last_try_timer"].cancel()
        except (KeyError, internet_error.AlreadyCalled):
            pass
        return True

    def _finished_cb(self, __, client, session, content_name, content_data):
        log.info("File transfer terminated")
        if content_data["senders"] != session["role"]:
            # we terminate the session only if we are the receiver,
            # as recommanded in XEP-0234 §2 (after example 6)
            content_data["transfer_finished"] = True
            if not self._receiver_try_terminate(
                client, session, content_name, content_data
            ):
                # we have not received the hash yet, we wait 5 more seconds
                content_data["last_try_timer"] = reactor.callLater(
                    5,
                    self._receiver_try_terminate,
                    client,
                    session,
                    content_name,
                    content_data,
                    last_try=True,
                )
        else:
            # we are the sender, we send the checksum
            self._send_check_sum(client, session, content_name, content_data)
            content_data["stream_object"].close()

    def _finished_eb(self, failure, client, session, content_name, content_data):
        log.warning("Error while streaming file: {}".format(failure))
        content_data["stream_object"].close()
        self._j.content_terminate(
            client, session, content_name, reason=self._j.REASON_FAILED_TRANSPORT
        )


@implementer(iwokkel.IDisco)
class XEP_0234_handler(XMPPHandler):

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

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