#!/usr/bin/env python3

# Libervia plugin for XEP-0084
# 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 base64 import b64decode
from pathlib import Path
from typing import Any

from twisted.internet import defer
from twisted.words.protocols.jabber import error, jid
from twisted.words.protocols.jabber.xmlstream import XMPPHandler
from twisted.words.xish import domish
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 _
from libervia.backend.core.log import getLogger
from tx_xmpp import disco, itx_xmpp, pubsub

log = getLogger(__name__)

# Supported image formats, in priority order
FORMATS = ("png", "jpeg", "webp", "gif", "svg+xml")

IMPORT_NAME = "XEP-0084"

PLUGIN_INFO = {
    C.PI_NAME: "User Avatar",
    C.PI_IMPORT_NAME: IMPORT_NAME,
    C.PI_TYPE: C.PLUG_TYPE_XEP,
    C.PI_MODES: C.PLUG_MODE_BOTH,
    C.PI_PROTOCOLS: ["XEP-0084"],
    C.PI_DEPENDENCIES: ["IDENTITY", "XEP-0060", "XEP-0163"],
    C.PI_MAIN: "XEP_0084",
    C.PI_HANDLER: "yes",
    C.PI_DESCRIPTION: _("""XEP-0084 (User Avatar) implementation"""),
}

NS_AVATAR = "urn:xmpp:avatar"
NS_AVATAR_METADATA = f"{NS_AVATAR}:metadata"
NS_AVATAR_DATA = f"{NS_AVATAR}:data"


class XEP_0084:
    namespace_metadata = NS_AVATAR_METADATA
    namespace_data = NS_AVATAR_DATA

    def __init__(self, host):
        log.info(_("XEP-0084 (User Avatar) plugin initialization"))
        host.register_namespace("avatar_metadata", NS_AVATAR_METADATA)
        host.register_namespace("avatar_data", NS_AVATAR_DATA)
        self.host = host
        self._p = host.plugins["XEP-0060"]
        self._i = host.plugins["IDENTITY"]
        self._i.register(
            IMPORT_NAME, "avatar", self.get_avatar, self.set_avatar, priority=2000
        )
        host.plugins["XEP-0163"].add_pep_event(
            None, NS_AVATAR_METADATA, self._on_metadata_update
        )

    def get_handler(self, client):
        return XEP_0084_Handler()

    def _on_metadata_update(self, itemsEvent, profile):
        client = self.host.get_client(profile)
        defer.ensureDeferred(self.on_metadata_update(client, itemsEvent))

    class UnsupportedFormat(Exception):
        """Avatar metadata exists but no supported format is found."""

    @staticmethod
    def _parse_metadata_info(
        item_elt: domish.Element,
    ) -> tuple[str, str, int] | None:
        """Parse avatar metadata item and extract ID, media type, and size.

        @param item_elt: pubsub item element containing metadata.
        @return: (avatar_id, media_type, size) if a supported format is found,
            None if avatar is disabled or no supported format is found.
        """
        try:
            metadata_elt = next(item_elt.elements(NS_AVATAR_METADATA, "metadata"))
        except StopIteration:
            log.warning(f"missing metadata element: {item_elt.toXml()}")
            return None

        # (priority, id, type, size)
        candidates: list[tuple[int, str, str, int]] = []
        for info_elt in metadata_elt.elements(NS_AVATAR_METADATA, "info"):
            try:
                avatar_id = str(info_elt["id"])
                media_type = str(info_elt["type"])
                size = int(info_elt["bytes"])
            except (KeyError, ValueError):
                log.warning(f"invalid <info> element: {item_elt.toXml()}")
                continue
            if not avatar_id:
                # Avatar is explicitly disabled
                # (https://xmpp.org/extensions/xep-0084.html#pub-disable)
                return None
            if not media_type.startswith("image/"):
                continue
            subtype = media_type.split("/", 1)[1].lower()
            try:
                priority = FORMATS.index(subtype)
            except ValueError:
                continue
            candidates.append((priority, avatar_id, media_type, size))

        if not candidates:
            raise XEP_0084.UnsupportedFormat(
                f"no supported format found in avatar metadata"
            )

        candidates.sort(key=lambda c: c[0])
        _, avatar_id, media_type, size = candidates[0]
        return (avatar_id, media_type, size)

    async def on_metadata_update(
        self, client: SatXMPPEntity, itemsEvent: pubsub.ItemsEvent
    ) -> None:
        """Handle PEP avatar metadata update event.

