#!/usr/bin/env python3

# Libervia plugin
# 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 typing import Final

from twisted.internet import defer, reactor
from twisted.words.protocols.jabber import jid
from twisted.words.protocols.jabber.xmlstream import XMPPHandler
from twisted.words.xish import domish
from tx_xmpp import disco, itx_xmpp
from zope.interface import implementer

from libervia.backend.core import exceptions
from libervia.backend.core.constants import Const as C
from libervia.backend.core.i18n import _
from libervia.backend.core.log import getLogger
from libervia.backend.core.xmpp import SatXMPPEntity
from libervia.backend.plugins.plugin_xep_0166.models import (
    BaseTransportHandler,
    ContentData,
)
from libervia.backend.tools.common import data_format

from .plugin_xep_0167 import mapping

log = getLogger(__name__)


PLUGIN_INFO = {
    C.PI_NAME: "WebRTC datachannels in Jingle",
    C.PI_IMPORT_NAME: "XEP-0343",
    C.PI_TYPE: "XEP",
    C.PI_MODES: C.PLUG_MODE_BOTH,
    C.PI_PROTOCOLS: [],
    C.PI_DEPENDENCIES: ["XEP-0166", "XEP-0167", "XEP-0176", "XEP-0234", "XEP-0320"],
    C.PI_RECOMMENDATIONS: [],
    C.PI_MAIN: "XEP_0343",
    C.PI_HANDLER: "yes",
    C.PI_DESCRIPTION: _("""Use WebRTC to create a generic data transport."""),
}
NS_JINGLE_WEBRTC_DATACHANNELS: Final[str] = (
    "urn:xmpp:jingle:transports:webrtc-datachannel:1"
)


class XEP_0343(BaseTransportHandler):
    namespace = NS_JINGLE_WEBRTC_DATACHANNELS

    def __init__(self, host):
        log.info(f"plugin {PLUGIN_INFO[C.PI_NAME]!r} initialization")
        self.host = host
        self._ice_udp = host.plugins["XEP-0176"]
        self._j = host.plugins["XEP-0166"]
        self._j.register_transport(
            NS_JINGLE_WEBRTC_DATACHANNELS, self._j.TRANSPORT_STREAMING, self, 10000
        )
        self._rtp = host.plugins["XEP-0167"]
        host.trigger.add("XEP-0167_parse_sdp_a", self._parse_sdp_a_trigger)
        host.trigger.add(
            "XEP-0167_generate_sdp_content", self._generate_sdp_content_trigger
        )
        host.trigger.add("XEP-0176_jingle_handler_send_buffer", self._on_send_ice_buffer)
        host.trigger.add("XEP-0176_ice_candidate_send", self._on_ice_candidate_send)
        host.trigger.add("XEP-0234_file_jingle_send", self._file_jingle_send)

    def get_handler(self, client: SatXMPPEntity):
        return XEP0343Handler()

    def is_usable(self, client, content_data: ContentData) -> bool:
        try:
            return content_data.app_kwargs["extra"]["webrtc"]
        except KeyError:
            return False

    def _parse_sdp_a_trigger(
        self,
        attribute: str,
        parts: list[str],
        call_data: dict,
        metadata: dict,
        media_type: str,
        application_data: dict,
        transport_data: dict,
    ) -> None:
        """Parse "sctp-port" and "max-message-size" attributes"""
        try:
            if attribute == "sctp-port":
                transport_data["sctp-port"] = int(parts[0])
            elif attribute == "max-message-size":
                transport_data["max-message-size"] = int(parts[0])
        except ValueError:
            log.warning(f"Can't parse value of {attribute}, ignoring: {parts}")

    def _generate_sdp_content_trigger(
        self,
        session: dict,
        local: bool,
        idx: int,
        content_data: dict,
        sdp_lines: list[str],
        application_data: dict,
        app_data_key: str,
        media_data: dict,
        media: str,
    ) -> None:
        """Generate "sctp-port" and "max-message-size" attributes"""
        transport_data = content_data["transport_data"]
        sctp_port = transport_data.get("sctp-port")
        if sctp_port is not None:
            sdp_lines.append(f"a=sctp-port:{sctp_port}")

        max_message_size = transport_data.get("max-message-size")
        if max_message_size is not None:
            sdp_lines.append(f"a=max-message-size:{max_message_size}")

    def _wrap_transport_element(self, transport_elt: domish.Element) -> None:
        """Wrap the XEP-0176 transport in a transport with this XEP namespace

