#!/usr/bin/env python3

# Libervia plugin for XEP-0465
# 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 typing import Optional, List, Dict, Union

from twisted.words.protocols.jabber.xmlstream import XMPPHandler
from twisted.words.protocols.jabber import jid
from twisted.words.protocols.jabber import error
from twisted.words.xish import domish
from zope.interface import implementer
from wokkel import disco, iwokkel

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 import exceptions
from libervia.backend.core.core_types import SatXMPPEntity
from libervia.backend.tools import utils
from libervia.backend.tools.common import data_format

log = getLogger(__name__)

PLUGIN_INFO = {
    C.PI_NAME: "Pubsub Public Subscriptions",
    C.PI_IMPORT_NAME: "XEP-0465",
    C.PI_TYPE: C.PLUG_TYPE_XEP,
    C.PI_MODES: C.PLUG_MODE_BOTH,
    C.PI_PROTOCOLS: ["XEP-0465"],
    C.PI_DEPENDENCIES: ["XEP-0060", "XEP-0376"],
    C.PI_MAIN: "XEP_0465",
    C.PI_HANDLER: "yes",
    C.PI_DESCRIPTION: _("""Pubsub Public Subscriptions implementation"""),
}

NS_PPS = "urn:xmpp:pps:0"
NS_PPS_SUBSCRIPTIONS = "urn:xmpp:pps:subscriptions:0"
NS_PPS_SUBSCRIBERS = "urn:xmpp:pps:subscribers:0"
SUBSCRIBERS_NODE_PREFIX = f"{NS_PPS_SUBSCRIBERS}/"
NOT_IMPLEMENTED_MSG = (
    "The service at {service!s} doesn't seem to support Pubsub Public Subscriptions "
    "(XEP-0465), please request support from your service administrator."
)


class XEP_0465:

    def __init__(self, host):
        log.info(_("Pubsub Public Subscriptions initialization"))
        host.register_namespace("pps", NS_PPS)
        self.host = host
        host.bridge.add_method(
            "ps_public_subscriptions_get",
            ".plugin",
            in_sign="sss",
            out_sign="s",
            method=self._subscriptions,
            async_=True,
        )
        host.bridge.add_method(
            "ps_public_subscriptions_get",
            ".plugin",
            in_sign="sss",
            out_sign="s",
            method=self._subscriptions,
            async_=True,
        )
        host.bridge.add_method(
            "ps_public_node_subscriptions_get",
            ".plugin",
            in_sign="sss",
            out_sign="a{ss}",
            method=self._get_public_node_subscriptions,
            async_=True,
        )

    def get_handler(self, client):
        return XEP_0465_Handler()

    @property
    def subscriptions_node(self) -> str:
        return NS_PPS_SUBSCRIPTIONS

    @property
    def subscribers_node_prefix(self) -> str:
        return SUBSCRIBERS_NODE_PREFIX

    def build_subscription_elt(self, node: str, service: jid.JID) -> domish.Element:
        """Generate a <subscriptions> element

        This is the element that a service returns on public subscriptions request
        """
        subscription_elt = domish.Element((NS_PPS, "subscription"))
        subscription_elt["node"] = node
        subscription_elt["service"] = service.full()
        return subscription_elt

    def build_subscriber_elt(self, subscriber: jid.JID) -> domish.Element:
        """Generate a <subscriber> element

        This is the element that a service returns on node public subscriptions request
        """
        subscriber_elt = domish.Element((NS_PPS, "subscriber"))
        subscriber_elt["jid"] = subscriber.full()
        return subscriber_elt

    @utils.ensure_deferred
    async def _subscriptions(
        self,
        service="",
        nodeIdentifier="",
        profile_key=C.PROF_KEY_NONE
    ) -> str:
        client = self.host.get_client(profile_key)
        service = None if not service else jid.JID(service)
        subs = await self.subscriptions(client, service, nodeIdentifier or None)
        return data_format.serialise(subs)

    async def subscriptions(
        self,
        client: SatXMPPEntity,
        service: Optional[jid.JID] = None,
        node: Optional[str] = None
    ) -> List[Dict[str, Union[str, bool]]]:
        """Retrieve public subscriptions from a service