        @param client: Client instance.
        @param itemsEvent: pubsub items event with avatar metadata.
        """
        entity = itemsEvent.sender
        service = entity.userhostJID()
        items = itemsEvent.items

        if not items or items[0].name == "retract":
            log.debug(f"Avatar retracted for {entity.full()}")
            await self._i.update(client, IMPORT_NAME, "avatar", None, entity)
            return

        try:
            parsed = self._parse_metadata_info(items[0])
        except XEP_0084.UnsupportedFormat:
            log.warning(f"Avatar for {entity.full()} is in unsupported format.")
            parsed = None
        if parsed is None:
            log.debug(f"Avatar disabled for {entity.full()}")
            await self._i.update(client, IMPORT_NAME, "avatar", None, entity)
            return

        avatar_id, media_type, _size = parsed

        # Check if avatar is already cached
        try:
            cached = self.host.memory.get_entity_datum(client, entity, "avatar")
        except (KeyError, exceptions.UnknownEntityError):
            cached = None

        if cached is not None:
            cached_uid = cached.get("cache_uid") if isinstance(cached, dict) else None
            if cached_uid == avatar_id:
                log.debug(f"Avatar already cached for {entity.full()} (id={avatar_id})")
                return
            log.debug(
                f"Avatar changed for {entity.full()} (old={cached_uid}, new={avatar_id})"
            )

        # Fetch avatar data if not already cached
        cache_data = self.host.common_cache.get_metadata(avatar_id)
        if not cache_data:
            cache_data = await self._fetch_avatar_data(
                client, service, avatar_id, media_type
            )
            if cache_data is None:
                log.warning(f"Failed to fetch avatar data for {entity.full()}")
                return

        log.debug(f"Avatar updated for {entity.full()} (id={avatar_id})")
        avatar_metadata = self._i.avatar_build_metadata(
            cache_data["path"], cache_data["mime_type"], avatar_id
        )
        await self._i.update(client, IMPORT_NAME, "avatar", avatar_metadata, entity)

    async def _fetch_avatar_data(
        self,
        client: SatXMPPEntity,
        service: jid.JID,
        avatar_id: str,
        media_type: str,
    ) -> dict | None:
        """Fetch avatar data from PEP data node and cache it.

        @return: Cache data dict with path and mime_type, or None on failure.
        """
        try:
            data_items, __ = await self._p.get_items(
                client, service, NS_AVATAR_DATA, item_ids=[avatar_id]
            )
            data_item_elt = data_items[0]
        except (error.StanzaError, IndexError) as e:
            log.warning(
                f"Can't retrieve avatar of {service.full()} with ID {avatar_id!r}: "
                f"{e}"
            )
            return None

        try:
            avatar_buf = b64decode(
                str(next(data_item_elt.elements(NS_AVATAR_DATA, "data")))
            )
        except Exception as e:
            log.warning(
                f"invalid data element for {service.full()} with avatar ID "
                f"{avatar_id!r}: {e}\n{data_item_elt.toXml()}"
            )
            return None

        with self.host.common_cache.cache_data(IMPORT_NAME, avatar_id, media_type) as f:
            f.write(avatar_buf)
            return {"path": Path(f.name), "mime_type": media_type}

    async def get_avatar(self, client: SatXMPPEntity, entity_jid: jid.JID) -> dict | None:
        """Get avatar data by fetching from PEP metadata node.

