# 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 Awaitable
import asyncio

from telethon.tl.types import ChannelForbidden, ChatForbidden

from mautrix.types import EventID, RoomID
from mautrix.util import background_task

from ... import portal as po
from ...types import TelegramID
from .. import SECTION_CREATING_PORTALS, CommandEvent, command_handler
from .util import get_initial_state, user_has_power_level, warn_missing_power


@command_handler(
    needs_auth=False,
    needs_puppeting=False,
    help_section=SECTION_CREATING_PORTALS,
    help_args="[_id_]",
    help_text=(
        "Bridge the current Matrix room to the Telegram chat with the given ID. The ID must be "
        "the prefixed version that you get with the `/id` command of the Telegram-side bot."
    ),
)
async def bridge(evt: CommandEvent) -> EventID:
    if len(evt.args) == 0:
        return await evt.reply(
            "**Usage:** `$cmdprefix+sp bridge <Telegram chat ID> [Matrix room ID]`"
        )
    force_use_bot = False
    if evt.args[0] == "--usebot" and evt.sender.is_admin:
        force_use_bot = True
        evt.args = evt.args[1:]
    room_id = RoomID(evt.args[1]) if len(evt.args) > 1 else evt.room_id
    that_this = "This" if room_id == evt.room_id else "That"

    portal = await po.Portal.get_by_mxid(room_id)
    if portal:
        return await evt.reply(f"{that_this} room is already a portal room.")

    if not await user_has_power_level(room_id, evt.az.intent, evt.sender, "bridge"):
        return await evt.reply(
            f"You do not have the permissions to bridge {that_this.lower()} room."
        )

    # The /id bot command provides the prefixed ID, so we assume
    tgid_str = evt.args[0]
    tgid = None
    try:
        if tgid_str.startswith("-100"):
            tgid = TelegramID(int(tgid_str[4:]))
            peer_type = "channel"
        elif tgid_str.startswith("-"):
            tgid = TelegramID(-int(tgid_str))
            peer_type = "chat"
    except ValueError:
        # Invalid integer
        pass
    if not tgid:
        return await evt.reply(
            "That doesn't seem like a prefixed Telegram chat ID.\n\n"
            "If you did not get the ID using the `/id` bot command, please prefix"
            "channel/supergroup IDs with `-100` and non-super group IDs with `-`.\n\n"
            "Bridging private chats to existing rooms is not allowed."
        )

    portal = await po.Portal.get_by_tgid(tgid, peer_type=peer_type)
    if not portal.allow_bridging:
        return await evt.reply(
            "This bridge doesn't allow bridging that Telegram chat.\n"
            "If you're the bridge admin, try "
            "`$cmdprefix+sp filter whitelist <Telegram chat ID>` first."
        )
    elif portal.mxid:
        has_portal_message = (
            "That Telegram chat already has a portal at "
            f"[{portal.alias or portal.mxid}](https://matrix.to/#/{portal.mxid}). "
        )
        if not await user_has_power_level(portal.mxid, evt.az.intent, evt.sender, "unbridge"):
            return await evt.reply(
                f"{has_portal_message}"
                "Additionally, you do not have the permissions to unbridge that room."
            )
        evt.sender.command_status = {
            "next": confirm_bridge,
            "action": "Room bridging",
            "mxid": portal.mxid,
            "bridge_to_mxid": room_id,
            "tgid": portal.tgid,
            "peer_type": peer_type,
            "force_use_bot": force_use_bot,
        }
        return await evt.reply(
            f"{has_portal_message}"
            "However, you have the permissions to unbridge that room.\n\n"
            "To delete that portal completely and continue bridging, use "
            "`$cmdprefix+sp delete-and-continue`. To unbridge the portal "
            "without kicking Matrix users, use `$cmdprefix+sp unbridge-and-"
            "continue`. To cancel, use `$cmdprefix+sp cancel`"
        )
    evt.sender.command_status = {
        "next": confirm_bridge,
        "action": "Room bridging",
        "bridge_to_mxid": room_id,
        "tgid": portal.tgid,
        "peer_type": peer_type,
        "force_use_bot": force_use_bot,
    }
    return await evt.reply(
        "That Telegram chat has no existing portal. To confirm bridging the "
        "chat to this room, use `$cmdprefix+sp continue`"
    )