        @param transport_elt: ICE UDP <transport>. Must be already a child of a <content>
            element.
        """
        content_elt = transport_elt.parent
        if content_elt is None or not content_elt.name == "content":
            raise exceptions.InternalError("Was expecting <content> element.")
        content_elt.children.remove(transport_elt)
        wrapping_transport_elt = content_elt.addElement(
            (NS_JINGLE_WEBRTC_DATACHANNELS, "transport")
        )
        wrapping_transport_elt.addChild(transport_elt)

    def _on_send_ice_buffer(
        self,
        client: SatXMPPEntity,
        session: dict,
        content_name: str,
        content_data: dict,
        transport_elt: domish.Element,
        iq_elt: domish.Element,
    ) -> bool:
        if content_data["transport"].handler == self:
            self._wrap_transport_element(transport_elt)
        return True

    def _on_ice_candidate_send(
        self,
        client: SatXMPPEntity,
        session: dict,
        media_ice_data: dict[str, dict],
        content_name: str,
        content_data: dict,
        iq_elt: domish.Element,
    ) -> bool:
        if content_data["transport"].handler == self:
            transport_elt = iq_elt.jingle.content.transport
            if transport_elt.uri != self._ice_udp.namespace:
                raise exceptions.InternalError("Was expecting an ICE UDP transport")
            self._wrap_transport_element(transport_elt)
        return True

    async def _file_jingle_send(
        self, client: SatXMPPEntity, peer_jid: jid.JID, content: dict
    ) -> None:
        call_data = content["app_kwargs"]["extra"].pop("call_data", None)
        if call_data:
            metadata = self._rtp.parse_call_data(call_data, self._j.ROLE_INITIATOR)
            try:
                application_data = call_data["application"]
            except KeyError:
                raise exceptions.DataError('"call_data" must have an application media.')
            try:
                content["transport_data"] = {
                    "sctp-port": metadata["sctp-port"],
                    "max-message-size": metadata.get("max-message-size", 65536),
                    "local_ice_data": {
                        "ufrag": metadata["ice-ufrag"],
                        "pwd": metadata["ice-pwd"],
                        "candidates": application_data.pop("ice-candidates"),
                        "fingerprint": application_data.pop("fingerprint", {}),
                    },
                }
            except KeyError as e:
                raise exceptions.DataError(f"Mandatory key is missing: {e}")

    async def jingle_session_init(
        self,
        client: SatXMPPEntity,
        session: dict,
        content_name: str,
    ) -> domish.Element:
        content_data = session["contents"][content_name]
        transport_data = content_data["transport_data"]
        ice_transport_elt = await self._ice_udp.jingle_session_init(
            client, session, content_name
        )
        transport_elt = domish.Element(
            (NS_JINGLE_WEBRTC_DATACHANNELS, "transport"),
            attribs={
                "sctp-port": str(transport_data["sctp-port"]),
                "max-message-size": str(transport_data["max-message-size"]),
            },
        )
        transport_elt.addChild(ice_transport_elt)
        return transport_elt

    async def _call_ice_udp_handler(
        self,
        client: SatXMPPEntity,
        action: str,
        session: dict,
        content_name: str,
        transport_elt: domish.Element,
    ):
        """Unwrap XEP-0176 <transport> element, and call its Jingle handler with it"""
        try:
            ice_transport_elt = next(
                transport_elt.elements(self._ice_udp.namespace, "transport")
            )
        except StopIteration:
            raise exceptions.DataError("Missing ICE UDP <transport> element.")
        else:
            await self._ice_udp.jingle_handler(
                client, action, session, content_name, ice_transport_elt
            )

    async def jingle_handler(
        self,
        client: SatXMPPEntity,
        action: str,
        session: dict,
        content_name: str,
        transport_elt: domish.Element,
    ) -> domish.Element:
        """Handle Jingle requests

