--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libervia/backend/plugins/plugin_xep_0444.py	Fri Jun 02 11:49:51 2023 +0200
@@ -0,0 +1,171 @@
+#!/usr/bin/env python3
+
+# Libervia plugin for XEP-0444
+# 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 List, Iterable
+from copy import deepcopy
+
+from twisted.words.protocols.jabber import jid, xmlstream
+from twisted.words.xish import domish
+from twisted.internet import defer
+from wokkel import disco, iwokkel
+from zope.interface import implementer
+
+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.memory.sqla_mapping import History
+
+log = getLogger(__name__)
+
+PLUGIN_INFO = {
+    C.PI_NAME: "Message Reactions",
+    C.PI_IMPORT_NAME: "XEP-0444",
+    C.PI_TYPE: C.PLUG_TYPE_XEP,
+    C.PI_MODES: C.PLUG_MODE_BOTH,
+    C.PI_PROTOCOLS: ["XEP-0444"],
+    C.PI_DEPENDENCIES: ["XEP-0334"],
+    C.PI_MAIN: "XEP_0444",
+    C.PI_HANDLER: "yes",
+    C.PI_DESCRIPTION: _("""Message Reactions implementation"""),
+}
+
+NS_REACTIONS = "urn:xmpp:reactions:0"
+
+
+class XEP_0444:
+
+    def __init__(self, host):
+        log.info(_("Message Reactions initialization"))
+        host.register_namespace("reactions", NS_REACTIONS)
+        self.host = host
+        self._h = host.plugins["XEP-0334"]
+        host.bridge.add_method(
+            "message_reactions_set",
+            ".plugin",
+            in_sign="ssas",
+            out_sign="",
+            method=self._reactions_set,
+            async_=True,
+        )
+        host.trigger.add("message_received", self._message_received_trigger)
+
+    def get_handler(self, client):
+        return XEP_0444_Handler()
+
+    async def _message_received_trigger(
+        self,
+        client: SatXMPPEntity,
+        message_elt: domish.Element,
+        post_treat: defer.Deferred
+    ) -> bool:
+        return True
+
+    def _reactions_set(self, message_id: str, profile: str, reactions: List[str]) -> None:
+        client = self.host.get_client(profile)
+        return defer.ensureDeferred(
+            self.set_reactions(client, message_id)
+        )
+
+    def send_reactions(
+        self,
+        client: SatXMPPEntity,
+        dest_jid: jid.JID,
+        message_id: str,
+        reactions: Iterable[str]
+    ) -> None:
+        """Send the <message> stanza containing the reactions
+
+        @param dest_jid: recipient of the reaction
+        @param message_id: either <origin-id> or message's ID
+            see https://xmpp.org/extensions/xep-0444.html#business-id
+        """
+        message_elt = domish.Element((None, "message"))
+        message_elt["from"] = client.jid.full()
+        message_elt["to"] = dest_jid.full()
+        reactions_elt = message_elt.addElement((NS_REACTIONS, "reactions"))
+        reactions_elt["id"] = message_id
+        for r in set(reactions):
+            reactions_elt.addElement("reaction", content=r)
+        self._h.add_hint_elements(message_elt, [self._h.HINT_STORE])
+        client.send(message_elt)
+
+    async def add_reactions_to_history(
+        self,
+        history: History,
+        from_jid: jid.JID,
+        reactions: Iterable[str]
+    ) -> None:
+        """Update History instance with given reactions
+
+        @param history: storage History instance
+            will be updated in DB
+            "summary" field of history.extra["reactions"] will also be updated
+        @param from_jid: author of the reactions
+        @param reactions: list of reactions
+        """
+        history.extra = deepcopy(history.extra) if history.extra else {}
+        h_reactions = history.extra.setdefault("reactions", {})
+        # reactions mapped by originating JID
+        by_jid = h_reactions.setdefault("by_jid", {})
+        # reactions are sorted to in summary to keep a consistent order
+        h_reactions["by_jid"][from_jid.userhost()] = sorted(list(set(reactions)))
+        h_reactions["summary"] = sorted(list(set().union(*by_jid.values())))
+        await self.host.memory.storage.session_add(history)
+
+    async def set_reactions(
+        self,
+        client: SatXMPPEntity,
+        message_id: str,
+        reactions: Iterable[str]
+    ) -> None:
+        """Set and replace reactions to a message
+
+        @param message_id: internal ID of the message
+        @param rections: lsit of emojis to used to react to the message
+            use empty list to remove all reactions
+        """
+        if not message_id:
+            raise ValueError("message_id can't be empty")
+        history = await self.host.memory.storage.get(
+            client, History, History.uid, message_id,
+            joined_loads=[History.messages, History.subjects]
+        )
+        if history is None:
+            raise exceptions.NotFound(
+                f"message to retract not found in database ({message_id})"
+            )
+        mess_id = history.origin_id or history.stanza_id
+        if not mess_id:
+            raise exceptions.DataError(
+                "target message has neither origin-id nor message-id, we can't send a "
+                "reaction"
+            )
+        await self.add_reactions_to_history(history, client.jid, reactions)
+        self.send_reactions(client, history.dest_jid, mess_id, reactions)
+
+
+@implementer(iwokkel.IDisco)
+class XEP_0444_Handler(xmlstream.XMPPHandler):
+
+    def getDiscoInfo(self, requestor, service, nodeIdentifier=""):
+        return [disco.DiscoFeature(NS_REACTIONS)]
+
+    def getDiscoItems(self, requestor, service, nodeIdentifier=""):
+        return []