        @param client: Client instance.
        @param entity_jid: entity to get avatar for.
        @return: avatar metadata dict if found, None otherwise.
        """
        service = entity_jid.userhostJID()
        try:
            data_items, __ = await self._p.get_items(client, service, NS_AVATAR_METADATA)
        except error.StanzaError:
            return None

        if not data_items:
            return None

        try:
            parsed = self._parse_metadata_info(data_items[0])
        except XEP_0084.UnsupportedFormat:
            return None
        if parsed is None:
            return None

        avatar_id, media_type, _size = parsed

        cache_data = self.host.common_cache.get_metadata(avatar_id)
        if not cache_data:
            cache_data = await self._fetch_avatar_data(
                client, service, avatar_id, media_type
            )
            if cache_data is None:
                return None

        return self._i.avatar_build_metadata(
            cache_data["path"], cache_data["mime_type"], avatar_id
        )

    def build_item_data_elt(self, avatar_data: dict[str, Any]) -> domish.Element:
        """Generate the item for the data node

        @param avatar_data: data as build by identity plugin (need to be filled with
            "cache_uid" and "base64" keys)
        """
        data_elt = domish.Element((NS_AVATAR_DATA, "data"))
        data_elt.addContent(avatar_data["base64"])
        return pubsub.Item(id=avatar_data["cache_uid"], payload=data_elt)

    def build_item_metadata_elt(self, avatar_data: dict[str, Any]) -> domish.Element:
        """Generate the item for the metadata node

        @param avatar_data: data as build by identity plugin (need to be filled with
            "cache_uid", "path", and "media_type" keys)
        """
        metadata_elt = domish.Element((NS_AVATAR_METADATA, "metadata"))
        info_elt = metadata_elt.addElement("info")
        # FIXME: we only fill required elements for now (see
        #        https://xmpp.org/extensions/xep-0084.html#table-1)
        info_elt["id"] = avatar_data["cache_uid"]
        info_elt["type"] = avatar_data["media_type"]
        info_elt["bytes"] = str(avatar_data["path"].stat().st_size)
        return pubsub.Item(id=self._p.ID_SINGLETON, payload=metadata_elt)

    async def set_avatar(
        self, client: SatXMPPEntity, avatar_data: dict[str, Any], entity: jid.JID
    ) -> None:
        """Set avatar of the profile

        @param avatar_data(dict): data of the image to use as avatar, as built by
            IDENTITY plugin.
        @param entity(jid.JID): entity whose avatar must be changed
        """
        service = entity.userhostJID()

        # Data
        await self._p.create_if_new_node(
            client,
            service,
            NS_AVATAR_DATA,
            options={
                self._p.OPT_ACCESS_MODEL: self._p.ACCESS_OPEN,
                self._p.OPT_PERSIST_ITEMS: 1,
                self._p.OPT_MAX_ITEMS: 1,
            },
        )
        item_data_elt = self.build_item_data_elt(avatar_data)
        await self._p.send_items(client, service, NS_AVATAR_DATA, [item_data_elt])

        # Metadata
        await self._p.create_if_new_node(
            client,
            service,
            NS_AVATAR_METADATA,
            options={
                self._p.OPT_ACCESS_MODEL: self._p.ACCESS_OPEN,
                self._p.OPT_PERSIST_ITEMS: 1,
                self._p.OPT_MAX_ITEMS: 1,
            },
        )
        item_metadata_elt = self.build_item_metadata_elt(avatar_data)
        await self._p.send_items(client, service, NS_AVATAR_METADATA, [item_metadata_elt])


@implementer(itx_xmpp.IDisco)
class XEP_0084_Handler(XMPPHandler):

    def getDiscoInfo(self, requestor, service, nodeIdentifier=""):
        # NS_AVATAR_METADATA is already advertised by ``add_pep_event``.
        # Only NS_AVATAR_DATA needs to be advertised here.
        return [
            disco.DiscoFeature(NS_AVATAR_DATA),
        ]

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