        @param service(jid.JID): PubSub service
        @param nodeIdentifier(unicode, None): node to filter
            None to get all subscriptions
        """
        if service is None:
            service = client.jid.userhostJID()
        try:
            items, __ = await self.host.plugins["XEP-0060"].get_items(
                client, service, NS_PPS_SUBSCRIPTIONS
            )
        except error.StanzaError as e:
            if e.condition == "forbidden":
                log.warning(NOT_IMPLEMENTED_MSG.format(service=service))
                return []
            else:
                raise e
        ret = []
        for item in items:
            try:
                subscription_elt = next(item.elements(NS_PPS, "subscription"))
            except StopIteration:
                log.warning(f"no <subscription> element found: {item.toXml()}")
                continue

            try:
                sub_dict = {
                    "service": subscription_elt["service"],
                    "node": subscription_elt["node"],
                    "subscriber": service.full(),
                    "state": subscription_elt.getAttribute("subscription", "subscribed"),
                }
            except KeyError:
                log.warning(
                    f"invalid <subscription> element: {subscription_elt.toXml()}"
                )
                continue
            if node is not None and sub_dict["node"] != node:
                # if not is specified, we filter out any other node
                # FIXME: should node filtering be done by server?
                continue
            ret.append(sub_dict)
        return ret

    @utils.ensure_deferred
    async def _get_public_node_subscriptions(
        self,
        service: str,
        node: str,
        profile_key: str
    ) -> Dict[str, str]:
        client = self.host.get_client(profile_key)
        subs = await self.get_public_node_subscriptions(
            client, jid.JID(service) if service else None, node
        )
        return {j.full(): a for j, a in subs.items()}

    def get_public_subscribers_node(self, node: str) -> str:
        """Return prefixed node to retrieve public subscribers"""
        return f"{NS_PPS_SUBSCRIBERS}/{node}"

    async def get_public_node_subscriptions(
        self,
        client: SatXMPPEntity,
        service: Optional[jid.JID],
        nodeIdentifier: str
    ) -> Dict[jid.JID, str]:
        """Retrieve public subscriptions to a node

        @param nodeIdentifier(unicode): node to get subscriptions from
        """
        if not nodeIdentifier:
            raise exceptions.DataError("node identifier can't be empty")

        if service is None:
            service = client.jid.userhostJID()

        subscribers_node = self.get_public_subscribers_node(nodeIdentifier)

        try:
            items, __ = await self.host.plugins["XEP-0060"].get_items(
                client, service, subscribers_node
            )
        except error.StanzaError as e:
            if e.condition == "forbidden":
                log.warning(NOT_IMPLEMENTED_MSG.format(service=service))
                return {}
            else:
                raise e
        ret = {}
        for item in items:
            try:
                subscriber_elt = next(item.elements(NS_PPS, "subscriber"))
            except StopIteration:
                log.warning(f"no <subscriber> element found: {item.toXml()}")
                continue

            try:
                ret[jid.JID(subscriber_elt["jid"])] = "subscribed"
            except (KeyError, RuntimeError):
                log.warning(
                    f"invalid <subscriber> element: {subscriber_elt.toXml()}"
                )
                continue
        return ret

    def set_public_opt(self, options: Optional[dict] = None) -> dict:
        """Set option to make a subscription public

        @param options: dict where the option must be set
            if None, a new dict will be created

        @return: the options dict
        """
        if options is None:
            options = {}
        options[f'{{{NS_PPS}}}public'] = True
        return options


@implementer(iwokkel.IDisco)
class XEP_0465_Handler(XMPPHandler):

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

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