        @param client: The SatXMPPEntity instance.
        @param action: The action to be performed with the session.
        @param session: A dictionary containing the session information.
        @param content_name: The name of the content.
        @param transport_elt: The domish.Element instance representing the transport
            element.

        @return: <transport> element
        """
        content_data = session["contents"][content_name]
        transport_data = content_data["transport_data"]
        if action in (self._j.A_PREPARE_CONFIRMATION, self._j.A_PREPARE_INITIATOR):
            session.setdefault("metadata", {})
            session.setdefault("peer_metadata", {})
            # we have to set application data despite being a transport handler,
            # because the SDP generation needs application data
            application_data = content_data["application_data"]
            application_data.setdefault("peer_data", {})
            application_data.setdefault("media", "application")

        if action == self._j.A_PREPARE_CONFIRMATION:
            await self._call_ice_udp_handler(
                client, action, session, content_name, transport_elt
            )
            try:
                transport_data["sctp-port"] = int(transport_elt["sctp-port"])
                transport_data["max-message-size"] = int(
                    transport_elt.getAttribute("max-message-size", 65536)
                )
            except (KeyError, ValueError):
                raise exceptions.DataError(
                    f"Invalid datachannel signaling element: {transport_elt.toXml()}"
                )
            transport_data["webrtc"] = True
        elif action in (self._j.A_PREPARE_INITIATOR, self._j.A_TRANSPORT_INFO):
            await self._call_ice_udp_handler(
                client, action, session, content_name, transport_elt
            )
        elif action == self._j.A_SESSION_ACCEPT:
            await self._call_ice_udp_handler(
                client, action, session, content_name, transport_elt
            )
            answer_sdp = mapping.generate_sdp_from_session(session)
            self.host.bridge.call_setup(
                session["id"],
                data_format.serialise(
                    {
                        "role": session["role"],
                        "sdp": answer_sdp,
                    }
                ),
                client.profile,
            )
        elif action in (self._j.A_ACCEPTED_ACK, self._j.A_PREPARE_RESPONDER):
            pass
        elif action == self._j.A_START:
            pass
        elif action == self._j.A_SESSION_INITIATE:
            # responder side

            # answer_sdp_d is a deferred handled in XEP-0167: it is called when the
            # frontend answers with its SDP.
            session["answer_sdp_d"] = answer_sdp_d = defer.Deferred()
            # we should have the answer long before 2 min
            answer_sdp_d.addTimeout(2 * 60, reactor)

            await self._rtp.send_answer_sdp(client, session)

            answer_sdp = await answer_sdp_d
            parsed_answer = mapping.parse_sdp(answer_sdp, session["role"])
            session["metadata"].update(parsed_answer["metadata"])
            self._rtp.propagate_data(session, parsed_answer)

            transport_elt.children.clear()
            ice_transport_elt = await self._ice_udp.jingle_handler(
                client, action, session, content_name, transport_elt
            )
            transport_elt.addChild(ice_transport_elt)
        elif action == self._j.A_DESTROY:
            # the transport is replaced (fallback ?)
            pass
        else:
            log.warning(f"FIXME: unmanaged action {action}")

        return transport_elt


@implementer(itx_xmpp.IDisco)
class XEP0343Handler(XMPPHandler):
    def getDiscoInfo(self, requestor, target, nodeIdentifier=""):
        return [disco.DiscoFeature(NS_JINGLE_WEBRTC_DATACHANNELS)]

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