# mautrix-telegram - A Matrix-Telegram puppeting bridge
# Copyright (C) 2021 Tulir Asokan
#
# 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 <https://www.gnu.org/licenses/>.
from __future__ import annotations

from typing import Tuple
from collections import deque
import hashlib

from telethon.tl.patched import Message, MessageService
from telethon.tl.types import (
    MessageMediaContact,
    MessageMediaDocument,
    MessageMediaGeo,
    MessageMediaPhoto,
    TypeMessage,
    TypeUpdates,
    UpdateNewChannelMessage,
    UpdateNewMessage,
)

from mautrix.types import EventID

from .. import portal as po
from ..types import TelegramID

DedupMXID = Tuple[EventID, TelegramID]


class PortalDedup:
    pre_db_check: bool = False
    cache_queue_length: int = 20

    _dedup: deque[str]
    _dedup_mxid: dict[str, DedupMXID]
    _dedup_action: deque[str]
    _portal: po.Portal

    def __init__(self, portal: po.Portal) -> None:
        self._dedup = deque()
        self._dedup_mxid = {}
        self._dedup_action = deque()
        self._portal = portal

    @property
    def _always_force_hash(self) -> bool:
        return self._portal.peer_type == "chat"

    @staticmethod
    def _hash_event(event: TypeMessage) -> str:
        # Non-channel messages are unique per-user (wtf telegram), so we have no other choice than
        # to deduplicate based on a hash of the message content.

        # The timestamp is only accurate to the second, so we can't rely solely on that either.
        if isinstance(event, MessageService):
            hash_content = [event.date.timestamp(), event.from_id, event.action]
        else:
            hash_content = [event.date.timestamp(), event.message.strip()]
            if event.fwd_from:
                hash_content += [event.fwd_from.from_id]
            elif isinstance(event, Message) and event.media:
                try:
                    hash_content += {
                        MessageMediaContact: lambda media: [media.user_id],
                        MessageMediaDocument: lambda media: [media.document.id],
                        MessageMediaPhoto: lambda media: [media.photo.id if media.photo else 0],
                        MessageMediaGeo: lambda media: [media.geo.long, media.geo.lat],
                    }[type(event.media)](event.media)
                except KeyError:
                    pass
        return hashlib.md5("-".join(str(a) for a in hash_content).encode("utf-8")).hexdigest()

    def check_action(self, event: TypeMessage) -> bool:
        evt_hash = self._hash_event(event) if self._always_force_hash else event.id
        if evt_hash in self._dedup_action:
            return True

        self._dedup_action.append(evt_hash)

        if len(self._dedup_action) > self.cache_queue_length:
            self._dedup_action.popleft()
        return False

    def update(
        self,
        event: TypeMessage,
        mxid: DedupMXID = None,
        expected_mxid: DedupMXID | None = None,
        force_hash: bool = False,
    ) -> DedupMXID | None:
        evt_hash = self._hash_event(event) if self._always_force_hash or force_hash else event.id
        try:
            found_mxid = self._dedup_mxid[evt_hash]
        except KeyError:
            return EventID("None"), TelegramID(0)

        if found_mxid != expected_mxid:
            return found_mxid
        self._dedup_mxid[evt_hash] = mxid
        return None

    def check(
        self, event: TypeMessage, mxid: DedupMXID = None, force_hash: bool = False
    ) -> DedupMXID | None:
        evt_hash = self._hash_event(event) if self._always_force_hash or force_hash else event.id
        if evt_hash in self._dedup:
            return self._dedup_mxid[evt_hash]

        self._dedup_mxid[evt_hash] = mxid
        self._dedup.append(evt_hash)

        if len(self._dedup) > self.cache_queue_length:
            del self._dedup_mxid[self._dedup.popleft()]
        return None

    def register_outgoing_actions(self, response: TypeUpdates) -> None:
        for update in response.updates:
            check_dedup = isinstance(
                update, (UpdateNewMessage, UpdateNewChannelMessage)
            ) and isinstance(update.message, MessageService)
            if check_dedup:
                self.check(update.message)