async def cleanup_old_portal_while_bridging(
    evt: CommandEvent, portal: po.Portal
) -> tuple[bool, Awaitable[None] | None]:
    if not portal.mxid:
        await evt.reply(
            "The portal seems to have lost its Matrix room between you"
            "calling `$cmdprefix+sp bridge` and this command.\n\n"
            "Continuing without touching previous Matrix room..."
        )
        return True, None
    elif evt.args[0] == "delete-and-continue":
        return True, portal.cleanup_portal("Portal deleted (moving to another room)", delete=False)
    elif evt.args[0] == "unbridge-and-continue":
        return True, portal.cleanup_portal(
            "Room unbridged (portal moving to another room)", puppets_only=True, delete=False
        )
    else:
        await evt.reply(
            "The chat you were trying to bridge already has a Matrix portal room.\n\n"
            "Please use `$cmdprefix+sp delete-and-continue` or `$cmdprefix+sp unbridge-and-"
            "continue` to either delete or unbridge the existing room (respectively) and "
            "continue with the bridging.\n\n"
            "If you changed your mind, use `$cmdprefix+sp cancel` to cancel."
        )
        return False, None


async def confirm_bridge(evt: CommandEvent) -> EventID | None:
    status = evt.sender.command_status
    try:
        portal = await po.Portal.get_by_tgid(status["tgid"], peer_type=status["peer_type"])
        bridge_to_mxid = status["bridge_to_mxid"]
    except KeyError:
        evt.sender.command_status = None
        return await evt.reply(
            "Fatal error: tgid or peer_type missing from command_status. "
            "This shouldn't happen unless you're messing with the command handler code."
        )

    is_logged_in = await evt.sender.is_logged_in() and not status["force_use_bot"]

    if "mxid" in status:
        if portal.peer_type != status["peer_type"]:
            evt.log.warning(
                "Portal %d in database has mismatching peer type %s (expected %s),"
                " trusting database as a room already existed",
                portal.tgid,
                portal.peer_type,
                status["peer_type"],
            )
            await evt.reply(
                "Mismatching peer type in command and portal table, "
                "trusting portal as room already existed"
            )
        ok, coro = await cleanup_old_portal_while_bridging(evt, portal)
        if not ok:
            return None
        elif coro:
            background_task.create(coro)
            await evt.reply("Cleaning up previous portal room...")
    elif portal.mxid:
        evt.sender.command_status = None
        return await evt.reply(
            "The portal seems to have created a Matrix room between you "
            "calling `$cmdprefix+sp bridge` and this command.\n\n"
            "Please start over by calling the bridge command again."
        )
    elif evt.args[0] != "continue":
        return await evt.reply(
            "Please use `$cmdprefix+sp continue` to confirm the bridging or "
            "`$cmdprefix+sp cancel` to cancel."
        )
    elif portal.peer_type != status["peer_type"]:
        evt.log.warning(
            "Portal %d in database has mismatching peer type %s (expected %s),"
            " trusting new peer type as there's no existing room",
            portal.tgid,
            portal.peer_type,
            status["peer_type"],
        )
        await evt.reply(
            "Mismatching peer type in command and portal table, "
            "trusting you as portal room doesn't exist"
        )
        portal.peer_type = status["peer_type"]

    evt.sender.command_status = None
    async with portal._room_create_lock:
        await _locked_confirm_bridge(
            evt, portal=portal, room_id=bridge_to_mxid, is_logged_in=is_logged_in
        )


async def _locked_confirm_bridge(
    evt: CommandEvent, portal: po.Portal, room_id: RoomID, is_logged_in: bool
) -> EventID | None:
    user = evt.sender if is_logged_in else evt.tgbot
    try:
        entity = await user.client.get_entity(portal.peer)
    except Exception:
        evt.log.exception("Failed to get_entity(%s) for manual bridging.", portal.peer)
        if is_logged_in:
            return await evt.reply(
                "Failed to get info of telegram chat. You are logged in, are you in that chat?"
            )
        else:
            return await evt.reply(
                "Failed to get info of telegram chat. "
                "You're not logged in, is the relay bot in the chat?"
            )
    if isinstance(entity, (ChatForbidden, ChannelForbidden)):
        if is_logged_in:
            return await evt.reply("You don't seem to be in that chat.")
        else:
            return await evt.reply("The bot doesn't seem to be in that chat.")

    portal.mxid = room_id
    portal.by_mxid[portal.mxid] = portal
    (portal.title, portal.about, levels, portal.encrypted) = await get_initial_state(
        evt.az.intent, evt.room_id
    )
    portal.photo_id = ""
    await portal.save()
    await portal.update_bridge_info()

    background_task.create(portal.update_matrix_room(user, entity, levels=levels))

    await warn_missing_power(levels, evt)

    return await evt.reply("Bridging complete. Portal synchronization should begin momentarily.")